YX150 Getting Too Hot

[Chromester]

Hey guys. For a while now my bike has been running really hot and im really not sure why. It isnt too lean so it cant be that, iv got it tuned nearly dead nutz. Last time it was doing that i remember my CDI was shot. When i changed it the motor ran warm like it is suppose to. For example today i poured some gas on the cylinder and it boiled off almost instantly and i know that it didn't run this hot before. So what could it be guys.

 

[DvDRip]

probly valve clearance

 

[no_crf50_here]

Low oil?
Have a IRK OR ORK installed, maybe it's come loose and your timing is off...

 

[Chromester]

yea might be the clearances, its been a little bit since iv done them. Around were do you guys run your timing. Do you run it around the middle, advanced or retarded. Yes i do have an IRK

 

[DvDRip]

welll a guy at the track on saturday did his valve that morning, I noticed his bike was running like **** and rattly, so we went n had a look and turns out he set the valves on the wrong TDC while the valves were on overlap. you couldn't even touch his stator cover it was so bloody hot, plug was whiter than white etc.

so set ur valve clearance again, this time make sure you're at TDC on the compression stroke, best way to make sure you're on the compression stroke is to rock the flywheel back and forth on TDC and if the tappets move up and down with the rocking then your on the wrong stroke, if the tappets don't move at all with the rocking then you're on the compression stroke

when on the compression stroke wiggle the tappet up n down if there's a shitload of freeplay then u've set them on the wrong stroke... make sure you come back and tell us if that was the problem

 

[sean01]

yeah i always remove the cam cover for getting tdc..
cam dot at 9 oclock and theres yr tdc..
cant *** it up tht way

but yeah im gonna have to agree... check yr valve clearance.

 

[Chromester]

well guys i redid my clearances, they were a little tight but not bad. It seemed to run slightly cooler but the gas still boiled off when i dripped it on the cylinder. Basically if i left my finger on there it would cook off haha. what could it be, last time it was my CDI but my bike also ran like garbage.

 

[DvDRip]

well if you already tried richening the jetting then it could be an air leak in the manifold making it run lean

 

[Chromester]

Hmm well from what i can remember it didn't run hot like this before winter. So maybe it could be a leak, ill check with some carb cleaner or something. Im getting alot of blowby so i might do another rebuild.

 

[sean01]

ya havent by any chance replaced the spark plug with the wrong one?

 

[Chromester]

Nope it is the same plug i had in there when it ran warm. Any more suggestions guys

 

[sean01]

how much blow by or smoke does it blow, and yeah check for an air leak... it has to be running lean

 

[sean01]

forgot to add..

a fuked engine will run hot...

 

[Chromester]

Haha fantastic lol, but yea the blowby is pretty bad. Say i unscrew the dipstick and let it sit there it would probably blow out of the hole haha. So im thinking iv got a glazed cylinder which is causing my bike to run abnormally hot. Ill check for the leak soon. Ill just tear it down give it a nice hone and slap in my new rings and piston then hope for the best haha.

 

[sean01]

how longs it been since the last rebuild...

if its been rebuilt a few times, it may need a new barrel.. too much honing just shortens the life of the engine and creates major problems down the track...

 

[Chromester]

Actually that is probably why my last rebuild didnt go as well as i would have liked. I didnt hone the damn thing haha.. So basically my rings probably never properly seated. Idk ill just rebuild it and do it right this time.

 

[sean01]

yep you must hone a bore to put new rings in..but wat people fail to do is check the piston to bore clearance...
a new bore and piston should have about 1 1/2 tho clearance... maximum allowed clearance would be no more than 2 1/2 tho..
not much to play with hey.. that why re-rung engines dont last tht long