Engine rebuild trouble - 125cc

Parsleap · 08-30-2020, 08:31 AM

Ok, so I’ve run up against some troubles in repairing my daughter’s 125 quad. Let me start from the beginning.

She had a piece of the “choke gate” in the carb break off and get sucked into the intake, where it lodged itself under the valve and bent it. I bought a new Carb and a new top end that I thought was right - turns out the top end wasn’t. But I ended up being able to use the new intake valve from the incorrect top end - was an exact fit.

In the process I took the engine apart - at least on the timing chain side - tensioner, oil pump cog, all that were in view. Learned how to time the engine and all that - I’m not afraid to learn on YouTube and tear things down and build them back - fun for me but I’m no pro by any means.

But there are a few things that have gone wrong, I fear. First, I found a small, dense solid metal cylinder in the oil catch pan i used under the quad. Will try to post a pic. I never recall seeing it in taking the engine apart. It looks like something from a clutch on other engines - but I never got into that side of the engine. The quad does reluctantly start and run, but has a clicking noise and seems to get very hot to the touch on the top end. I have a nearly identical quad that’s running fine and can start and run to compare - it doesn’t seem to get nearly as hot just sitting at idle.

So can anyone offer advice? I did pull the oil pump cog and shaft out and put it back in when playing with the timing chain. And it took me a while to figure out I’d bought the wrong top end (28 vs 32 tooth cog and engine not staying in time was the giveaway - but it took me a while). This metal cylinder - is it a weight from a clutch? A piece of a pump assembly that inadvertently fell out?

I haven’t gone beyond idle cause I don’t want to tear it up worse if it’s not getting good oil. But my daughter is on me to get this thing fixed and get her riding again. Any help appreciated.

Bruces · 08-30-2020, 08:47 AM

We need a picture of what you have ,

Parsleap · 08-30-2020, 09:56 AM

OK - put photo in. Thanks for any help in advance!

Parsleap · 08-30-2020, 10:12 AM

Note: It is entirely possible that this cylindrical piece is entirely unrelated to the rebuild, and somehow a kid found a piece on the floor and threw it in my catch pan - but I just don't know. Nevertheless, i still have the clicking sound as it idles and feels like it's running hot.

Bruces · 08-30-2020, 10:13 AM

I think that’s from the timing chain tensioner

Parsleap · 08-31-2020, 10:17 AM

I thought it might be from the tensioner too - sitting atop the spring. But that piece is a black plastic like piece that is tapered. and this piece is too big of a diameter to go in the spring or in the body of the tensioner tube (whatever that thing with the multiple holes is). So I don't think its the tensioner bolt/tube/spring - but that was my first guess as well.

08-30-2020, 08:47 AM	#2
Bruces Join Date: May 2018 Posts: 1,586	We need a picture of what you have ,
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08-30-2020, 09:56 AM	#3
Parsleap Join Date: Aug 2020 Posts: 4	OK - put photo in. Thanks for any help in advance!
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08-30-2020, 10:12 AM	#4
Parsleap Join Date: Aug 2020 Posts: 4	Note: It is entirely possible that this cylindrical piece is entirely unrelated to the rebuild, and somehow a kid found a piece on the floor and threw it in my catch pan - but I just don't know. Nevertheless, i still have the clicking sound as it idles and feels like it's running hot.
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08-30-2020, 10:13 AM	#5
Bruces Join Date: May 2018 Posts: 1,586	I think that’s from the timing chain tensioner
	1

08-31-2020, 10:17 AM	#6
Parsleap Join Date: Aug 2020 Posts: 4	I thought it might be from the tensioner too - sitting atop the spring. But that piece is a black plastic like piece that is tapered. and this piece is too big of a diameter to go in the spring or in the body of the tensioner tube (whatever that thing with the multiple holes is). So I don't think its the tensioner bolt/tube/spring - but that was my first guess as well.
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