2007 EXC 450 bogging sometimes

[35racer]

I'm a little confused... so hoping someone here can see something I am missing.

With the stock tank, when the fuel got below frame rail, the bike would bog some... even after I switched it to reserve.

I put a 3 gallon tank on and now it seems to start bogging when half full (after using 1.4 gallons). I am guessing this is about the same time I am below the frame rails again?

Anyway, when I put the new tank on I looked closely at the petcock and all seemed OK.

I guess my questions are:

With a stock or a 3 gallon Clarke tank... about when do you need to go to reserve?

If it's not a problem with the petcock or reserve circuit... any other ideas?

[bajadog]

Just a thought.

If there are a lot of bends in the fuel line to the carb or if you have
a inline filter, maybe with the full tank the fuel gravity feeds better, and
as the gravity pressure drops you don't get the same fuel flow.

[35racer]

interesting... but no funky bends and no inline filter.




The more I search the more I see others have bogging issues that seem to be jetting related.

My bike runs perfect until the fuel gets lower. I don't think it's related to motor temps but am going to pay close attention to that next.

I'll run the fuel down and start a ride on reserve and see what happens.

[compmoto]

is there adequate venting for the tank/cap ? if it flows out good , does it "run out" of venting capicity towards at that point? I had a issue with a new billet cap recently. It ran good in the pits, then after the start, it started to bog ...pulled the vent hose, from the frame nipple, and problem solved. Those one way vent hose thingys ,instead of the frame ...

[35racer]

I have a Clarke oversized tank and cap (problem was happening with stock tank too, though)

I have the stock overflow hose into the frame... doesn't appear to be any check valve.

However, next time it happens, I will pull the hose off and see if anything changes.

Having said this... I looked closer at the connection between the tank and the carburetor.

Can someone tell me if the 90 degree nipple on the carburetor should rotate freely? (talking about the nipple that the fuel hose is attached to... hose goes from the petcock to this nipple on the carb)

Anyway, I notice that mine rotates freely and that if I rotate it downward (which is where it seems to naturally go), the path of fuel from the tank goes down and then back up?

I wouldn't think this would cause a problem, but trying anything at this point.