300RR Overheating

[173_wrench]

WE have a 16 300RR race that overheated yesterday at a race in south Missouri. The race was muddy, not deep and it was raining, lower 50s. Bike started heating 3ed lap. We put water in it every lap after that, 3 more laps. We are new to Beta and 300s. Are they hard to keep cool? It was holding pressure, the rad. was covered with mud, but so was every rad. there. My son is leading the points and we have a race next weekend. I plan to take it apart tonight. Any help would be greatly appreciated.

[Enmerdeur]

I have a 2014 300 that I have never boiled over. I have ran it in one muddy race with it without issue. Not sure if it was as severe as what you encountered. There have been some issues with head orings not sealing on the 300. Might want to check that.

[redbone477]

I would say you may have something else going on. Beta's are known for not boiling over and running hot. I've had my 13 300rr since new and never overheated it. I had bad o-rings and it didn't overheat then either. Maybe jetting is lean and it's getting hot. Just thinking of things to check?

[NZMarkb]

As above
Something else going on, Beta's have great cooling
My fan hardly ever comes on, unless stop start de-arrowing in the forest

[bikesparky]

Head O-rings. Replace with KTM ones and problem gone!
They don't really overheat, it's the pressure from the gas entering the cooling system pressurizing it and pushing coolant out.

Beta had a bad batch of O-rings, the inner leaks. You can feel the weak spot running it trough your fingers.

[woodsrider412]

Replace the head O rings and remove the thermostat if it is still in. Tell Logan to go get em.

[hawaiidirtrider]

Sounds like something else is going on..so maybe the o rings etc?.. Beta 300's aren't known for boiling.. It sounds like your course is still sort of fast and flowing.. I'm just guessing. For me ..my Beta has boiled in the past but it's because we are doing super slow muddy..no air flowing riding in technical. My cr 250 honda that I had before my beta I did lots of mods to address overheating.All my bikes I have overheating mods added ..so when I got my Beta 300 I just got a fan first off.. and an overflow tank.. a high pressure cap etc... but we do the slow tech stuff here. I don't know what kind of racing your son does .. I don't know the kind of courses you guys run.. if it's fast or slow or what.. but most Beta don't overheat. was your son fanning the clutch lots too? that will be part of it in the mud.. idk. you might take off the thermostat too.. take out the internals maybe.. That O ring thing might be something. I haven't had problems with my 13 300rr or my 15 300 rr but like I said I put the fan right off etc.

[twmtatenrost]

just to help prevent mud clogging up the vanes on the radiator - get some of your missus 's old tights or pantyhose you lads call it and zip tie to around the vanes- the muck should slide off !!

[173_wrench]

Thank you all for your replies. We washed the bike then I rode it, it ran good. Used a temp. gun to try to see if thermostat opened, it opened but not full open, but it was only in the low 150s. Pulled the thermostat, heated in water it opened at 160 full open by 180. Pulled top end orings look and feel good. The good news is piston and cylinder looked good. I also checked the water pump and replaced the seal. I think I will replace the piston and rings, I have a set of KTM origs to use. I don't think its lean, didn't show signs of detonation. I going to check the clutch to.
Thank you for all the help.

[hawaiidirtrider]

get a fan...i did.