New To ATCs - Just got an 85 ATC 125m

[jeepvolks]

I got this trike for next to nothing and would like to get it running. I'm pretty good with working on small engines and wondered where to start with compression issues. I'm getting like 15 lbs on my compression gauge and I think it's supposed to be more like 175 lbs. I can remove the pull start and turn the engine with one hand without much problem and can hear that it does have some compression due to the swoosh coming from the carb air intake. Where should I start? I think the local shop charges $60.00 to bore and tell me which ring set to go with.

[Robosnow]

15lbs compression. hmm.....Just a quick question....what steps/how did you check the compression? Also find out for sure what the compression is supposed to be. 185 seems high.

[dustrunner]

i betting it a stuck or bent valve.. or valve trane problem..

[jeepvolks]

I haven't done much. I downloaded a short manual for this model and that's where I got the 175 lb number. I'm going to pressure wash the whole trike this evening so I can disassemble the top end without filling it with oily sand. I tried to follow the procedure for adjusting valves, but I'm not totally certain I did it the correct way. I did notice when adjusting them, there is some side-to-side play in the rocker arm. I have a compression gauge that threads into the hole and has a hose with the gauge at the other end. I threaded it into the spark plug hole and pulled the starter cord a couple of times and it doesn't go above about 18 lbs.

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[jeepvolks]

Head is off. I'm trying to get the cylinder off now, but it will probably not happen until tomorrow evening. This is what it looks like inside. There's quite a bit of oil at the bottom (towards the ground) and also thick brown and black carbon:

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[jeepvolks]

I believe this is a good indication of the engine being run with low or no oil. Would I be wasting my time to rebuild the top end or should I be concerned about bottom end problems also?

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[fabiodriven]

That's not something that we can answer. You can tear into it and inspect everything, or you can do the top end and keep your fingers crossed.

Is this an 85 124M or an 86? There is a huge difference between the two. The 85 has the "laydown" motor and and 86 is a more standard "upright" style.

[thestud25]

I do not see any broken rings. How was the wrist pin bearing? Were both C Clips there? I would drain the oil through a screen, check to see if there are any metal shavings or chunks, and if not those are good signs that the bottom end may be fine. Is there much play in the rod? if it was ran real low on oil you may want to check the crank bearings. Best of luck.

[jeepvolks]

It's definitely an 85 model. It says so on the side of the frame and also says manufactured in 08/84. Everything else seems to be checking out. All components from the piston were there including the clips and such. I dropped the cylinder off to be bored and honed. Once I find out how much had to be taken off, I'll order a new piston and ring set. I'm going to hope for the best and see how it goes. I did have to cut one of the long cylinder bolts off due to heavy corrosion about halfway down and the fact that the cylinder wouldn't come off over it. The other three look perfectly fine. One bolt, top end gasket set and those little metal sleeve things that go over the bolts into the head and cylinder are also needed. Once I have this thing running (hopefully), I'll figure out how to make a seat from scratch since there's nothing left of the original one.

[fabiodriven]

It's good you noticed the dowels. Many guys overlook them and they are a very crucial part.

[beecj0]

Good luck, and keep us posted.