96 rebuild won't start

[Darryl stahley]

I have my ski at a my buddy's garage where they work on cars he has a mechanic who claims he worked on skis in the past and when you talk to him he really seems to know what he's talking about, the ski is back together and it won't start and it backfires sometimes ,the mechanic is telling me it's because of bad gas if that's the case why when he puts fresh gas in the carbs it still don't start I told him these are the same symptoms I had when I brought it to the garage ( backfiring , won't start , low compression ). I asked the mechanic to check the compression and his reply was the compression would still be pretty low because there is know oil in the cylinders yet because it hasn't started yet and the oil pump hasn't pumped any oil in yet is this guy full of shit ? And does anyone have any ideas why it might not start and what to try

 

[jdanthony]

Did you have new top end done?

 

[mikidymac]

Yes he is full of crap.
1. Why's he running a new engine on bad gas.
2. Fresh gas down the carbs will make it run not backfire.
3. Compression should still be high on a new engine regardless of it running yet or not.
4. He should have primed the oil pump before starting it in addition to running fresh premix on the first tank of gas.
This guy doesn't have a clue what he is doing.

 

[Shovelmike]

I agree with the above. Find a real mechanic.

 

[Mickirig1]

What has he done to it?

 

[Darryl stahley]

Yes top end rebuild

 

[Darryl stahley]

Put fresh gas down the carbs still didn't start , how high should the compression be

 

[mikidymac]

An a new engine it should b at least 130-140 but I have seen them 150 also. 150 is perfect and where you would expect it to be after a few hours of running.
Hopefully he shaved the RAVE valves too or they can hit the new larger pistons.

 

[Darryl stahley]

Put fresh gas in carb and cylinders still won't start sometimes backfires it seems like it's not getting gas but putting gas in carbs or cylinders it has to be getting gas. Any idea what's the lowest compression it will start on and anything else i can try to solve the problem Thank you

 

[jdanthony]

Timing is off

 

[jdanthony]

You shouldn't be asking what's the lowest... Just check it , let's rule that out first. My bet is the rotary valve is in wrong

 

[mikidymac]

If he just did the top end the rotary valve shouldn't have been touched. But since the "mechanic" doesn't have a clue who knows at this point.

 

[XP 787]

So he gave you back the ski not running after a top end? What engine is it? 720,787? Post current compression numbers.

 

[Darryl stahley]

787 motor still at garage I'm gonna check the compression my self tomorrow

 

[Darryl stahley]

Tested the compression this morning no more than 80 in either cylinder now I know why he wouldn't test it last week when I told him to check it

 

[XP 787]

My bet is he didn't even do the top end and just took your money. That sucks. Have you talked to your buddy about this yet?

 

[mikidymac]

I hope you get all your money back. There is no way a new top end would be at 80 psi. Did he even do anything?

 

[jdanthony]

Ripping you off sounds like! Get your money back!

 

[Darryl stahley]

He did do the top end I actually went to the machine shop to pick up the parts and I have yet to give him any money at least I got something positive going for me so far I have know idea what to do every time a mention something they have an answer I can't get them to realize they don't have a clue for instance they keep telling me. The compression is low because there is know oil in the cylinders yet and it won't start because of bad gas but they put fuel in the carbs and the cylinders and it don't start that's clearly not a gas problem

 

[mikidymac]

So......
What pistons did you use?
Did the machine shop match and bore the cylinders to the new pistons?
Did he put the pistons in the correct way with the arrow facing the exhaust port?
Did he check the squish to make sure the correct base gasket was being used?

And as you know now, no new top end with or without oil should ever be below 120 psi.

 

[XP 787]

Pull the head and post some pics.

 

[Darryl stahley]

The machine shop did match everything up I'm not sure what pistons they use and I wasn't there to see if it was lined up properly I wouldn't know the difference I don't know shit about motors