[Ryno]

All,

One of my 1st post on here and have a little question with a big story behind it. Last week I installed an MC head on my 06 EC250 and was previously running LTR needle and this jetting. 42pilot, LTR needle in middle position, 185 main. 30deg-90deg at sea level. New England terrain.

I had the chance to run a higher compression head from an 06MC and was told to bump the pilot up to 45 and run the main at 185. I had very good luck with the LTR needle and stuck with that needle. The person I got the head from did not use the LTR needle and was using the stock needle. 50/50 Sunoco race fuel was necessary.

Anyways, the bike flat out ripped and I could not believe the pull from the bottom into the midrange. We just had our 1st harescramble in Maine this Sunday, 20degrees and dry air with plenty of frozen ground and ruts. My bike ran great for the 1st 5 laps of a 6mile loop and about 1/2 way through the 5th lap it started making some knocking noises, almost like a rattling crank bearing. Well I was doing pretty well in the A250class so I kept running it. The knock would get worse as I chugged the motor so I kept it in the RPMs a little more. Well the last lap it died in a corner and wouldn't start. Sounded almost like it ran out of gas I sat there for a couple of minutes bummed but then looked and plenty of gas. Kicked, kicked ,kicked, choked it and it fired up and the knock was gone for bit and then came back near the finish. Finished the race but discovered I was pretty much out of coolant. I think I was just running hot and boiling the fluid out over the course of the race, the terrain wasn't that bad with a quite a bit of speed and I've never boiled my bike out of fluid in the summer.

Was the LTR needle too lean off of the pilot and making the bike run hot? The bike is torn down and the lower ring was siezed and the head 0-rings were rock hard from being so hot. Cylinder is within spec and everything else is checking out OK. Thank goodness for TORCO- 12miles with no coolant!!!! I'm looking for root cause??? Any suggestions?
Les, do you have any experience running your needle in the MC250?