95 XP- running RICH or running LEAN???

[vallentinerocks]

95 XP all stock, no mods. Rebuilt both carbs, changed all the original fuel lines, Compression on both sides 125PSI, low speed at 1.5 turns, high speed at 0. DOES have leaking crank and/or rotary valve seal leaks since oil comes out of exhaust periodically when have been able to throttle up. Had been sitting for over 6 months unwinterized and uncovered by the last owner. been in my garage for 4 months. I have yet to take it out to water.

SO... I can get the ski to fire up and idle without starting fluid. First start = high idle and can get response when throttling up and ill shut down in a few seconds. (its in my garage). Second start = starts up and idles lower, but when throttling, has little or no response and will die. Inspect plugs, Mag side plug seems a lot wetter then PTO side.

Recently on one starting attempt, it fired up, revved up high RPMs on its own, and when i pulled Lanyard to kill, it didnt shut down and RPMs were still high. Motor shut down when i throttled up before i could reach for the choke lever.

So basically now, the ski starts almost everytime and randomly idles right or idles high, but definitely issues since im getting weak or no response out of the throttle and will die. U think its running RICH or running LEAN right now??? Im Leaning on the LEAN side. Please Help. Im not all that knowledgable on carbs and tuning them.

 

[Bills86e]

That is very low psi. Gas cannot completely burn. I bet *plugs are wet, leaking NS. Did you do a "leak-down test after you re-assembled them?

 

[vallentinerocks]

Is 125 PSI really that low? i know 140 to 170 is fairly normal for two stroke... crap. but both cylinders are about the same atleast. leaking NS? can you tell me what you mean? ... i have not done a leak down test. what do i need to do one?

 

[- BiRkS_]

125 psi is fine for a ski of that age. As long as the psi across both cylinders is within 5 psi and above 110psi your ski is fine in the top end. HOWEVER, a leaking crank seal will always cause a lean condition as extra air is coming in the crankcase (carbs feed into crankcase) It is impossible to tune a ski out of the water. (back pressure on exhaust, load on engine, etc) You will need a plug wrench and a flat screw driver to adjust carbs and a spare set of plugs incase you foul your first set.
Take it to the water and warm up the ski (take it for a spin for about 5 mins). Take the ski for a WOT run and see how it performs. Shut the engine off while it is at WOT (dont idle down, just pull kill lanyard) and pull the plugs. If they are white or light tan, its running too lean=possible engine damage if left at this setting. If it is black and juicy or sooty, too rich. Adjust the "H" or high screw(s) accordingly-turn out if its running too lean, turn in if its running rich. You want to acheive the exact same plug colour on each side. (tan, light brown) Always richen your ski up a tiny bit to be safe. Too rich will foul plugs. too lean will cook your engine. For the idle circuit or "low" circuit, adjust each carb EQUALLY so you have the smoothest idle and a fast pickup when you pin the throttle. If you experience a "bog" when you pin the throttle, open up the idle circuit 1/8 of a turn on each side and try again. Keep turning it out until you get rid of the bog. Once you have the idle circuit set, NOW you can set the idle speed. Turn the idle speed screw in to increase RPM or out to decrease RPM. idle rpm should be around 750-800 rpm. I always richen my idle circuit a little more so i always have a crisp and responsive throttle with no bog. Lets face it, our skis never idle for long, so running idle circuits rich wont foul plugs. Also a richer idle circuit will acheive very quick "hot" starts.

Hope this helps. I dont think you will have much luck tuning the engine as a leaking seal will make it very hard. You'll be fighting a loosing battle. Your best bet this winter is to pull the engine and re-seal the bottom end and go through the carbs making sure they're clean. Factory specs for the carbs is 1.5 turns out from bottom (L) and O turns out for (H)

FYI: a leak down test is very simple. If you have a compression tester with a quick connect, attach a compressed air hose to it with about 60-80 psi. listen for leaks out of carb (air going past rings) or around the PTO (rear main seal) Its impossible to tell if your front seal is bad with the engine still in the ski.

 

[LouDoo]

125psi is very low, at 120 the ski probably won't even run in the water. I'm afraid it's time for a top end rebuild. Your ski came with either a 720 or a 787, if you have a 787 you might get a slight improvement in compression by cleaning and adjusting the RAVE valves, it might buy you some time. But really it comes down to this, either do a top end rebuild now or replace the engine later.

Bill is much more knowledgeable than me and I think he will tell you the same thing.

Lou

 

[Seadoobuddy]

I doubt if it matter much anymore as this thread is 5 months old. I hope he sees it and tells us what he did

 

[LouDoo]

Thanks, SDB, I didn't realize that the thread was that old. I saw it as a new post. However this is an example of why you need to check your compression, like we were talking about the other day.

Lou

 

[Seadoobuddy]

He was on line in Sep't so maybe he'll see this and answer.

I'll check compression later as I have the pump off and the rave valves out and it's fill of Anti-freeze right now.

Do I need to seal the point of connection between the pump and the hull when re-installing the pump? if so with what?