Engine trouble. overheating, doesnt sound right
 

Hi guys, ive got a k4 sv650, just completed a good once over on the bike after a winter of commuting. everything seemed to be running perfectly, but 500miles after back on the road, its suddenly reading as seriously overheating (130oC) and the engine def doesnt sound its usual self. I'll list exact problems:

• Idle speed - I noticed a few days ago seemed to be slower, now v low. also when first starting the idle doesnt automatically increase.

• Not firing correctly - not the usual roar, thought was firing on one cylinder, but both exhaust outlets get hot.

• Cant maintain a low temperature at any speed! fast or slow. Managed to limp home last night at 14- 20 mph @ 125-130 oC. Reading from the digital display. Didnt notice any boiling over or anything, although it did seem hot. As you sit on the bike, the RHS rad pipe was hotter than the left.
• All fuses seem to be ok.
• Done some work on it recently which includes, oil change (10w40 fully synthetic), K&N air filter, Iridium plugs, added scottoiler, s/s brake lines, general tidy up all over. (incase i could have done something wrong)
• Seems to be a bit clunky thru the gears, but was figuring this is prob due to a slightly loose chain.
• Checked coolant levels and seem to be fine
• the rad fans didnt come on at anytime

I cant seem to see any problem anywhere, spk to a garage they said 4 week wait to see my bike. I hope from what ive described, someone can shed some light.

Many thanks

Tom

Re: Engine trouble. overheating, doesnt sound right
 

I think the water doesn't circulate when the engine is cold to help the engine warm up quickly. Once up to temperature it does circulate to keep cool. I think its a thermostat valve that opens, maybe yours has packed in or you pumps gone? Your fan aint coming on because the water in the radiator where its sensor is isnt getting the hot water circulating past it.

Wait until someone more experienced confirms or tells me im talking ******** lol, either way stop riding it until its sorted.

Re: Engine trouble. overheating, doesnt sound right
 

Yeah I would whip the thermostat out and take it for a spin.

Re: Engine trouble. overheating, doesnt sound right
 

If it's getting hot and the radiator fan isn't coming on... something sounds wrong there. Can you test that the fan switch works? Maybe whatever should be telling the fans to come on is failing to do that.

I'll second testing the thermostat - in a pot of boiling water, suspend it using a wire. Don't let it rest on the bottom or side of the pot, it'll get too hot too fast.

Re: Engine trouble. overheating, doesnt sound right
 

OP: Have you checked the coolant level, low coolant can cause the fan not to function - if the switch isn't immersed in coolant it can't tell what temp the system is at, also low coolant may not circulate correctly, that would cause the cooling system not to function.
It's certainly worth testing the 'stat - but it would be most unusual for a 'stat to fail shut, they're designed and constructed specifically so that they will fail open. The fan not coming on is more telling, at speed the fan shouldn't be necessary at all, so the temperature should drop/not rise even if the fan/switch/whatever were faulty.