Letting some steam off

[Rabbitist]

Ok so I was out yesterday at ashby moto park. The going was tough as its quite deep loose stuff that was wet. My problem is my bike was running hot.. Infact I couldnt even get round a lap without my radiator overflow spewing out steam.. Anyone any ideas on the problem? Its a 2000 model ec 250.. Any help would be appreciated?

[Jakobi]

Originally Posted by Rabbitist

Ok so I was out yesterday at ashby moto park. The going was tough as its quite deep loose stuff that was wet. My problem is my bike was running hot.. Infact I couldnt even get round a lap without my radiator overflow spewing out steam.. Anyone any ideas on the problem? Its a 2000 model ec 250.. Any help would be appreciated?

Airflow to the rads? Or were they caked in mud? Or not sufficient flow to going too slow? Thick deep loose soil will also load the engine much more. If you were a tad lean the bike would also run hot.

[blitz11]

Could be radiator cap. Buy a KTM 1.4 bar for $10, and try that. Could be bad water pump impeller. Those were plastic, and of questionable quality. You can buy a replacement aluminum impeller if the cap doesn't fix it.

[Todd5774]

I don't think it was the conditions. My bike was there although I wasn't and my fiend reported that the bike ran great, and had no problems with it at all.

Are you using water or coolant? Using the expansion tank?

Could be you need to upgrade to a higher bar rad cap.

[Rabbitist]

Thanks guys I used mainly water as I ran out of coolant mix so it was 70/30 coolant to water when it recomended 50/50 also ive just rebuilt the top end with a re nikasil plating and piston the end gap on the rings was possibly up to 0.05mm tight on 0.4mm gaps however I cant see that effecting it.. Also ran an extra cap full of oil to 5 litres of 97ron fuel at 50/1.. I recon the first port of call could be draining and flushing the coolant then put the right 50/50 mix in and check out the impeller.. Cant see the cap making any difference as it was spewing the steam out of the overflow pipe which is just below were the cap seals and if the cap wasnt sealing it would be coming from there right.. The bike was clogged with mud and I was having to rev the nuts off her to get anywere and I definately wasnt fast infact it was second gear all the way..lol any advice welcome cheers

[PEB]

THe 1.4 cap will hold more pressure, and when it lets loose it will come out the overflow tube. Adding more antifreeze will raise the temps not lower them.

[Rabbitist]

thanks again i didnt realise that of course its a sealed system it makes sense now were can i get a cap from here in the uk?

[Jakobi]

I'm still going to say you were running a touch lean. Fresh top end has now resulted in a better ring seal, thus better compression. We all know higher compression needs a bit more fuel, or higher octane at least. You then added more oil to the mix (while only a little it will make a difference). More oil displaces the effective fuel, thus leaning things out. You also rode in conditions that was putting extra load on the engine which also increases a bit more fuel.

[Rabbitist]

thanks jakobi could someone explain the expansion tank to me im guessing its the plastic tank just above the rads.. ive seen coolant in there before never really got why cheers

[Rabbitist]

Anyone know were to get an ally impeller from in the uk?