Stuck Valve?

[nakomis0]

Well I tried starting my bike again, and just like last time.. the pipe started to glow red within about 20 seconds.

It has fresh gas, and a big fat jet. Jetting it to rich wouldnt do that, would it? I don't think so.

My quad was hit by a truck real hard last summer and hasn't been rode sense. I think when the truck hit it, maybe it stuck a valve or something.

Thats the only thing I can think of. You guys got any opinions on what would cause my pipe to glow red? Its both pipes BTW, but the one with the sharper bend turns red first.

And how do I tell if the valve is stuck. I know I probably have to take the head off. But how do I go about checking after that?

Thanks.

[Matt400ex_17]

Its not a stuck valve! If you had a stuck valve the quad wouldnt start at all because of compression. I bent one and it had like 5 psi and woudlnt start! my guess would be something is clogged or somethin that your exhaust is heating up see if everything is getting through or if its stuck!

[gojk]

Have you checked all of the intake boots to make sure they are sealed tight and that all the clamps are tight. I left a clamp loose one time and it ran like **** so I knew something was wrong right away.

[nakomis0]

Originally posted by Matt400ex_17
Its not a stuck valve! If you had a stuck valve the quad wouldnt start at all because of compression. I bent one and it had like 5 psi and woudlnt start! my guess would be something is clogged or somethin that your exhaust is heating up see if everything is getting through or if its stuck!

Isn't there something with the valves that would make it do this? Its all I could really think of.

Would a clogged exhaust be the only thing that would cause this?

[nakomis0]

Originally posted by gojk
Have you checked all of the intake boots to make sure they are sealed tight and that all the clamps are tight. I left a clamp loose one time and it ran like **** so I knew something was wrong right away.

All checked, all clamps and everything is ok. The problem is either in the motor or in the exhaust. (I think)

Deff check out the silencer but there are a few more things that youshould look at.

How does it run?

Any smoke from the exhaust?

Check the plug and condition.

Try running it with the choke on (richen the mix) and see if it helps.

Has it been this way since it crashed? What changed?

I seriously am thinking it is somehow lean, and even if its jetted higher there could be something else causing it. The only thing that makes me question this thought is the accident and if it could have caused any internal engine problems etc. So maybe look for and do a comp test for any air leaks into the cyl or any other area that could have been hit in the crash.

Then again it could just be the low temps. I have a friend that pushed his raptor 1/2 mile plus in 7" of snow cause it shut down from running so lean and he didnt know to choke it up to make it richer etc. Funny he didnt get off the couch for two days :)

[nakomis0]

Well I havent rode it, but its a dog to try and start. Backfiring and coughing before it gets warmed up, and then it does idle, but not very smoothly. (It ran perfect before the accident btw)

Not much smoke from the exhaust, an occasional flame every now and then.

The plug, very black. I also thought it was a lean jetting, the main was 175(8), and I bumped it to like a 190 (the next size jet I had handy).

I did remove my exhaust today and looked inside it. Couldnt really tell much, if it was clogged it would probably be in the packing.

Tomarrow, I'm going to get fresh plug, drop the main jet to a 178, and toss the stock exhaust back on. Hopefully it is just a clogged exhaust.

If that doesn't work, I'll go get a compression tester and start looking for internal damage to the motor from the accident.

(It is kinda hard to remember if I took that darn paper towel out of the exhaust ports when I did my frame swap.:huh ..ha!)

I'll let ya guys know tomarrow evening what happens. Thanks for the replies.

Well I havent rode it, but its a dog to try and start. Backfiring and coughing before it gets warmed up, and then it does idle, but not very smoothly. (It ran perfect before the accident btw)

Now that sounds a little exteme for a lean air/fuel mix :) actually that sounds a bit more involved.

First thing I am thinking is that when you are starting and idleing etc its not on the main jet so the 190 isnt doing much if anything.

I would also look into the timming etc cause it would be possible for the crash to have caused a shock to machines drivetrain that could have transfered to the motor

I guess its gonna be a game of trial and error till you find the problem.

[ChadEXer]

I very seriously doubt its a clogged exhaust. If the exhaust was clogged it still shouldnt heat up like that and if it was clogged bad enough to do something like that it would make the bike sound very funny and you could hear it,,,almost like you were holding your hand over the end of the silencer. Its definately a lean condition. I think you should take the carb back apart and check to make sure that it isnt clogged up,,,and also check to make sure your fuel line isnt clogged or pinched anywhere or the fuel petcock on the tank isnt bent or clogged or something. or it could possibly be a slipped timing like 440ex4me said. Checking the compression would probably be a good idea too. If that doesnt work then it beats the he!! outta me! But whatever you do dont ride it that way or you will end up blowing the head gasket or maybe even something worse!

[nakomis0]

Well I wanted to bring this topic back up.

I replaced the spark plug, and found the carb was loose around the boot. So I fixed them problems.

I rode the bike for about 10 minutes. It felt decent, but needed to be jetted a little better. So I think its fine as far as that goes.

But... theres always a but....

The pipe still got red after a very short time.

I also noticed the oil tank was waaayy filled. One change I did when I rebuilt my bike was, put on a used oil cooler.

Do you think something clogged in the oil system would cause the pipe to glow red?

I'm thinking sense the oil flows from the cooler into the tank, that mayeb that used cooler was dirty, got dirt in my oil tank and then clogged up that metal screen at the bottom of my oil tank.?:huh

Just a quick guess, I wont get around to checking it out till next weekend.

But back to the question, Do you think a clogged oil system could cause the pipe to glow red?

[ChadEXer]

Absolutely it would!! It would make the entire motor run pretty hot if your werent getting enough oil flowing to the motor!!