G1 overhaul issues, low compression, no power

[G1yamahauler]

Hi,
I am resurrecting an old cart 85-86 G1 gas
I have had a chance to fire up the cart after replacing the crank seals and crank bearings. I have not changed anything with the top end as of yet. There was some minor scuffing on the exhaust side of the piston.

Two issues I have now is that there seems to be a lack of power, and lack of ability to climb small grades. Flat ground it will get to speed but not super fast.

I have roughly 60psi compression on testing the cylinder. Will this cause the lack of power issue? I have ran it around off and on all day it runs just a bit stronger with the choke 1/4 closed. I thought it was a fuel issue and checked the fuel pump, filter and cleaned the carb. However the mixture screw does nothing to change how it runs.

Can anyone offer any advice as to getting this engine running strong again.

Thanks!

[Spicyunicorn]

60 psi is very low and most likely your problem believe they are about 120 psi new

[G1yamahauler]

If cylinder is in decent shape with no major scoring, do you think I can hone and measure for what piston is needed standard vs over sizes? Or am I better of with new cylinder and piston kit?

[Spicyunicorn]

if it was me id buy over sized piston and take it to a local machine shop and have them bore it out. that way you know cylinder is true top to bottom.

[Field6565]

Originally Posted by G1yamahauler

If cylinder is in decent shape with no major scoring, do you think I can hone and measure for what piston is needed standard vs over sizes? Or am I better of with new cylinder and piston kit?

I would buy the kit. Comes with a new cylinder, piston, wrist pin, clips and all gaskets in order to do the rebuild. I just did one last week and when I was done it was nice knowing that all parts were new. I put a compression tester on it when I was done and had 125 psi.

[smallblock450sl]

Kind of depends of the cost for each job. If you can get the cylinder bored for 75/80 dollars, a new OS piston/rings/gasket set would be cheaper then an aftermarket top end kit. I do recommend OEM parts though. 60 lbs...man, that shouldn't even fire up

[Spicyunicorn]

kit is alright but you can buy gasket set for 20 and piston and rings for 50-60 and my machine shop only charges 50 for machine work so you're looking at 130ish vs 255 for the complete kit. just my opinion though

[smallblock450sl]

Originally Posted by Spicyunicorn

kit is alright but you can buy gasket set for 20 and piston and rings for 50-60 and my machine shop only charges 50 for machine work so you're looking at 130ish vs 255 for the complete kit. just my opinion though

I like saving money

[G1yamahauler]

Thanks for the advise! This forum is great.

[G1yamahauler]

Sent it in to machine shop. Have to use a .50 oversize kit. I'll post what my after readings are when finished.