300/440/550 JS550 is a bitch to restart
- Thread starter dean85gt
- Start date
D-Roc
I forgot!
- Location
- Dirty River Rider
you coming to rock point tonight?
cookerq62
Life's Been Good
- Location
- Upper Bucks, PA
Just put it on the hose. You will know right away. I don't get why you would look for a water leak by checking compression? It could be an exhaust gasket.
Polish jet pilot
4aces4aces4aces4aces4aces
- Location
- Warsaw, Poland
All 550 have the same issue. I fixed mine by routing fue;l lines directly from tank to carb, making sure my vent valve works, and that my fuel returns via a restrictor...starts everytime....
that was going to be next weekend. Dont think I am going to bring it the way its been acting up just incase
leaking head gasket...when hot
the WaTeRhAwK
fryin' up a/m electrics..
- Location
- okc
yes, it is possible to have an exhaust leaking water, and back pressure from the pipe stuffing it into the post compressing cylinder(s) with the unspent fuel. It is best to check for one thing at a time (short of disassembling the engine) and by deduction track down the gremlin.
another problem is, if his crank seals are on the verge of needing to be replaced, the engine will also be easy to start until operating temperature is reached, and then leak enough to cause the symptoms.
the WaTeRhAwK
fryin' up a/m electrics..
- Location
- okc
if one plug is wet, do you mean in terms of water? or fuel? water will usually "bead" up, or a blended mix of water and fuel will look "milky".
the WaTeRhAwK
fryin' up a/m electrics..
- Location
- okc
then it's probably what cooker was saying, a leaky head gasket. if you have a torque wrench, or you can get ahold of one, it's easy to take the head off, check it and put it back on. you'll probably need another head gasket. it's rare to be able to reuse one, depending on the shape of it when you separate the part. exhaust gaskets are even worse at tearing up on removal. the head mating surfaces and exhaust surfaces are the only two places you are going to get water in, unless you turn the ski on it's right side in the water, and residual water in the exhaust pours into the exhaust ports.
I just went for an hour ride...It ran great the whole time. As soon as I shut it off it wouldnt start. I brought it home and tried a compression test (it was still hot). I only got around 100-115 psi out of both cylinders, but the battery was quiet low at this point. I did have the charger hooked up on the battery but it was still struggling
the WaTeRhAwK
fryin' up a/m electrics..
- Location
- okc
if you do a compression test when it's cold, and you get 150 psi, then it gets hot and you're down to 100-115, you most likely have a warped head.
also, it's not necessary to run a head gasket, as there is no squish interference with the 440's and 550's, like on the larger displacement motors. the edges of the piston crowns never clear the deck of the cylinders.
with a stock head that hasn't been milled or anything, you can use laquer thinner or chemtool B-12 to clean the mating surfaces and glue the head straight to the jugs with threebond 1211 or an equivalent such as yamabond. by omitting the headgasket, it will raise your compression as much as a head milled .030 (give or take a few thousanths). although, of coure the mating surface of the head and the cylinder deck has to be in good shape.
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Well...after some riding tomorrow I think I am going to tear the head off and bring it to the machine shop to be milled. Should I actually mill it a significant amount or just enough to have a square surface?
the WaTeRhAwK
fryin' up a/m electrics..
- Location
- okc
if the head is warped a little, you can resurface it yourself with a sheet of 220 grit sandpaper masking taped to a sheet of flat glass of a decent thickness. like 1/4" thick. using a "figure 8" pattern. if you get it milled you will definitely have to run a gasket so your compression won't be too high for pump gas.
Polish jet pilot
4aces4aces4aces4aces4aces
- Location
- Warsaw, Poland
I'd mill it. 550's have a lot mof meat on the head. Plus 550 heads are cheappp if anything goes wrong with it..
But I still don;t think starting is caused by the head. Either carb / fuel line or starter.
But I still don;t think starting is caused by the head. Either carb / fuel line or starter.
the WaTeRhAwK
fryin' up a/m electrics..
- Location
- okc
I was thinking his popoff pressure may be too low, so when he kills the motor, the whole time it's winding down, it's loading the engine up with too much fuel. but that doesn't explain the "milky" substance on the plug, that's water mixed with fuel.
Polish jet pilot
4aces4aces4aces4aces4aces
- Location
- Warsaw, Poland
True, but I was thinking that he might be actually subbing it and since a lot of water gets into that hull quickly maybe he ingested a bit...one way or the other if you want to have a good running 550, you must do everything once and for all...otherwise it will be wrenching time on the beach till infinity....
Popoff is another thing to look at but I ran my carb on stock settings after I did all fuel routing etc and it ran nicely.
A mikuni 44sbn would cure all his problems....
Popoff is another thing to look at but I ran my carb on stock settings after I did all fuel routing etc and it ran nicely.
A mikuni 44sbn would cure all his problems....