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Hey guy's.
I don't post much but read tons on here. Thought I'd finally make a post and see if we can figure out what i have going on.
Quick background on the bike, its a 86 Trx70 that my dad bought for me as a kid. I rode it for years until one day I decided to tear the engine apart. My guess this was in 1996-1997. I had a stripped spark plug thread and wanted to learn how to pull the head off. We that's as far as i got. The quad sat like this all the way up until last year when i decided its time to get it running. I bought a used head and cylinder off Ebay. Had a shop clean it up and got the correct size piston for it. I put everything back together as manual showed. The quad started up, it smoked very badly and had a awful click/knock to it. You could even see oil dripping from exhaust head bolts. After digging into it deeper i came up with a stretched cam chain. So i called Spanglers, one thing lead to another and i couldn't help myself, i ordered the full 88cc kit with carb and race head.

I wanted to do this right and take my time. I tore the quad back apart. Installed new timing chain, new cylinder, piston and head. Put the new carb and throttle cable on as well. Had everything torqued, double and triple checked. It fired right up, sounded very good, no more chain knock from cam chain. But still noticed just a light blue haze from exhaust. I went ahead and ran it thinking maybe just some left over oil in exhaust. Ran a tank or two of gas through it, still has a light blue haze of smoke.

Called Spanglers back, he told me check a few things, piston rings placement, etc... i ordered a new gasket kit, tore it back apart. Everything looked as it should. I reassembled it with new gaskets. Started it back up, still just a slight haze of smoke. I went ahead and let my little girl ride it all summer to see if it gets better or worse. Sometimes it had a haze other times not to bad, But you can always smell the oil burning some. What am i doing wrong? What am i missing? When i tear it back apart, how can i see where it is leaking oil into cylinder? Sorry for the long post, just want to give as much info as i can.
Here is a picture of it. Pretty cool this thing has been in my possession for 33 years...
I was hard on it as a kid, so took a lot of new parts during the rebuild!!
273301
 

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It could be due to old valve guide seals or a crack in a valve guide, especially if you bought a used head and didn't have it torn down and completely rebuilt
 

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X2^.
It's also VERY easy to spin the piston ring gaps out of place...too close, when you're trying to get the piston started into the cylinder bore. Especially that razor edge on the big bore cylinders. By the time you're done fighting it in there...the rings are not where you had them positioned.
 

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Discussion Starter #5
I thought after the first rebuild that it very well could be the head, not knowing its history. But the second time around i used the 88cc kit race head. Brand new out of the box, do you think it could be leaking? How can someone tell? Compression or leak down test? Is there a way to tell once I dissemble the engine?
I really was careful with the rings. I know it can happen but what are the odds 3 times in a row? There has to be something i'm over looking.
 

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Check your crankcase vent. If there is a blockage, it will force oil past the valve seals. If you have a venting cap you could use on the valve cover, that would be a quick way to test the theory.
 

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Check your crankcase vent. If there is a blockage, it will force oil past the valve seals. If you have a venting cap you could use on the valve cover, that would be a quick way to test the theory.
X2 this^^.
Check the vent.
 
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