Superjet (650) Running Lean & Hot

smoofers

smoofers

Rockin' the SQUARE!!!!
Site Supporter
Location
Granbury, TX
Hey all, I have a '91 SJ with a stock 650. Only mods on it currently are a ProTec F-series pipe (stainless chamber) along with the carb re-jetted with ProTec's specific jet kit (I think its a 135H 120L?). Stock F/A with only one screen installed. Prop is a solas 14.5x18.5. I have also installed a trimpot on the rev-limiter.

Last weekend it started falling off on the top end so I richened it up and started reading plugs. They were practically white... richening was doing nothing.

Last night I blew out the fuel pickup, cleaned out the clean fuel filter, blew out the fuel line and eliminated my fuel selector. SO right now, fuel comes from the reserve pickup to the fuel filter, straight into the carb.

I also took apart the carb, jets were clean, internal filter was clean, and I blew out the passages with carb cleaner and compressed air.

This morning I tried it out. Same thing, I went all the way to 2 3/4 turns out on my high speed screw and the plugs are still white. The low end is at 1 3/4 turns out. I checked all my cooling hoses, blew them out and verified the pump was flowing water through them. Right now the motor seems to be running way to hot, the manifold sizzles a bit when you drip water on it and the head is hotter than it should be (by touch). I don't know what else to check at this point.... Any ideas? I also haven't been able to find much info on this ProTec pipe setup that I am running. It feels to me like I should have way more grunt and top end (I know its a 650). To me it feels like a bone stock 650. Again, any input, tips, or suggestions would be greatly appreciated. Thanks in advance.


EDIT: I forgot to mention, where I have been riding lately is shallow and sandy. Is it possible my cooling passages are filled with sand? Maybe enough to prevent proper cooling but not enough to impede coolant flow? Just wondering....
 
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smoofers

smoofers

Rockin' the SQUARE!!!!
Site Supporter
Location
Granbury, TX
Update:

So in the last few weeks I have:

-Disassembled the carb and cleaned it again (seems spotless, carb was rebuilt in March with a new, genuine Mikuni rebuild kit)

-Pressure tested the motor @ 8 PSI - It lost about 1 PSI over 15 minutes. Small air leak at the manifold to case gasket right under the carb (tiny leak)

-Pulled the head; cylinder walls and pistons both spotless with no scratches gouges, etc. Cooling passages were very clean as well, only calcium deposits (minor)

I haven't pulled the intake manifold to check the reeds - I don't have a new gasket yet, and with the head off there is a pronounced "poof" from the transfer ports when the motor is turned over... they seem okay. If I were to pull the manifold and use 1211 to seal it back up would that be suitable?

My main goal is to get the motor running properly so that I can at least ride 2 more months. I DO NOT want to spend any more money on this motor as it is a 650 and will be replaced by next year with a 701. I just want to ride for 3 more months...

Thanks in advance...
 
ryan

ryan

Location
baldwin ny
whats the temp of the chamber when you do a plug chop? its the pipe is steaming out you cant get big enough jets to make it rich. toss some water on the chamber after a long high speed run (as fast as a 650 will go is not a high speed run lol) should get a little sizzle. if the pipe is on fire you need to get more water in the chamber.
 
ryan

ryan

Location
baldwin ny
go up on the main jet. try a 140 see if you start to get color on your plugs. the yamahas run the best with a very lite brown close to white plug. you need a tac to dial it in the right way.
 
ryan

ryan

Location
baldwin ny
carb was checked and cleaned? guess not to good.
did not know this was a running set up and it went bad. no pump no gas there you go.
 
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