Really confused on jetting

[aflawinhumanity]

engine Mods:
Air box removed 350 main, tors elimanator kit w/ idle scew and k&n filter
Pro curcuit pipe and silencer

So I thought I had a 270 main jet but I just took it out and its a 350. does this seem a little big? Well I was running lean and fried my piston. My plug is white, and everything over heated like a son of a biotch. I ran this carb all last summer and winter(just put air box lid back on to richen up) and I never had a problem. Now this season I have burned 2 top ends. I am going to rebuild the carb completely but is there something I should know about jetting?

 

[slickerthanyou]

I would think 350 with lid removed is good, Do you pre mix or inject?

 

[royalt67]

A 350 sounds HUGE. Toomey supplies a 310 in their pipe kit that also adds a filter and removes the airbox lid. Very similar to your setup.

What step is your needle on? If it is stuck too far down in the jet, it could be leaning you out something fierce.

Also, is it possible your main jet is partially clogged? That would affect things too.

 

[bagds10]

350 sounds big with your setup. with my setup i am running a 330

 

[little3mil]

engine Mods:
Air box removed 350 main, tors elimanator kit w/ idle scew and k&n filter
Pro curcuit pipe and silencer

So I thought I had a 270 main jet but I just took it out and its a 350. does this seem a little big? Well I was running lean and fried my piston. My plug is white, and everything over heated like a son of a biotch. I ran this carb all last summer and winter(just put air box lid back on to richen up) and I never had a problem. Now this season I have burned 2 top ends. I am going to rebuild the carb completely but is there something I should know about jetting?

Air leak alert! click the link at the bottom of my sig if you want to stop blowing topends

 

[aflawinhumanity]

i premix 32:1

My needle is at the second notch from the top.
As far as I can see there is no build up or residue in my jets or anywhere in my carb.

When I blew it both times I was cruising at 1/4 throttle in sixth gear on a gravel road. I very seldom road ride.

 

[royalt67]

AIR LEAK.....^^^^^^ If not, try dropping to the #3 position to richen the mid. 1/4 throttle might indicate a small pilot, as well.

 

[little3mil]

your probly masking a lean condition with fat jetting

 

[aflawinhumanity]

your probly masking a lean condition with fat jetting

But all last summer I rode this setup and had no problems. I never went down the road. I onlt went to quarrys, sandpits, trails, and the track. No problems til I've gotten on the road. I'm thinking you guys are right with the air leak

 

[little3mil]

a new topend could last a while before it leans out and pops from an airleak, its such a small airleak and fat jetting would help it stay alive a while longer too

 

[aflawinhumanity]

So my buddy that owns a motorcycle shop said that the leak is most likely from my stator side gasket. Would this cause me to run lean?

 

[brandoz28]

probably a stator seal but yes, that would cause an air leak

 

[yb200]

So my buddy that owns a motorcycle shop said that the leak is most likely from my stator side gasket. Would this cause me to run lean?

the stator gasket will not cause an air leak

 

[royalt67]

Just to be clear, a stator/flywheel cover gasket is different from a stator side crank seal. The crank seal is the big worry, it is a lip-type seal that seals the crankcase where the crank rotates. Don't forget the clutch side has one too, both are potential problems. That is why you do a leak down test to find them. Reed gasket, intake manifold, base gasket, and head gasket, are also possible. Any air/vacuum leak can cause a lean condition.

If you take off that stator cover and find any oil, even a film on the inside of the cover, then replace the seal. If you have ever noticed a need to add transmission oil, replace the clutch side seal.

 

[xJust_Causex]

sounds like an air leak, but since you said you were at 1/4 throttle I would check your pilot jet and drop your needle to richen it up.