Symptoms associated with valves out of adjustment

[Mesquito Creek]

Can someone describe some of the typical symptoms that would be
associated with the valves out of adjustment on a 350 cc yamaha four
stroke motor?

Here is what I am observing:
Good idle
Good low and mid range through the powerband
Missing or cutting on the very top end when rpm/speed is held hot on
the throttle...

Symptoms occured at the first of year start up after performing
maintence:
Clean air filter (removed the box completely cleaned it), new spark
plug, fresh oil, adjusted clutch, drained tank put new gas.

[Anssi Lehtinen]

Post by Mesquito Creek
Can someone describe some of the typical symptoms that would be
associated with the valves out of adjustment on a 350 cc yamaha four
stroke motor?

Bad starting is the most obvious one.

Post by Mesquito Creek
Good idle
Good low and mid range through the powerband
Missing or cutting on the very top end when rpm/speed is held hot on
the throttle...

Sounds more like carburetion issues (not enough fuel due to bad fuel
level or clogged main jet) or ignition crap. Both of these are
something that could happen in a period of inactivity. Valves are not
very likely to go out of adjustment when the bike just sits.

[john]

Post by Mesquito Creek
Can someone describe some of the typical symptoms that would be
associated with the valves out of adjustment on a 350 cc yamaha four
stroke motor?
Good idle
Good low and mid range through the powerband
Missing or cutting on the very top end when rpm/speed is held hot on
the throttle...
Symptoms occured at the first of year start up after performing
Clean air filter (removed the box completely cleaned it), new spark
plug, fresh oil, adjusted clutch, drained tank put new gas.

hmm
removed air box.......
check for air leaks from the air box
to the engine where the air goes into the
cylinder. While bike is idling spray wd-40
or some other combustible spray that
won't hurt the motor around the air box, rubber
boot from air box to the carb, carb to cylinder boot...
Check the seal that you smeared filter grease on
of the air filter to the air box to see if the air is bypassing
the filter...

if you have leaks then the bike will run lean
at high rpm's this is really bad & kind of bad
at lower rpm's

[Russell H.]

You may want to check that the spark plug is gapped correctly.
Too wide a gap will cause top end misfiring, although it will be OK the
rest of the time.


RH

[BKR]

Post by Mesquito Creek
Can someone describe some of the typical symptoms that would be
associated with the valves out of adjustment on a 350 cc yamaha four
stroke motor?
Good idle
Good low and mid range through the powerband
Missing or cutting on the very top end when rpm/speed is held hot on
the throttle...
Symptoms occured at the first of year start up after performing
Clean air filter (removed the box completely cleaned it), new spark
plug, fresh oil, adjusted clutch, drained tank put new gas.

I had exactly the same symptoms with My XT 350 during its break in
period. I took it back the dealer under warranty, and they found that
it was a small fragment of plastic or rubber that was partially blocking
the main jet in the vacuum controlled side of the dual carburetor system.
It was an easy fix and I got it back the next day.

BKR XT350

[Dave Gjessing]

Didya check the valves?

[Mesquito Creek]

Thanks for the suggestions, I will re-check the recent maintenance work for
errors and stick with fuel/carboration issues. I will hold off on the labor
intensive process of checking the values...

Post by Mesquito Creek
Can someone describe some of the typical symptoms that would be
associated with the valves out of adjustment on a 350 cc yamaha four
stroke motor?
Good idle
Good low and mid range through the powerband
Missing or cutting on the very top end when rpm/speed is held hot on
the throttle...
Symptoms occured at the first of year start up after performing
Clean air filter (removed the box completely cleaned it), new spark
plug, fresh oil, adjusted clutch, drained tank put new gas.

[Volker Bartheld]

Hi!

Taking off the carb(s) and cleaning them sounds like allot more work
than checking for valve clearance "if" that's what "you" think is the
problem.

You seem to never have done that with a YZ426. Checking (and even worse:
adjusting) valve clearance is no fun here. Hrhrhr.

Adjusting valves is just topped by changing fork oil without having a
cartridge holder. ;-(


Volker

_
@: v b a r t h e l d @ g m x . d e * 3W: a c h i l l e s . g m x h o m e . d e

[Mesquito Creek]

It my wifes 1998 yamaha warrior. Sounds to me from the posts that the off
season inactivity is more likely fuel/carb,... or my maintenace work which
was more in the area of fuel and carb..

On Thu, 04 Sep 2003 22:52:54 GMT, "Mesquito Creek"

Post by Mesquito Creek
Thanks for the suggestions, I will re-check the recent maintenance work for
errors and stick with fuel/carboration issues. I will hold off on the labor
intensive process of checking the values...

Taking off the carb(s) and cleaning them sounds like allot more work
than checking for valve clearance "if" that's what "you" think is the
problem. Sounds like a fuel related problem IMO tho.
You never said what year bike this was on, it doesn't have a points
ignition does it?
MurMan

[D&L]

Check the carburetor for a hidden fuel filter under the fuel valve seat.

Doug
Folsom, Calif
2003 KX500 (the Hulk Returns)

Post by Mesquito Creek
Can someone describe some of the typical symptoms that would be
associated with the valves out of adjustment on a 350 cc yamaha four
stroke motor?
Good idle
Good low and mid range through the powerband
Missing or cutting on the very top end when rpm/speed is held hot on
the throttle...
Symptoms occured at the first of year start up after performing
Clean air filter (removed the box completely cleaned it), new spark
plug, fresh oil, adjusted clutch, drained tank put new gas.