I have a bit of spare time at the moment so am trying to sus out why my MC21 doesnt pull into the powerband porperly, I sent some time on this last year with Barry, we have eliminated the thought that it could be the valves by having them locked open, this didnt solve it and they seem to turn freely when connected up.

So I figured its time to check the carbs, I did this and found it was running 175 180 main jets, I am also using the oil pump and do not think the powerjets are blocked...this seems way to big for me, but does anyone know a way of checking if the power jets are blocked or not, I cant get the ally screws out as they seem stuck.

The bike is relatively standard apart from modified air box, carbon cans and an m-max.

I want to put the bike back to standard and start from there but I cant seem to ge at the powerjets...any ideas?

I have blown down the power jet tubes into the carbs and they seem clear...does this mean they are not blocked ?

hve you tried a screwdriver that fits the ally screw head really snugley
_________________
MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

Best one I have, most tools are at my parents house so I may have to pop over there later and get one. My thoughts were that as I can blow down the tubes then they must be clear, can anybody let me know if this is true?

I know I should get them out and check really, was just hoping someone could let me know. Will have another go later or tomorrow.

Cheers

You can see if there's a passage way through the jets by firing carb cleaner into the brass inlet tubes. However, this won't tell you that they're clean, just that there's a hole in there. The only real way is to pull the pwrj's out and have a look.

Hi just got my nsr running and read somewhere to use 150 jets bike is standard apart form wiring splices (MC21) bike ran perfect without air box on but the moment I put the air bow back on it wouldn't pull over 5500rpm.
Put standard 128 jets back in and it revs alway through to redline but not ridden it yet as still waiting on some parts from japan.

Leigh, I’ve a spare set of std carbs sitting on my NSR shaped garden sculpture. You can borrow them to test it all out if you like. Comes with an air box fitted and gave em a clean out a few months ago.

Can't let you have em I'm afraid as the bike is on a promise to one of our friends in the Colonies.

Thanks for the offer.

I apparently have a standard airbox top ont he way and have just been out and bought some 150 main jets (to try with modified air box lid), Once the bike is running to a reasonable level I will take it up to the dyno in aylesbury and get it set up properly. If its still not running right with the 150's I will put the standard lid back on and go back to the 128 and work from there.

If that fails then I may be on the blower to you go borrow the carbs...at least that way I can eliminate the jetting as the problem.

CHeers

Has Chris dyno'd your MC28 with the 21 fly wheel? I'd be interested to see an over lay with my MC28 using the HRC card. Also have you tried your new HRC card yet. Are you thinking of taking that to Chris as well?

racer38 wrote:
Has Chris dyno'd your MC28 with the 21 fly wheel? I'd be interested to see an over lay with my MC28 using the HRC card. Also have you tried your new HRC card yet. Are you thinking of taking that to Chris as well?

You won't be using the MC21 flywheel with the HRC card will you?! You'll have to worry why the MC28 won't pull into the red next otherwise!
_________________
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!

Yes he did do the dyno work on my MC28, I had a shagged chain at the time and a sticky back brake, he said I would get more power by replacing the chain than any other mod!!! I had a chain on order at the time and it came a day later.

Whilst the bike was completely stock except the JHA pipes it was making a whopping 48.5 bhp, after the flywheel was added it went up to 51.5, torque also went up from 23.7 to 24.1. He reckoned I could see an increase of about 4bhp when I sorted the back brake and the chain. The curve is really quite funny, you can really see the tight spot on the chain. I am tempted to go for a ride up there just to see the difference now the chain has been replaced.

I have not set up the HRC card yet and am not sure if I am going to , only wanted it incase I loose the standard one as they are getting harder to get hold of. I dont really want to go chopping up the loom.

No Andy i wont be using both together. I dont really want to touch the engine at all on the MC28, its never let me down in the 7 years I have had it and it goes resonably well so I will leave it as it is. I have got some new rings to go in but dont really want to take it apart...if it aint broken and all that !!!

Just the bodywork that will be played with...just made an order to tyga, got some new JHA cans to go on then its off to a paintshop (any ideas yet wayne ??) !!!! And I promise it will never be dirty again !!!