My MC21 boogs at 6-7k, power valves work fine.
i have 140 mains, i made the airbox mod. This goes away when i remove the filter foam, then the bike runs clean.

shall i open more holes in the airbox? i have also cut the front cover big holes as tygas cover.

any help pls?

Demetris

have you tryed washing the fillter? it sounds just like what mine was doing before i gave the fillter a clean

Fenton

The airfilter is brand new OEM filter. I guess i have to open more 1" holes i have 2 on top and 2 on the sides. plus the front big holes are cut as Tygas Photo.

I think you have more than enough holes. 4 x 1" holes is more than enough.

If its running rich on WOT at 6-7k then you will need to drop the main jet down a size or two, If its on part throttle then you will have to have a play with the needle postion.
_________________
If I have to take the carbs off once more...

demetris74 wrote:
My MC21 boogs at 6-7k, power valves work fine.
i have 140 mains, i made the airbox mod. This goes away when i remove the filter foam, then the bike runs clean.

That would certainly indicate a rich mixture. As Stephen says though, it depends on the how the bike acts regarding throttle position (and load of course), which part of the carburetion system you need to tune.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

Guys

My apologies, Have just realised that on the airfilter i have x4 10cm holes, 2 on top and 2 on the side,

I was based my thoughts on 10cm holes that we have to drill not 1". I guess that is the reason it runs rich, I will drill the top ones 1" andtry the bike again, Is the rich condition (Not much air) has to do with the bike been difficould to start? the only way to start the bike, is to remove the lower plug and poor some fuel in the champer. Then it starts. Is this retaled to the rich condition as well?

Thanks for the enlightenment guys

demetris74 wrote:Guys

My apologies, Have just realised that on the airfilter i have x4 10cm holes, 2 on top and 2 on the side,

Do you mean 10mm?

10cm holes would be very big, and probably leave no lid!
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

God sure i have mixed the sh..t out of the measures

yes dave 10mm

I now made the 2 top holes 1", dint have the chance to start the bike, but still can't start only if i poor some fuel in the chamber , then it starts. guess thats another problem, but i am sure it will be fine with main jets.

James

You need to make 4 1 inch/25mm holes.
_________________
Harley Davidson is the worlds most efficient way to turn petrol into noise without the harmful side effect of horsepower.

Thank you all guys,

I cant test the bike as it rains for 2 days now (Strange)

I am sure all will be ok, Only problem left now is the starting problem.


Thanks again to all

James

Stephen

Does it really matter on where on the side the 1" holes should be drilled? at the back or just side to the front intake holes?

Demetris

Everything we do is with holes in the front slope of the airbox (if you must use an airbox! ) and have had very good results like this.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

Should be on the airbox lid surely?

If you drill below the filter, there's no point fitting it!
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Thanks guys

i think i solve the problem, have closed the lid holes and, went from 140 to 150 mains, the bike now starts form second kick. dint have the chance to ride it yet.

That is the magic advice from Andy. Always start from up and go down on mains. if i knew that before will save me 1 month of kicking .

Thanks guys

Demetris