Starting/valve questions

[Agitator]

I have a '94 husky wxc 610. It usually starts first kick (choke and no throttle) and runs flawlessly. Today was a different story. The bike started first kick, but then stalled. I was able to restart it a few times and it would promptly stall. I finally started it and held the throttle at a high idle.. maybe 2500rpm. After a while, I wanted to see if it would idle.. cut the throttle.. it died.

I kept trying to restart it, but it backfired a few times (never happened before) and kicked the kick starter back on my foot really hard :uh: I figured I'd use the compression release to reduce this.. I started hearing the engine kick every now and then (no choke) but when it kicked, I'd hear a clank :fft: I figured this was because of the decompression mechanism holding the exhaust valve open. I tried w/o the decompression lever pulled. Still got the clank. I don't want to get the engine running only to fry my valves because they are improperly adjusted.

I have run the bike several times since the valve adjustment, but only a total of 15-20 minutes. It has run fine until today.

My valves are set at:
Intake: .004
Exhaust: .006

I asked about the clearance before, but want to make absolutely positive it is correct.

Also- if someone could please explain why improperly adjusted valves will fail, I'd appreciate it. I know that having valves properly adjusted is crucial... I'd just like to know more about it.

Thank's.

 

[Agitator]

Update:
I dumped the carburetor bowl. There was garbage in the bottom... gnarly. I cleaned it and put it back on... I had a feeling the jets were already clogged though. same problem

I drained some gas outta' the tank to check it and there were little white thingies in it. I decided to buy an inline clear filter to help keep the gas entering the carb clean, as well as to provide an inspection window.

I cleaned the freakin' carburetor again. Still no starty. Same backfiring issue, too.
Maybe my ignition timing slipped or something. My foot hurts.

Please give me a hand, guys.
Thank's

 

[76GMC1500]

Did you clean the jets? Also, if the idle air screw is downstream of the slide, it is a fuel passage and may also be clogged. Why not check your valve lash? It's really easy to do. A valve adjusted too tight will fail because the valve never fully closes against the valve seat. The valve needs to spend time on the valve seat to transfer heat from the valve into the cylinder head and to the jacket water. If the valve never closes, it overheats and burns. It also makes the bike hard to start because you lose compression. A valve ajusted too loose costs you power because you lose valve lift and duration.

 

[Agitator]

yes, yes. I cleaned all the jets very carefully, as well as the fuel screw passages. I have checked my valve lash. I just didn't know if what I set 'em to was right. Also- I agree that the valves can be damaged by being imporperly set, but This would not cause my particular problem, because the bike used to run with the compression release pulled... when I went to start it.

My valves are set to:
intake: .004
Exhaust: .006


I finally got a hold of the potential answer!
a few days ago: bike ran
Now: no run

I removed the supertrapp endcap and plates/spark arrestor from my pipe to clean them in solvent. When I put the discs back, I think I overtightened them, which might cause excessive back-pressure... This would explain it. If exhaust cannot escape the pipe, the engine'll start and then stall as pressure builds. also- it would explain the nasty backfires and kicking-back of the starter. The clanging I heard (only after the engine tried to run) could be the exhaust pressure from the pipe opening the exhaust valves and flowing back into the cylinder, due to the excessive pressure...

Tomorrow, I'll yank that sucker off and give 'er a kick.

 

[Agitator]

Well. Removing the silencer tip did absolutely nothing to help the problem. I decided to check my valve adjustments. They hadn't moved. I reset them just in case though. I talked with George Erl and he said to attack the pilot jet again. So, since I trust what he says and have explained what I've already done, I went back to the carburetor for the fourth time!

I didn't find anything in any of the jets, but i know that the little particles do a good job at playing phantoms. I blew all the jets out, after removing them, and I ran copper wire through. I then sprayed carb and choke cleaner through them all. I get a clean stream through the pilot jet, so I think it is clear. I'll give it another look today before I put it all together.

I'm going to pop the flywheel and check that the stator has not moved on its mounts... that would advance/retard the timing and give me problems..
Do you guys know where the mark is on the case of the engine (that you align the stator with)?

Thank's again.

 

[levert]

Blocked fuel vent on your gas tank?
Try running without your gascap.

 

[Agitator]

That's a good idea. I have a full carburetor bowl everytime I check and the vent works though.

I found the problem!!!!!!!!
Before I obsessed over the carburetor before assembling it, I thought I"d check the flywheel. I popped it off and found a sheared key! AHA!
I had thought the key was all right- it seemed okay when I looked before. now I know... I'll properly torque the flywheel nut next time. I asked george for the right torque rating. He's sending me some flywheel keys as I type this.

I'll report back after I get the keys/try to start it again.
Thank's again, guys!