Compression on a OEM 701 with ada girdle and 35CC domes. (New question regarding crank)

As the thread indicates imm in doubt about what compression to expect - and if i should replace the piston rings.

Imm getting a 180PSI on the front and 175PSI on the back.

Its a OEM 701 with ada girdle and 35CC domes.

Cheers
 
Location
Stockton
Yes you have some uneven compression there. Most likely your right you have some piston, piston ring and cylinder wall wear. I have that set up on my wife's Rn I'll take a reading later and send it to you. The wife's are even @ last check and if I remember 175 each hole and runs like a top. A couple things to keep in mind the advertised compression numbers are a guide, actual readings can very, the other thing is rings cant seal low spots in the cylinder wall or over scoring, the cylinders also tapper wear with the top of the cylinders diameter getting larger as compared to the bottom of the cylinder, the ring is square so you loss ring sealing surface with a tapper worn cylinder. How long have those pistons been in there? Is it time for a top end rebuild?---- what's concerning some is the uneven readings between the two, a tear down and inspection will help determine the extent
 
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Location
Stockton
Ok tested the wife's, ran it for a bit, removed both plugs, throttle wide open, crank until see highest reading, front hole 175 rear hole 160 WTF! Found oring on gauge at threaded end splitting leaking out my reading, fixed that ring and didn't tighten so tight re-ran rear cylinder 175 now :)
 

ProSouth

Seriously, Don't be a dick.
Location
kawasakis suck
5lbs isnt anything to worry about it. worry if one continues to drop. rule of thumb is 8-10% difference. so at one 180, the least it should be 162. just keep an eye on it.
 
Cheers for all your answers :) Ive decided to do a full teardown since I've never inspected the engine myself - only just got it a few seasons back, so it was time for a full inspect anyway. Also it was time for a new set of crank seals so bottom needs to go off anyway. The pistons and cylinders were pretty scuffed and had a lot of wear - no wounded they weren't the same. Piston rings did look fine though.. Imm going to send the cylinders to my local shop to go to a 82,5mm bore - and get a new set of ProX. So now to my next concern - after taking the crank out completely I've noticed some noise from the front bearing (closest to the flywheel) - is that ok? Theres also a tiny bit of wobble at the last bearing. What possibilities do i have if i need to change some? Can i do it myself with a press and a rebuild kit - or how is it done? (See video) at
(Listen to sound at first bearing)
Any advice is welcome :)
 

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Location
Stockton
Yes those bearings are pretty noisy! The crank does press together but must be trued during assembly so it's in phase. It's probably not worth trying to attempt it yourself, needing special tools, V blocks, dial indicators, rebuilt cranks are pretty cheap, SBT has them, you could send yours out to Crank Works for a rebuild or buy a new Hot Rods crank. On used cranks be careful, I bought a used stroker cylinder and matching stocker crank on Ebay from an actual jet ski performance shop in So Calif, both were advertised good, inspected, only 8 hours of use and ready to go with new Wiesco pistons and rings, fresh hone. WRONG! Piston to cylinder wall clearance was at .007 and the crank was twisted out of phase by like an inch or more and the bearings were noisy, so both needed rebuilding. I have pic of the crank I'll try to post.
I see you have a dry pipe, I had that pipe on my old ski as we'll, make sure you have enough octane if you run wide open at times, I made the mistake of running 87 octane @ wide open throttle and it took the top of my piston off. After that I ran 110, I like to be able to hold the throttle open, then later blended 50/50 110 with 91, no problems. Then Gave my wife the ski so after a while seeing she never ran it wide open I used 91 with no problems. Now my friend owns it so we are back to blending, now it's 1 gallon 110 with 4 gallons 91 so it's close to 94.7 ish. He Rec rides, jumps wakes most, occasionally holds it open a very little. Friends that want to ride it always seem to pin it open even when you tell them not to so watch out. Got electronic water injection? Helps the low end
 
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Thanks for the input - but bare in mind I live in denmark - so not many to send the crank too for rebuild :/ Ill try to figure out who to send it too. Your talking about eletronic Water injection - hows that done?
 
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