95 sp 587 backfire

[mikidymac]

Did you ensure coils are going to proper plugs. Sometimes the simple stuff will get you.

It's a wasted spark system so both plugs fire at the same time. It really doesn't matter what plug wire goes on which plug.

 

[Ryan356]

I also checked for twisted crank last night and seemed fine.

 

[Ryan356]

I have suspected the valve cover even though it is new. When you put it on it has that metal to metal feel and sound almost like the seal in there isn't even being squished..I have an extra seal maybe I'll put two in... I'll try anything at this point.

 

[Ryan356]

So reading thru some of the initial comments and also recalling this project from the start I think I might order the makuni rebuild kit as it sounds like the cheap kits have been reported to potentially dump excessive fuel in some cases. This would potentially explain why it appears that I am losing spark at high rpms. Basically under slight vacuum the carb provides appropriate amount of fuel but once vacuum increases under higher rpms the cheap diaphragm let's loose and dumps the fuel to it causing it to backfire. I'm going with that logic for the moment and ordering the complete kit. The original one I ordered with needle and jets was only 24 bucks so I'm thinking I got what I paid for.

Also the original engine was replaced as there was a ton of blow by oil coming out the back end due to a chipped piston (root of problem was oil pump wasn't hooked up correctly but that has been remedied). It actually did run prior to new engine without backfiring and the only thing I changed outside the engine was rebuilding the carb with that cheap kit...

 

[mikidymac]

As we say over and over and over again, only genuine mikuni parts.

 

[Ryan356]

So I finally got a chance to put the genuine makuni carb kit in. I put all in per instructions, did all tests per manual and all checked out. The check valves were working and all this time. Fired it up and there is no longer a backfire but the engine does cut out due to what I believe is the rev limiter. So making some progress just need to test on the water... so cautiously optimistic.

 

[Ryan356]

Finally got the ski in the water and runs great. Seems like the makuni carb kit was the trick. Thx for all the assistance.