86 G1 replaced crank bearings and seals and honed cylinder new rings, compression still not great

[Kapnkrunch]

Bought an 86 G1 a couple months ago. Got it to run by cleaning the carb and a lot of cranking. Cart needed to crank a lot with choke to start sputtering and than it would run, maybe 15-20 seconds of cranking. Compression was at 90psi. Later found the clutch side crank bearing was shot, split the case and replaced both bearings and seals. I also honed the cylinder and replaced the rings on the standard piston because the end gap was out of spec.

I don’t own a bore gauge so I was hoping the cylinder wasn’t too wore out to require the next size piston. The piston was within spec at the skirt. Also, Forgot to check the end gap before I installed the new rings and ran the cart.

The cart starts slightly easier when cold but still needs to crank for 10+ seconds before it starts sputtering and finally fires. I likes the choke for about 10 seconds or so then runs great. Checked compression right after the rebuild and it was only 92psi so am assuming my cylinder was too wore out?

My question is will I have any long term issues running the cart for a while with what I assume is blowby at the rings? It has more power than before but not much. Do you think my compression will rise much after the rings break in?




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[sho305]

It likely needs a bore job, 2 strokes are more sensitive to low comp (lose power) and wear the cylinder more. So you end up needing a bore job and piston more than with a 4 stroke. If it runs sure you can run it. You can turn it by hand and check how much is leaking past rings. and get an idea. The cylinder usually wears more at the top, at the front to rear way.

Used to be able to buy a fitted cylinder/piston kit for those but not sure now.

[Lochlin]

Man, 92 is still pretty low. A top end kit for your cart is $200 - $250. That might be worth the investment at this point? At least you will know that everything matches as it should (at least in theory).

I wouldn't be overly concerned about the ring gap. That you were able to install the rings without having to file probably means that they were close to spec out of the box. If one broke it wouldn't run at all.

[Kapnkrunch]

Thanks for the responses everyone. Since I’m on a tight budget I may run it for a little while and then think about a bore and oversized pistons this summer. I usually like using as much oem parts as possible but I may do a top end kit if the bore job is a lot locally.

The help of folks on this site is what encouraged me to tackle the bearings, I was afraid of splitting the case but there was so much good info and advice on this site I made it happen.


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[mikeasis]

silly question, are you for sure the chassis AND engine is an 86 because if the engine is an 82 then that's perfect compression. look behind the primary clutch on the cylinder and see if its stamped J10 or J17.

Compression could go up after the rings seat, but how much im unsure.

[Kapnkrunch]

Originally Posted by mikeasis

silly question, are you for sure the chassis AND engine is an 86 because if the engine is an 82 then that's perfect compression. look behind the primary clutch on the cylinder and see if its stamped J10 or J17.



Compression could go up after the rings seat, but how much im unsure.

Not a silly question , I did read about the low compression years on the forum. The serial on my rear frame rail is J31-141286. The same serial is stamped on I believe the flywheel side of the case half. I am trying to attach a pic of it but I haven’t setup an account I guess.


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[Kapnkrunch]

[Kapnkrunch]

There is the pic of the stamp on the case, it was behind the clutch like you said.

Another random question. What are these tubes for up front? Is it part of the horn?




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[Lochlin]

SOB. I keep forgetting that those darn '82s being outliers with regard to low compression engines.

Speaking of outliers. Whatever type of tube system you have there is an oddity. It's certainly not stock. What's on the other side of the round pieces that the tubing goes into? Where does that tubing go to? That type of tubing is what is used with and air horn but I have never seen anything resembling those discs.

[Kapnkrunch]

The tubes look like they go up under the dash area near the horn button so I’m assuming it’s something like that.

I had the oil pump apart when I did the rebuild and it seemed the work fine. I premixed the first tank and pulled the little oil hose line going to the carb and ran the cart on jacks and oil weeped our. Still not sure I was to trust a 33 year old oil pump though.


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