New owner--Flat acceleration at 1/2 throttle and beyond--FIXED!!

[sclark]

Hello, Happy Thanksgiving and thanks in advance for any help.

I purchased an 03 Valkyrie with 3,500 miles. The previous owner mentioned that he had spent nearly a thousand dollars getting the carbs right, but something is still amiss.

Bike starts, idles (just an occasional muffler pop at idle) and runs smoothly up to a 1/4-1/2 throttle magnificently in 1st gear (RPMs around 4,000) when I upshift to 2nd.  If I continue to accelerate at around 1/2 throttle, acceleration goes flat at about 3,000 rpms and stays there through wide open throttle.  The bike continues to run and does not backfire or run erratically--it just stays at 3,000 rpms and does not accelerate.  If I pull in the clutch, the rpm's race to 7,000 near instantly.   This phenomenon occurs in the same manner in 3rd, 4th and 5th.  Applying the choke has no effect.

I removed the tank and found it very clean.  Changed the fuel valve to a Pindle.  Desmogged  and capped all intake vacuum lines.  Plugs look a little rich.  With the bike running, I sprayed brake cleaner around the intake  and carb seals with no change in rpm, so no vacuum leak there.

Thoughts.

[sclark]

Forgot to mention, I removed the aircleaner--it was clean.  I noticed there was no top gasket, so I ran a silicone bead to ensure a good air seal--no change to the problem.

[8Track]

Air cleaner was going to be my first suggestion.

If the fuel delivery is ok, then you may have ignition problems.

[old2soon]

3500 miles. How LONG was this machine sitting before you got hold of it?? Get at least 2 bottles B-12 Chem Tool. Put a full bottle in tank(watch the paint)and run it low R P Ms under 2000 to make sure it gets in the slow circuits-25-30 miles let it sit overnight and get out the next day and see what happens. Might take more than 1 or 2 applications. I M H O-3500 miles on an 03 you have clogged/varnished/dirty jets. Others should chime in and impart their knowledge. And-Welcome To Our Sandbox. IF you decide to feed the animals here-drop the food DO NOT put it near their mouths you COULD lose an arm!!  RIDE SAFE.

[sclark]

Thanks,

I tried 1/2 bottle of seafoam with no change.  What is odd, is that it appears to happen at all cylinders, as it is not erratic, just no acceleration.  The low speed circuit runs near flawlessly.  Seems like the flat acceleration only occurs under load (if I pull the clutch in while it is flat, the engine races smoothly to max rpm).

I can tell that whatever mechanic he took it too, they removed the carbs.

[Ricky-D]

Check the cable and linkage to insure you are getting to actual full throttle.

***

[sclark]

Just checked the throttle linkage--smooth operation stop to stop.

[sclark]

After reading other posts of flat acceleration, it may be an airflow problem--either too much or not enough.  I will raise the tank 1/2 inch tomorrow and if no change, then I will try to restrict air to the air box (that seems to be the problem for over seas Valk's with smaller main jets--wonder if the PO's mechanic changed the main jets and put smaller ones in......)

[Michvalk]

The plugs being black would lead me to believe it's running rich. Not enough air, or, pilots not set correctly? Just a guess.

[sclark]

I generally agree, the only problem with reading plugs is it should be based on pulling the plugs in conjunction with each carb circuit and not a one size fits all condition.  But do agree, they are overall rich.  Given the performance remains smooth even though no acceleration and rpms rev high when the load is removed (clutch pulled in) seems like the culprit would have to be upstream of the carbs as it is highly unlikely that all carbs would be bad.  That is unless the mechanic did something to all the carbs...like change to incorrect jets or was trying to get more power, etc.

[98valk]

did u cap the carb bowl vent lines? they should be open to atmosphere.
also check tank vent line.

[sclark]

The only capped lines are the intake vacuum lines.  I will check the tank vent line--I know it is attached, but will check that there is no blockage.  When you say carb vent lines, are those the same as the drain lines??  If so, they are attached and drain well.

[98pacecar]

As much as I hate to say it. It sounds like the ''mechanic'' had no clue,,, n' just kept trying things, n' charging the previous owner for every one of them. Hence the killer bill, with no result. .....

The problem, was either never found by him,, or perhaps even,,,, made worse.

Look hard... at the carbs...

Something like this,, may be your easiest,,, solution...

http://www.ebay.com/itm/1998-98-Honda-Valkyrie-GL1500C-Carbs-Carburetors-GL-1500-S104255-15-/111222500508?pt=Motorcycles_Parts_Accessories&hash=item19e560ac9c&vxp=mtr

[John Schmidt]

What type of intake filter is installed? If an OEM paper version then it should have a gasket. If a K&N, it doesn't use a gasket. The gasket is an integral part of the filter's outer structure and the gaskets for OEM are to be removed.

[sclark]

The air filter is the OEM.  There was a gasket on the bottom, but not on the top.  I ran a bead of silicone along the top to ensure a good seal.

[Westsider]

did u cap the carb bowl vent lines? they should be open to atmosphere.
also check tank vent line.

+1 kinked vent line... its an open (vented) system, that's why you should also keep it full of fresh gas,,, eat lots of turkey.....

[Gryphon Rider]

Could this be an ignition control module (ICM) issue? I seem to remember people having trouble with their aftermarket Dyna 3000 ICMs, but a faulty Stock ICM might be the cause also. The best way to check would be to borrow an ICM from someone local and see if the problem disappears.

[sclark]

Interesting thought on the ICM.  I somewhat assumed they either worked or not.  Additionally, without an engine load, the rpms will smoothly race to redline.  Hopefully will get another run or two in in a couple of hours with the tank raised to see if it is a restricted airflow problem.

[old grouch]

I am not an expert, but I think you should take another look at the throttle linkage.   

Check the cable and linkage to insure you are getting to actual full throttle.

***

  Just because the operation is smooth doesn't mean it is actually pulling the carbs all the way open.  With no load, I suspect the engine will go to red line with a lot less than wide open carbs.  Pop off a couple of the intake runners, one on each side, twist the grip all the way & verify that the butterflies are actually all the way open.  Just my $.02 and worth all you paid for it.   

[sclark]

Great point--will do!

[Skinhead]

Could this be the classic fuel line/quick disconnect problem?  Check for fuel line droops, and if there is a quick disconnect or fuel filter installed remove it and put the bike back to stock.

[sclark]

There is no fuel line quick disconnect.  The hose runs straight from the pingel fuel valve to the T and then to the carb rail.  All flow "downhill".

[Patrick]

The above posts offer good advice, but, nothing so far has seemed to help ?  Hmmm, my thought was also restricted fuel flow, but, that doesn't seem to be it. Before removing the carburetors, see what the pilots are set at. Generally they come set at 1.75 turns and setting them at 2.25 turns helps a lot. If checking the jet size, the bowls can be removed without removing the whole assembly.

[sclark]

Checked the fuel tank vent line and it is unrestricted.  Raised the tank 1/2 inch and no change.

Will check butterfly mechanisms next to ensure the mechanical linkage is getting to wide open throttle.

After that, most likely will check main jet size, but that may be next weekend.  Really appreciate the continued support and ideas.

[98valk]

The only capped lines are the intake vacuum lines.  I will check the tank vent line--I know it is attached, but will check that there is no blockage.  When you say carb vent lines, are those the same as the drain lines??  If so, they are attached and drain well.

there is a tee for the venting the carburetor bowls. it is located above the fuel supply tee on both banks. called air vent tubes pg 5-19 of tech manual.
being flat above 3-4k rpms sounds like either too much air for the amount of fuel or not enough fuel. if the airbox has not been modified its not getting "too much air". if the carb vent lines are capped fuel flow will be restricted.

[sclark]

Unfortunately I ownly have a Clymers manual.  There is a T that connects the crankcase breather to the carb  bank on each side.  Is that the one you are referring to??

[longrider]

Just a thought here.... If the engine idles smooth I would assume the carbs at least after a few minutes should be full.. For the first half minute or so of rapid acceleration the bike should accelerate normally.   IF it is starving for fuel  ie: a pinched line or whatever it will then bog. .  If I were to turn off my fuel valve the bike would run normally till the bowls reached a low level maybe half a mile or so at heavy throttle, then bog.   Start with the easiest first.  Replace the mains as the lows will run the bike at low RPM.  I think you will be surprised at the outcome.

Warren

[sclark]

Fixed!!!!

I disconnected the hose that runs from the bottom of the crankcase breather to the T that goes to the Carb banks.  Took her for a spin and wow, being new to the Valk (previous HD's), I wasn't quite prepared for the arm stretching acceleration!!  Running great.  I reconnected the hose to the crankcase breather and the problem immediately returned.  Will figure out what the deal with the crankcase breather is later--the drain hose is clear, but who knows.  Thanks again for all the ideas!  Great group of like minded people here.

[R J]

The hose you disconnected, is there a restriction in the hose?

Run a coat hanger, one ya straighten out, and see if ya get any resistance pushing it through.   Or blow air through it if you have a compressor.

I don't how it happened but I had a bee hive in mine one year, many moons ago.

Never did figure out how he got in and out.      When I stuck an air hose to this hose there was a blurp, splat and it was cleared out.     A couple of dead bees were in the hive.     I had it in a jar in the shop, a customer seen it and picked it up, splat, glass all over the firkin floor.      That was when we put the rope up that said employees only, which has been taken down now.

[sclark]

The hose from the crankcase breather to the the T and carb banks was unrestricted.  I also placed a vacuum pump on the crankcase breather and it did not hold suction, which indicates it is unrestricted, but something is still not right.

[sclark]

Hey gents, need a little more help.  I was just looking at an online parts manual and it shows that the bottom outlet on the crankcase breather is actually a drain and that it T's into the drain tube from the air filter.  If so, then the PO's mechanic had incorrectly hooked the carb vent hose to the crankcase breather drain!   Out of curiosity, what does the carb vent hose connect to (from the carb bank to the T then to what)?????

[98valk]

Hey gents, need a little more help.  I was just looking at an online parts manual and it shows that the bottom outlet on the crankcase breather is actually a drain and that it T's into the drain tube from the air filter.  If so, then the PO's mechanic had incorrectly hooked the carb vent hose to the crankcase breather drain!   Out of curiosity, what does the carb vent hose connect to (from the carb bank to the T then to what)?????

the two carb vent hoses connect to the rear carb assy frame. there are two holes that the hoses go into facing towards the engine, they remain open to atmosphere.
 the crank case vent tube connects to the bottom of the airbox. your clymer manual should show most of this esp the emissions section.

[sclark]

still a little confused.  Their is a fuel vent hose coneected to each carb bank and they route to a T.  From the T is a single hose--what does it connect to??  The clymer manual does not show.  thanks

[Bone]

Have you seen this in shoptalk ?

http://www.valkyrieriders.com/shoptalk/fiche.htm

After you click on the link you will see several Valkyrie Microfiche

Look at GL18, GL19 & GL20
Click each picture for an expanded picture

[sclark]

thanks, wasn't aware of the microfiche, but unfortunately it does not show what the single hose attaches too.  No worries, I will just put a vented cap on it.

[98valk]

still a little confused.  Their is a fuel vent hose coneected to each carb bank and they route to a T.  From the T is a single hose--what does it connect to??  The clymer manual does not show.  thanks

they shouldn't be connected together.

download the service manual for free
http://www.valkyrienorway.com/download.html

[old2soon]

I'm glad you are on the road to getting sorted out.  Had my I/S out today and at least 3 incidents of pulling away from a dead stop on dry pavement-easing out the clutch in first gear and DROPPIN the hammer she broke loose and I lit up the rear tire.  On at least one incident when I upshifted to 2nd and nailed it it broke loose a 2nd time.  AND I might add-i'm runnin D/S on the rear. AND that Nexen 5000 on the back is NOT/NO WAY/AIN'T GONNA HAPEN giving me any cause for concern. When you get to use the FULL potential of one of these machines you will understand WHY most of us that own one walk around with DAT GRIN on our pie holes most all of da time!!    RIDE SAFE.

[Denny47]

As posted by CA, the carb vent hoses Do Not connect to anything, they just go into the two holes at the rear of the carb. connecting frame They are 5/16 ID. These vent the two carb banks. The vent hose, 1/8 ID, from the fuel tank connects at the rear left of the gas tank, runs down behind the engine to a T, then another hose goes from the other leg of the T to under the engine for drain purposes, the third leg of the T is left open in case the end of the hose gets clogged up with mud, etc. A vented cap will not help on the carb vent hose because they do not vent the gas tank.

[sclark]

Thanks much!

[salty1]

Hello, Happy Thanksgiving and thanks in advance for any help.

I purchased an 03 Valkyrie with 3,500 miles. The previous owner mentioned that he had spent nearly a thousand dollars getting the carbs right, but something is still amiss.

Bike starts, idles (just an occasional muffler pop at idle) and runs smoothly up to a 1/4-1/2 throttle magnificently in 1st gear (RPMs around 4,000) when I upshift to 2nd.  If I continue to accelerate at around 1/2 throttle, acceleration goes flat at about 3,000 rpms and stays there through wide open throttle.  The bike continues to run and does not backfire or run erratically--it just stays at 3,000 rpms and does not accelerate.  If I pull in the clutch, the rpm's race to 7,000 near instantly.   This phenomenon occurs in the same manner in 3rd, 4th and 5th.  Applying the choke has no effect.

I removed the tank and found it very clean.  Changed the fuel valve to a Pindle.  Desmogged  and capped all intake vacuum lines.  Plugs look a little rich.  With the bike running, I sprayed brake cleaner around the intake  and carb seals with no change in rpm, so no vacuum leak there.

Thoughts.

I may be dense and missing something, what was the fix? Anything in particular that allowed the engine to rev properly under load?