Super Jet 2000 SJ won't start, has great spark

[BlasterBen]

The ski started earlier in the year, then it went to running on one cylinder, and now it wont start at all. The ski has really good spark in both plugs, and sounds like it wants to start, but just wont. The carb is very clean. The only engine mods are B-Pipe and ADA girdled head with 35cc domes. Any help is greatly appreciated.

 

[WaveDemon]

4 things needed to make an engine run:
fuel
spark
compression
timing

if you have spark, pour a little gas down the carb or spray ether to try to get it to run. If that doesn't work do a compression test. If that doesn't work try a different CDI.

 

[BlasterBen]

Took the top end off today. Pistons had a very dark, thick, sooty build up. No pitting on the back piston, and maybe the size of a pencil eraser pitting on the front cylinder. Domes were pitting free, but had soot around the ring of them, but nothing on the apex of it. Could this be the signs of a top end going? I dont have a way to test compression, but I dont believe the ski has ever had a top end done, and it may finally be time.

 

[Matt_E]

I can't see your oicture, but there should not be any pitting at all.
You can buy or even rent a compression tester at any automotive store.

 

[BlasterBen]

Pic works now, had trouble with Picasa Web. I think I will have to try a tester. I am at a loss for things to try. I figured it was either the coil or plug wires, but it wasnt. I checked the carb and it was as clean as can be. But I also figured it would at least start with a bad top end, unless it is that far gone.

 

[Pablo]

Carb dribble from bad needle/seat flooding engine is my guess if u have spark, fuel, and compression.

 

[BlasterBen]

Do I replace the needles? How do I go about adjusting the needles to fix the dribble? I will test compression, but I think I will go for a new top end either way.

 

[FlightPlanDan]

"carb very clean"...It ran earlier in the year...that's a pretty big window...Did you pull the carbs and take them apart? Could just be an ethanol thing. If you had pulled the carb then you would have had a look at the needles. (hi-lo)
If you checked the jets, then you must have checked the needle/seat assy.
A new top end won't help if your carb is gummed up.

Is it backfiring when you turn it over?

 

[BlasterBen]

It wont turn over, it ran earlier in the year but very ty, and only once. Since then it has been trying to start but either not starting or only on one cylinder. The carb was completely apart. I think I had checked the jets.

 

[FlightPlanDan]

If you've dumped fuel directly into the carbs, and the spark is good, You really need to check compression b4 doing a new top end.
Even if it's just to know why you're spending money.

a 701 with an ADA head/35cc domes should give you about 185 psi. How old is the gas? Just curious. Plugs? Get the simple stuff outta the way first.

 

[BlasterBen]

Plugs are new. I will try new gas. If that doesnt help I will report back.

 

[DC SUPERJET]

I wouldn't say it sounds like it wants to start, and it WILL turn over. It chugs and chugs with no real ignition.

 

[aramis]

check the reeds?