Anyone know about Waverunners? - PeachParts Mercedes-Benz Forum

dannym · #1 06-05-2007, 08:32 PM

I posted about this at the "other place" but I thought I would get some input here. This is what I have so far:

I bought a Yamaha Waverunner 3 for $100. It's a 1990 2 stroke engine.
The guy I bought it from said he had it out on the lake and lost power. He brought it in and took it home where it sat for probably a year.

It was really low on oil but it wasn't totally out. I cranked it up once and it ran rough with lots of smoke. I didn't want to run it for long out of water. The fuel was 2/3 full but it was old fuel.
Fast foward a month later;
Someone told me there should be a hose in the engine compartment to run it out of the water. I found that and put a hose on it. I took the main fuel line going to the carburetor and stuck it in a jar of fresh 92 octane fuel. It sounded like it wanted to start but it didn't. There was a lot of smoke coming from the carburetor. When I cranked it and hit the throttle it made a kind of wet sucking sound and still didn't start.
I think I can get it running. probably just needs a carburator rebuild??

Things I know:
-The shaft spins freely with no obstruction. I did clean out some fishing line.
-The plugs are good and getting spark.
-It's taking fuel, the level in the test jar went down.
-It seems like it's getting good compression. I didn't test it with a gauge but I cranked it with my thumb over the plug hole and it blew out pretty forcefully.

And the latest:

I got a carburetor rebuild kit $54 and that went well.

The problem is I was doing a test run before I decided to pull the carburetor and hooked up a hose to the engine before starting. Now i hear that your supposed to start the engine first then put the water on. The guy at the shop said it wouldn't start because the spark plugs were under water??

So I go out and pull the plugs and fire it up but didn't see any water. The guy said to do this to get the water out??
Anyway I put my finger over plug #1 while cranking and it pushed out very forcefully. Did the same to #2 and it was very weak. So now I'm thinking that water bit may have been a costly mistake.

I'm going to pull the cylinder head off and check clearance. I don't mind replacing the rings but no way am I tearing into the bottom end.

Yeah I know water doesn't compress but I figured there would have to be some kind of safety device. Reed valve maybe? helical spring on the head? It's a positive displacement motor running on the water for heaven sake!

I've been looking over yamaha's website, which is totally awesome btw. They have every part listed with a diagram of every system on the jetski. Didn't see a hosebib in any diagrams.

The saga continues....

Danny

rwthomas1 · #2 06-05-2007, 09:49 PM

Like any other engine, your first step is a compression test. I am guessing that there is low compression on one or both cylinders. Instead of just rings, if the craft is worth the money, tear out the block/head and ship it off to a specialized shop for rebuild. I did this with a snowmobile engine a while back and it was quite reasonable. There are a few specialized re builders out there so start searching the web. RT

Emmerich · #3 06-05-2007, 09:50 PM

Does it have a separate oil tank or do you pre-mix? If you need to pre-mix, your fuel better have the oil in it. You can run any of these motors without water, they use it for cooling so you cannot do it for long.

I guess it has some sort of centrifugal clutch to engage the impeller, so you cannot goose it because the impeller jas water fed bearings and those would seize up in a hurry out of water.

If you have water in the engine you are toast. The engine runs just like a regular boat engine, except it has some sort of ability to not dump fuel everywhere from the carburetor if you flip it over or do big tricks with it..

dannym · #4 06-05-2007, 10:26 PM

seperate oil tank, no premixing.

I'm going to take the cylinder head off and check clearances. Hope it's not toast.

Danny

Emmerich · #5 06-05-2007, 10:36 PM

Good news is 2 strokes are usually stout and without a valve train to worry about, rebuilding is easy.

ytr1903 · #6 06-06-2007, 06:14 AM

We have a couple of old, old jet skis in our group. They are 1985 Kawasaki 2 strokes. If you don't treat the fuel at the end of the season, the carb will gum up with deposits from the oil and gas. Try removing the carb and giving it a really good going over with a carb cleaner and then blow out all jets and orifices with compressed air. This is easy to do and cheap. Also, as an aside, even though the waverunner has a seperate pump for the oil, we disconnected them after the first year of use. The pumps were known for failing (back then) and bingo you have a seized engine. We have been mixing oil for 22 years and putting Stabil in the tank each fall. No problems.

Tom

catmandoo62 · #7 06-06-2007, 09:05 AM

guy said he was out on the lake and lost power.you also say the number 2 cyl is low on compression.you my friend have a burnt piston.what happens is the outside crank seals fail and the cyl sucks in too much air causing a lean condition.pull the head and look around the outside of the piston,beings it does still have some compression on that cyl.you can more then likely save the cyl without reboring,but the engine will have to come out.to replace all 3 crank seals. the crank has to be separated,this is a job for a shop with a jig to put it back together correctly.the center seal is a double seal and you could probably skip replacing that one,this would save you alot of time and money as you could probably replace the outer seals without pulling the bottom end apart.you gave 100 for it,you will have probably another 3-400 in it if you do all 3 cranks seals.so you still won't be doing to bad on the deal and you'll have one you know is good.for the price of pistons,i'd throw in a set of wiseco's.way better then the factory pistons and maybe 5-10 bucks more.

dannym · #8 06-06-2007, 06:35 PM

Well, you were right. Took the cylinder head off and the piston is shot. The cylinder is scored too. Not too bad but it can't stay that way.

Wish I could take a picture but my girlfriend has my camera and she won't be back till Sunday.

So my options are:
Remove engine and replace oil seals.
Bore out cylinder and put in larger pistons.

If it was you would you replace the inner seals?

Wiseco pistons are a good idea. Is this job a DIY if I don't replace the inner seals?

Darn! I was really hoping it was only the carburetor.

danny

Emmerich · #9 06-06-2007, 06:47 PM

What does a new motor cost? Sounds like for $100 its not a bad deal even with the new work needed.

catmandoo62 · #10 06-06-2007, 08:03 PM

how bad is the cyl scored,i took apart a ski-doo with a burned piston and the cyl was scored pretty good,took it to the shop and he ran a hone thru it a few times and it all cleaned up,we didn't have to bore.so it might be worth taking the cyls to a shop and see what they can do with it.

dannym · #11 06-06-2007, 09:58 PM

Just by running my finger over it it doesn't seem too bad. Taking the cylinders off and bringing them to the shop isn't a bad idea. I didn't think of that.

The shop I went too doesn't seem too bad but I think I'll shop around for a rebuild price to see if their competitive. By then I'll have a good idea of what I'm in for.

Also, are the cylinders sleeved? It kind of looks like it is. Maybe that's just the water jacket?

Danny

dannym · #12 06-07-2007, 10:07 AM

It doesn't seem to have an inner oil seal:
http://www.yamaha-motor.com/waverunner/parts/home.aspx
Waverunner, 1990, WRA650D Waverunner III. Look at Crankshaft Piston section.

That makes it a whole lot easier. I figure I have 2 options.
1-Bore out cylinder and replace pistons, Wiseco maybe depending on cost. Replace oil seals and bearings while I'm at it.
2-New cylinders with new stock pistons, wiseco maybe depending on cost. New oil seals and bearings.

The more I think about this the more I think I can repair it myself. I'll probably have the shop install the rings. I don't have a ring grinder to adjust end play. Axial play will have to be adjusted too. Not to mention I don't have a ring expander. But this shouldn't be too hard.

Would I have to replace the connecting rods for the pistons? I would think not as long as they are both the same?

I'll be getting prices in the next few days. Should be interesting.

Danny

catmandoo62 · #13 06-07-2007, 11:00 AM

they must use some type of a sealed bearing between the rods to seal the cyls from each other.the rings aren't bad to put on,just roll em onto the piston,there will be little pins in the ring grooves to keep the rings from riding over the ports in the cyls.so you can't put them on wrong,also replace the wrist pin bearings(12) also yamaha has a special gasket sealer.yamabond i believe it's called,you will want to use it.otherwise you will have leaks.

JenTay · #14 06-08-2007, 10:10 AM

Quote:

Originally Posted by dannym

The saga continues....

Danny

Best advice from Jentay.....these things are best rented not owned. Think about it, is there really a FREE puppy?

A boat is not an asset, it's a liability.