Super Jet Kinked pulse line = power loss?

kawa js550

kawa js550

Billy Racing
Location
Michigan
I have been trying to get my superjet tuned for a while now and I bout T adjusters to try and get it better and it seems like its something more then just tuning it. I can ride it fine but it will have no power anywhere and wherever I adjust the mixture screws it still doesnt have the power it should have. I noticed that my pulse line was kinked but I didnt have time to put a new one on. Could this be my issue? I put a check valve from a 550 on but I dont think that would be the issue.
 
mbrick

mbrick

Location
Los Gatos, CA
If the pulse line is kinked so it is not able to pump adequate fuel then yes I could see that limiting power and running awful.

You should probably put on a new pulse hose of the correct length so it does not kink, and then resume tuning.
Also make sure your carburetors are fresh with an OEM (not aftermarket) rebuild kit.

What is the rundown on the engine?
Compression? Leak down test results?
 
kawa js550

kawa js550

Billy Racing
Location
Michigan
mbrick said:
If the pulse line is kinked so it is not able to pump adequate fuel then yes I could see that limiting power and running awful.

You should probably put on a new pulse hose of the correct length so it does not kink, and then resume tuning.
Also make sure your carburetors are fresh with an OEM (not aftermarket) rebuild kit.

What is the rundown on the engine?
Compression? Leak down test results?
Click to expand...
160 even compression, passed leak down test, 61x/62t freshly rebuilt, carbs were rebuilt before winter. Im really thinking its the pulse line because it idles great but when u get on it, it falls on its face and I think the pulse line is making it hard to tune. When I replaced the line I replaced it with some aftermarket soft hose, so im going to use some old oem hose to make the new pulse line
 
kawa js550

kawa js550

Billy Racing
Location
Michigan
Just to close out this thread, I found the problem. Pulled the motor and did a leak down test. There was a BAD air leak where the brass fitting for the pulse line goes into the case. Fixed that and now it passes the test! Also pulled the pump and midshaft, they seem fine, but there was no shims on the pump and the driveshaft was not center so I shimmed it and reinstalled everything. Hoping with a little tuning this thing will have all of its problems worked out!
 
kawa js550

kawa js550

Billy Racing
Location
Michigan
Dug into the carbs and they were disgusting! I wish I had the knowledge that I have know, when I first bought this ski. Been fighting for 2 years trying to get this thing to run right. Tried to pop off test the carb and it couldnt even hold pressure and air leaked out through the gaskets. Person before stripped 2/4 jets, which need to be replaced. Ski is all stock and had a 2.3 n/s in it, which explains why I could never tune it. The lesson to be learned here is if you buy a used ski, go through everything!
 
flyHigh

flyHigh

Location
Germany
The more knowledge you have the easier you can get a good deal on something used most of the time. Did you get it all working after that time?
 
kawa js550

kawa js550

Billy Racing
Location
Michigan
flyHigh said:
What gaskets where leaking? Do you mean the oring from the n/s?
Click to expand...

The gaskets on the the fuel pump side were leaking. I tried to do a pop off test and the carb wouldn’t even hold any pressure. The n/s was too big making the ski run too rich and virtually untunable. We will see if this fixed everything but I’m pretty confident this is the problem because everything else on the ski has been gone through and I now just circled back to the carbs.
 
flyHigh

flyHigh

Location
Germany
Okay I see what you mean. Sounds like your on the right track. Get a 1,5 n/s i thinks thats what they recommend in the mikuni manual for 38's. Since those carbs cant flow more than a 1,5 n/s can deliver. I guess you have studied the mikuni manual already.
 
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