Just picked up a 1992 MC21SE with no airbox lid. Any ideas?? Not runnin' so good. Shawnzo _________________ 1985 TZR 250
1988 TZR 250 Marlboro Replica
1992 NSR 250 SE
Do you want to keep it that way for improved airflow, or do you want to fit a lid?
It's not unheard of to runwithout a lid - just tywrap the filter in place - though in my experience, it makes the bike very LOUD!
Just make sure you re-jet accordingly. _________________ MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
Without the lid the bike runs way too rich in the midrange. Read somewhere that K&N filters do the same and bike runs best with lid in place. _________________ 1985 TZR 250
1988 TZR 250 Marlboro Replica
1992 NSR 250 SE
Running without airbox lid will make you lean on stock jetting, not rich. I ran my NSR without a lid or filter, but I had a full JHA jet kit _________________ The Chopster
Can running without an airbox lid and stock jets cause lean enough conditions to sieze the motor?? _________________ 1985 TZR 250
1988 TZR 250 Marlboro Replica
1992 NSR 250 SE
Taking the lid off an airbox usually means that the flow of air to the carbs is less restricted. This means that there's effectively more readily available air to mix with the fuel being metered out of the various jets in the carb - the charge temp before the carb almost always drops slightly and the intake velocity can on occasion go up etc.. it all gets a bit complicated an beyond me frankly but it makes sense that the running conditions change at different throttle positions and not an arbitrary value when you mess with the airbox so you need to re-evaluate the whole carb setup.
That usually results in the mix potentially being too lean (too much air / not enuff juice) and the engine could get too hot and either sieze up from the heat / lubrication failure or if the bike it tuned, make other factors become more crittical.
Personally, I'd leave it alone and make sure the filter is clean and the carbs set up as best you can.
_________________ These aren't the droids you're looking for.
Hey thanks Andy. The bike is new to me and I have not taken it out for a maiden voyage. I did speak to the previous owner, and he rode it for two weeks (only!!! He cannot get it licensed in California) at speeds up to 180 km, so I guess its alright. Just seems to run flat at about 6500--9000rpms. _________________ 1985 TZR 250
1988 TZR 250 Marlboro Replica
1992 NSR 250 SE
There will be a flat spot until you jet it correctly. Do you what the jetting is now? We can do you a GRP MC21 airbox lid, PM me if you are interested.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You cannot download files in this forum
