07 WR450f Burning Oil

I got to looking at the diagrams of the carb and think I've figured it out. The fuel is drawn even with the air meter (The slide) and thus has a far higher signal than when the booster is on the atmosphere side of the air meter.

Told you I'm still wrapping my head around these.

I got to looking at the diagrams of the carb and think I've figured it out. The fuel is drawn even with the air meter (The slide) and thus has a far higher signal than when the booster is on the atmosphere side of the air meter.

Told you I'm still wrapping my head around these.

ok, so is that inline with the adjustment i need to do with the needle ?

If I'm looking at it correctly, yes.

I would trust JD as the authority, if they said mount it backwards I'd probably do it.

ok, so today we ripped the bike down and pulled the carb 3 times adjusting the jetting each time. No change to the mid range bog or what we call hesitation. low rpm's are fine, but 1/2 throttle she just chokes. We are now led to believe that maybe the valves could need adjusting or that it may be an ignition issue. I will be calling the local Yamaha dealer tomorrow to get the bike in for further diagnostics since we are at a loss.

MJ=168

PJ=65

LJ=45

Needle=4

Idle Screw=2.5 turns out

have you played with the accelerator pump on the carb? both timing and jet size? From my understanding getting it tuned in properly cures a lot of bog issues. just a thought.

have you played with the accelerator pump on the carb? both timing and jet size? From my understanding getting it tuned in properly cures a lot of bog issues. just a thought.

The accelerator pump only works when the throttle is moved quickly, and really is used in tuning off idle throttle response. If he is rolling the throttle on and it's bogging as it is revving up then it is a jetting issue.

Question: does it clear up and run on the top end once you get through the midrange? If it it bogging out all together and doesn't come back it could be as simple as a pinched breather line on the carb. Check the routing of all the breather hoses to see if they are pinched or clogged. Even one pinched tube can choke out the carb.

The accelerator pump only works when the throttle is moved quickly, and really is used in tuning off idle throttle response. If he is rolling the throttle on and it's bogging as it is revving up then it is a jetting issue.

Question: does it clear up and run on the top end once you get through the midrange? If it it bogging out all together and doesn't come back it could be as simple as a pinched breather line on the carb. Check the routing of all the breather hoses to see if they are pinched or clogged. Even one pinched tube can choke out the carb.

the bike runs well in low end rpm's in all gears. as soon as i get to the mid range the bike hesitates badly and i cannot get past it to the top end. we ripped the carb apart many times and put everything back, so i highly doubt the breather tube is pinched. we would have seen that. it seems like the bike is mis-firing or maybe the valves need adjusting. :smirk: the bike is currently at my local bike repair shop being looked at. they are the experts and should be able to diagnose the issue. thanks for your reply and i will revert once i find out what the actual issue is.

Why is your pilot jet so big??

You should be 45 or 48, not 65.

Why is your pilot jet so big??

You should be 45 or 48, not 65.

+1, prolly a "fat finger"

I got my bike back today and its running great. The issue was the timing on one of the exhaust valves. It was off by one tooth causing the hesitation and mid range bog. Thanks everyone for trying to diagnose the issue.

Ok, i got issues again. I have been on 4 rides/50 miles since i got my back from the shop. The bike to me has been running outstanding until the last ride which was last sunday. Went out for about a 11 mile ride and the bike ran beautiful until the last 1/2 mile. All of the sudden the infamous "midrange bog" appeared again. Low end was fine until about 1/2 throttle and then she sputtered and choked. (this happened in every gear). Thankfully i was close to home and was able to nurse it back to the garage. I have no clue what this could be now. My thoughts are maybe: fouled plug, valve issue or possibly an electical problem. The original issue was that the timing was off. How possible could it be that the timing slipped ? Can this happen ? I havnt had a chance to pull the spark plug yet. It is a process to get to the spark plug on this bike. Im waiting on a new starter motor to arrive. Once this arrives i can do one rip down and check the spark plug at that time. In the meantime, Any ideas or suggestions is much appreciated.

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