OMG what did I do?

[Waternut]

I've been troubleshooting my 750sx for a while now and decided I try rejetting to what factory pipe recommended (88 and 155) for my setup instead 76 and 175 currently in it. With my current setup I got it to run great except down low with these jets using a really low pop off pressure.

I increased the low jet size, left the high at 176, and increased the pop off pressure back to stock. I fired it up in a garage for 5-10 seconds and it ran seemingly well. When I went to close the door and go inside I noticed a 2 foot puddle of black gas and oil underneath my exhaust. Am I just running so rich now that the gas is spewing out the exhaust? At first I thought I had really blown a piston or something. I opened up the top end so I could see the pistons and they look cleaner than any 2 stroke I've ever seen before. There was a little gas on top of the pistons and some light carbon build up but the rest looked fine. Pictures coming soon... Any ideas what is going on?

 

[shawn_NJ]

Were you cranking it alot before it started? Same exact thing happened to me 3weeks ago, while tuning (AND RUNNING TOO BIG OF A LOW JET) (120L in my case) and cranking alot. This was also on an SX motor. Your ski is fine..lol Scared me at first as well. I'd lower your "low" speed and run it on the hose for awhile to blow it out.

What carb setup are you running?

 

[Waternut]

Ok the picture makes the pistons look much much blacker than they really are but it is.

 

[Waternut]

Were you cranking it alot before it started? Same exact thing happened to me 3weeks ago, while tuning and cranking alot. Your ski is fine..lol Scared me at first as well. Run it on the hose for awhile to blow it out.

That's exactly what I was doing. I cranked it a ton trying to figure out why I couldn't get gas into the carb. :You_Rock_Emoticon: Thanks

 

[shawn_NJ]

What carb?

 

[Waternut]

Keihin CDK II 38mm I believe. Usually it gets gas back into it near instantly.

 

[shawn_NJ]

I could not get the stock 38 to work good with the 750/coffman setup I am running. But I got it ok.... If you want, I will look at what jets I ended up at on sunday. I ended up putting a 46SBN on, and the tuning problems I was having were gone.

 

[Waternut]

I could not get the stock 38 to work good with the 750/coffman setup I am running.

I believe you completely.

 

[shawn_NJ]

Only tip I can give you with the 38 is that the "proper" adjustment area is EXTREMELY narrow. Meaning that even less than a 1/16th nudge in either direction the ski will fall all over itself. With the 46, I can be off 1/4turn and the ski will still go. This was just my personal experience, but you really have to take your time to find the sweet spot.