[ugmw177]

HI all,
late 2016 I purchased a 98 xl1200 [non pv motor] that the owner had run with the middle oil line off.. melted the piston. Anyhow, I rebuilt the engine...new pistons, had the jug bored .5mm over, cleaned the crankcase and used new crank seals and gaskets. pressure test held 10psi for a couple of hours. I rebuilt the carbs at the same time...using mikuni genuine kits. Installed engine with new oil lines and new fuel filter etc. did the breakin for 10hours. Ski ran great the rest of 16 and all of 17. this spring had it out and it runs good but at the last say quarter inch of throttle pull it starts bogging down. once you back off the throttle it runs fine again.
I put in new plugs, cleaned the fuel cutoff switch [it was not dirty] checked the lines etc..all good. Compression test shows 120psi on all three. took it out again and it still does it. Any suggestions.

 

[rodsatheart]

Prob. needs the carbs cleaned. The last 1/4 of throttle is where the high speed screw comes into play.
Normally break-in for a 2 stroke is 1 tank of fuel. The 4 strokes have a 10 hour break-in. I would also make sure the choke is opening up all the way.

 

[ugmw177]

Hi Rod,
Thanks for the reply. It actually turned out to be that the clamp securing the main exhaust hose to the stinger pipe had come loose and was allowing exhaust gas to fill the engine compartment. Engine was trying to run on mix of fuel and exhaust gas...New clamp nicely torqued down and it runs great again