A way to figure individual cylinder mixture out

[rug_burn]

Check this:

   I been playing around with my carbs, trying to get the original smoothness back - that of of the Valk's incredibly smooth 6 cylinder engine.  Problem is that once you let the carbs get gunked up, you gotta pull them all apart, clean them, than sync them both in vacuum and mixture to get that back.    The vacuum sync is easy, mixture's the hard part.

   In my case, I let my bike sit just a little too long after having the clutch rivets shear, and moving to a new house, getting the old house rented, etc, before could fix the clutch issue.  And even though I did start it at various intervals throughout the year it was down, still the gas went bad.

   So, I pulled it apart again, and put in new  a new petcock, carb gaskets, idle jets, cleaned the needles, and main jets, and carb bodies (probably not quite as well as I should have), replaced all the 4.5 mm vacuum hoses, etc, and synced them.
   Still, however, it was noticeably too lean on some cylinders, and maybe rich enough on others.  You  could tell because it just smelled hot after a short ride, kind of sagged when you gave it small throttle increases, and my $25 Harbor Freight IR thermometer verified that yeah, the temps were all over the place, sometimes they didn't even seem to make sense.   It didn't smell rich anymore when it was idling, like it did from the factory, and it idled unevenly.  Reading the plugs pointed out in a rough way, but was not precise enough for fine tuning.
   But then I tried writing down on a sheet of paper the exhaust pipe temps when I started it up from totally cold.   And then every 5 minutes for, say 25 minutes, and made a  chart.  This proved valuable, and told the story of what was going on.
   Because what we know is that a cold carburated engine will run lean and need to be choked until it reaches operating temperature, right?  
   And at operating temperature  lean cylinder will run hotter than a rich one, assuming it isn't misfiring.
   Valks, of course are set pretty rich from the factory, so you don't need to choke them much if at all at the factory setting, so the cylinders are not misfiring too lean like a normal engine would be.

   So, what you do is start the bike up from cold, and then using your IR thermometer, make a history of the exhaust pipe temps at t=0, 5 min, 10 min, 15 min , 20 min, and 25 min which gets you into the area where the fan kicks on, and the temps stabilize.  
    I make two columns:  cyls #2, #4, #6 on the left  (just like the layout of the bike itself) and #1, #3, #5 on the right, leaving plenty of room to write the temps.  Then record the data (temps).
   Now shut it off, get a beer, retire to a chair at the work bench and analyze the data.

   In my case, I had some cylinders that started out to be the hottest ones, then heated up to be running cooler than the rest.    What happened was that they didn't misfire at all at the beginning because they were so rich and heated up quickly, but were so rich at op. temp. that they were running relatively cool.  These are the rich ones, in case you haven't guessed.  
   Then others started out much cooler, misfiring because they were too lean, then got to be the hottest ones at operating temperature, because then they were firing every time closer to peak ignition temperature.    These are the ones that are too lean.
   So now go along and open the mixture screws on the lean ones 1/4 or 1/2 turn at a time, and if some seem way too rich, close them the same way.  
  
   So the rule is  (in your 25 minute measurement period):  
         If a cylinder starts hotter than the rest, then ends up cooler than the rest, it is rich.
         If a cyl starts cooler than the rest, but ends up hotter than the rest, it's too lean.

   You gotta pick one that's just a little on the rich side to be your target cylinder, and adjust the rest to it.  You're trying to get the mixtures all the same.
   Do this a couple times you'll get a feel for it and see how it works.  I got mine almost perfect finally, after dicking with it for a couple years using various other techniques.
   Using this I was also able to figure out that my #3 and #4 cyl vacuum hoses had pinholes in them, I think from using every known carb cleaner at one time or other to avoid having to pull the carbs.   Which didn't work by the way.  One of them attacked the crap out of the rubber, but I got no idea which.

   From being a pilot (and an engineer) you learn that peak power is just a little on the rich side of peak exhaust gas temp (EGT), and slopes off gently as you get richer.   Power slopes off quicker on the lean side of peak, and then begins to misfire.   So manufacturers like to keep the mixture rich if possible, in other words if not forced to by emissions controls.   But Valks are so rich from the factory, they kind of overdo it.   I made mine just a little leaner.

    But anyway-  I know it took a while to explain, but it enabled me to get my bike pretty close to factory tune, and it's really pretty easy to do.   But admittedly, it may not be everyone's cup of tea.  
      There it is, for what it's worth.

[dpcarson]

Check this:

   I been playing around with my carbs, trying to get the original smoothness back - that of of the Valk's incredibly smooth 6 cylinder engine.  Problem is that once you let the carbs get gunked up, you gotta pull them all apart, clean them, than sync them both in vacuum and mixture to get that back.    The vacuum sync is easy, mixture's the hard part.

   In my case, I let my bike sit just a little too long after having the clutch rivets shear, and moving to a new house, getting the old house rented, etc, before could fix the clutch issue.  And even though I did start it at various intervals throughout the year it was down, still the gas went bad.

   So, I pulled it apart again, and put in new  a new petcock, carb gaskets, idle jets, cleaned the needles, and main jets, and carb bodies (probably not quite as well as I should have), replaced all the 4.5 mm vacuum hoses, etc, and synced them.
   Still, however, it was noticeably too lean on some cylinders, and maybe rich enough on others.  You  could tell because it just smelled hot after a short ride, kind of sagged when you gave it small throttle increases, and my $25 Harbor Freight IR thermometer verified that yeah, the temps were all over the place, sometimes they didn't even seem to make sense.   It didn't smell rich anymore when it was idling, like it did from the factory, and it idled unevenly.  Reading the plugs pointed out in a rough way, but was not precise enough for fine tuning.
   But then I tried writing down on a sheet of paper the exhaust pipe temps when I started it up from totally cold.   And then every 5 minutes for, say 25 minutes, and made a  chart.  That's the key.
   Because what we know is that a cold carburated engine will run lean and need to be choked until it reaches operating temperature, right?   
   And at operating temperature  lean cylinder will run hotter than a rich one, assuming it isn't misfiring.
   Valks, of course are set pretty rich from the factory, so you don't need to choke them much if at all at the factory setting, so the cylinders are not misfiring too lean like a normal engine would be.

   So, what you do is start the bike up from cold, and then using your IR thermometer, make a history of the exhaust pipe temps at t=0, 5 min, 10 min, 15 min , 20 min, and 25 min which gets you into the area where the fan kicks on, and the temps stabilize.   
    I make two columns:  cyls #2, #4, #6 on the left  (just like the layout of the bike itself) and #1, #3, #5 on the right, leaving plenty of room to write the temps.  Then record the data (temps).
   Now shut it off, get a beer, retire to a chair at the work bench and analyze the data.

   In my case, I had some cylinders that started out to be the hottest ones, then heated up to be running cooler than the rest.    What happened was that they didn't misfire at all at the beginning because they were so rich and heated up quickly, but were so rich at op. temp. that they were running relatively cool.  These are the rich ones, in case you haven't guessed. 
   Then others started out much cooler, misfiring because they were too lean, then got to be the hottest ones at operating temperature, because then they were firing every time closer to peak ignition temperature.    These are the ones that are too lean.
   So now go along and open the mixture screws on the lean ones 1/4 or 1/2 turn at a time, and if some seem way too rich, close them the same way. 
 
   So the rule is  (in your 25 minute measurement period): 
         If a cylinder starts hotter than the rest, then ends up cooler than the rest, it is rich.
         If a cyl starts cooler than the rest, but ends up hotter than the rest, it's too lean.

   You gotta pick one that's just a little on the rich side to be your target cylinder, and adjust the rest to it.  You're trying to get the mixtures all the same.
   Do this a couple times you'll get a feel for it and see how it works.  I got mine almost perfect finally, after dicking with it for a couple years using various other techniques.
   Using this I was also able to figure out that my #3 and #4 cyl vacuum hoses had pinholes in them, I think from using every known carb cleaner at one time or other to avoid having to pull the carbs.   Which didn't work by the way.  One of them attacked the crap out of the rubber, but I got no idea which.

   From being a pilot (and an engineer) you learn that peak power is just a little on the rich side of peak exhaust gas temp (EGT), and slopes off gently as you get richer.   Power slopes off quicker on the lean side of peak, and then begins to misfire.   So manufacturers like to keep the mixture rich if possible, in other words if not forced to by emissions controls.   But Valks are so rich from the factory, they kind of overdo it.   I made mine just a little leaner.

    But anyway-  I know it took a while to explain, but it enabled me to get my bike pretty close to factory tune, and it's really pretty easy to do.   But admittedly, it may not be everyone's cup of tea. 
      There it is, for what it's worth.

That is an excellent write up RB.  I appreciate this info.  I had one carb that just doesn't seem to be acting right after putting everything back together, and it seems to be running lean.  I even noticed that the popping side smells hotter than the other side.  This is excellent info and I will be getting this data together this week!!  thanks so much for the detailed info.

[WintrSol]

Nice technique; beats the service manual procedure, even if it takes longer. Mine idles a bit rough, not so much others notice it, but I do. Time to get out my IR thermometer!

[WintrSol]

Wow, that really works well. Did a temp sample run, and assumed they were all rich, so I tweaked those reading richer than the rest to lean them out some. Used my digisync to check and rebalance the carbs, then measured again. My pilot screw tool (Motion Pro) has clicks every 1/8 turn, so I estimated how much to turn from the temp differences, and turned them in 1, 2, or 3 clicks. Another temp run, and down to two carbs a bit rich. A couple more clicks on each, and they all heat up to within 5 degrees of each other, and the idle is so much smoother now. Maybe my mileage will go up a point or two.

[ridingron]

Interesting.

[rug_burn]

   That's funny-  you did way better than I did!   I gotta go back re-sync and do mine one more time.
   Glad it worked well for you.

[98valk]

Nice write up.

Per Mikuni any carburetor setting is only good for a +/- 25F ambient temperature range.

I'll do tuning at 70F for a 45F to 95F range.

[WintrSol]

Nice write up.

Per Mikuni any carburetor setting is only good for a +/- 25F ambient temperature range.

I'll do tuning at 70F for a 45F to 95F range.

Also nice to know. Luckily, it reached about 70F while I was tuning her.

[Gregory Scott 16248]

I checked my carburetors pre the above post checking every 5 minutes. Starting at 5 minutes I had the following results. 1999 Interstate, carburetors just had a complete rebuild and pilot screws set @ 2-1/4 turns out and ran Digi-Sync, idle set @ 950 rpm.

Start to 5 minutes with choke, than choke off.
5  minutes. Cyl #2 195, #4 280, #6 280, #1 160, #3 185, #5 235
10 minutes Cyl #2 270, #4 290, #6 300, #1 235, #3 260, #5 270
15 minutes Cyl #2 300, #4 270, #6 310, #1 215, #3 250, #5 275 fan on
20 minutes Cyl #2 250, #4 280, #6 290, #1 250, #3 260, #5 258 fan on
25 minutes Cyl #2 285, #4 285, #6 285, #1 250, #3 255, #5 280 fan on

From the data at 25 minutes it looks like Cyl #1 @250 and #3 @ 255 are running a little rich?

Or is Cyl. #2, #4, #6, #5 @285 running lean?

The exhaust doesn't smell rich and no noticeable smoke from pipes.

I didn't adjust the pilot screws per the manual, only set @ starting point 2 1/4 turns out. I will need to adjust the pilot screws next and resync and check the temperatures again.

Bike runs great so I may just run it and check the spark plugs first before changing anything.

Anyone have an opinion or advice?

Thanks, Greg

[98valk]

I checked my carburetors pre the above post checking every 5 minutes. Starting at 5 minutes I had the following results. 1999 Interstate, carburetors just had a complete rebuild and pilot screws set @ 2-1/4 turns out and ran Digi-Sync, idle set @ 950 rpm.

Start to 5 minutes with choke, than choke off.
5  minutes. Cyl #2 195, #4 280, #6 280, #1 160, #3 185, #5 235
10 minutes Cyl #2 270, #4 290, #6 300, #1 235, #3 260, #5 270
15 minutes Cyl #2 300, #4 270, #6 310, #1 215, #3 250, #5 275 fan on
20 minutes Cyl #2 250, #4 280, #6 301, #1 250, #3 260, #5 258 fan on
25 minutes Cyl #2 285, #4 285, #6 285, #1 250, #3 255, #5 280 fan on

From the data at 25 minutes it looks like Cyl #1 @250 and #3 @ 255 are running a little rich?

Or is Cyl. #2, #4, #6, #5 @285 running lean?

The exhaust doesn't smell rich and no noticeable smoke from pipes.

I didn't adjust the pilot screws per the manual, only set @ starting point 2 1/4 turns out. I will need to adjust the pilot screws next and resync and check the temperatures again.

Bike runs great so I may just run it and check the spark plugs first before changing anything.

Anyone have an opinion or advice?

Thanks, Greg

see example #2 to determine if rich/lean idle.

http://www.4secondsflat.com/Spark_plug_reading.html

[rug_burn]

    Those all look pretty good and even to me.  Looks like those temps are in degrees C, is that right?   I'm used to seeing the end temps around 350-450F.
    That first reading should be taken right after you start it, within the first minute or so to get the best look at it.  The first few minutes is where the temps change most rapidly.    I did a few tests starting at (in reality)  t=30sec, then t=3 min, 6 min, 10 min... something like that.  The more data points you get, the better resolution you have to see the pattern.
     I noticed the front two cylinders always read a little cooler than the rest, seems like it's just because they're out in fresh cooling air a little more.   You seem to have some of  that going on there, too.  It's also good to put about a 2" block under the kickstand to make the cooling situation as equal on both sides as possible.
  Yeah, it could be the entire left side is a little lean, but it's hard to say without a little finer look t those first few minutes.
   I remember when I found those vacuum hoses with the pinholes, the cylinders would start out cold and stay that way all way through the test, but still not really misfire.  It was kind of strange, and made me investigate further.  My bike would also backfire loudly on long decels with the pinholes in the vacuum hoses.

[Gregory Scott 16248]

   Those all look pretty good and even to me.  Looks like those temps are in degrees C, is that right?   I'm used to seeing the end temps around 380-450F.
    That first reading should be takes actually right after you start it, within the first minute or so to get the best look at it.  The first few minutes is where the temps change most rapidly.    I did a few tests starting at (in reality)  t=30sec, then t=3 min, 6 min, 10 min... something like that.  The more data points you get, the better you can see the pattern.[/size]

The readings are in Fahrenheit and taken about 3" from the start of the exhaust pipe at beginning of first bend. I have Two Brothers 6 into 6 pipes.

The start readings were with the choke on that is why I didn't include them.

Start readings: Cyl #2 90, #4 130, #6 130, #1 170, #3 200, #5 230 I started with Cyl #2 and finished with #5 that is why the readings go up so much.

I have a trike so it sits level, all hoses are new and the bike is desmogged.

[98valk]

   Those all look pretty good and even to me.  Looks like those temps are in degrees C, is that right?   I'm used to seeing the end temps around 350-450F.
    That first reading should be taken right after you start it, within the first minute or so to get the best look at it.  The first few minutes is where the temps change most rapidly.    I did a few tests starting at (in reality)  t=30sec, then t=3 min, 6 min, 10 min... something like that.  The more data points you get, the better resolution you have to see the pattern.
     I noticed the front two cylinders always read a little cooler than the rest, seems like it's just because they're out in fresh cooling air a little more.   You seem to have some of  that going on there, too.  It's also good to put about a 2" block under the kickstand to make the cooling situation as equal on both sides as possible.
  Yeah, it could be the entire left side is a little lean, but it's hard to say without a little finer look t those first few minutes.
   I remember when I found those vacuum hoses with the pinholes, the cylinders would start out cold and stay that way all way through the test, but still not really misfire.  It was kind of strange, and made me investigate further.  My bike would also backfire loudly on long decels with the pinholes in the vacuum hoses.

interesting you bring up "cooling" since I have seen different temp colors on the plugs.  It has to do how the coolant enters and exits the heads. the tech manual shows the flow pattern.    The front cylinders will be coolest and right rear the hottest, coolant exits there and left middle is hottest where coolant exits. This middle exit btwn the front and middle cylinder actually shows a difference on plugs btwn the front two.  
Most of this cannot be completely tuned perfect without fuel injection and a computer and doesn't really matter unless one is racing for that last .01 btwn win or lose.
This is a classic example of why for over a decade top racers, including NASCAR tune each cylinder like it is a single cylinder engine.

[WintrSol]

I made my readings with the bike parked nose into my garage door and corner of the porch above it, so little wind stirring around it. But, I had my meter set to .95 emissivity (flat black paint), so my readings maxed out about 165F, with it pointed about 1.5" below the header bolts, and about 1" from the surface. I know I would have gotten much higher readings if I had remembered to reset the E for chrome (.06); most meters without E settings must assume a nominal value higher than that, guessing from those posted.

I went for a ride today, but outdoor temps never got over about 55F, and the coolant barely reached thermostat temp, and then only a few times, so I don't know how much (if any) getting them to better match have affected it, other than the somewhat smoother idle when warm. Warmer weather is coming though. In any case, it sure doesn't hurt to have a better mixture at idle.

[WintrSol]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

[98valk]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

chrome has a slight insulating effect.

[WintrSol]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

chrome has a slight insulating effect.

Not only that, low-E surfaces reflect all that is around them, and emit little of what's behind them, so aiming your meter is a big part of getting a consistent reading. If I really wanted to get this right, I would put a dot of high-temp flat paint on each, to get a better reading, but I'm not THAT anal.

[98valk]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

chrome has a slight insulating effect.

Not only that, low-E surfaces reflect all that is around them, and emit little of what's behind them, so aiming your meter is a big part of getting a consistent reading. If I really wanted to get this right, I would put a dot of high-temp flat paint on each, to get a better reading, but I'm not THAT anal.

 

[Avanti]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

What make IR thermometer are you using that has these different settings?

[WintrSol]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

What make IR thermometer are you using that has these different settings?

One I bought from HobbyKing for model use (no longer stocked), but that is made by ZyTemp, model TN105i2. No telling if they still actually make it, as HK says it is discontinued.

[Gregory Scott 16248]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

What make IR thermometer are you using that has these different settings?

One I bought from HobbyKing for model use (no longer stocked), but that is made by ZyTemp, model TN105i2. No telling if they still actually make it, as HK says it is discontinued.

I'm using a cheap $40 BLACK+DECKER TLD100 thermometer reads up to 350 deg. That is why my readings are 3" below the header bolts and about 1-2 inches from contact. I was looking for a consistent reading that I could measure. The manual says to use a black spot on a shiny surface for a more accurate reading. The meter has no special settings other than F. or C. and is what I already had from another home project.

[WintrSol]

Most default to .95, which is what flat paints, heatsinks, and many other surfaces measure; they make stick-on labels that are also .95, so you can get a valid measurement with a standard meter or camera, but they aren't rated for exhaust pipe temperatures. Your dot of paint has to be about the same size as the area covered by the meter, which for mine is equal to the distance, so 1" away equals 1" diameter circle. Not doing that, as long as I get fairly repeatable readings.

[98valk]

Most default to .95, which is what flat paints, heatsinks, and many other surfaces measure; they make stick-on labels that are also .95, so you can get a valid measurement with a standard meter or camera, but they aren't rated for exhaust pipe temperatures. Your dot of paint has to be about the same size as the area covered by the meter, which for mine is equal to the distance, so 1" away equals 1" diameter circle. Not doing that, as long as I get fairly repeatable readings.

good info 

[9Ball]

I set my meter for the E of chrome (.06), and it went over limit soon after I started the engine, so upped it to .10, and still not high enough. Set it to .25, and final readings were around 290F, within 15F, so I think I'm still good.

What make IR thermometer are you using that has these different settings?

One I bought from HobbyKing for model use (no longer stocked), but that is made by ZyTemp, model TN105i2. No telling if they still actually make it, as HK says it is discontinued.

Curious, what model use are you referring to?  If you want then you could pm me if you don’t want to hijack this thread.  Thanks.

[WintrSol]

Right here: http://www.zytemp.com/products/tn105i2.asp

[rug_burn]

 I graphed mine in Excel, like any pointy headed engineer would do:





take a look-  I think this was before I adjusted last time and fixed that pin-holed vac hose on #4
Time's on the horizontal axis, in minutes after startup.  I'll try to do the labels better on the next chart.

Seems to me that at about 15 minutes, where several cylinders change their temps markedly, is where the engine must have reached operating temperature-  suddenly the lean ones stop misfiring and run hot like they eventually do, and the rich ones which were about right for the cold-engine condition are now too rich.
    I gotta go out and test it again soon as my broken arm gets better.     Some day I'll learn to act  my age...

[Gregory Scott 16248]

Seems to me that at about 15 minutes, where several cylinders change their temps markedly, is where the engine must have reached operating temperature-  suddenly the lean ones stop misfiring and run hot like they eventually do, and the rich ones which were about right for the cold-engine condition are now too rich.

I think that at 15 minutes the timing is changed by the Engine Coolant Temperature sensor or ECT sensor circuit in your ECM as the engine has reached it operating temperature.

Reference: http://www.valkyrieriders.com/shoptalk/ect-mod.htm

I have done the MOD using the Optional Potentiometer (Pot), but I have not had the time to test it out. This riding season is coming and I will try it when the temperature warms up in Pittsburgh.

Greg

[rug_burn]

Hey-  that mod looks worthwhile- thanks.   I'd like to see what the circuit looks like on paper, kind of hard to get it from those pictures.   
    I, probably like most of us, have noticed that flat spot in the power right around 3000 rpm.  Maybe this is what causes at least part of it.  I think it's also the speed the mechanical vibration in the engine maxes out.
    But I was going to mention to you (in response to your earlier comment) that for this technique of making a record of the exhaust temps to work I think you gotta let it warm up without the choke on.   If you don't, you lose a lot of info about rich vs lean.   That being said, I haven't done all that many test with it;  I could be wrong about that.
    I just can't get over how everything swaps places on that graph at 15 minutes after start.  It would be interesting to monitor and record engine coolant temp to see what's going on there.   I gotta read up up a little about that. 

[98valk]

Hey-  that mod looks worthwhile- thanks.   I'd like to see what the circuit looks like on paper, kind of hard to get it from those pictures.   
    I, probably like most of us, have noticed that flat spot in the power right around 3000 rpm.  Maybe this is what causes at least part of it.  I think it's also the speed the mechanical vibration in the engine maxes out.
    But I was going to mention to you (in response to your earlier comment) that for this technique of making a record of the exhaust temps to work I think you gotta let it warm up without the choke on.   If you don't, you lose a lot of info about rich vs lean.   That being said, I haven't done all that many test with it;  I could be wrong about that.
    I just can't get over how everything swaps places on that graph at 15 minutes after start.  It would be interesting to monitor and record engine coolant temp to see what's going on there.   I gotta read up up a little about that. 

[98valk]

Hey-  that mod looks worthwhile- thanks.   I'd like to see what the circuit looks like on paper, kind of hard to get it from those pictures.   
    I, probably like most of us, have noticed that flat spot in the power right around 3000 rpm.  Maybe this is what causes at least part of it.  I think it's also the speed the mechanical vibration in the engine maxes out.
    But I was going to mention to you (in response to your earlier comment) that for this technique of making a record of the exhaust temps to work I think you gotta let it warm up without the choke on.   If you don't, you lose a lot of info about rich vs lean.   That being said, I haven't done all that many test with it;  I could be wrong about that.
    I just can't get over how everything swaps places on that graph at 15 minutes after start.  It would be interesting to monitor and record engine coolant temp to see what's going on there.   I gotta read up up a little about that. 

the curve in the intake tubes located inside of the air box, causes the flat spot at 3k rpm.  I took the curve out and made them a straight shot into the carbs,

the curve does two things, epa intake noise reduction and slight mild torque boost down low but prevents more pull on the top end.




the center divider was a test which has since been removed.

[turtle254]

Hey-  that mod looks worthwhile- thanks.   I'd like to see what the circuit looks like on paper, kind of hard to get it from those pictures.   
    I, probably like most of us, have noticed that flat spot in the power right around 3000 rpm.  Maybe this is what causes at least part of it.  I think it's also the speed the mechanical vibration in the engine maxes out.
    But I was going to mention to you (in response to your earlier comment) that for this technique of making a record of the exhaust temps to work I think you gotta let it warm up without the choke on.   If you don't, you lose a lot of info about rich vs lean.   That being said, I haven't done all that many test with it;  I could be wrong about that.
    I just can't get over how everything swaps places on that graph at 15 minutes after start.  It would be interesting to monitor and record engine coolant temp to see what's going on there.   I gotta read up up a little about that. 

the curve in the intake tubes located inside of the air box, causes the flat spot at 3k rpm.  I took the curve out and made them a straight shot into the carbs,

the curve does two things, epa intake noise reduction and slight mild torque boost down low but prevents more pull on the top end.




the center divider was a test which has since been removed.

Need a better pic ... can't see what you did?

[98valk]

only one I have saved from long ago.  The oem tubes are curved going into the carbs, mine are straight now.  I removed the curve section.  I enlarged the picture. it that enough, I could try larger but I only use photostash and it only allows a certain size.

[turtle254]

Thanks , looks like you kept the flare on the inlet end .. how did you do that?

[98valk]

Thanks , looks like you kept the flare on the inlet end .. how did you do that?

pulled them out, cut the curve out so that I had two flat sections so the flair and main tube could be parallel to each other and then siliconed them together. Been that way since '01, and 55k miles later. bought my '98 leftover new in '00.
having the curve actually adds some bottom end torque, but not that much and not worth it for the increase in the mid-range to red-line.  and with the little less torque off the line, the rear tire last a little longer.
Per Vizards book having a straight shot into carbs picks up about 5 HP on a 63 HP engine he said he was testing which he considered major on a small engine.

Interesting that for the ST1100, so many have stated re-jetting the carbs never work. Well those intake tubes are actually a 90 degree bend from the pictures I have seen. very restrictive.

good book to read see chapter nine, intake ram pipes.

https://www.amazon.com/How-Build-Horsepower-David-Vizard/dp/1884089143

another book to read and the first I read from Vizard, has a good section on headers and exhaust.
some is outdated mainly carburetors, however there is a section on Individual Induction systems.

https://www.amazon.com/Performance-Economy-David-Vizard/dp/0931472091

[rug_burn]

Greg Scott:
  I plotted your data the same way-  here it is:



This is what we do during the lockdown...

I added a 75 degree starting point for all cylinders

I don't see any strange behavior around reaching operating temperature like mine had. 

[Gregory Scott 16248]

Hey-  that mod looks worthwhile- thanks.   I'd like to see what the circuit looks like on paper, kind of hard to get it from those pictures.    
    I, probably like most of us, have noticed that flat spot in the power right around 3000 rpm.  Maybe this is what causes at least part of it.  I think it's also the speed the mechanical vibration in the engine maxes out.
    But I was going to mention to you (in response to your earlier comment) that for this technique of making a record of the exhaust temps to work I think you gotta let it warm up without the choke on.   If you don't, you lose a lot of info about rich vs lean.   That being said, I haven't done all that many test with it;  I could be wrong about that.
    I just can't get over how everything swaps places on that graph at 15 minutes after start.  It would be interesting to monitor and record engine coolant temp to see what's going on there.   I gotta read up up a little about that.  

I have to use the choke or the engine stops. After about 1 minute I can keep it running with the throttle, but it doesn't like it and it would void the test. It's rather cold still 40-50 deg. Maybe in another month it will be around 70 deg.

I have a water temperature gage and after 15 minutes the temp. gage reads 170 deg.

From the graph it looks like almost everything lines up after 25 minutes. I think the engine is warmed up at this point.

[rug_burn]

When it warms up a little, and you get some riding time on your trike, could you tell us your thoughts on that mod?  I'.m not too sure I understand what it does, electrically.
Thanks.