back cylinder 30psi - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

mako224 · 08-21-2011, 08:10 AM

1997 gp1200v 110 hours.

Oil line to #3 cylinder came off at the pump and while running on the water engine shut down. Engine will idle; however, 3rd cylinder only occasionly. While idling you can hear noise from the 3rd cylinder, clack ...

Pulled head and cylinder is in tact, there are a few horz nicks on the cylinder wall at midpoint closer to the carb side of the cylinder.

I have been reading many post on the forum and some say hone the cylinder while some say you cannot. The cylinder holds 30 psi, the other two are at 100 psi.

Can you hone the cylinder or does it require re-sleving ? Any suggestions will be much appreciated.

junebug · 08-21-2011, 09:14 AM

change cly piston and rings also if it has a cat take it out put ib a d plate and chip gotton on line mix fuel 50 to 1 forget the pump make sure the rod bearing end is not bluish in color if so your going to have to change it

mako224 · 08-21-2011, 09:47 AM

From looking at the engine .. appears that all three cylinders are casted as a single unit. I have looked up the cylinder part $875.00 no including piston, rings, gaskets, etc

Was looking for a more economical way to attack the problem and if there are any suggestions, I'm open to read all.

Thanks

junebug · 08-21-2011, 11:40 AM

mabe get prof ck than make dis

Ernest T · 08-21-2011, 01:12 PM

It always the #3 going out. You will need to carefully inspect your crank. The #3 oil line lubes the rear bearing and it will often get cooked when that cylinder fails. If there is any "gritty" feel to the bearings or any other damage the crank will need to rebuilt also............could get expensive.

Although it can be done, IMO its never a good idea to put in an odd sized piston in one cylinder leaving the other 2 alone. You are setting yourself up for failure down the road. Best bet is to bore out all cylinders and put in 3 new pistons/rings, etc.. You might want to look at an SBT top end kit, which makes it pretty simple: Yamaha 1200 Non-PV Cylinder Exchange Top-End Kit -- SBT Jetski Engines, Parts & Accessories, if the crank is OK.

Don't forget to replace the oil lines and put on some good quality clamps to prevent the problem from happening again. A lot of guys recommend the Oetiker clamps for the oil lines.

mako224 · 08-21-2011, 02:04 PM

Thanks for the help. This seems the better choice. I haven't taken the cylinders off yet and checked the crank; however, from pushing the pistons down by hand and spinning with the starter there isn't any noticable noise or feel.

I will check the bearing closer once I remove the cylinders, if accessable at that point.

I just wasn't sure about the option of honing and trying new piston and rings since I had 30 psi with damage. The cylinder wall does have several areas that are scraped vertically and just rear of the intake ports 5 or 6 horz nicks.

The piston looks fine the hed gasket shows no blow by, and there is no fowling on the plug tip.

Ernest T · 08-21-2011, 03:20 PM

I've always been told if you have a scratch deep enough to catch with a finger nail you should look at re-boring versus honing the cylinder. If you have very light damage, honing may be an option, but I'd check the bore with a gauge to be sure its within spec., before you hone only.

pwcpro · 08-21-2011, 11:16 PM

Go with a cylynder exchange from sbt. Pretty tough job if you are familiar with it