Bimota Forum

[BessZ]

Hi All.
I have a 98 Bimota SB6 with less than 7k miles on it.
Iv'e changed loads of stuff due to the E-rubish- fuel eating stuff.

I can't get it to rev flat out!
If i warm it up, then hold the throttle full quickly, it revs & dies repeatedly.

I have tried everything in my knowledge.
If I flash some fuel/brake cleaner round the middle carbs it revs sweet. But can't see an airleak! I think it is just dragging the vapours in the air trumpets but it does make a difference more in the middle 2 pots.

Cleaned the carbs a few times. They where scruffy inside but now look mint.
Float levels are abot 14.7mm.
Changed the plugs twice (got rid of the iridium units).
Swapped the carb rubbers & O rings. Changed the diagpram in the fuel tap.
Seems like it is dragging in air, but where from? I really haven't missed much & I'm no dummy.

I have never seen the bike running properly but it was all pretty much standard.

I have blanked a lot of stuff off to eliminate stuff, makes no difference.

Starting to think about raising the needles out f shear desperation but I can't see why I would need to.

Any ideas?

I do have a clip of it doing this.
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BessZ

[brian]

What does it ride like? Mine has never revved cleanly under no load either but it seems to ride fine.

I'm assuming you've checked the air filter, fuel filter, fuel lines etc.
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[Jonny B Bad]

If the bike’s pretty much original, it’s more likely it’s running rich than lean. These carbs have a step at the bottom of the slide, which means that the needle does not sit square in the bore of the needle jet. The latter wears and delivers too much fuel. Whilst 7k miles doesn’t sound like a lot, 500 miles of pottering can wear the needle jets. If you replace the needle jets and needles, if the latter look grazed, and put something under the nylon washer to eliminate the step, this may be your fix. Needless to say, lifting the needles can only make it worse, if it’s running rich.

Iridium plugs are fine in this motor, provided it’s not running rich - they are not as tolerant of rich running as standard plugs.

Have the carbs been balanced?

Is it running the original mains? Proper branded Mikunis, not after-market crap?

Testing full throttle needs to be under load.

Good luck!
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What, Jonny's gone!