‘98 tourer high revs

[peter]

Hi All, haven't been here in a while. My '98 tourer runs fine up to 4k but doesn't want to run any harder than that. Great throttle response up to 4k rpm but totally gags over that. Any ideas??
Thanks,
Peter
PS miss my buddy Bill Ferguson (Big BF) who looked after my bike for years.

[WintrSol]

So, does it do this in all the gears, or just the top gears? Also, how is it running when it stops accelerating - feel like it's starving for fuel, or just doesn't go?

[peter]

I haven't ridden it yet through the gears, but it bogs down badly between 3 and 4k in neutral. Feels like it's fuel starved. I can get it to run at those rpm's but it takes working the throttle. Maybe a fuel line either is kinked or has a leak?

[98valk]

good chance the OEM petcock diaphragm has failed. simple rebuild.

[peter]

Great idea, thank you. Is there a simple test or is it easy enough just to pull it and inspect? Hope this is the case, easy fix
Peter

[f-Stop]

If you have a Mighty-vac or something similar, you can pull the #6 carb's vacuum hose from the #6 intake manifold and see if it holds a vacuum.  (Doesn't take much vacuum to test it.  Also, check for cracks or leaks on the #6 hose) Or you could use the old "suck on the hose and hold on the tongue" test on the same #6 vacuum hose.

These Cover Sets only last about ten years...

[peter]

I'll give it a try, thanks much.

[98valk]

These Cover Sets only last about ten years...

that's why I installed a Pressure/Vacuum Snubber in the vacuum line to extend the life of the diaphragm. going on 20 yrs now.

[Jims99]

If it's been sitting awhile, may also want to check exhaust, make sure nothing climbed in.
Also try some gas treatments. Sounds like something simple (

[longrider]

I would be thinking it's dirty main jets.  It will run up to 4000 on the pilots if the throttle is eased up. It is  starving after that

[peter]

So it turns out I had my petcock on reserve by mistake (duh). Once corrected to "0n" it ran great, problem solved. But why did it run worse on reserve? The tank was half full, not near empty, would that cause this? Hey, I'll take the win..

[The emperor has no clothes]

So it turns out I had my petcock on reserve by mistake (duh). Once corrected to "0n" it ran great, problem solved. But why did it run worse on reserve? The tank was half full, not near empty, would that cause this? Hey, I'll take the win..

There have been occasions when I didn't have the petcock fully seated in the reserve or on position. Sounds like that may have been the issue. If you have the chrome engine hangers this is more likely to be a problem.

[peter]

Interesting and I do have chrome engine hangers, sounds like you're spot on, thank you!
I tried posting a pic but it failed to post...

[98valk]

Interesting and I do have chrome engine hangers, sounds like you're spot on, thank you!
I tried posting a pic but it failed to post...

I have the hondaline chrome hangers installed since '01. zero problems turning the petcock with them installed.

[The emperor has no clothes]

Interesting and I do have chrome engine hangers, sounds like you're spot on, thank you!
I tried posting a pic but it failed to post...

To be clear, the chrome hangers aren't a problem themselves. But if the petcock selector is mounted to them with any slight binding, it can keep the petcock detents from lining up correctly.

[Jims99]

I would check filter next time you have your tank off. Could have a little buildup around reserve level. Try switching to reserve again and see what happens. You don't want to find out if it's working or not at a time of need.

[rug_burn]

   On my Valk, the fuel flow seems to be restricted the lower the tank gets on reserve... It runs, and won;t quit, but noticably lacks power, and it gets worse the lower the fuel level gets.
   This could be a planned design feature to make it clear that it's going to die on you real soon if you keep going without a fill-up, or it could be because the filter screen on the fuel intake tube in the tank it partially clogged up with crapola of some type or other, especially at the bottom of the screen...  which is what I think it is caused by (maybe I could check that next time i pull the tank?)
   

[The emperor has no clothes]

   On my Valk, the fuel flow seems to be restricted the lower the tank gets on reserve... It runs, and won;t quit, but noticably lacks power, and it gets worse the lower the fuel level gets.
   This could be a planned design feature to make it clear that it's going to die on you real soon if you keep going without a fill-up, or it could be because the filter screen on the fuel intake tube in the tank it partially clogged up with crapola of some type or other, especially at the bottom of the screen...  which is what I think it is caused by (maybe I could check that next time i pull the tank?)
   

Yes, you should check it. Could also be a cover set starting to fail, or a leak in the vacuum line.

[peter]

To my embarrassment I had my tank on reserve for some reason. Once the petcock was "on", the bike ran normally. I put it back on reserve and the problem reoccurred, gagging over 4k. So my issue is limited to the reserve fuel line.
Thanks for all the responses

[Chrisj CMA]

To my embarrassment I had my tank on reserve for some reason. Once the petcock was "on", the bike ran normally. I put it back on reserve and the problem reoccurred, gagging over 4k. So my issue is limited to the reserve fuel line.
Thanks for all the responses

There's no such thing as a reserve fuel line on a Valkyrie. You may have some debris in the tank blocking the reserve pick up or a faulty petcock although I never remember hearing of a petcock behaving like that.

[0leman]

Just wondering, is it possible the "reserve" setting is not going into the reserve slot, so only a portion of the gas is flowing to the carbs???  If there was a blockage on the fuel filter in the tank, why would it effect the gas flow when the tank was full or at least over the top of the blockage? 

[Willow]

Just wondering, is it possible the "reserve" setting is not going into the reserve slot, so only a portion of the gas is flowing to the carbs???  If there was a blockage on the fuel filter in the tank, why would it effect the gas flow when the tank was full or at least over the top of the blockage? 

And that makes most sense as the reserve position receives fuel for the full length of the fuel strainer.  If there was a blockage low it would show up only when the level of the fuel was at the lower part opened by the reserve setting.

[da prez]

Remove tank. Drain fuel. Remove petcock. Rebuild petcock and replace vacuum lines. If strainer is distorted, install a new one
. Easier in shop than on roadside.

               You owe me two cents.
                          da prez