82' G1 low compression issue

[buggiebradshaw266]

Hello guys I'm a newbie. I have a 82' G1 has the gov. an oil pump bypassed. It has power spring, 12 in Hazard wheel set, Grant GT steering wheel and new leather seat skins.
My problem is the cart doesn't wind all the way out. When it is jacked up, you can push the pedal down about half way and it seem to be fine but when you go from there to full throttle it sputers and won't wind out unless you pull the choke out then it winds all the way out . When driving it with a load on, it won't wind out even with the choke pulled out. I had a tech at buggies unlimited tell me that a ring may be bad if the compression is below 110lbs.
Well I did a comp. test and it only hit 88-90lbs. It was just rebuilt last year and we bought it during the break in period.
Would this be possibly why it can't wind out with a load on it? Could it not have been broke in properly? Sorry explaination is so long guys.