Flywheel Weight causing low end BOG

7 replies to this topic
  • Mike_from_WA

Posted September 17, 2002 - 07:12 AM


I have a 99WR with all the free mods. I'm running a very open pipe (Pro Circuit).

Have WR timing, and jetting just about spot on.
EKN #3
MJ 165
PAJS 1/2 turn = 65
PS 2 turns
APJ .020

Before adding a 12oz flywheel weight I had snap wheelies in just about any gear at any speed.

Had good snap from closed throttle with no bog.

Now after adding a 12oz flywheel weight I have that closed throttle to snap open BOG. Sometimes it boggs then BAAAAROOM picks right up, and sometimes it bogs almost to a backfiring sound then dies.

As long as the throttle is open a little and then I snap it open it runs fine.

What should I try first clip position or APJ.

[ September 17, 2002, 10:14 AM: Message edited by: Mike from WA ]


Posted September 17, 2002 - 07:20 AM


The only thing you should have to do is adjust the APJ. The weight slows the balancer rotation just enough that the splash of fuel from the APJ is enough to cause the hesitation. I had the same exact problem with my WR....You can use an RC Wheel Colar to adjust the APJ Rod (Did this on my WR), or the P-38 Lightning which I used on my YZ.

Bonzai :)

[ September 17, 2002, 10:21 AM: Message edited by: YAMAKAZE ]

  • Taffy

Posted September 17, 2002 - 09:55 PM


it's that old problem that i haven't really heard anyone else aknowledge;


so take your PC right down and it'll then disappear.


  • Mike_from_WA

Posted September 18, 2002 - 07:39 AM


So do you think I should go to a 38PJ and 55 or 65 PAJ? Or could I lean out the PC with larger PAJ say a PAJ75

Would delaying the squirt on the APJ fix the problem instead of changing PJ? I'm already down to about the smallest squirt I can get. I have a 99 so to delay the squirt I would have to bend the tab out.

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  • Taffy

Posted September 18, 2002 - 01:05 PM


make the squirt start early and finish even earlier! that's what i reckon.

don't change the ratio just to lean out the PC. go 38/60 and that should do it. you're just a little unlucky that's all.

also don't forget to adjust your PS to the best position to snap the throttle with.


  • Mike_from_WA

Posted September 18, 2002 - 04:03 PM


Thanks Taffy.

I'll give it a try tomorrow and post results.

  • Mike_from_WA

Posted September 21, 2002 - 05:12 AM


I adjusted my APJ to start immediately when the throttle is moved and a very short duration.

Then using the FS went from 1/2 to 2 1/2 turns out and got most of my snap from closed throttle back. The BOG is almost gone at 2 1/2 turns.

I guess my next test is to try just changing the PAS which is set at 65 to maybe 60 or 75.

Then I'll try the 38PJ and 60PAS.

  • Mike_from_WA

Posted September 21, 2002 - 02:11 PM


Well I went to Taffy's recomendation.

Thanks Taffy.

38PJ, 60PAS and my snap is back very little BOG from closed throttle when snaping it open.

I think I just need some more riding to adjust the fuel screw and maybe slight adjustment to the APJ.

Good wheelies from just a little throttle and whack it open in first and second gear.


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