Compression drop

Dfan1

Dfan1

Location
Clermont, Florida
I have a ported 61x 735 that is 3yrs old
And been run mostly in surf. I fouled my plugs this weekend changed them out and ran good , At the end of the ride it bogged a couple times.
I checked compression and the rear cylinder has dropped 10 psi to 175 it was at 185 new and The front is still at 185 with 35cc domes btw. Im thinking i made need to have a look, maybe change the rings. Anybody have any opions on this ?
 
CRJ

CRJ

Hibernating
Location
Toronto
pull the head to see if theres some damage. was this after running or on a cold motor? Ive seen strange things happen, last season i had a piston crown chip on a 90's waverunner that was on the stock motor with perfect compression. dropped the rear cyl to around 80psi and it bogged/ran bad cause of it. Id have it honed and put in fresh rings regardless while it is apart, if its began dropping it will only get worse.
 
air blair

air blair

you are the reason
Location
thumb, mich again
I'd be worried, Think of it this way. What caused it and is it done yet? I rolled the dice and ran mine but ya it could wipe out more than a top end in the end. The scoring on cylinder I'm sure is allready present


Air blair cell
 
CRJ

CRJ

Hibernating
Location
Toronto
Yes you should. flush all bearings and make sure they spin silky smooth. its more expensive to fix a blown crank then to have it rebuilt. SBT's from jet maniac are like $200. Milky looking cylinder is water intrusion. Find the source. Also looks like chips out of piston crown. What broke/let go? remove the motor and take the cylinders off. photograph everything.
 
Quinc

Quinc

Buy a Superjet
Location
California
Check your reeds and make sure all the screws and peddles are still in tact. Also check your carb butterfly and that both screws are still in it.
 
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