Have done about 30 miles on the new top end now so on the way back from its MOT (which it passed yay!!) I gave it some beans.

The bike was jetted in hot weather last summer and was a bit rich but as it was really warm and muggy (which is unusual for the UK)I was happy with what I had.

When I gave it some tonight it felt really rich and wouldnt rev out in 1st, 2nd or 3rd then went good when I went up into 4th and 5th.

the question is (now I know what the site says about any mods afecting jetting) would a new top end, mains and crank seals affect the jetting this much?

I didnt pull the plug when I got home as it really wouldnt have helped but the cans are really quite wet..

cheers
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MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

Well it did have seized rings and shot seals so I would hazard that a re-jet may well be in order.
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If I have to take the carbs off once more...

Thanks Steve...

BTW bearings should be with me on Wednesday.
_________________
MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

I'd guess you now had compression where you didn't really before!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Whats a good range of jets to order then?

cant keep raiding fontyyys LOL
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MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

128 through to 210 is best.

You'll be ok with 128-150 mind if its just the air box and pipes you've done.
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If I have to take the carbs off once more...

Whoa! Where's the jetting discussion prefect?
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Still smoking...

Where would be a good place to buy said jets....and roughly how much are they each?
_________________
MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

wb wrote:
Whoa! Where's the jetting discussion prefect?

He only comes out when specific sizes start getting banded about that all and sundry think they can use too!
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Andy.
NSR-WORLD.COM

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Allens Performance, they're a couple of quid each, you've got the smallest jets I own (other than a pair of stock 128's), so you want some 130's, 132's and some 135's, and (if you feel brave some smaller than stock sizes too).

Steve, didn't your '18 end up leaner than stock?
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

Haven't seen an MC21 need to go leaner than stock yet, although have seen one that liked smaller slows!
_________________
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.

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Leaner than stock shows balls.

Yeah mine ran 2 sizes smaller than stock but thats not recmmended at all.

As Andy said, never seen a '21 run that lean... anythings possible though!
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If I have to take the carbs off once more...

I bought a kit from Ebay last year which ran from 120 - 140 and only cost me about £20. I have searched for the dealer but they're no longer doing them.

I'm currently using two of the lower ones, so you're welcome to borrow the bigger ones if you like? Will PM with the sizes I'm using.
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball