RE:cr125 coolant probs

[oldskool]

hi all on my cr125 87 mod when i go out riding the first ride everything goes good,come back have a break check coolant all good then go out again when the bike is throttled hard then backed off the coolant blows out the overflow pipe and the cap.the bike dosent seem to over heat and only blows about 200ml out.does anybody know what could be causing this.thanx gary

[mainline]

I think all the honda experts are on their way to the nats. There's a good bike mechanic over this way if you need a contact?

[oldskool]

thanx paul i might give him a ring something telling me it could be a blockage of some sort coolant flowing good one way but not the other

[E74]

sounds like its overheating, have you checked the water pump impeller and more inportantly its housing..

[frostype400]

did the 87's still have the rot problem?

[E74]

did the 87's still have the rot problem?

Thats the first place i'd been looking.

[oldskool]

no havent checked either e74 not knowing much about water cooled bikes or bikes in general thought id put it up here.the thing thats got me is it dosent do it for the first ride usually half hour 45 mins,within 10 mins of rest the coolant and radiators are cool to touch then within 3-4 mins it starts doing the blowing out the cap thing.dont know if there like cars or not but the coolant isnt getting frothy or bubbling it will idle without blowing out its only when its reved hard then backed off and the coolant seems to flow alright at a low rev with the cap off.day off work tomorrow and have to get it out to wash it so i might pull a few things off and check the bits you mentioned.cheers and thanx gary

[Rossvickicampbell]

check to see whether you have an elusive partial blockage - soemthing in the pipes - there one minute and not the next?

cheers

Rossco

[oldskool]

thanx all just rang a few radiator places from what i explained they seem to think its the cap and as i absolutely flogged the guts out of it for at least half hour or so with this prob i dont think its overheating(but i have been wrong once before )i just think after giving it a hiding for that long non stop racing a crf250 and keeping with it or in front of it something major would have happened .thanx all ill try the cheap things first and just keep going till ive replaced the whole cooling system if i have to .thanx again cheers gary

[RMJJ]

How hi do you fill the rads in the first place.
Do you fill them to the top of the filler neck. It'll blow coolant out if you do because as it gets hot it expands and the pressure over comes the cap. You need to either measure it in or fll it to half way between the top of the fins and the filler neck.
Not sure why it doesn't do it on the first ride.

Is the head gasket ok, air lock maybe. does it have an air bleed plug/screw

[oldskool]

yeh it has an air bleed screw i was filling it right up but its only halfway now ive put a different cap on it the one that was originally on the bike had 0.9 stamped on it the one ive just put on came with the second hand radiator and has 1.1 stamped on it.took the hose off the water pump yesterday and put the garden hose in the top of radiator and the water seems to flow through without any blockages.ill see how it goes on sunday with the new cap.thanx cheers gary

[RMJJ]

without a doubt that will be the problem. It should be 1.1 bar. 0.9 is too low.
What ambient temps are you riding in ?

[oldskool]

hi rm i recently changed the radiator on the right side of bike and used the original cap that came with the bike so ive put the cap on that came with the replacement rad that is 1.1.been riding at coomera goldcoast so the temp has been around the 28 to 30 mark.havent ridin it yet with the new cap but will this sunday so ill see how it goes.thanx cheers gary

[oldskool]

thanx all seems like problem solvered went out today with a different cap and all seems good thanx again everyone cheers gary