70hp compression or fuel issues?

Just got my engine back from the shop from a tune-up. They did not do it due to low compression. I had 105,125,125 on the three cylinders and they say that is to low. What is the low limit?

My initial problem was engine dies as I open the throttle. It seems to idle a little rough but stays running. It ran fine last year. Seems like a simple carb job, but the shop says no, it is low compression. Any advice would be helpful.

Thanks

Re: 70hp compression or fuel issues?

It's not so much the "low limit" as it is the disparity between your high and low numbers. The 20psi variance isn't a good indicator and points to something being amiss. Could point to carb problem, too (carb running lean means less lubricant going to that cylinder). That would be the cause, low compression would be the result. Might be able to SeaFoam it back up there, but I'm not holding my breath...

Re: 70hp compression or fuel issues?

my first thought is,the shop isnt too sharp.Even with 20 lbs missing(if it is really low)the eng should perform.I agree about the possible carb issue.Get yourself a cheap comp.guage.and a can of fogging oil.Then re do your comp test ,first without spraying oil ,then spray into cylinders and coMpare.I believe the shop should have asked you to have cyl.head removed to inspect the cylinders.if ccylinders show to be without obvious scoring,Id suggest a decarbonization with seafoam.After the process ,recheck comp.Usually ,a true blown cyl will have ) or comp readings very low.My thought is they didnt go far enough to find the problem.But,perhaps you didnt want them to.If the engine hasnt run well at all this yr .its likely the carbs. #1Have you run the engine much this year with the poor performance #2 What yr.eng
#3 do you mix oil and gas or do you have a VRO set up that mixes the oil and gas automatically.?

Re: 70hp compression or fuel issues?

The motor is a 1976 70HP Seahorse. I have had the motor running on muffs for about a half an hour and ran OK with no load on the engine. When I took it to the dock it would die when throttle was applied (under a load). It would set their and Idle around the water OK. I have ran the motor appox an hour this way. I will decarbonize with sea foam tomorrow, any extra special procedure for that or just follow the directions on the can? I do premix and use a 50:1 ratio of 93 octane and Pennzoil 2stroke marine oil. Thanks for you help!

Re: 70hp compression or fuel issues?

No need for 93 octane. Regular is just fine as far as I know. Agree with giving it a decarb.