Wierd engine noises

[25Cameron25]

Lately my 2007 Crf250r has been making some strange noises when it gets hot. It makes a howling/whistling sound after 2 hours of hard riding. The wierd part is...it does it even when the bike is turned off, if i just roll down a hill in first. but it wont do it in neutral. it also always does this pinging noise when going low 3rd, 4th, or 5th. but after reading up on that im pretty sure its your chain...even if its set to the right slack...which mine is. ok well this motor has about 22 hours on it. and i have never opened it up. i am going to change the oils and oil filter, and clean the air filter again today ..maybe that will somehow help. and obviously check for particles in my oil and oil filter. but please help. it kind of scares me. it cuts my riding short.

 

[bwood]

Check your trans oil level. My 05 will make the "whirling" sound when the oil is low (best way I know to describe it) like my 99 Cr did. I don't use the oil level check screw. I put in about 50cc more than the manual state (700cc I think) and all is good. The motor has about 25 cross country races on it since Nov 05 and I'm guessing about 300 hours on it. I have replaced the piston, intake valves, valve springs and seals and the associated gaskets. The bottom end is stock. I change the oil every 3 practice rides or every race weekend. I use Silkolene Race 4T 10W-40 (full synthetic in both the engine and trans, it is clutch safe). All has been good so far. I did notice some small aluminum shavings in the oil filter last time I changed the engine oil. I'm thinking it is oil pump related as it is mounted inbetween the cases. I plan on a rebiuld this winter (crank, piston, valves and anything else I find) and hope to get 3 more years from it.