Need Help cooling 2001 YZ250F

[Mlynch128]

I Have a 2001 YZ250F that was recently restored not long ago piston,rings, bearings, replace top and bottom end parts etc. But haven't punched it out or anything crazy . and I've been trying to get it to run cooler in an attempt to have it start better once I take it for the initial hard ride. I use engine ice I have a boyesen water pump on it and have replaced the original bowl with and R&D bowl / mixture screw . Should I get better rads ? Etc ? Has anybody ever put a small fan on their rads like some quads have ? I'm in need of some help guys . 

[morphrider]

There is a mod out there where you zip tie a bottle to the frame, in essence making it a overflow bottle, then as it cools it sucks it back in. Mine only runs hot if I take it to the dunes, so I just don't anymore. Have you tried a different radiator cap?

[firstnewbike]

it you replace the radiator cap, use a stock pressure cap

I would not use a high pressure cap you will split a radiator tank...

stock radiators are very thin and not very strong

also is the bike jetted correctly, that will have a big affect on how hot the engine runs

PETE

Edited August 2, 2017 by firstnewbike

[Mlynch128]

I haven't tried a new rad cap but now that I know it will split it I think I'm just going to upgrade to better rads as well as a cap. I did the jets myself per the FMF kit to match the FMF header and exhaust that I put on with the other mods . And everything seems to be good in that department but I'll keep that in mind for sure . I appreciate all the help ?? ! 

[DarrellH3]

I doubt you will see any benefit from replacing the radiators. Getting the card dialed it will make the biggest difference. Do you have an adjustable pilot jet screw? 

[0macman0]

This bike will always be a beast to start when hot, no way around that. As for the heat, carb tuning and valve adjustment will be the biggest contributors. I was also under the impression that the WR had larger radiators? Not sure if that is true or not.

[Mlynch128]

On 8/3/2017 at 7:37 PM, DarrellH3 said:

I doubt you will see any benefit from replacing the radiators. Getting the card dialed it will make the biggest difference. Do you have an adjustable pilot jet screw? 

Yea I do I have a mixture wcrebon my machine . What do you recommend i do ,?

[0macman0]

Yea I do I have a mixture wcrebon my machine . What do you recommend i do ,?

 

I set the idle mixture screw by turning it in small increments till it idled highest, then turn open 1/8 to 1/4 additional. Then set idle speed with idle speed adjuster. If it is set right, you will have no popping on decel

 

I really doubt that this would be the cause of your heat problems though. It would be on one of the higher circuits like needle or main. Does it make good power?