Header Pipes,1 Hot,1 Cold????

[XR400RMan]

Ok as some of you know my 1991 Honda XR250R is burning oil, Taking tomorrow to fix, Well today I went out and Wondered if my valves were heavily carboned and were opening, Well I knew the intake valves were atleast opening because it is still running so its getting air,fuel into the cylinder, So since the XR250R's have 2 header pipes(1 for each exhaust valve)I wondered if they were opening and everything, I know I wouldn't have known if they were to loose or to tight but just making sure they were atleast opening, So I started the bike and let it idle for about 4 to 5 minutes, And while the bike was still running I reached down and touched the left header pipe, it made my finger sting so it was "HOT", Then I touched the right header pipe and I could hold onto it and it would not burn me, It was still pretty cold to the touch, Should I stop riding the bike? What could be wrong? Is it most likely the right exhaust valve is not opening all the way? Any suggestions? Thanks Matt

 

[DEA]

I'll take a stab at it. I would think it to be very warm to touch , but any way. you could check the valve clearance for a very tight valve(which would result in low compression) from holding the valve open all the time. If you adjust it and it's till low on compression it's bent or burn't etc. If it dosen't open at all or very little,( most likley) look at the rocker arm & adjuster(broken,missing etc.) or maybe cam lobe worn off :think: If you don,t have a leak down tester, but have a rubber tipped blow gun. set eng. at top dead center of compression stroke( like adjusting vaves) and hold crank shaft bolt blow air into cyl.through spark plug hole & listen for air escaping through ex. pipe. You can try this first for a quick check. Also, I belive the compression release mechanism work off of the right side
p.s I'm shure you'll get some more ideas

 

[DualSportr]

C'mon XR400man, just get it fixed!!! I can't believe you're still on this subject.

Yes, both pipes should be more than warm to the touch, yes the problem is that one of the exhaust valves is now so gunked up that it's not flowing correctly (or isn't even opening - which is infinitely worse).

Remember when I said that if you DIDN'T get the smoking problem fixed soon you'd start to see more problems. Guess what!!! Here's one of 'em!!

Look, I don't mean to be so rude and sarcastic, it's just, well, gee, you're beating a near-dead horse here. And you know the cure.

Fix the danged thing already!

 

[XR400RMan]

Dualsportr I haven't been riding the bike, I haven't rode it in about 2 1/2 weeks now, I just went out to warm the bike up and then checked that and thats when I noticed it, Were taking it today to get it fixed, Matt

 

[jmics19067]

buy the manual! buy the tools you need to do the job! and do it yourself ! sounds like it too me you are having problems with finding someone qualified to do it in your neighborhood! live ,make mistakes, and learn!!! dont worry about buying the special tools for measuring the cylinder and piston for right now. buy a dozen donuts and a few coffees and ask the local a machine shop to do you a favor measuring everything while offerring the goodies up. While it is a difficult diplomatic skill try and ask as many questions to the guys eating the donuts while not becoming a pain in the but. ask if you can sweep the shop for them afterschools and saturdays so you can learn .

 

[DualSportr]

<<Were taking it today to get it fixed, >>

Excellent! Tell us how it turns out, okay?

 

[XR400RMan]

Sure will Dualsportr, My dad wanted to tear it down so bad himself but He's got so much to do at work that he couldn't do it, Oh well. Anyways I will tell you all what the problem is when I get it back. Thanks Matt

 

[XR400RMan]

Ok didn't get to take to bike to the shop on Friday, I am really dissapointed. My dad left work and got home in the truck,GOt the the tie downs out and the phone rung and his work needed him for SOMETHING so he had to spend a great deal of time on the phone and then had to go meet some guy, So today(Sunday) my dad and I went out and since the shop was closed he was going to check the valves, He asked me which one was staying cold and I told him the Right Exhaust valve when your sitting on the bike, So he had me start the bike and let it run for about 5 mins, The right one he could hold onto and it was just a little warm but the left one was blazing hot. So he took the right timing plug out and there is "alot of play between the rocker arm and Valve, By the time the rocker arm gets about to the end of its travel it just barely compressed the exhaust valve and then the rocker goes back up, So he took the left timing plug off and it was not like this, He had me turn the engine over till the left exhaust valve was opened and it was in spec. So my question is could this be letting my bike burn oil? I have been hearing some internal engine noise since I had the bike and this is where it was coming from so since most of the exhaust gases were being pushed out of the left exhaust valve could this have messed anything up? My main question is could my bike burn oil because of this? Well Dualsportr I let you know that much, Hate we didn't get to take it to the shop though? Matt

 

[DEA]

Sounds like it's(right side ex.valve) either way out of adjustment &/or the lobe on camsfaft is wiped off
ps "BUY THE MANUAL"
It'll make a good father-son project :D

 

[XR400RMan]

DEA could this make the engine burn oil though? I have a great Clymer manual but I am not going to attempt doing anything to the engine unless my dad is watching over me, He has just had so much things to get done at work, When he gets home he's just wore out. Oh well we'll see.Mattt