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Post by catchacuda on Jul 13, 2019 0:15:52 GMT -5
Is any body at all familiar with this engine? From what I can tell its based on a Honda design. I'm trying to see why my daughter's friend's atv has no compression. 107cc is cast on the cylinder,the engine tag says xye152fmh. It's a 4 stroke.
Any input is appreciated. I plan on verifying cam and crank timing, checking out the valve adjustment and if necessary, pull the cyl.
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Post by 90GTVert on Jul 13, 2019 7:37:12 GMT -5
Sounds like the pitbike style engine. 107cc is what they usually call a 110. Pretty much like most engines when looking for compression loss. I can't think of any 1 widely known cause for that particular engine. You can try a few drops of oil in the plug hole and see if compression goes up, but if you find that nothing is off with the cam timing or valve adjustment, you'll be pulling it apart anyway.
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Post by catchacuda on Jul 13, 2019 22:38:57 GMT -5
Thanks Vert, I appreciate the reply. From what I've found, it does seem to be really common in pit bikes. It literally is making no compression, I'm told they were riding it and it just stopped.
They cleaned the Carb after looking in it and finding a lot of junk and corrosion. My thought is maybe something restricted the carbs fuel and it leaned out and melted down. I guess I'll find out soon enough, though I can't get to it until the 20th.
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Post by catchacuda on Jul 27, 2019 12:23:19 GMT -5
Choke plate and screw were missing in the Carb, went into the engine! There's now a new engine on the atv, but it's idling high, and Carb adjustment is having no effect. I ran out of time yesterday, but I'm thinking there's an air leak causing the current condition.
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Post by 90GTVert on Jul 28, 2019 8:14:11 GMT -5
Air leak would be my first guess as well.
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Post by catchacuda on Aug 16, 2019 18:48:37 GMT -5
Well I can find no signs of an air leak. Sprayed all over with it running and noticed no change in idle. New Carb on it just because. Same as before, idle screw and low mix screw adjustment change nothing. It settles down with the manual choke on, when off, the RPM just sit way too high for an acceptable idle. I've got to be missing something.
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Post by catchacuda on Aug 17, 2019 10:36:36 GMT -5
I may be rambling to myself but that's quite alright. Now I'm just wondering if maybe it's simply jetted way too lean. This thing came stock with a cone filter.
I'm almost tempted to take the jets out of one of the carbs and enlarge them just to see the effects. If there is a change for the better, I'd buy a jet kit.
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Post by 90GTVert on Aug 17, 2019 15:58:48 GMT -5
Does the old filter fit? You could see how it acts with that. Another option would be trying to restrict some flow through the filter with tape to see if it then peps up. That's easier than boring out jets to get an idea of what you need to do.
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Post by catchacuda on Aug 17, 2019 20:13:52 GMT -5
The old filter is the same cone type, same deal. I figured since it's much better with the choke on, it must be pretty lean.
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Post by catchacuda on Sept 24, 2019 13:29:56 GMT -5
Finally found the problem. It was so simple, I feel silly. The throttle cable's exposed length (where it hooks into the Carb) was too short. Even with the cable's adjustment all the way in, too short. The slide/needle would never seat fully.
Put the old cable back on and it
runs great now.
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