Can't get over 4,500rpm in gear

[Morse]

Indybob

Actually its pattern for revving is a little different than that.  At WOT it pretty much does a sputter down around 2K.  No matter where in the rpms I give it WOT it will respond by doing nothing until 2k and sputtering there or if under 2k will sputter it's way up to there.  I can only get it up and going with around 1/4 throttle or less.  any more than 1/4 will give me a burst of speed for just half a second or so then nothing until I'm in that 2k range at which time it starts alternating between power and no power, which is what I mean when I say 'sputtering' above.  If I am in a low gear at WOT and 2k it will jerk me around, like a manual transmission car does when you start going badly in first and it jerks you back and forth.

1)Basically it will bring itself back to life when I come off the throttle.  Almost immediately, there might be a fraction of a delay but not much if it's even there. As soon as it hits 1/4 it's back to life.  I'll check this more in depth the next time I get a chance to ride it. (hopefully tomorrow)

2) It is 100% repeatable and exactly the same

3)yes, I mean the green sensor on the T. housing. P/N 36151-MT8-003

4)not yet, that's for the next ride too.  I will report results.

[Skinhead]

Just a thought, have you checked the fuel strainer, and which petcock Are you using?  OEM?

[Morse]

I've checked the strainer and rinsed out the tank, put compressed air through it.  I'm using an aftermarket vacuum petcock at the moment. OEM was leaking and this one was cheaper than the rebuild.  I have a high-flow non-vacuum petcock too which I used without any filter or in tank strainer(just for a test).  It made no difference.  I've checked the flow on the aftermarket vacuum one I'm using.  It comes out pretty fast.

[Ricky-D]

In an earlier post you identified carburetor #4 as a potential problem.

If it were me, I'd concentrate my attention on that carburetor

And the first thing I would want to do is verify all the passage are open and free of crud.

The jets are clear, the slide and all peripheral items are proper, and there is no apparent problem.

Get it so that that carburetor is no long displaying the bad characteristic that drew your attention.

***

[tonybluegoat]

I have stock 100 mains and 35 slows, I know for certain that they are clean.  I thought about going up but it just seems like the bike should run fine with stock jets.  Seems more like I'd be bypassing the problem rather than fixing it.  Honestly, at this point, that would be ok to me so long as it ran.

 I'm going to put swapping the mains off for now only because of the way it looses power.  If I WOT I loose all power until the bike drops down to 2000 or so rpms then sort of jerks me back and forth, launching itself forward and engine braking hard, which gets worse the longer I hold the throttle.  Figure if it were too small of mains I would only have so much power and then it would top out and stay there no matter the extra throttle.  Please correct me if I'm wrong on that, i definitely could be.

Pretty certain there's no air leak, I've lost count of the number of starter fluid bottles I've gone through searching for one.

There is no Dan marc or anything in fuel line, just 3/8 hose with no extra slack and no filter, new tank screen, tried 3 different petcocks.  No K&N, brand new OEM air filter, new air box seals, and now have a second (seemingly unmodified) airbox on it.

Leathel, I've been thinking about coil grounds too.  I'm going to try your idea of removing the ground wire and seeing the results, might throw some extra grounds on just to check.

You're probably right. With a jet issue it just bogs down it doesn't surge and brake. I had a car that did that when I was teenager. It was the fuel filter, but you've already checked all that stuff.  It sucks that this isn't fixed yet.

[indybobm]

A couple of months before I got out of the Navy in 1972, I bought a 57 Chevy without motor and transmission. I built and installed a 283 and 3-speed transmission and attempted to drive it to Indiana from California. It had a fuel delivery problem many times on the trip. I replaced the fuel pump in Reno but that did not help. After I got back home I discovered the problem. Evidently the PO had lost the gas cap and had used a rag  crammed into the fill pipe. the rag ended up inside the gas tank and would periodically shut off the flow of gas. You find some strange problems in used vehicles.

[pancho]

Thanks Pancho.  I've looked at them and they seem properly oriented, they look like the picture in the manual (17-12).  I've read that if they fail they totally go out but you never know, it is listed as a possible cause of a weak engine in the troubleshooting section of the manual. I should probably just swap them and make sure.  I'll need to check if the 'wing P/N is the same.  Those ones are way cheaper on ebay. Either do that or find a cheap peak voltage tester.

I've been thinking of coming at this a different way.  Rather than trying to solve the problem I'd just like to make a difference in the bike, worse or better.  So far everything I've done hasn't had any effect at all.

My thoughts at the moment are on either side gapping the plugs or getting some of the reduced central electrode plugs to see if I can make the spark a little stronger or weaker and see if that changes my top rpm or throttle response.

I am thinking of changing out the mains on 5 and 6 to roughly 110s because 5 and 6 are easiest to get to and because i'm drilling them (from an extra set of 100s) myself and would rather drill 2 than 6.  Obviously if there is any positive difference I'd swap out them all out with non-drilled larger jets.

swapping pulse generators.

Does anyone know what all of the sensors are that affect timing or anything with the ignition system?  So far I've swapped the ect and the ICM and checked all relays and fuses.  I'd like to either unplug every sensor that would have any affect or swap it out.  

Could the kill switch or ignition switch possibly play a roll in this?

I have I/S springs coming in today in case the diaphragm springs are too strong to let them open (possible but unlikely that PO swapped them with the wrong springs)

Any other ideas would be welcome.  Thanks

You have done much Morse, and the telling statement is So far everything I've done hasn't had any effect at all.


Being that the bike had been partially disassembled, I wouldn't trust anything. I don't know if the timing belts/pulse generators/pulse rotor (trigger wheel) has been messed with, But, I would give them a close inspection. They can be installed incorrectly as there has been a previous post about this, and although their failure mode is usually dead, they each have a coil in them which may be able to come loose or get intermittent and cause erratic operation. I think the only way to get a clear picture of their operation would be with an oscilloscope as they may be producing the correct peak voltage, but at the wrong times. Also the pulse rotor can be installed upside down, although I don't know how this would make the bike run.

lnstall the ignition pulse rotor with its "OUT SIDE" mark
facing out, aligning the rotor key with the crankshaft keyway.

from the service manual

After all that you have done, this is just the area where I would put a bit of attention, if for no other reason than to rule it out. The WOT action is counter intuitive for this,,, makes me think of something opening up and admitting gushes of air,,,  but still...

Good luck Morse, not sure what my mindset would be in your position....  I guess patience is the answer.

[indybobm]

The solution to this problem will not be one that is found on a troubleshooting chart.

[rug_burn]

    The fact that is falters like that at higher rpm, then catches back on after a while sounds like a fuel problem.   Like maybe it uses up all the fuel in the carb bowls, then has to wait for a while until they fill back up before running strong again.  And the fact that it can't maintain power at higher load settings, like when it's running at higher speed / higher drag situations points in the same direction, like the fuel flow doesn't keep up with the need for more power.    I know it sounds like we're just grabbing at straws at this point.

    What  Pancho was saying about something opening up letting in air also makes sense, but there's really nowhere between the carbs ans the heads for this to happen, except those o-rings on the head, and the sleeves that go between the carbs and intake tubes.  These are all good, too?   I always use a mirror and good flashlight to check the backside of these, but I assume you've already done this about 20 times by now.

[Morse]

Ricky-D- I think I forgot to mention that I got number 4 and all the other carbs to quiet down.  The problem they were having was backfiring through the exhaust.  I just had to richen them up a little with the mixture screw, only about half a turn got the popping to stop on number four.  I don't have any backfires or pops right now.  I'm also pretty certain the carbs are as clean as I can get them, I tore them all the way down and soaked them individually first in carb dip then in a boiling lemonjuice water mix.  I did this to the jets too and blew everything out with compressed air.  I rebuilt everything that might be getting old too, replaced air cut off o-rings and lines, inspected diaphragms, replaced all rubber parts, made sure needles were not shimmed and were stock.  They were as spotless as I could get them when they went back on.

pancho- I have checked that the OUT SIDE mark is visible on the front of the TW and it is.  I have some other pulse generators on the way.  I was planning to swap the TW out too.  There are some 6 degree ones online for ten bucks free shipping.  The only non-advanced wheel I can find is closer to fifty dollars with shipping.  I'd rather put on an OEM TW but for ten bucks I'll just swap back to the STD ICM and try the six out.  I've read I'll need to use premium if I do that.

Indybobm- I'm certainly hoping it's not something plain I could have found through some deep reading of the manual (not that I haven't done that).  Be sort of embarrassing if it were something real basic.  

I still haven't gotten a chance to take it for another long ride.  The roads around me are too busy to get much chance of really testing anything so I need a good hour chunk or so to take it up to the reservation just north of me and run it around. I'll be doing the plug pulling and inspection then, looking for wetness.  The one night I had I found I'd killed the battery earlier in the day trying to troubleshoot the front brake light switch (build up in the switch, cleaned it out and it's all good).

I put in I/s springs for the diaphragms and checked for blockages in the crank case breather area.  Nothing in the breather but I think the problem actually got worse with the springs.  I only took it around the block but it definitely seemed worse, I'll report if I'm right on that after my next longer ride.

If it is worse with the springs installed to me that points to a bad spark.   My thought is I'm getting more air and fuel into the chambers at less throttle (because the diaphragms open sooner and more easily now) which causes higher pressure at lower throttle than before and higher pressure makes good spark harder to achieve.  Is my reasoning sound there?

[indybobm]

I think that best thing go try if possible is to try a different fuel tank. Look at previous post about the problem I had with a 57 Chevy.  This has all the symptoms of a fuel delivery problem.

[Morse]

Rug_burn - I think the float bowls are filling up because of how long the thing takes to die once I turn the petcock off.  I have gone on rides with the petcock off accidentally and I got it to stumble(past 1/4 throttle) then go back to working again after that until it exhausted the fuel in bowls (at which point I realized I forgot to turn the petcock on).  To me that seems like the bowls are filling but I figure a good way to test it would be to get it to the point where it stumbles (doing its 2000rpm jerk-around) then shut off the petcock.  Seems like if the bowls weren't filling it would run out of gas almost immediately after that.  I'll do that on my next ride.

I have been looking for air leaks too.  The intake O-rings were leaking before but I've replaced them with the red-eye replacements and tightened them down right, no more leaks.  The airbox is on and checked with a mirror and starter fluid.  On the bright side I am getting pretty good at getting those sleeves to seat right.

[Morse]

Indybobm - my thoughts on checking for a fuel issue actually came from a dude on goldwingdocs.  He suggested getting a can of carb cleaner (i'd rather use starter fluid to avoid getting carb cleaner on the diaphragms) and attaching a piece of tubing to it.  Stick the tube up under the tank into the airbox, crotch the can until up to speed with the stumble, then spray.  If it's a fuel issue I should be able to get over my rpm limit with that. 

I figure I could also IV bag the fuel in, another gas tank is too expensive for me to put money into right now.  I will say though the fuel comes out plenty fast when the tank is off the bike.  I've had to drain about 2 gallons from it a couple times when swapping petcocks and with all of the petcocks (with the gas cap closed) the fuel emptied entirely in about a minute or so with no interruptions or change in flow.

[Ricky-D]

Ok, I understand.

One thing you may not realize is, that blowing into certain areas of the carburetor will sometimes fail to clear that area, and can actually clog it up more by compacting the clogging material.

I also feel that it is possible, that to overcome a lean condition caused by clogged passages, turning the idle screw may overcome the lean condition at idle, but at higher throttle settings the lean condition caused by the clogged passage is still present and is not ameliorated by the turning of the idle screw.

Just wanted to put that out there.

[Dr K]

Was the exhaust off the bike when you got if so it could be plugged that Will limit RPM

[Beer van Huet]

Morse, if you think you have the fuel- and ignition pretty well covered, the problems you state sound familiar to an issue we have with the export version.
We have smaller jets and in order to get the air supply right, Honda installed a piece of foam inside the airfilter housing cover intake. Now, if this piece of foam gets deteriorated or is missing, the bike runs pretty similar as you describe.
This all doesn't apply to you but the point I want to make is that if the system gets too much air (and runs lean), it will stall at a certain RPM (usually 3000-4000 RPM), backfires and sometimes produces black smoke from the exhausts. Fuel consumption also increases dramatically. If you ride it, it feels like you are missing one or more carbs.
I was really surprised to see that a small piece of foam the size of a cell phone inside the cover intake would make such a huge difference and how bad the engine would run if the volume of air isn't exactly right. Like a diesel tractor.
So, if the carbs are assembled correctly and you did not experience this before, perhaps you should be looking at the air supply instead real closely.

[hubcapsc]

Ok, I understand.

One thing you may not realize is, that blowing into certain areas of the carburetor will sometimes fail to clear that area, and can actually clog it up more by compacting the clogging material.

I also feel that it is possible, that to overcome a lean condition caused by clogged passages, turning the idle screw may overcome the lean condition at idle, but at higher throttle settings the lean condition caused by the clogged passage is still present and is not ameliorated by the turning of the idle screw.

Just wanted to put that out there.

ultrasonic-cleaned jets and new jets are probably the most reliably clean
jets... Attic Rat ultrasonic cleans carburetors that go through his shop I believe.
I've struggled to get the stone-aged carburetor in my 8n clean so it would run
right, and when I gave up and got my buddy Dan who is an actual skilled
mechanic to have a go at it, he showed me how my jets and some of
the orifices in my carburetor were still clogged with stuff you could see
when he got it out.

-Mike

[Ricky-D]

^^^^^^
That

[Morse]

Well, I've been out of town and away from the bike for a little while.  Was researching, looking at all the microfiche while I was out. Beer Van Huet got me thinking if the export F6C starts acting like mine does without the pre-filter, I'm probably getting too much air from somewhere.

I found something amiss in the way I put the bike together, I think.

My question is, where do the carb vent tubes run to? And I mean the ones that come out of the plastic joiner-tube T. (#13 in this fiche https://www.partzilla.com/catalog/honda/motorcycle/1998/gl1500c-a-valkyrie/carburetor-tubing)  I have mine running to a T and then straight to the airbox.  They are not running to the secondary air intake that usually goes to the smog equipment, I have that one blocked off.   The hole that the vent tubes are running to I now believe is an airbox drain hole.  

In the fiche copy-pasted in the above paragraph I am missing #16 and #19 and all the tubes (excluding #13, which I have) that are attached to 16 and 19.

In all the fiche I've looked at the hole from the airbox that my vent tubes are currently running to is supposed to have a tube that runs to a T under the plastic crankcase container that is just behind the ignition switch.  

Using this fiche as reference -- https://www.bikebandit.com/oem-parts/1998-honda-valkyrie-gl1500c/o/m151423#sch32585 -- on my bike tube #24 is where tube #9 is. Also tube #23 and T-joint #1 are missing.

The airbox hole for tube #23 is where my carb vent tubes are currently attached.
 
 

[Morse]

http://www.valkyrieforum.com/bbs/index.php?topic=52532.0

After reading this thread I feel pretty certain this is what is happening to my bike.

Feeling pretty dumb right about now.

I see from the pasted thread above that those air purge tubes don't run anywhere, just through the holes in the front of the carb bracket.

I suppose I'll be getting some tubing to connect the airbox drain to the reddish tube that drains out the bottom of the crank case container.

[The emperor has no clothes]

http://www.valkyrieforum.com/bbs/index.php?topic=52532.0

After reading this thread I feel pretty certain this is what is happening to my bike.

Feeling pretty dumb right about now.

I see from the pasted thread above that those air purge tubes don't run anywhere, just through the holes in the front of the carb bracket.

I suppose I'll be getting some tubing to connect the airbox drain to the reddish tube that drains out the bottom of the crank case container.

Those lines that you call the purge lines definitely don't hook to anything. They go thru the top of the bracket and hang there free to the atmosphere. I'm a little confused about what you call the reddish tube. Are you talking about the drool tube ?

[Morse]

Yes, I meant the drool tube. 

After taking those purge lines off the airbox the bike now runs great.  That was my problem the whole time.

I got some tubing and a T and made the proper drain tube for the airbox that joins to the drool tube.

Big thanks to everyone on here who helped me out.

A little frustrated that it was so simple this whole time but it's hard to stay mad about it after taking my first ride.  Very impressed by how smooth it is and by how much power it has.

Looking forward to putting on many, many miles.

I am going to make another post on here just as an FYI with as many key terms that would lead a searcher with the same problem to their answer faster than looking over these last three pages.

Thanks again,
Morse

[hubcapsc]

A little frustrated that it was so simple

It is GREAT that it was simple. You fixed it and now you can ride  ...

-Mike

[Avanti]

A little frustrated that it was so simple

It is GREAT that it was simple. You fixed it and now you can ride   ...

-Mike

and now you know all about your bike, what could be better.

[pancho]

WOW,,,,     I can see it.


Now you got your bike Morse!!

[The emperor has no clothes]

Yes, I meant the drool tube. 

After taking those purge lines off the airbox the bike now runs great.  That was my problem the whole time.

I got some tubing and a T and made the proper drain tube for the airbox that joins to the drool tube.

Big thanks to everyone on here who helped me out.

A little frustrated that it was so simple this whole time but it's hard to stay mad about it after taking my first ride.  Very impressed by how smooth it is and by how much power it has.

Looking forward to putting on many, many miles.

I am going to make another post on here just as an FYI with as many key terms that would lead a searcher with the same problem to their answer faster than looking over these last three pages.

Thanks again,
Morse

it's very good of you to follow up with a post to help others that may have this issue.


In thinking about what was happening with carbs hooked up this way, I'm curious if I understand what was going on ?

The carb vent lines were not allowing the slides to get over a certain height because of pressure in the lines ?

[Toovalks]

CONGRATULATIONS... this has been a real nail biter/headknocker

[Hook#3287]

Some good news.  Turned #4 mixture screw out 3/4 turn and cleared up the backfire.  Turned out I had little backfires from the brake side too, turned them all out until the popping stopped. 

Hey Morse, glad you found the issue.

I guessing you already considered it, but a carb sync and re-adjustment should be in the future.

Good luck and enjoy the ride.

[pancho]

In thinking about what was happening with carbs hooked up this way, I'm curious if I understand what was going on ?

The carb vent lines were not allowing the slides to get over a certain height because of pressure in the lines ?

Think about it this way meathead,, carburetors work on the principal of delivering fuel from a place of high pressure (atmospheric pressure) to a place of less pressure (engine vacuum). Since the vent lines were connected to the air box below the filter, at some RPM (2500?), the pressure in the carburetor bowls was approaching the pressure of the engine vacuum. There was nothing to move the fuel into the intake.

That may be a bit simplistic, but I believe it roughly explains most of what was happening.

[The emperor has no clothes]

In thinking about what was happening with carbs hooked up this way, I'm curious if I understand what was going on ?

The carb vent lines were not allowing the slides to get over a certain height because of pressure in the lines ?

Think about it this way meathead,, carburetors work on the principal of delivering fuel from a place of high pressure (atmospheric pressure) to a place of less pressure (engine vacuum). Since the vent lines were connected to the air box below the filter, at some RPM (2500?), the pressure in the carburetor bowls was approaching the pressure of the engine vacuum. There was nothing to move the fuel into the intake.

That may be a bit simplistic, but I believe it roughly explains most of what was happening.

Thanks  that makes sense. I was thinking about it more in terms of the constant velocity slides.

[pancho]

With partial vacuum being supplied instead of atmospheric pressure inside the carburetors, I'd be thinking  none of the circuits were working correctly.

Being that it is so easy to reproduce, I may do it at some time just to examine it further........   HA.