Bimota Forum

[Doctor_jim]

Hello guys!
Been almost done with the full rebuild of the YB9 SR and I’ve got a question regarding the stock settings for the carbs, since I suspect that the previous owner had a Dynojet (or similar tuning kit) installed!! The pods seem to be shorter and are gray VS the stock longer black ones from Yamaha.
He has been running the bike with a racing exhaust and without filter!!! No wonder the engine didn’t last too long..

I’ve changed the motor for a used one with low kilometers, switched back to stock air filter and stock exhaust.
I’ve bought another pair of carbs from a Yamaha FZR600R (Genesis)- which has the stock jets and needles etc. as stated in the Yamaha manual (main jets 118, pilot jets 35 and N1YA needles).

What I haven’t been able to figure 100% is if the Bimota used the exact same settings for the carbs, or if they indeed change the jets and needles because of their exhaust and air filter, which is of course different than what Yamaha used.

I would honestly prefer to just get everything back to stock and not use any modified parts or setup.

Best regards,

Dimitris
_________________
Greek- Australian guy, located in Germany
I love classic bikes

Well just one Bimota so far, it's an YB9 SR

Ducati 450 Desmo, 900SS, ST2, DS1100
Moto Guzzi V7 Sport, V7 Spezial, v65
Lots of Hondas, BMW's, Triumph etc.

[Jonny B Bad]

As far as I know, the SB6R was the only bike where Bimota knew that they had changed the induction to such an extent that they re-jetted the carbs. A YB8/10 for instance came with the carbs just as they would have been fitted to a 1989 FZR1000, despite having a completely different air box and filter. So I think you’re safe to assume that the YB9 came with standard spec Yam carbs, although that’s no guarantee that they would work as well on the YB9. Probably worth a trip to the dyno. I assume Bimota fitted their own air box?
_________________
What, Jonny's gone!

[Doctor_jim]

As far as I could find out using the parts manual, the only change is the main Jet indeed- which is bumped up to 135 instead of 118 for the yamaha.
I’ve changed the jet and tried the bike and seems to be working better. I am also thinking about giving dyno a try- but the local guy told me practically to forget about it since getting ahold of the coils and plugs etc and trying always to check these parameters because of space limitations is a nightmare for him..

Anyways I’ll have to drive a bit around and try it out checking the plugs etc.
But that going to happen after I drive to the MOT and register the bike first

Best regards and thanks for the reply,

Dimitris

[Doctor_jim]

As far as I could find out using the parts manual, the only change is the main Jet indeed- which is bumped up to 135 instead of 118 for the yamaha.
I’ve changed the jet and tried the bike and seems to be working better. I am also thinking about giving dyno a try- but the local guy told me practically to forget about it since getting ahold of the coils and plugs etc and trying always to check these parameters because of space limitations is a nightmare for him..

Anyways I’ll have to drive a bit around and try it out checking the plugs etc.
But that going to happen after I drive to the MOT and register the bike first

Best regards and thanks for the reply,

Dimitris
_________________
Greek- Australian guy, located in Germany
I love classic bikes

Well just one Bimota so far, it's an YB9 SR

Ducati 450 Desmo, 900SS, ST2, DS1100
Moto Guzzi V7 Sport, V7 Spezial, v65
Lots of Hondas, BMW's, Triumph etc.

[Fschiesari]

I have the same problem I think, however my issue is slightly different.
My plugs (CR9E) are dark after 200 km only.
My carb settings are the following:
main jet: 118
Needle N1YA, with 2,15mm of spacers
minimum jet should be 35 (I did not have the chance to verify it).

Can anybody check if, by chance, my settings are fine? I'm not able to understand why my plugs are so dark even if I feel the shims on my needle should be almost fine.

Thanks
Fabio