Issues with 225dx, I thnk it's timing.....

[Serious Tim]

Picked up a 225dx for my girlfriend, the story is that it just quit running, the guy had assumed that it had no spark, but never checked.

Getting spark fine, but very low compression. With the plug out, you can see that the valves are moving, and when kicked over with the electric start, you can feel wind coming out of the plug hole.

This leads me to believe that the timing is way off (figuring a valve is open during the compression stroke), that I have either a broken chain guide, or it slipped out of time somehow.

I figured this out this morning while thinking about it for a while. With the timing that far off, what do y'all think that is the most likely situation?

[Yamada]

It is really easy to check the timing.
Remove the plug big plug near the pullstarter on top of the engine case with a flat screwdriver. Then remove the cam cover on the left side of the head ( left side) Then turn the engine slowly by hand and look into the hole for the T mark. After you found it, check the mark on the cam sprocket. There is a arrow casted in the head and a line on the cam sprocket. Everything should line up.

[Serious Tim]

Thanks for the great advice!

I checked, and the timing seems dead on. The cam sprocket mark is pointing directly downward with the T mark exposed through that hole.

The compression tester I used on the engine was an older kind with a rubber grommet, so it's possible that it didn't seal all the way, who knows. My good one didn't have the right size for that plug hole. When cranking, I can feel the engine sucking air in on the carb.

Next is the spark......it isn't the brightest, but I can feel a decent jolt from the plug wire (accidentally became the ground for the plug during a test), so maybe it's the CDI after all.....

[Yamada]

Thanks for the great advice!

I checked, and the timing seems dead on. The cam sprocket mark is pointing directly downward with the T mark exposed through that hole.



The cam sprocket is suppose to be pointing upward. Make 1 more turn of the crankshaft, the mark on the cam sprocket is suppose to point a arrow casted into the head.

[Serious Tim]

Didn't see any arrow casted in the head, but I'll try to examine more closely. There was no slop in the chain at all, which I'd think you'd expect if the timing was off somehow? Considering, that the story was that it was running, then quit....

[MonroeMike]

There's a manual for that 225. Maybe that could help you out some more.

http://www.3wheelerworldforums.com/showthread.php?t=56218

[Serious Tim]

That does help, I'm going to check rocker arm clearances, etc as well.

But here's the thing I'm up against now. I replaced the ignition stator coil because the spark was weak, now I've got a bright blue spark and still nothing. The carb is going to need going through, but I assumed with either some ether or gas in the plug hole, that it would fire, but no go.

Next step is to get a known good compression tester and recheck the readings.....

[Serious Tim]

Got the compression tester, and I get a whole 20 PSi :(

[Cert88]

If it was running and just quit... the valves could have gotten bent....so when one of the valves should be seated it is not sealing correctly and you arent getting good compression....This is caused from either incorrect timing or over revving the engine..

But if you never heard the trike run yet...double check your timing and valve clearances....once they known to be correct, take off the head...turn it upside down, pour some gas in head and see if it holds the gas and doesnt leak through the valves...that is a quick test to see if the valves are seated pretty good.....

if all of those steps pass, than you might need new rings, or a bore.

[mmiguy2103]

do a leakdown test