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So I'm at 40 hours on my 2014 yz250, doing a piston and just wanted to get some input from the 2 stroke experts.
Some info on the bike.
* bone stock except PC shorty silencer and rb designs head mod made to run on pump gas (done at 15 hours)
* I'm still using some race gas because I'm still afraid to run straight pump after all the stories I heard, plus we have shitty gas here and I can't find ethanol free anywhere close. Lately I have been doing 3 gallons of premium pump and 1 gallon vp110 mixed 32/1 with amsoil dominator. Was running 50/50 race gas at first but trying to wean off
* stock jetting except went up to a 180 main from 178
First thing I noticed when taking the subframe off was a bit of what looked like premix in the air boot and some in the carb. Which made me think I was running super rich.
Popped the head off and was amazed how clean it was. Except a bit of wet oil on the side
Picture of spark plug, from what I've looked into it looks pretty good. Has a little brown to it
Picture of the piston, looks a little different from ones I've pulled out of my previous ktm 250 2 strokes. My only thought is because I had the head done to run pump gas and I'm still using race gas.
Comparison to other pistons from ktm, you'll see the difference I'm talking about on top with carbon build up. Bottom 2 are from ktm
Anything I should be concerned about?
Some info on the bike.
* bone stock except PC shorty silencer and rb designs head mod made to run on pump gas (done at 15 hours)
* I'm still using some race gas because I'm still afraid to run straight pump after all the stories I heard, plus we have shitty gas here and I can't find ethanol free anywhere close. Lately I have been doing 3 gallons of premium pump and 1 gallon vp110 mixed 32/1 with amsoil dominator. Was running 50/50 race gas at first but trying to wean off
* stock jetting except went up to a 180 main from 178
First thing I noticed when taking the subframe off was a bit of what looked like premix in the air boot and some in the carb. Which made me think I was running super rich.
Popped the head off and was amazed how clean it was. Except a bit of wet oil on the side
Picture of spark plug, from what I've looked into it looks pretty good. Has a little brown to it
Picture of the piston, looks a little different from ones I've pulled out of my previous ktm 250 2 strokes. My only thought is because I had the head done to run pump gas and I'm still using race gas.
Comparison to other pistons from ktm, you'll see the difference I'm talking about on top with carbon build up. Bottom 2 are from ktm
Anything I should be concerned about?
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If the plug has seen a lot of heat (pre-ignition,detonation) they will basically start to melt. The piston crown gives an ashy appearance . Bit of blow by past the rings as well.
Should I stick with adding in just a bit of race fuel or go straight pump? Would my mix but with c12 be a better option?
I put a new plug in when I head the head done. What can be done to stop detonation, that was the reason I had the head done in the first place.
Will the stuff on top of the piston scrape off? And if so, is it flaky/gritty? Looks a little like coolant, but can't tell completely.
Otherwise looks ok to me (non-expert).
Also some better pics of the spark plug. It's hard to tell but it doesn't look like any of the insulating material is gone, just a little black in that spot. Idk I could defiantly be wrong
> Amsoil dominator is designed to be ran at 50:1. With that being said, I always ran 44:1 and never had a oil reared failure. I'm an Amsoil dealer and have plenty of experience and knowledge of that product.
> Like previously stated, it looks like you were burning a little bit of coolant. It doesn't look terrible though. I would say fresh O-rings and gaskets will fix that issue. Check all water jackets for any cracks. Also, lay your head on a sheet of glass and make sure it's 100% flat.
Looks like you have a head leak and you're burning coolant, from the white flakey stuff on the piston top.
From the underside of the piston it doesn't appear that you're running too hot, but there is an excessive amount of oil hanging around and the rings look washed and not seated.
As suggested check the head surface for flatness, install new piston and rings, new o-ring and gaskets, then cut back to 50:1 on the premix.
Have any idea what the new cc and squish clearance of the head is? There may be no need to run race gas, other than fuel consistency.
dominator is a great oil but its not a storage oil. Interceptor was designed for boats, jet skis, sleds. Dominator is a competition oil
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