97 Valk 18,000 miles falls flat on its face at 3,000 rpms.

[Pipes]

Replaced vacumm lines replaced pet rooster still runs flat! Took Cobra exhaust off this spring.Went back to stock. Seems to be running rich. Any suggestions? Don't know if rejeted when Cobras were put on !
I live in Mi. Any experienced Valk mechanics close to Lansing Mi?

[Gavin_Sons]

clean the carbs. souns like you may have a main jet or 2 clogged. i had the same problem. chased it for 3 years before finally deciding to pull the carbs. had 2 main jets clogged. fixed my problem 

[Ricky-D]

There's a lot of riders that have gone big when rejetting because of changing exhaust pipes. It sounds as if that could be your problem, so I suggest to investigate and see what if anything has been done to the carburetors.  First thing I would do is look at a needle/slide and see if it is an aftermarket needle or a stock needle that has been shimmed. It needs to be stock with no shim. It easy to tell an aftermarket needle because it will have a clip and slots for adjustment. As I said, it needs to be stock with no shim. You can pull a float bowl and inspect the jets. they should also be stock. #35 slow and #100 main. Getting back to stock running condition should solve your problem.

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[gordonv]

I'm usually a big one for doing what is easy first, try the carb cleaner.

1/2 can of Berryman B-12 in 1/2 tank of Techron fuel. Take it out and run it in those rpms that is giving you trouble. 1/2 hr or so. Let it sit over night. Repeat. Take it out and run the tank down, refill and see how she's behaving.

With Cobras installed/removed, I would do like Ricky-D suggested, and check to see what is in there. A very good chance that it's not stock, and with the removal of the pipes you want it back to OEM.

[98valk]

Replaced vacumm lines replaced pet rooster still runs flat! Took Cobra exhaust off this spring.Went back to stock. Seems to be running rich. Any suggestions? Don't know if rejeted when Cobras were put on !
I live in Mi. Any experienced Valk mechanics close to Lansing Mi?

if the cobra jet kit was installed with the pipes, it is only mainly different needles which are very rich. the kit never changed Main Jets, it should never have been called a jet kit.
too rich will not cause it to run bad at 3k rpm. something else is going on. did u replace petcock with new? if not install a new diaphragm kit.
make sure tank vent line is not clogged.

[Gavin_Sons]

Pull the carbs and clean them, like I said,  I dealt with the same issue for 3 years,  everyone here was having me chasing ghost.  Ricky even told me my motor was old and worn out  decided to pull the carbs a week before a trip and found 2 clogged main jets. I man dozens of bottles of seafoam through it with no results.  Ended up replacing all my jets and needles. Runs perfect now.

[falconbrother]

Was it running good before and then started going flat?  What changed?  If you bought it that way I'd think the main circuit in the carbs is the problem. 

[Gavin_Sons]

Any news on this? Would like to hear what the problem was if you found it.

[Pipes]

No luck yet? New Petcock,,vacumm lines, cleaned carbs,stock jets . Still falls flat. Honda tech has been trying to figure out. Has had no luck. Trying process of elimination any suggestions ? Please

[pitbull]

I have similar issues with my Valk, a 97 standard with 35k on it.
Mine seems to bog down worse if I have a pillion on.

I've read somewhere it could need the tappets adjusting or one of the ignition coils is weak and struggling under load.

When I've got some spare time I'll adjust the tappets and check the coils.

[Ricky-D]

You say stock jets, but nothing about the needles. The needles have a greater influence that the jets.

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[98valk]

You say stock jets, but nothing about the needles. The needles have a greater influence that the jets.

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R-D,
the MJ has the most influence. U always tune for best MJ first and then everything else. any other way and perfect tuning will be off.

[Pipes]

Yes I also replaced needles last week. Still runs flat!

[Blackduck]

If you are having this work done by a shop it maybe cost effective to have it run on a dyno with exhaust analyser and see just what the problem is..
Quick check is run it and when it falls off, wind the enricher (choke) on and see what happens.
Have you done a spark plug check? Run it at speed, shut it off and coast to a stop. Pull the plugs and check the colour.
How long have you had the bike and has this been a problem the whole time?
Cheers Steve

[Ricky-D]

Well, if the carburetors are all back to stock configuration and you are still having the same problem, I suggest to look at the trigger wheel and insure it is also stock OEM. Some have modified the stock wheels improperly, installed them wrongly and other. If there's an aftermarket trigger wheel, I'd suggest to change it out to stock, in attempting to get the bike running properly.

I should mention this, (even though you said you changed them out) that the vacuum hoses, if incorrectly routed to the wrong connections, can cause running problems. There is a thread regarding desmogging the engine that addressed the problem of incorrect routing of the hoses which, although I cannot remember the particulars, dealt with similar type running problems.

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