SBT Admin. or others, could use your HELP!

[lee_leses]

I'm trying to put my GP1200 back together after replacing the motor mounts and I could really use some help at this point. I'm totally stuck unless someone with experience can help at this point cause I don't have the experience to know how this should sound or feel out of the water.

The first hurtle was when I tried to start it. No starter at all at first. That was easy because electrical is my "thing." Apparently one of the connectors was not seated right.

So, then the mechanic who's working with me (all automotive experience, no 2-stroke experience), and I started it about 3-4 times. It climbs up to high RPM with the throttle plates almost fully closed and sounds knocky and horrible to us. I choked it to bring the RPM's down to run it for a second. One of the times it was at about 2-3k for a second and sounded like the engine was running smoothly and as it should, but mostly sounds bad and won't idle at 1500 RPM or so. We were pretty careful (at least we thought!) to not mess with any of the adjustable things and to put it back together as close to the way it came apart (adjustment wise) as possible.

If you look down into the carbs, you can see that the front carb's throttle plate is fully closed when you're not on the throttle lever on the handlebars, but the middle one is open a hair more than the front plate, and the back throttle plate on the rear cylinder is open a hair more than the middle one. The back throttle plate is open maybe 3/16 of an inch? My friend has a lot of experience with carbs like these and can't find a way to adjust them. Is this a normal way for the plates to be, and has anyone seen something like this before?

Also, would it be advisable to add oil directly to the gas until I can ensure that the oil injection pump is bled right and working, or make up my silly mind whether to go premix? With the engine not running I made sure the oil hose oil was flowing before I put it on the bottom of the oil pump and I opened the bleeder screw. We saw oil flow out of all three holes in the air cleaner when the engine ran, but i'm scared to death that the oil injection will not be right and blow a cylinder or the whole engine!

Lee B.

[Matt_E]

Re: SBT Admin. or others, could use your HELP!

The carb adjustment should be easy. There's a linkage from carb to carb...because there's only one throttle wheel (throttle cable is attached to this) that opens/closes all three carbs. On this shaft, you will find a set screw on the mid and rear carb. Should have a T-Handle. Turn that, and you adjust the idle position of those throttle plates.

So, if you only replaced a motor mount, you really didn't take the engine apart, did you?

[wmsky]

Re: SBT Admin. or others, could use your HELP!

How much of the engine exactly did you take apart? Did you take the carbs and intake manifold off? The fact that it goes to high RPM with the throttle plate almost closed and sounds knocky might mean you have an air leak somewhere in your intake and the engine is running very lean.

[skraggy]

Re: SBT Admin. or others, could use your HELP!

wmsky has a point with the air leak...but it will usually run off and scare the #$@* out of you...check to make sure the throttle cable is routed correctly and not hung up somewhere causing it to not be in the idle position.

Next...since you put new motor mounts in.....Make sure that you get the coupler aligned properly.You will most likely need to shim the mounts in different locations than where they were before.I believe there is a tech article covering this,if not,check back and I(or someone else) will let you know how to do it.This is a very important process whenever replacing a motor or mounts.

On the throttle plates...they need to be the same.That may be the reason that it was idling high...IOW,that could have been your air leak.

EDIT:Also,next time you go to start it,make sure you have a plan on how to choke it in case it runs off...you must cover all three carbs to kill it.

[1fastski.com]

Re: SBT Admin. or others, could use your HELP!

you should always premix your fuel on a rebuild or new engine . you need to know your carbs are right so you dont blow the engine and if the engine is not alined right you can break things also enen damage the crank . if you cant get it right bring it down { iam about 1hr from philly }

[lee_leses]

Re: SBT Admin. or others, could use your HELP!

Thanks for all the ideas and help everyone.

Again, THANK YOU to SBT for hosting this forum!!!

And 1fastski, thanks for the offer to actually look at the "unit." Do you have a phone number. I see you have a website, but what town in Jersey are you in? I haven't had time to look you up online. I have training today at work from 3-10pm, but if you don't mind you could call me and leave your phone number - 2155302029. I very well may need help at this point.

I really should have specified that the engine was not all apart and exactly what was. The engine had to come out because the inserts that the into-the-hull bolts go into had issues that had to be fixed. In order to get the engine out, I took off the plate that holds all the throttle, oil injection, and choke cables, the air cleaner, and the "U" shaped part of the exhaust. Everything else was not touched. The adjustments on the cables/carbs were not touched, so i'm not sure why it's running so bad. That was a great point about having a plan to kill the engine if it won't shut off. I was vaguely aware that that can happen, but didn't take it seriously until the engine ran wildly out of control. And yes, that did scare me to death! I also thought about an intake side leak. Nothing was touched or smashed in the removal process. That said, I can't see without an air leak how it could run that fast with all three throttle plates mostly closed. If anything, I expected the idle to be messed up when it went back together and not want to idle without dying. I understand first hand now the frustration that guys must feel when they've spent $3000 and the craft still won't run right...

Well, at least the starter still works after all these years, nothing else is right now... LOL!

I will look for the throttle plate adjustment tees.

Should I panic about the 1 or 2 run away starts and the rough running? I *think* i've been pretty conservative and careful running the engine since it was reassembled, but i'm already wondering if the engine is already damged from the few rough running/fast running starts it's had. Are there engines hard to damage when you work on them unless you lean out a carb or have no oil flow to the engine or a cylinder???

Lee B.

[Matt_E]

Re: SBT Admin. or others, could use your HELP!

I wouldn't say you need to panic about two or three runaway starts. But you do need to find the cause and you need to fix it.

[anapg77]

Re: SBT Admin. or others, could use your HELP!

Lee call me if you still are having problems.

302-593-3649

J-ME

[1fastski.com]

Re: SBT Admin. or others, could use your HELP!

iam down by atlantic city { 15 min away } the waltwitman is 60 miles from us i think . easy to find if you need me my number is 609 926 5100

[lee_leses]

Re: SBT Admin. or others, could use your HELP!

Thanks everyone. I would have liked to talk to you tonight but I have this training tonight.

It would be REALLY nice if this ski would run again right someday before i'm bankrupt! heh heh

Hopefully we can talk this week if i'm still having problems... I probably will be.

Lee B.

[lee_leses]

Re: SBT Admin. or others, could use your HELP!

Thanks for all the help everyone!

Things are getting a LOT better, but I still could use some additional input. Today we inspected the fuel and pulse hoses, and adjusted the throttle plate on the last carb that was open too much at idle.

The ski started right up and ran on the flush kit with no problems. It sounds pretty much like it did before it was taken all apart now. It's hard to believe that a few small adjustments could make such a BIG difference! (?)

The only real issue I can see, if at all is it seemed to me that the engine was vibrating a lot at idle. I know there's no good way to quantify that, but at idle the word Yamaha on the stock exhaust gets kind of blurry from the vibration. As soon as you give it a little gas, the engine gets almost totally still and the word Yamaha is standing still.

Is that normal, or would a good jet-ski mechanic be able to smooth out the engine motion at idle?

The only things we really adjusted at all was the last throttle plate by loosening the two screws on it's cam, and my friend backed the idle screw off two full turns counterclockwise.

I'm unsure why we would have to adjust the idle screw at all, i'm not sure why my friend did that to tell the truth.

Can someone tell me the difference between the 1 idle screw on the first carb and the 3 trolling speed screws on each carb? I don't get that.

Should I put the idle screw back where it was?

Lastly, does anyone vote for taking the time to take the air cleaner off yet again and installing the Riva fittings in the carbs as per their instructions, or just do that thing the other ski owner did with positioning the fittings on top of the air cleaner?

Thanks Again!

Lee B.

[GPkiwi]

Re: SBT Admin. or others, could use your HELP!

These are a big 3 cylinder engine and to be get them smooth at idle is very hard (impossible really)

What is your idle rpm?.............even on the ski's own tach.

The first idle screw adjusts the whole idle with all three carbs. This only opens the butterflys to get your idle. The 3 trolling speed screws adjusts the carbs on thier own which you would set first and fine tune with single idle screw on the fist carb.

[lee_leses]

Re: SBT Admin. or others, could use your HELP!

Thanks!

On the factory gauge, the idle looks to be about 13-1500. I may just have never noticed how much the engine vibrates at idle. I'm *nervous* because I just went through the broken motor mount ordeal and the six week ordeal to get the parts, do the research, and get it back together again! It may be normal. As I said, when you get on the gas the engine smooths RIGHT out and appears ready to race someone.

Thanks for clarifying the adjustment screws for me. Since the ski was running okay before this incident, there really would be no reason to touch the trolling speed screws, right?

And how much would it affect the idle in theory turning the idle screw two turns counterclockwise? Like 50rpm or 500rpm? (Just a rough idea).

Lee B.

[GPkiwi]

Re: SBT Admin. or others, could use your HELP!

If it's 1300-1500 rpm out of the water then it's to low as when you put it water it will die on you. For example my 98 GP1200 STOCK Ides at 1300 rpm in the water! and out is around 2800-3000rpm. A few people have told me this is high (Really not sure) but set my idle from the manual 1300+ or - 50rpm for trolling. I take it as what ever it idles out of the water that's what it will be- if you get my meaning.

So I would bump your idle up a lest to 2500rpm's out of the water so your have a chance of it to start in the water and hopefully to keep an idle, Then set it to around 1300rpm. If it dies on you before you can set your idle (trolling) just adjust the idle screw alittle and restart your ski............and try again etc etc.

[lee_leses]

Re: SBT Admin. or others, could use your HELP!

Thanks! That was so helpful!

That explains why the engine is vibrating so much at idle, we backed the idle off way too much.

After hearing what you said, I would like to try to raise the idle up to where it was and maybe a little more. I've always felt that it idles too rough out of the water on the flush kit like it wants to die.

A tiny bit faster in the water would not matter to me as far as I can figure.

I can't believe I may actually be getting close to having this back together again right. I DID learn a ton about jet-ski's in the process. My police adademy driver trainer always said no-one should be allowed to drive a car unless they can change a tire and at least understand at least the basics about how the car runs. Knowing your jet-ski seems even more important since you can get stuck on the water.

Lee B.