650R boil over

I bought a 2000 XR650R three months ago, drove it around the block, and then tore into it. I went on my maiden voyage today (55 miles in the Sierras, 80 degrees) and about half way into the trip we hit a rocky, rutted, technical section. After about 10 minutes of climbing and pawing at a near idle (rekluse clutch) the bike boiled over terribly. No airflow over the rad's. I've installed a 1.6 bar cap, new Napa thermostat (two small holes drilled in the flange), and Fluidyne radiators. Any input or is this typical despite my "fixes"?

Is the bike uncorked? Mine used to overheat quickly since the rejet there hasn't been a problem, but summer is here so I'll see pretty soon.

Yep, uncorcked with QS carb. I did notice decel backfiring but assumed that the rekluse was promoting that. the darn thing does not disengage. No coasting. Another 650 with me didn't have a overheating issue. I don't believe water pumps go bad?

My bike is uncorked. It would overheat often in tight trails. I took out the thermostat because it never gets too cold where i live. That made it not overheat as much but still does sometimes. I have found that if you back out the pilot screw half or quarter turn then the problem will often go away. Problem is on the stock carb screwing out the pilot too far creates a flat spot. Its a compromise. :applause:

try usng engine ice

Engine ice and working on the jetting seem to be good places to start.

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