Posts
347
Joined
3/10/2016
Location
Nor Cal, CA, USA
Hey guys, pulled the header off my 450 and found all this deposit/grit in my exhaust port. I run 100LL, could this be lead deposits or aluminum from the motor being spit out? Bike ran great, but I’m going to pull the top end apart this weekend now
Yes, lead. 100LL is not ideal fuel for modern 4-strokes. They run absolutely fine on pump super unleaded.
2nd - Looks like unburned lead. Should probably check your spark plug too, might have lead deposit on the electrode.
Noted, thank you guys. I’ll stray away from straight leaded and do a 50/50, it’s just hard to trust pump fuel in CA these days.
Keefer seems to really like Vp rx96. I think it is about the cheapest fuel you can get in a can too. If you have a Sunoco dealer around you can usually get it by the can or pumped into your own jug for about $10/gallon. They have a couple of unleaded blends.
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I’ll add some more confusion here… pulled the cylinder and head and found some sand like material on the top of the piston. The intake is spotless, no dirt. Skirts of the pistons are near new, and the valves on the head show clean burn. Any ideas here?
That's all lead deposits. Leaded fuel is terrible for engines if you let them sit. If you know it is going to sit for a few weeks you need to run pump gas or some premix thru it or at a minimum, spray some wd or fogger down the spark plug
Well it finally clicked and I feel dumb for it. Initially I pulled the spark plug to check the burn, forgot about it and was blowing the engine compartment with compressed air to get ready for disassembly. So that explains the sand on top of the piston. From here on out I’ll be cutting it 50/50 with pump, but that piston looks darn good for 100 hrs. Rotella for the win!
Lots of airports are switching over to UL94 unleaded AV gas. You could check your local airport and see if they have it. I have yet to see anyone running it in an MX bike but I believe it is 97 (R+M)/2 octane
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