boyesen ap cover w/40lj

Thanks for the part numbers. 12 dollars for a little jet :naughty: Oh well it's only money. What exactly doese the leak jet do and why would going from a stock 70 to a 40 make a big difference?

Try Sudco, they're about $8. I just orderd 3 mains, 3 pilots, 2 pilot air, 2 leak, & 1 starter jet from them yesterday, for about $50 shipped. Much cheaper than Yamaha. :naughty:

it works dang good with the 40, when i talked to boyesen they said they never tried it with a different lj and were aiming for it to work with the stock 50 (05 model) but i don't see it working any better than it does with the 40!

i just picked up a 40 leak jet this weekend to test with my 250f and the boyesen ap cover.

i wanted to test a 50 but they didn't have it in stock.

Yep I waited 2 weeks on my BAPC (boyesen accelerator pump cover) and it was well worth it, just waiting on my leakjet from buttbandit, i mean bikebandit, this will be a dream come true for rock climbing. :naughty:

WR450 owners I have the #40 leakjet if anyone needs one -

There is no leakjet for the YZF450 - 2003 :naughty:

ya apparantly none of the yzf4-- ever had one. sorry about the confusion i guess it only applies to WR's :naughty:

ya apparantly none of the yzf4-- ever had one. sorry about the confusion i guess it only applies to WR's :naughty:

agreed - So what does it do for WR's??? Why do you think that the YZF's do not have it?

just curious// :naughty:

The leak jet is a bleed off for the AC pump. It lets the excess fuel from the pump "Leak" back into the float bowl. Thus, the smaller the jet the less "Leak" and more squirt you have from your AC pump. The YZ 450 carb is simply plugged so it gets the full squirt. Probably because of the quicker revving motor. Some guys with the WR's have soldered the leak jet closed.

A good test for these pump covers would be to actually test the squirt of your AC pump while you have your carb off. You could test volume and duration as well as getting a visual on control.

-Lowedog

The leak jet is a bleed off for the AC pump. It lets the excess fuel from the pump "Leak" back into the float bowl. Thus, the smaller the jet the less "Leak" and more squirt you have from your AC pump. The YZ 450 carb is simply plugged so it gets the full squirt. Probably because of the quicker revving motor. Some guys with the WR's have soldered the leak jet closed.

A good test for these pump covers would be to actually test the squirt of your AC pump while you have your carb off. You could test volume and duration as well as getting a visual on control.

-Lowedog

agreed - the boyesen kit comes with a gap tool for the ac pump to set it at 100mm to start testing

Boyesen has not tested this cover with leakjets - infact they did not know the YZF had no leakjet - This may be the issue with WR's needing the #40 as James Dean tested w/o much success

Before I go ahead and buy either the Boyeson or the P-38, does anyone know the parts numbers for a #70 starter jet and 120 pilot air jet? I was just at the local delaership and no one seems to know anything. :naughty:

Kevin

2003 WR450

#70 Starter P/N: 3TJ-1494F-15-00

I can only find a PAJ up to 100. That p/n is 7A9-14943-27-00 ...SC

Thanks Steve,

I read that NCmountainman was using a 120 pilot air jet and I also read that a 48 pilot jet works best with a 100-125 pilot air jet, so I just wanted to get that number. Why does the manual give different jet names than the Yamaha website? Hey NC if your out there, any idea what the part number is on your 120 PAJ?

Kevin

2003 WR450

no i forgot to write it down , it came from sudco :naughty:

The SUDCO part # for the 120 Pilot air jet (slow air jet) is 019-431. Their retail price list says it's $5.30.

OK, test my bike after the P-38 pump cover addition. I still have abog, but I know I don't have it dialed it perfectly. I got it close and the bog was significantly reduce with a much more snappy response. I'm going to check what leak jet I have and get that straightened out before I make a final judgement.

I don't think the '99 has a leak jet. I loosened the throttle possition sensor and turned it as far as it would go clockwise. This seemed to help, but sometimes the motor seemed to idle too fast. But at least it didn't stall on me like it usually does at slow speed. I'm glad this thead came up because, I thought I was the only one with an off idle dead spot. I am going to play with the throttle position sensor some to see if I can get the benifit of increased low end with out the sometimes to fast idle. But the weired idle changes is better than the unexpected stalls, but I cannot depend on the same engine braking.?

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