Gx200 clone valve adjustment

[eljefino]

Ten year old Predator 6.5 hp engine on my snowblower. No air filter, jetted slightly richer, otherwise stock. Might have 100 hours on it, which "they" say is valve adjustment time.

Spontaneously died. Pulling the rope showed almost no compression.

Adjusted for 0.005" cold on both intake and exhaust, as recommended on youtube, LOL. This gave it ALL the compression, I could barely pull the cord!

Brought my kid out, who, at 13, just had a small engine class at school. (!) He worked on a Briggs, though, LOL. As an educational moment on something I was going to either junk or table until spring (I have a spare snowblower), I started showing him how to adjust the valves and the effect it had on the pull rope.

Well, wouldn't you know it, without any feeler gauge involved I tightened things and found the sweet spot where it pulled over like new. Just for grins I put it together and it ran better than it had in a while, no more "lean surge" at high RPM/ low load.

What gives? I'm aware there's a compression release doohickey, but doubt it's the problem. Fiddling with the actual clearance should make it run terribly if it's covering for a broken one of these.

 

[fantastic]

If the valves are too loose it doesn't open up the compression release on the exhaust camshaft lobe.

 

[andyd]

Valve seat recession. My BIL scored an Isuzu Trooper for 500$ that was down on power. He adjusted the valves and drove it until the body rusted out. My son wasn't so lucky with a '99 CRV. It burnt an exhaust valve in #4. 1/2 a@@ driveway fix to replace 2 valves only, got 65K more miles out of it.

 

[TheLastWord]

Kudos for you and your son!

A small engine class in school?? Public or private?

There is still hope for America.

When I was in seventh grade, every student, boys and girls, took 12 weeks of woodworking, (and 12 weeks cooking and 12 weeks ceramics). Every student, among other things, built a 5 ft step ladder. It is still in my sisters basement in great shape. Wisconsin schools 50's and 60's. Quite a sight to see 75 lb girls lugging that thing up into a school bus.

Got off on a tangent. I have never had to adjust valves on MANY Honda GX or Chonda clones. Other posters are good.

Those Predator 6.5 hp are still one of the best values anywhere.

 

[mk378]

If the valves are too loose it doesn't open up the compression release on the exhaust camshaft lobe.

Yes this also happens on the Briggs twin, which despite having an electric starter also relies on compression release. It will turn part way then stop on the compression stroke like the battery is weak.

 

[meep]

I have the same 6.5hp predator. The compression release mechanism has often gotten stuck on mine, making it impossible to pull… the force required feels like it will rip the starter mechanism apart.

after disassembling the engine twice, I discovered that a couple of meaningful taps with a hammer on the case where the camshaft bearing sits does the trick.

the release mechanism is very small, and sits on crude metal on an unfinished portion of the cam. the spring holding it is very small, and thus it gets easily stuck.