YZ426 sumo bog on highway

Hi guys.

I recently finished my super moto conversion on my 2000 YZ426 and now after installing a WR stator, doing the stator mod, BK mod, FMF jet kit, and no air box lid I now have one more issue with my bike. That is other then the silly chain rub.

When I ride on the highway and I'm at a constant speed for a little bit I get this weird bog when I give it gas. Then the bike wants to die and I have to pump the throttle to keep it running. If I pull in the clutch and give it gas it will die unless I pump the throttle. But once I get back to stop light to stop light it goes away.

Any one have any idea as to what this could be?

Check your float level if that's not it try to go down 1 or 2 sizes leaner on your main it might be running to rich on the main.

To rich will make it bog.

You did the BK Mod check the Diagram make sure it didn't rip, did you check the squirt timing.

I put the WR trans in my 426 you like it.

Hi guys.

I recently finished my super moto conversion on my 2000 YZ426 and now after installing a WR stator, doing the stator mod, BK mod, FMF jet kit, and no air box lid I now have one more issue with my bike. That is other then the silly chain rub.

When I ride on the highway and I'm at a constant speed for a little bit I get this weird bog when I give it gas. Then the bike wants to die and I have to pump the throttle to keep it running. If I pull in the clutch and give it gas it will die unless I pump the throttle. But once I get back to stop light to stop light it goes away.

Any one have any idea as to what this could be?

Edited by marv02

Check your float level if that's not it try to go down 1 or 2 sizes leaner on your main it might be running to rich on the main.

To rich will make it bog.

You did the BK Mod check the Diagram make sure it didn't rip, did you check the squirt timing.

I put the WR trans in my 426 you like it.

I measured the float height when I had the carb apart for cleaning and new jets. So I know that's good. I also installed a new AP pump diaphragm and adjusted for both timing and length of squirt.

I put the bike on a dyno yesterday and it was a little rich on the main and the needle so I dropped the main to a 165 and I moved the clip up one.

It just doesn't make sense to me for it to bog out at constant throttle.

Check the vent in the gas cap and the check valve in the vent hose. One way is to crack the cap loose on the road when it starts acting up.

I tried removing the vent hose while I was riding and it helped for a minute but then it came back. I'll try swapping fuel caps with my buddies bike and see if it helps. I checked the valve on the vent tube and its working correctly.

I took the plate and steel ball bearings off of the inside of my fuel cap and rode with it like that today. Still had the bog after riding on the highway for a couple mins.

Has anyone else replaced their fuel line with clear line? I did and installed a in-line filter. I noticed that right when I start the bike the fuel flows with no bubbles. But after I have been riding there are a ton of bubbles in the line.

Anyone know how to fix that?

I would try the clear fuel hose trick on the bottom drain port hold it straight up turn the valve open and see where the fuel level at I think it you fuel level to low.

The fuel level should be just above where the fuel bowl and the carb body mate up at.

I would try the clear fuel hose trick on the bottom drain port hold it straight up turn the valve open and see where the fuel level at I think it you fuel level to low.

The fuel level should be just above where the fuel bowl and the carb body mate up at.

I tried this trick tonight when I got home from work. Upon hooking up the line and opening the drain valve I looked closely at the level and it looked good. The other thing I did is looked closely at was the fuel line going from the tank to my fuel filter and to my carb aaaannndddd... I found my problem. I had thought that since I had 1/4" line and my filter was 1/4" I didn't need to put clamps or zip ties on the fuel line. My mistake. I had a leak at the bottom/outlet side of my filter.

I ripped the old line setup off my bike and put a new piece of fuel line and zip tied both ends. When the weather warms back up I'll go and give it a shot on the road.

Thanks for your help guys.

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