400 two-stoke mod life expectancy

[mrtwostroke]

amsoil dominator 40:1. yes I know it is a racing oil. It's easy cause I run it the dirtbike as well. two diffferent oils would be a pain. but I run lots of rpm most of time. some say at low rpm dominator is too thick and could stick the rings. maybe a myth i'm not sure

If you are familiar with these atvs and the placement of the fuel petcock in tank it is very easy to run the float bowl dry at less than 1/2 tank.

Did act like it ran out of gas twice. would idle coasting to a stop, but woulding take throttle acted like it was lean. I was tuning doing plug checks, and clutching. It goes fast probably 70 mph, speedo stops at 60. But i'm going gear it down with some scrambler sprockets.
That definatly is a good question, can a bike that almost seize end up with a collapsed piston. No visible signs of it getting close though. Kind of like when I removed a bearing from a bore, we heat them up so they expand against the bore. crushing them is what it is doing then they cool and almost fallout. (in a gearbox at the machine shop, not in my motor). One thoery of mine as well, my brother and friend don't like really agree. but who knows.
My friend who is my boss at work, doesn't like wiseco pistons he says the piston is too weak. Holes in the intake skirt are bigger than necessary. He also says just lay the piston on piece of alu and hit it with a soft hammer accross the wristpin. and it will flex back out to size. just go till it measures right again. he has done this few times over the years in a bind. Even with the wiseco's in his 6 sec drag car. but usually only a couple thou.
I need another cly, i'm in bind to finish out the year. Should I go big bore or sleeve it back down to size. I'm not sure yet.

[duster]

Sounds about dead on man...

Sounds like you ran fuel lean or temp hot, but with very good lubrication.
Swelled the piston, yet it didn't sieze... it collapsed.
Then after it cooled down... SLAP-SLAP-SLAP.

I run Amsoil mix oil also... on stock jetting... but I use the Saber professional instead.

I've tried it at several mix ratios... starting at (you're going to fall over) 64:1.
I started from there and worked my way up... 72:1, 80:1, 96:1.

Seems to run best on the latter 3 and stock jetting.

I've ran it 96:1 most of the time (2 oz to 1.5 gallons).
But after I fixed a leaky needle jet recently, I went to 80:1 (just easier 8oz/5 gallons).

I ran 96:1 for a year though... no problems.

My jetting is a hair fat though I think.
Starts without choke... and seems to run a little fat over 80 degrees.


Mine is stock though... and to my knowledge has the stock piston.

[duster]

Oh... and I would send it to Rick and let him do his thing...

[uncertifiedmechanic]

Who cut those fenders down for ya?

[mrtwostroke]

I'm a long ways from Rick and all the other tuning places. Their port jobs would be interesting but as far as boring and honing go. People here pay me for that stuff.
I can do it myself.

Im thinking about doing a stroker on it. I've got two extra cases and a couple of clynders. Does anyone know if RCR will sell a stroker crank separate?