Overheating Ec300

[normanator27]

Hi,
my 08 model is overheating when its quite hot. It overheated on the weekend just gone when it was 32degrees and quite humid. it was pretty muddy so the pace wasnt that quick but i wasnt flogging the bike by any means. Its also overheated previously on similarly hot day or maybe a little warmer but dry day, albeit at a gentle pace as i was alone and doing a little exploring. Its all pretty good until after around 30-60 minutes then after hitting the pipe a bit, it starts to surge for revs a little (sort of sounded like a rotary engine) when the bike isnt moving. It also leaks a bit of what I can only presume is oil from where the spark plug screws in when its overheating.Ive been reading a few posts about dodgy radiator caps so i'll have to try and get my hands on another one and see if thats it. If anyone could give me a clue to other things I could be checking that would be great. Thanks.

[gassergrant]

Check the water pump is working mate. Pop a hose of and run a garden hose through to see if there's any blockages. Or if it has a thermostat check that's working
I had a leak from the plug it's been over tightened and compressed the washer to much

[Simmo737]

Water pump failure, cap not holding pressure, leak (pinhole, rad pressed edges etc or into cases) and coolant loss, "use by date" on coolant ( if it's boiled, change can help).

[normanator27]

Originally Posted by Simmo737

Water pump failure, cap not holding pressure, leak (pinhole, rad pressed edges etc or into cases) and coolant loss, "use by date" on coolant ( if it's boiled, change can help).

I dont think its leaking as the fluid level never went down. The coolant was changed when i did the piston and rings about 40 hours riding ago, although ive changed that again anyway. next step i'm going to check the thermostat and impeller as the bike has done about 120 hours and im assuming the impeller is the original one. i'll also try the garden hose thing the last bloke suggested as well.

thanks for the tips gents ive got a starting point.

[gassergrant]

take the water pump cover of and kick it over to see if it move and maybe try and hold it to see if it spins or not.
I ran my cr with a broken pump it worked fine in the winter and did not seize or boil over I think I was bloody lucky tbh well until it seized up due to the bridge not being re leaved

[webmaster]

If the bike has been overheating and it has a non-metallic water pump impeller - remove the water pump cover and check it. it is probably "toast".

if you have a non metallic impeller - even if the impeller looks good - replace with an upgraded machined alloy impeller - it is more efficient and more durable.

Also check for anything that might make it run lean - check for air leaks at carb insulator and clean carb to ensure pilot is clear. Switch from oem jetting specs to different needle and richer pilot if you haven't already.

jeff

[Lincolnlock]

I'll bet the bike is running lean. With it being 32 degrees you'll probably need to turn the air screw in a bit.

[normanator27]

I'm running a 42 pilot, 175 main with a N3EG needle on the second from top clip position. edit: the air screw is out 1.5 turns. the plug colour is good with scope to run a little leaner according to a mechanic friend. Still i'll check all the things youre recommending. What are youre thoughts on my jetting specs?

[Caravan Monster]

If not coolant or jetting related, it may be worth checking the flywheel side main bearing. Remove the plastic flywheel cover, grasp the flywheel firmly and check there is no up / down movement. When the main seal starts to go, it causes lean / erratic running and overheating. Hopefully not this, but only takes a few minutes to check.

[Simmo737]

Originally Posted by Lincolnlock

I'll bet the bike is running lean. With it being 32 degrees you'll probably need to turn the air screw in a bit.

32 degrees c not f, about 90f, if anything it will be richer