2017 300rr Coolant Leak ... Only During Warmup

[Jebster]

Great tip to watch how turbulent the coolant flows, mine looks "normal". I must be lucky as far as the o-rings go.

I did tighten the 4 screws on the housing a little. No more leaks at this point and I musta' looked a dozen times while riding it today. Before I tightened the screws I noticed that the joint in the housing was weepy. Hopefully we're good.

[dirtbird]

Checked mine whatsoever.
Looked normal as well.

[bikesparky]

I find it extremely hard to believe a bad head oring will blow coolant almost vertical, into the frame triangle, and on the Tstat. Its the Tstat housing or a clamp.

Well it did on mine. The thermostat seems to be the weakest link and that's where it was leaking.
Replaced the O-rings yesterday and all good now. No more leaks and found a heap of power back.
Must have been leaking compression a fair bit.
I'm not exaggerating but it feels like 10-15 hp at least.
The idle sounds crisp again, like as it did new.

[cluffie]

2017 beta, 15 hrs and blown orings.

Before the ride it fouled the plug which i thought was strange as i have never fouled a plug on my various ktm 300's in over 600hrs of riding. anyway i changed the plug and it started up ok but alot of wet stuff came out the back which again i thought was a bit strange but i took off and went riding. bike was running ok and we did 100kms in about 5hrs of tight style riding. when i got home i noticed coolant on the trailer that had been pushed out of the bike. the bike was completely cool and i loosened the radiator cap and it went puff with some pressure coming out. Then i twigged,head o ring has gone and the radiator system is getting pressurised excessively.

Rang the dealer and he said i'll send you some orings but i said i would rather use some ktm ones from my ktm shop,as i have never had an issue with them. fixed it today and all is good again,no leaking and it seems to be running a little smoother. Hopefully it will last or i will have to get the head checked and milled flat if needed but i'm pretty confident it will be ok.
i'm bloody annoyed about this issue and don't really like the idea of pulling down a brand new bike. even if it is a simple job.

Personally i prefer the pin dowel setup on the ktm head that eliminates any chance of movement between the cylinder and head then the beta setup which is relying on the bolts to hold it in place.

[NZMarkb]

All I have to say is:
Silicon Hose Kit and trow away that stupid plastic thermostat

[cluffie]

Went for a 100km ride over 5hrs today giving the bike a hard workout and the bike is sweet. No leaks,no excess build up of pressure in the radiator,no coolant dissapearing.

Ktm head o rings in the beta = fixed. (for my problem anyway). i suspect my o rings were faulty and leaking from brand new or very shortly after. Bike seemed to run a bit better then it ever has.

[bikesparky]

Went for a 100km ride over 5hrs today giving the bike a hard workout and the bike is sweet. No leaks,no excess build up of pressure in the radiator,no coolant dissapearing.

Ktm head o rings in the beta = fixed. (for my problem anyway). i suspect my o rings were faulty and leaking from brand new or very shortly after. Bike seemed to run a bit better then it ever has.

Mine was the same. Beta has a shit O-ring supplier. You would think they address that straight away.

[cluffie]

went on another 70 km ride on sunday with a large group. bike performed flawlessly and better then from new,no leaks and the coolant level never moved. its a pity that a $14 set of orings failed and could of destroyed my engine if i was inexperienced with bikes.