98 gp1200 compression

[Herb]

Hi. Can anyone tell me if 100 psi on all three cylinders is something I need to or can do something about. out side of a rebuild? The ski also idles very rough and tops out at 6000 rpm.

[fosgate99]

you have problems there. Do all 3 have 100? Do you have oil injection? Mods? Info???

[Bryan Glynn]

125 is stock, but if you get an even 100 I would suspect a bad gauge before damage. Try a known good gauge.

[Herb]

Well, it is an even 100 lbs on all three cylinders, it may be a bad guage, I'll have to get another to make certain. No mods on the ski that I know of, everything looks stock, The exhaust is very loud though, almost intolerable from the pass. seat on the water. Out of the water with the seat off the majority of the exhaust note seems to come from the engine compartment if that means anything. Took it out today, started right up and ran good, vibrates alot in idle. top speed only 54 and top rpm 5500-6000. Thanks for the help.

[Herb]

OH, and it is oil injection, switching over to premix next week.

[Bryan Glynn]

The noise and vibration is normal for that ski. I would still suspect a bad gauge, but your RPMs are low. Try new plugs, gapped at 0.024" and see what happens.

[Herb]

Thanks Bryan. Getting plugs this week. Will update when I do.

[torquenut]

I had a GP that I just put an engine in and forgot to tighten the exhust pipe to rubber hose clamp. Man was it load when I fire her up. Also if this is good check the rubber hoses to the water box and after the water box they are known to break, good luck and keep the faith.
:D

[Herb]

new plugs set at .024 did the trick, also helped the vibration. 87 octane helped the smoke. runs great, thanks. New trim tabs made a huge difference.

One more thing, would like to tune the carbs, since the motor is stock, can I just reset to the stock settings. I starts right up, well, when the choke is out and the throttle is fully open, and I don't want to not be able to start it.

[Bryan Glynn]

Yes, go back to stock settings.

[Herb]

thanks again. This baby finally moves like it should. Am still sore from last weekend. Took a 100lb 17yr old out for a spin and had a blast. Had her laughin', screamin' and crying all at the same time. Tore it up. Couldn't imagine what engine and pump mods would be like.

[ptg24]

hey herb what are your rpms maxing out at now?

[Herb]

around 7000