Rebuild Struggles

Before cracking it I check the compression with a harbor freight tester. This should be a fresh pump gas motor. 200 front and 195 rear which seems high.
 
you said you rebuilt the engine correct? did you happen to do an air leak after assembly? if not, defintely do an air leak test to verify the engine is sealed up tight. compression test too just to verify both cylinders make even compression. i do both of these on every new engine i assemble as insurance and peace of mind. also check your popoff and jetting in the carbs. also something i do everytime i go through a carb is verify correct popoff.
I would have to ask someone about a leak test. Not sure how to do that.
 
Also for what it's worth, I've installed those carbon tech reeds in a bunch of skis and occasionally (a coupla beers scenario) I find the reeds have a big gap. I flip them and reinstall the other way and they seal without any gap. I didn't think they had an orientation but some certainly do! Hate to make you rip the beast apart again but while your in there best to check.
I was going to check that as well.
 
I would have to ask someone about a leak test. Not sure how to do that.
You'll have to remove the carbs and exhaust. You can use expandable freeze plugs to plug the openings or make a block off plate. Then use a hand held pump like for checking popoff, connect that to the pulse fitting on the engine, pump the engine up to 8-9 psi and let it sit for 10 or so minutes. You can spray windex around case halves and gaskets to check for leaks.
 
Well it was the woodruff key. Took the chance of putting it back together since the key was stuck to the flywheel. It could have fell out when I removed it but had some black around its location and when pulled off the flywheel there a clean spot where it sat.

After putting everything back fingers crossed it fired right up and had a good ideal. So happy the ski is up and running. It’s been a project for sure.

Want to thank Some area riders that gave me support building it back up and all the great folks on here. It’s a great community and I appreciate all the comments!

One thing through this process I noticed my compression came up. The front is 190 and the rear is 200. The idea of this boat was to be an old style limited class with just bolt on and run pump gas. This puts me in the avgas zone.

Probably change the domes out to lower the compression but seeing a spread between cylinders what would you guys do? Was the rule not a 5% differential is normal but on the higher end? Thoughts on this would be helpful.
 
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I'm running 195psi per hole in my 735 with pump gas. This is with 35cc domes. If you're running 35cc domes you should be fine with pump gas. It's fully ported with all of thr bolt ons and have put 5 seasons on it like that and it's still running excellent.
 
Location
dfw
I'm running 195psi per hole in my 735 with pump gas. This is with 35cc domes. If you're running 35cc domes you should be fine with pump gas. It's fully ported with all of thr bolt ons and have put 5 seasons on it like that and it's still running excellent.
I have burned pistons with “pump gas” compression. Make sure your ignition timing isn’t too advanced and the carbs are set rich of peak rpm.
 
looking for the paperwork now but I think I ordered 35cc domes that are currently on the ski. They rate them at 185lbs.

If 192cc is still pump gas I should be ordering 36cc which calls out 177lbs. I’m making the assumption if this rebuild pushed me 10lbs above the 177lbs turn into 187lbs and I should be good. I’m asking the question as I do the math since I’m unsure of what the exact outcome will be.

Any thoughts?
 

ScottS

X
Site Supporter
Location
Savannah, GA
looking for the paperwork now but I think I ordered 35cc domes that are currently on the ski. They rate them at 185lbs.

If 192cc is still pump gas I should be ordering 36cc which calls out 177lbs. I’m making the assumption if this rebuild pushed me 10lbs above the 177lbs turn into 187lbs and I should be good. I’m asking the question as I do the math since I’m unsure of what the exact outcome will be.

Any thoughts?
I would check the compression with a decent gauge, I would not trust Harbor Freight
 
Location
dfw
The gauge can be checked against any known gauge.. Its the schrader valve thats the wild card with every compression gauge. Thats why they're only good for comparisons between cylinders.
 

Myself

manic mechanic
Location
Twin Lakes AR
This is an ADA head with domes that can be switched out. You might be right on the stock set up?
What I meant was 36cc is 36cc..........won't matter on the brand, or even the squish band for that matter. If it's 36cc on a 701, it should only make around 175psi. So that's sort of wierd.
 
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