Will not go over 4200 rpms. found problem

[semo97]

We rebuilt my sons '99 Is. this summer new frame and forks from a T-bone 5yrs. ago. the bike has been in the family for ten yrs. Bike was stored in climate controlled garage and sea foam ran through it the last time it ran. All back together starts right off runs smooth. sync. the carbs, checked the ignition time all good new plugs, new fuel vacuum lines, carbs were cleaned, tank was clean, ran some techron through the first 2 gallons. The problem is it will go to 5000 rpms sitting in neutral but will act like it chokes out and drops to 4200 and runs smooth. 1st. gear 4000 no more starts to chokes out, 2nd. 3700, 3rd. 3400, 4th. 2600 5th. 2000 that is the max in all the gears. We checked the gas tank vent line it is good, good vacuum to petcock. It is the stock petcock could it be bad? All the throttle cables working good, and it opens the carbs all the way. May need to pull carbs and clean and new jets. Need some advice on what could be the problem and things to check. I will try and answer any questions you may have. I am in Tx. and the bike is in Il. We did put a longer main fuel line to the Ts it may have a hump in it and not flowing down hill.
Thanks.
Paul

[Chrisj CMA]

Does it have the OE petcock.  May be starting to o fail.

[bill-jr]

What about the T thing in vent line?
Coils good ? Check your spark plugs ?

[semo97]

Yes, new plugs, will check coils and connections tomorrow. Yes it is the stock petcock original never  changed.

[Scottrtho]

Since the power bog depends more on load and not always the same rpm...I would suspect fuel issue and not spark related. My first step would also be to confirm good fuel feed flow.

[Steel cowboy]

You may want to check the diaphams in the carb's. If it was sitting they might have gotten hard. As not to be corrected, "they lift the needles out of the main jets". You can check them with out pulling the carb's out, they sit under the second cover on top of the carb's. Good luck.

[Blackduck]

Is the airbox cover stock?
You get the same RPM limit if it is opened up.
Other than that check the carb slides are all fully opening and not binding.
After that it is time to clean the carbs

[John Schmidt]

Agreed, sounds like a fuel delivery problem. Do a vacuum check on the petcock to see if it holds, if not...then either replace or rebuild. I'd go with replace with a Pingle. Also, get rid of the excess fuel line between the petcock and the T distribution point. That will cause you even more problems.

[Ricky-D]

I'd suggest to be careful messing with the carburetor diaphragms. They're easy to damage and expensive to replace. Besides, there is hardly ever a problem with them and when there is, it's usually an operator error from screwing with them.
Jus sayin

***

[Chrisj CMA]

Yes, new plugs, will check coils and connections tomorrow. Yes it is the stock petcock original never  changed.

I highly suspect the petcock is limiting fuel at the high demand situation.

[Gideon]

I believe both John and Chris are correct. You have a problem with your petcock.
It's up to you if you rebuild the OEM or go with a Pingle.

[Bigwolf]

I am thinking fuel starvation as others have said. 

However, you did say it was T boned hard enough to have bent the frame.  So I am wondering if the crash damaged the valve cover or timing cover.  If there was damage there, you could have bent valves or the cam timing could be wrong, or both.  Unless of course you have already dealt with that in the rebuild process.

[semo97]

I should have given more details but thought I might get to cared away. The bike ran fine after the crash and it was totaled before my son  bought it back from Ins..it was at a dealership  that gave the figures on cost to rebuild and they ran it and checked the engine out that is why he bought it back. The bike was started every week for a yr. no leaks of any kind and then was put up until we both could get together and do the rebuild and get parts we needed. Internal and external of the engine are fine like all said fuel starvation.  The frame had bent at the neck lower forks  bent, fender bent one rotor bent. The bike was layed down before impact, had no where to go, moving traffic to the left and  stopped traffic lined  up on the right and a left turn at 45 on to a narrow gravel street not many good options and only seconds to make a decision. It has been 4 yrs. but we did it together worth waiting for. I thank all of you for your advice and wisdom, I will give a report when it is running like it used too.

[big poppa pump]

The frame had bent at the neck

And you bought a new used frame without any damage when you started rebuilding this bike, Right????

[signart]

That fuel line you lengthened

[semo97]

We got a clear titled frame not from a wreck.

[Willow]

Just an observation regarding fuel starvation.  There are six carburetor bowls full of fuel,  If you have a fuel delivery problem to those bowls the bike will use the fuel in those bowls and THEN begin to act like it's running out.  That's not what the OP described.  If the limit is immediate the problem has to be in fuel mixture to the cylinders not to the carburetors.

[Chrisj CMA]

Just an observation regarding fuel starvation.  There are six carburetor bowls full of fuel,  If you have a fuel delivery problem to those bowls the bike will use the fuel in those bowls and THEN begin to act like it's running out.  That's not what the OP described.  If the limit is immediate the problem has to be in fuel mixture to the cylinders not to the carburetors.

Well, who knows...but, its not really that simple.  When my petcock started to go bad it would starve out almost immediately in high demand situations.  What I believe happens is the flow into the carburetors is reduced so the engine is running normally on float bowls that are not full as they should be.  Just barely getting along if you will.  Then as soon as the demand significantly increases there is not a WHOLE bowl of fuel to use up just the last bit before trouble starts.

[old2soon]

Where ZACKLY in Illinois? My brother-da prez-lives near Island Lake Il. He knows his way around a Valkyrie. Is the M/C in Texas or Illinois? RIDE SAFE.

[semo97]

Pleasant Plains Il. near Springfield, the gas lines was redone and the petcock will be checked out this weekend.

Where ZACKLY in Illinois? My brother-da prez-lives near Island Lake Il. He knows his way around a Valkyrie. Is the M/C in Texas or Illinois? RIDE SAFE.

[da prez]

  Just my two cents worth. Go back to basics and check the entire fuel system. ,Do not just look and say I did that.  Check petcock vacuum and if the vacuum line has fuel in it , It will work , but it needs to be rebuilt. Fuel line to long will not work properly. It will be something simple , and getting radical before doing basics will lead back to basics. I have the experience to prove it.

                                         A L W A W S   do the basics  F I R S T

                                                          da prez

[semo97]

Update, fuel lines were shortened and routed straight to the T. Petcock was opened could not see a problem, went and relocated the spring to hold the diaphragm open all the time. We know to shut the fuel off every time have been doing it for yrs. I still and try to shut off or turn on my st1300 after six yrs. A good habit never to stop. Got 500 to 1000 more rpms. 1st. will go to 4500 easy but will brake traction  if you twist it hard never went over it was time to shift, 2nd will max at 4300 and will brake traction if you hit it hard before the 4300. 3rd., went up 700 rpms 4th., went up 800 rpms 5th., went up 1000 rpms to 3K.  All gears (except 1st. did not push it over 4500) spit and sputter when you throttle it over that certain rpm, when you back the throttle off it will hit a spot where it will catch and just  rocket forward and run fine until you go over a certain rpm in each gear for example 3k in 5th. I feel we are still not getting enough fuel for the throttle roll on at those certain rpms. I am thinking a new petcock is needed. Could there still be some restriction in this petcock even changing the spring  to hold the diaphragm open? Thanks for all the advice.

[big poppa pump]

Update, fuel lines were shortened and routed straight to the T. Petcock was opened could not see a problem, went and relocated the spring to hold the diaphragm open all the time. We know to shut the fuel off every time have been doing it for yrs. I still and try to shut off or turn on my st1300 after six yrs. A good habit never to stop. Got 500 to 1000 more rpms. 1st. will go to 4500 easy but will brake traction  if you twist it hard never went over it was time to shift, 2nd will max at 4300 and will brake traction if you hit it hard before the 4300. 3rd., went up 700 rpms 4th., went up 800 rpms 5th., went up 1000 rpms to 3K.  All gears (except 1st. did not push it over 4500) spit and sputter when you throttle it over that certain rpm, when you back the throttle off it will hit a spot where it will catch and just  rocket forward and run fine until you go over a certain rpm in each gear for example 3k in 5th. I feel we are still not getting enough fuel for the throttle roll on at those certain rpms. I am thinking a new petcock is needed. Could there still be some restriction in this petcock even changing the spring  to hold the diaphragm open? Thanks for all the advice.

Forget the spring, diaphragm and all the crap. Gut out the innards of the diaphragm and convert it to an O-ring. Use JB weld and seal the weep hole and the vacuum hole. Assemble the petcock with the gutted out diaphragm (now an O-ring) in between the halves along with Permatex fuel resistant (blue) gasket and sealant.

[Crackerborn]

May sound stupid, but did you check the petcock screen inside the tank? Rust and foreign matter will build up and stop flow.

[semo97]

May sound stupid, but did you check the petcock screen inside the tank? Rust and foreign matter will build up and stop flow.

Yes it was checked, all questions and advice are good questions and advice.

[gordonv]

Just following the chain of thought.

You've converted the petcock to be "free running", no more vacuum. Just a regular pingle now.

Have you tested the flow through the petcock? Pull the fuel line from the carb, and put it into a container, turn it on for 15 sec. x 4 to give you a minute flow rate.

I know in the Shadow manual, you do that, and compare the results to the book and see if your fuel pump is putting out enough LPM of fuel. But how much does a Valkyrie need? Compare to a working good one?


From reading your posts, you are not going hard on the throttle, wide open, but "rolling" onto the throttle. I've never tested mine, to see how high RPM I can go in each gear, but I would think they should all be limited to the same rpm that the motor can handle. So why would there be max RPM in different gears? The speed changes by gear/rpm, but what else? Fuel and air should be the same based upon RPM, maybe a little more fuel based upon load (flat road, hill, passenger(s)).

[The emperor has no clothes]

Just following the chain of thought.

You've converted the petcock to be "free running", no more vacuum. Just a regular pingle now.

Have you tested the flow through the petcock? Pull the fuel line from the carb, and put it into a container, turn it on for 15 sec. x 4 to give you a minute flow rate.

I know in the Shadow manual, you do that, and compare the results to the book and see if your fuel pump is putting out enough LPM of fuel. But how much does a Valkyrie need? Compare to a working good one?


From reading your posts, you are not going hard on the throttle, wide open, but "rolling" onto the throttle. I've never tested mine, to see how high RPM I can go in each gear, but I would think they should all be limited to the same rpm that the motor can handle. So why would there be max RPM in different gears? The speed changes by gear/rpm, but what else? Fuel and air should be the same based upon RPM, maybe a little more fuel based upon load (flat road, hill, passenger(s)).

The rpm's should only be limited by the rev limiter or fear. I don't think I've hit the limiter in 4th or 5th. But that was only because I didn't want to.

[semo97]

there is a rev limiter and have not hit or are trying too. At the beginning of all this with the bike it would only go to 2k in 5th. and max speed was 60mph now it is going to 3k some improvement. We will check fuel flow from tank if we can find an amount it needs for rpm red line or near that. We do not run our bikes hard just need some point for reference.

[The emperor has no clothes]

there is a rev limiter and have not hit or are trying too. At the beginning of all this with the bike it would only go to 2k in 5th. and max speed was 60mph now it is going to 3k some improvement. We will check fuel flow from tank if we can find an amount it needs for rpm red line or near that. We do not run our bikes hard just need some point for reference.

Sounds like its got to be a petcock or carb issue. The cover set rebuild kit is not that expensive. And taking the carbs off and cleaning them is free, just time.

[Chrisj CMA]

Just following the chain of thought.

You've converted the petcock to be "free running", no more vacuum. Just a regular pingle now.

Have you tested the flow through the petcock? Pull the fuel line from the carb, and put it into a container, turn it on for 15 sec. x 4 to give you a minute flow rate.

I know in the Shadow manual, you do that, and compare the results to the book and see if your fuel pump is putting out enough LPM of fuel. But how much does a Valkyrie need? Compare to a working good one?


From reading your posts, you are not going hard on the throttle, wide open, but "rolling" onto the throttle. I've never tested mine, to see how high RPM I can go in each gear, but I would think they should all be limited to the same rpm that the motor can handle. So why would there be max RPM in different gears? The speed changes by gear/rpm, but what else? Fuel and air should be the same based upon RPM, maybe a little more fuel based upon load (flat road, hill, passenger(s)).

The rpm's should only be limited by the rev limiter or fear. I don't think I've hit the limiter in 4th or 5th. But that was only because I didn't want to.

I don't think a stock Valkyrie will hit the rev limiter in 5th gear.  I have had mine wide open and at 130 indicated, speed was still creeping up but I proved what I set out to, that it would hit 130 indicated.  I think I was within a couple mph of max speed and did not hit the limiter.

[signart]

You need to know if you have to go upstream or downstream from the fuel line T.
I would remove the Valk tank and rig up a remote tank and hang it high above the frame. You say it only revs to 5k out of gear and drops off. This should eliminate any tank, valve, or vent issues and isolate where you should concentrate your efforts. Good luck.

[semo97]

 All lines from the T go down hill. A petcock kit or new petcock may be next. I owned the bike for 4 yrs. before my son took it. I as well never hit the rev limiter never tried. 130 for the big valk is impressive. Thanks again gentlemen

[signart]

What about the line from the petcock to the T?  Is it oem length?   Hopefully the petcock repair will do the trick, but something to check out.

[Crackerborn]

When I put a Man-Marc solenoid on (Pingle CH1311 petcock), I made the line too long and thought everything was flowing downhill and had fuel starvation at higher RPM. Once I corrected that issue, I had no more fuel starving. You will swear the line is too short to connect to get a good downhill flow. The vacuum line and petcock are the other likely candidates to cause fuel starvation. You could drain the bowls to see of there is trash there, but since the problem seems to manifest under load, it is unlikely the carbs are problem.

[semo97]

This bike was de-smoged by me back in 06.  Those that have did this you know you plug the secondary air hole to the air box. I threaded the hole to screw in a short bolt. When putting the bike back together the 3/8" air line that Ts and goes to the carbs was put into the hole that I plugged. You guessed it it will not work the carb properly. I reread the de-smog to my son over the phone and the light came on. that line needs to be open for air. My son pulled it out and went for a ride and it is the same old Valk it was before the crash. Thank you to all for your input.