02 YZ426 with new Bog Issue

13 replies to this topic

Posted May 30, 2004 - 10:23 AM


Just got my bike back from the shop with the newly installed Hot Cams (Decompressor) Man these cams are sweet! Starts with one or two kicks every time and NO decomp lever to pull anymore...

There does however appear to be a downside..... I never had a throttle bog like most folks did with this bike. I did have one with my 99 YZ400 but was able to fix it with the Taffy MOD with no problem. I did a search for somthing cconcerning adjusting the pump on the 02 but the results I'm getting lead to no conclusions.

Anybody out there with an 02 426 satisfactorilly resolved the Bog issue?

Thanks in advance...

Bonzai :thumbsup:

  • Satch0922

Posted May 30, 2004 - 11:14 AM


The only time mine ever has or had a bog issue all I did was clean the carb and it went away.

  • jespertheil

Posted May 30, 2004 - 12:18 PM


I had the same problem. I mounted a WB E-series exhaust and then it was gone.. You can really feel the powerdifference in 3rd gear turns.. :thumbsup:

  • John_H

Posted May 30, 2004 - 07:15 PM


FYI, I've got a bog now too after putting in 450 YZ cam. :thumbsup: Never was as bad as this and haven't been able to fix it with the BK mod. I think it can be fixed with jetting and squirt duration adjustment, but haven't had time to really work on that. If I do, I'll let you know.

  • Satch0922

Posted May 31, 2004 - 02:59 AM


sounds like a jetting, fuel screw, cleaning issue. If changing a pipe made it go away then your jetting was wrong.

The cam swap tends to make some of the bikes run a little rich. Check the end of your muffler...is it black with soot?

  • moto2000

Posted May 31, 2004 - 06:19 AM


You didn't install the cam yourself? Are you sure they timed it right? The timing marks mimic a stock 450 cam, so you need 13 pins to time it right. You would have no way of knowing this by looking at the crappy instruction sheet they provide with the cam. Maybe pop the cover and check this first.


Posted May 31, 2004 - 06:47 AM


I didn't use the 450 cam. I purchased the correct Cams from Hotcams for the 426 that were pre indexed at the factory. I did completely disassemble the carb and cleaned out each passage with carb cleaner and blew them out with an air hose. I guess I'll put the bike on a stand and play with the pump squirt duration this afternoon. The ceramic center of the plug is still a med bronze so the pilot (35) is still good to go. I'm running an FMF Ti-4 which tends to lean out the mixture so I know that's not the problem, and the pump diaphram is in good shape. Most likely dropping the squirt duration will do the trick.... I'm off today so I guess I'll play with it awhile.


Bonzai :thumbsup:

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  • moto2000

Posted May 31, 2004 - 07:04 AM


The Hot Cams auto cam index marks DO NOT match the stock 426 ex cam marks...not even close. I compared them side by side. If you try to time it by the marks you'll be a tooth off.


Posted May 31, 2004 - 08:27 AM


Thanks for the info, I'm going to give them a call about this in the morning.

I do believe that I have found my "self indused" shot in the butt.... I disassembled the carb again a little while ago and found that during reassembly I did not ensure that the tiny(smallest) O-ring in the pump cover was properly positioned, subsequently the O-ring was half in and half out of its groove. Now crushed it will have to be replaced.


Bonzai :thumbsup:

  • HotCams

Posted June 02, 2004 - 09:12 AM


When installing our YZ426 exhaust cam, only look at the left timing mark on the cam Hot Cam(circled in red), and line that up even with the valve cover surface, and your done. Dont look at the top mark, or count pins, and it will be right on.

Posted Image

  • Ga426owner

Posted June 02, 2004 - 10:19 AM


When installing our YZ426 exhaust cam, only look at the left timing mark on the cam Hot Cam(circled in red), and line that up even with the valve cover surface, and your done. Dont look at the top mark, or count pins, and it will be right on.

Posted Image

there ya go Bonzai!
Where you been hiding? :thumbsup:


Posted June 03, 2004 - 08:19 AM


Hanging out with Lane Wilson and Mark Waddle for the last couple of months gypsying around from MX Track to MX track. Gotta get back into the woods and do some rehab. Got Hurt pretty bad first half of the GNCC season and have been nursing a pinched nerve in the back. Better living thru chemistry you know......

Haven't heard much from you since Hal left the company....No more spies....

We need to get together again soon.... Doing Barnesville this weekend.

Bonzai :thumbsup:

  • Ga426owner

Posted June 03, 2004 - 08:30 AM


Hanging out with those 2 will make you crazy but faster! :lol:
Were probably going to BigCedar sunday - they changed it and added tons of sawdust. I may be interested in a trip to Monster Mountain fathers day weekend with the Ga Vet Riders - camping out, if your interested. :thumbsup:

Be careful in Barnesville and kick a few of those 4wheelers for me!

Oh - Hal is doing well & is very happy with retirement. :awww:


Posted June 04, 2004 - 06:04 AM


I might be up for that....

I'll let you know.

Bonzai :thumbsup:

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