97 gtx top end rebuild

[bunkej]

I have a 97 gtx and want to know if i myself should do a top end rebuild. I dont know much on how to do it but with help i think i could. I just had the carbs rebuilt by professionals and they told me my #2 cylinder was low on pressure. I need to know where should i buy the pistons, what size i should get, and how to tell if i need it rebored or whatever. Im guessing age caused ot to lose compression but not for sure and was also wonder if i should replace the oil pump even though it goes through a whole gallon every 7 times i go out.

 

[racerxxx]

Pump the brakes. What is the actual compression numbers? Just being told one is low doesn't mean it's time. An actual number is better. So, what did they tell you?

 

[Dr Honda]

Yep... what he said.


If it's "Low" but OK... it may go a few more years.


If is dead... well... it's time for an entire engine.

 

[bunkej]

Pump the brakes. What is the actual compression numbers? Just being told one is low doesn't mean it's time. An actual number is better. So, what did they tell you?

So I did a compression test and it read 123 both cylinders with the 3/4 adapter and 155 in both with the 1/2 adapter. I think the tester may be faulty I am going to get another one soon. But when I did the test there was oil all over my tester. I did the test after a day on the lake. It bogs when u give it throttle and if you feather the throttle it starts jumping like its going to take off and then bogs and it will do that for a little then it takes off but if I go full throttle it bogs to half speed. (Ps my mechanic said my #2 piston has 101 psi in it and they just rebuilt my carbs for 300$)

 

[Dr Honda]

That was nice of them to charge you so much, and then say it wouldn't work.

Get a gauge that is known to be good, and let us know what you find.

 

[racerxxx]

^^^^^^^^^ x2

 

[bunkej]

So i looked over the rave valve and one was stripped out of the plastic cap. i replaced the plastic cap with a different one i found laying around, it was different looking but it fit. So i out it all back together and did a compression test, 130 in each cylinder!!! (shout out to mike and daves pro marine in brookville Indiana who told me it was 101!!) So i put the spark plugs in, hooked a hose up to it and started it. RUNAWAY SEADOO!!! I revved it up to see if it would bog and the thing just took off 7000 rpms for about 2 or 3 min. I took of spark plugs, disconnected the mpem, still ran!! turned the gas off and finally stopped. WHAT IS GOING ON??? Also is the engine done for after that?

 

[mikidymac]

That is a lean runaway. IT has an airleak somewhere and is running so lean it doesn't need a spark just like a diesel. The fastest way to kill it is to pull the choke.

If it actually ran for 2-3 minutes at 7,000 rpm it is probably toast.

See if it will turn over and if it will check the compression again but do not start it.

 

[AdamXP800]

2-3 minute runaway?? Holy crap batman. The first time a runaway happens it will almost cause you to poop your pants. Like stated, pull the choke if it happens again. Sounds like you have an air leak somewhere



96 XP800!
Keep the 2 strokes alive!

 

[Dr Honda]

The way to stop a runaway is to pull the choke. Kills it every time.


But I agree... if it was 2/3 min... it may be done. Check the compression again.


FYI... you can't check a "Bog" without a load. (so in the lake) AND... you will never get a runaway with cooling water, and a load on the pump.

 

[soccerdad]

When I first started on my GSX last year it had a MPEM problem. During troubleshooting I thought I had a carb problem or something related. So I did the DUMBEST thing possible. I had the carbs off, so I squirted a little premix into the intake with the carbs off and hit the start button. The thing fired and went straight to max revs. Duhhhh. It ran until the fuel burned off which seemed like a hour. (actually just seconds). Scarred the sdlfkdjfe out of me. Hit the stop button, pulled the lanyard and was about to run when it stopped. No choke to pull then.... Motor still runs great today. LUCKY.

 

[spx787]

Holy crap [MENTION=69521]soccerdad[/MENTION] that's funny. A buddy of mine has a Wave Raider and he had it running on the hose and had a lean runaway. He called me freaking out. "I pulled the plug wires and it kept running WTF man?" I explained to him what the flash point of fuel was and how you don't NEED a spark for combustion just heat. I told him to pull the choke if it happens again lol!

 

[bunkej]

okay so thankfully my compression was 130 in each. The front spark plug had turned whitish and the back stayed the same blackish color. Now... how does one go about finding this air leak?

 

[mikidymac]

It is typically the o-ring on the rotary valve cover or a carb gasket. But as we know not much is typical for these old skis. The only way to be sure is a leak down test. Plenty of info here on the subject.

 

[bunkej]

okay so im still having this bogging problem and its really making me mad. So I put new gaskets and o rings on the rave valves, took it to the lake the other day and it still had a bog on acceleration. I could feather the bog out and still ride it, but about 10 min in it acted up real bad. After about 10 min of riding and feathering it out, it started bogging at 7000 rpms and surging power up and down. It acted like the rave valve dropped again, but it didnt. I had to pull the choke about halfway out. So i know that it means its lean but why after 10 min start acting like that? why not at the start of the trip?

 

[mikidymac]

I can't say it enough and feel like I keep repeating myself but we are here to help so... STOP riding your seadoo's if you have to feather the throttle to keep them running. It will not get better and you are running lean so in short you will burn your top end up. 99% of the time you have a carb issue and 98% of the time it is caused by the gray fuel lines deteriorating from the inside. The carb filters and jets get partially plugged and the engine gets starved for fuel and in a 2-stroke lubrication too.

So sorry for the rant it was in general and not just for you. Lets get this thing fixed before winter.

Let us assume your compression is good and no air leaks.

What exactly did the shop do to the carbs and what parts were replaced?
What color are your fuel lines?
Was the on/off valve replaced?
Was the fuel filter replaced?

 

[bunkej]

so the shop i took it to told me that they rebuilt the carbs and cleaned it thoroughly, i dont know how truthful they were about it because they lied about my compression. I replaced all the fuel lines, but the fuel selector looked good, also the fuel filter looked clean. Is there anyway i can easily bypass the fuel selector? Also could it be a bad mpem?

 

[bunkej]

Also i turned it on today, and it just blew out tons of smoke. After a while it calmed down. Then after i let it cool down for a bit and pulled the spark plugs. There was smoke coming out of one of my spark plug holes. It just kept smoking out of that one hole, and not the other. What's going on here? Is it just time to say the engine is toast?

 

[Coastiejoe]

I'm guessing it is a bad crank seal. If it sits for a while the oil seeps past the seal and into the cylinders. It will smoke big time until the oil burns off.


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