01 yz250 heat problems

[spdfrek]

I have a problem,I just got my bike back together and road it a bit today.What happened was it started normally,ran great for about 10-15 minutes of riding...then slowly it seemed to loose the hit in the power band...got a lil quieter exhaust note...and lost some top end....I felt the top of the radiator which to my suprise was pretty darn warm.Its only 68 outside today so it shouldnt come close to burning the back of my hand when i touch it i wouldnt think...At least,ive never had this problem before.


Heres what was recently done to the bike-
Rear shock rebuilt
New rear tire
Had radiators removed to clean the valve on the front of the engine(was tired of oil puddles after my rides)refilled with fresh 50/50 mix
Silencer repack
Added a spring to the exhaust pipe
Oil change


I checked the level in the radiators and it was fine,nice and green,and with the bike idling the coolent seemed to flow great.I check all over but i didnt see any air bleed screws for the cooling system so ill assume there is none.


Exhaust took a few hard hits before i bought the bike,pipes a bit dented and actually seems to be bent out of place a tad,the thing dosent line up smooth to the engine,has a slight angle to it,replacement pipe will prolly be ordered.


Factory silencer,just a fresh set of fiberglass....shouldnt be a big deal

Oil was changed...fresh gear saver 80w in the tranny...seems to work great.


A few weeks back i dumped the bike in about 3' of water,but we drained it and clean the filter and all that and it was running fine till i took it apart to do the shock and stuff.So is there something i may have overlooked?It starts easy,runs good,compression isnt to low,my buddys 00 yz kicks over a fair amount easier.I can test the compresion if i take off the seat and tank i suppose....if someone wants to know the exact number.Any help would be great thanx

Joey

[spdfrek]

Well i did a compression check....120-130PSI....guess i better replace the piston and things...pro-x?vertex?leaning towards pro-x but i dunno...Good place to order from?Should i get a factory sized replacement?Thanx

Joey

[YZGreg]

I like Wiseco pistons my self because they've been around for ever and they're forged, unlike pro-x (which is just a cheaper = to oem piston) and Vertex which has a coating on the skirts to make it last longer. I would go for a Wiseco since they last longer than the two brands you want and they're about the same price.

[Dell30rb]

When you drown a 4 stroke, water gets in the oil. This is probably what caused your problem... you can get it running again, but it is advisable to change the oil asap...

[YZGreg]

But his bike is a 2 smoker.

[steiner]

check your power valve

[psycho393]

It was the piston. Secondly explain why a power valve would make it heat up?

[steiner]

the power valve changes how the bike runs.

[YZGreg]

The PV just changes the exhaust port timing to give it more bottom, If it got stuck it would just have no bottom and run crappy thats all, it wouldn't heat it up.