Bog Bog Bog

I have a 98' YZ400F. It is stock jetting, pipe ,everything. I just rode it about 3 weeks ago and it ran great. Now it takes longer to warm up and there is a bog off idle that has never been there. Anyone know where to start first? Right after idle when the throttle is applied it bogs for a second or so and then runs great. It starts easy and idles well too.Thanks.

Did you wash the bike 3 weeks ago? Look for water in the fuel. If not that, there's something stuck in a jet.

Yes, I washed it. Changed the oil and cleaned the air filter. Do you think it's probably in the pilot circuit? Thanks.

That's where I'd go with it. Start by removing and inspecting the jet access plug for water.

it could be the AP also. I have found the rod for the AP stuck (rusted) on those carbs.

Thanks for the suggestions. I went ahead and changed my plug and cleaned the petcock. Never cleaned the petcock since I built the bike. The plug had been in there over a year. Just thought I would start fresh. I'll try these suggestions tommorrow. Thanks again.

I have just now had an opportunity to look at this carb. Once I had it off the bike I found that an o-ring on the plastic T for the vents was rotted. I can't find a part number or any breakdown that shows the o-ring. Anyone know what to call this o-ring or where to find it? I also found that the AP rod would not move until I forced it. I'm still going to take the carb apart and check everything over. Since I have it apart I figured I would replace anything that was worn out. The area where the o-ring is at is where the two black plastic tees are held in by a rod that snaps over them to hold them in the holes. I can probably post a pic if need be. Thanks. :excuseme:

Google: Sudco

I think I found the o-rings, but what is the model of carb I have? On top of the carb it says CR Flat. The only other numbers I find are 5BE1 00MA12. Thanks for the Sudco site. They have basically everything. Thanks.

The latest one is the FCR-MX. I believe yours is the FCR, the one just before that.

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