Hi all i bought my MC21 about 18 months ago and have now finished it

Yesterday i took it for its MOT passed no problems anyway i just took it easy after having a full engine rebuild but on the way home i thought id open it up alittle but it has no midrange just flat but when its gets into the higher revs it takes off pulling great through all the gears if i keep the rev high but if i let the revs go down it has no pull seems to be bogging down

When i bought the bike it had nikkon gp style pipes fitted, drilled air box and M Max box fitted. I have kept the same modifacations but changes the pipes to Dog Fighters.

Tonight after reading the jetting infomation on the site i decided to take the carbs to bits only to discover the plastic juntion part (photo) to have broken whould this cause a problem?? anyway i carried on and removed the carbs to see what size jets are fitted but the seem to be standard 128# i would have thought having these modifactions it would have had larger main jets fitted but if that was the case my theory of too much fuel and getting bgged down would be right out of the window!

Any help in the right direction would be greatly apperciated

Thanks Simon

Admin: No specific jetting discussion in the public forums please, as per the forum rules.

Any replies quoting jet numbers will be deleted.
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Andy.
NSR-WORLD.COM

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

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Andy wrote:Admin: No specific jetting discussion in the public forums please, as per the forum rules.

Any replies quoting jet numbers will be deleted.

Were do I discuss these issues?

There is a section in the subscribers members are for specific jetting questions (Under the Racing Section, there is a "Setup" section, ask in there).

cgallant wrote:There is a section in the subscribers members are for specific jetting questions (Under the Racing Section, there is a "Setup" section, ask in there).

Unable to access that part of the forum?

Haven't experienced it myself but I would expect a check of the powervalve operation/RC servo and adjustment would be in order as well?

After you fix/replace the broken bit.

When you do get to discussing the jetting, make sure to check needle height, slow jet, etc and list ALL the sizes/positions.

Midrange is not generally main jet.

Andy has a handy tuning guide buried on the site somewhere which will help no end in establishing if there is something way off in the carb set up.

Jet chart.
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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!

Have you fixed the "t" joint? At this point, changing jetting isn't going to do you any good until you get that part replaced.

Also, there is a Jha setup manual for a modified NSR. Would be a good starting point. But as always, specific jetting recommendations is nearly impossible to provide on an internet forum without risk. There are plenty of "guides" on what jets do what, who to tune a 2-stroke based on conditions, setup, etc.. Andy pointed to the jetting chart that addresses what each jet does what. Look for the Jha setup manual to see what they recommend based on their setup.

HRC has some good publications for jetting on an RS250 (jetting is jetting for the most part, so that guide will help you with what to look for and what to do for your specific needs).

joeys boy wrote:

cgallant wrote:There is a section in the subscribers members are for specific jetting questions (Under the Racing Section, there is a "Setup" section, ask in there).

Unable to access that part of the forum?

Me neither ? Couldn't find any links to click ;-(
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MC21R ; MC21SP , plus some other none Honda 2t's

Here is the link to the "Setup Information" forum in the subscribing members area:

Setup Information

This is in the Supporting Members Forum, Racing, Setup Information forum.
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Charles Gallant

Thanx Charles - I was looking on the Racing link not the racing Forum