Bimota Forum

FraTz250 · Joined: 08 Oct 2017 Posts: 6

Hello
I have a problem with my Bellaria. There is a hole in mid range and if I hold the revs over it the bike runs like hell but if the revs are fallen under 7000 rpm you have to use the clutch or the engine doesn't rev higher. For me it sounds like it is too lean.
So it would be nice to know the right jet sizes and carb set-up.
Had anyone this problem before, too?

Greets from Germany
Franz

Jonny B Bad · Joined: 05 Dec 2009 Posts: 564 Location: NE London

How many Kms has the bike done? Has it steadily got worse, or is it a new purchase? My guess is that the needle jet and needle are worn and it is running rich. I would start by replacing both. Allens Performance Parts can sell you both from their on-line shop. Good luck.
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What, Jonny's gone!

FraTz250 · Joined: 08 Oct 2017 Posts: 6

Thanks for the answer.
I will look for these parts. The bike has got 42.000 km
Yes it's difficult to identify this problem. I own the bike for 2 years now and it stays the same.What I've done is cleaning the carbs. I will now change the needle jets and needles and clean and Synchronisize again the carbs.
Greets Franz

Admin · Posted: Tue Feb 06, 2018 11:42 am Post subject:

Hiya

Wear on the attomiser tubes is a common problem on the downdraft carbed Yamahas. Makes then run rich through the mid range.

Katy

FraTz250 · Joined: 08 Oct 2017 Posts: 6

Hi
Thanks for your answer.
The bellaria uses the fzr 600 3he engine. So uses the yb9 bellaria the same jetting like the fzr 3he?
Does anyone know this ?
Thanks Franz

Jonny B Bad · Joined: 05 Dec 2009 Posts: 564 Location: NE London

Can't tell you whether Bimota used the same jetting as Yamaha, but a good clue is that if it has Mikuni branded main jets with a square with a smaller square in the bottom right hand corner, the jetting is probably as originally installed by Bimota, whilst if the mains are unbranded, it indicates that somebody has been in there. At 42,000 kms the needle jets will definitely be worn, if they are the originals, albeit you probably will not be able to see that wear with the naked eye. The other thing to remember is that the rougher the motor runs the faster the wear on the needle jet.
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What, Jonny's gone!

Admin · Posted: Wed Feb 07, 2018 10:39 am Post subject: