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SB6R Fueling Issues? Not wanting to REV in gear.
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Tue Oct 15, 2019 3:43 pm    Post subject: Reply with quote

Extra stupid question.

What are the main carb connections, and were should they go?

At the top there are two "vents" they control the pressure inside the slides. When you blow air into them, the slides move up. Right now on my bike they are not really connected to anything. They just loop over the top of the carbs and stop. Should they be connected to the port on the left side of the air box top?

Starting to really question the "as found" condition of everything.
I am used to the Honda Kehin CV carbs. They have an opening in the mouth of the carb that controls this air/slide function.
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gunslinger



Joined: 15 Feb 2017
Posts: 19
Location: Denmark

PostPosted: Tue Oct 15, 2019 5:59 pm    Post subject: Reply with quote

Do You still have the problem with: not being able to accelerate over 5000 rpm ?.
but OK in low revs ?

If so - have you checket the carb diapgrames for holes/cracks ?

Regarding the mysterious holes/tubes to carbs:
(im not familiar with sb6R)
normally a mikuni cv carb needs ambient pressure. This is usually done by a rather large diameter hose that just ends up somewhere Very Happy and maybe ending in some sort of airfilter, preventing little ants/bees/leaves from entering the carb.

hope this helps Smile Wink
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SB6 mk1. YZF750R.FZR1000
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Tue Oct 15, 2019 9:25 pm    Post subject: Reply with quote

I do still have the issue.
The diaphragms appear to be fine. Checked them over, and the slides work as they should on the bench.
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Jonny B Bad



Joined: 05 Dec 2009
Posts: 555
Location: NE London

PostPosted: Wed Oct 16, 2019 9:24 am    Post subject: SB6R Reply with quote

Much was made by Bimota of the ram-air on the 6R, particularly the extra top-end it gave over the predecessor 6. However the 6R was being produced at the time that the V-due was taking the whole company down the toilet and presumably corners got cut, particularly those corners which would not be too noticeable to customers - I'm not setting this out as fact, as I wasn't there, I'm just trying to join the dots to come up with a plausible story!

At the back of the carbs are 2 float bowl breathers. These need to be connected together with 8mm hose and then vented into the brass fitting on the left underside of the airbox lid via a small in-line filter. The 2 slide breathers have much larger bore hoses which face toward the front of the bike and (on those bikes which were not finished properly) are taken through 90 degrees towards the bottom of the bike by a 90 degree filter. The last short piece of hose needs to be pulled off the 90 degree filters and the latter need to be twisted through 90 degrees so that they face the underside of the airbox lid. Two holes need to be made in the underside of the lid, rubber grommets inserted in the holes and the filters pushed into the grommets, which will hold them in place.

With that set up, the ram-air takes air forced into the inlet at the front of the bike at higher than atmospheric pressure, into the airbox and through the throat of the carbs. By plugging the slide and float bowl vents into the airbox lid they are subjected to the same elevated pressure as that in the air box. This plumbing is not going to cure any major problems in fuelling - those are due to other things, but they will make the bike run as Bimota intended with their original development of the 6R, to overcome the less than optimal breathing of the 6.
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Jonny B Bad



Joined: 05 Dec 2009
Posts: 555
Location: NE London

PostPosted: Wed Oct 16, 2019 9:32 am    Post subject: SB6R Reply with quote

Much was made by Bimota of the ram-air on the 6R, particularly the extra top-end it gave over the predecessor 6. However the 6R was being produced at the time that the V-due was taking the whole company down the toilet and presumably corners got cut, particularly those corners which would not be too noticeable to customers - I'm not setting this out as fact, as I wasn't there, I'm just trying to join the dots to come up with a plausible story!

At the back of the carbs are 2 float bowl breathers. These need to be connected together with 8mm hose and then vented into the brass fitting on the left underside of the airbox lid via a small in-line filter. The 2 slide breathers have much larger bore hoses which face toward the front of the bike and (on those bikes which were not finished properly) are taken through 90 degrees towards the bottom of the bike by a 90 degree filter. The last short piece of hose needs to be pulled off the 90 degree filters and the latter need to be twisted through 90 degrees so that they face the underside of the airbox lid. Two holes need to be made in the underside of the lid, rubber grommets inserted in the holes and the filters pushed into the grommets, which will hold them in place.

With that set up, the ram-air takes air forced into the inlet at the front of the bike at higher than atmospheric pressure, into the airbox and through the throat of the carbs. By plugging the slide and float bowl vents into the airbox lid they are subjected to the same elevated pressure as that in the air box. This plumbing is not going to cure any major problems in fuelling - those are due to other things, but they will make the bike run as Bimota intended with their original development of the 6R, to overcome the less than optimal breathing of the 6.
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Wed Oct 16, 2019 11:45 am    Post subject: Reply with quote

Thanks for the information, that makes a lot of sense.

I couldn't figure out why the slide breathers just looped over the top of the airbox and stopped. My bike doesn't have any way right now to get the slide breathers into the airbox, will have to modify things.
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Mon Oct 21, 2019 1:25 am    Post subject: Reply with quote

Seemed to just want some larger main jets.

Pulls great now!
Time for some new tires.
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Evilchicken0



Joined: 12 May 2010
Posts: 2996
Location: London

PostPosted: Tue Oct 22, 2019 10:20 am    Post subject: Reply with quote

yay !!!
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Evilchicken0



Joined: 12 May 2010
Posts: 2996
Location: London

PostPosted: Tue Oct 22, 2019 10:20 am    Post subject: Reply with quote

yay !!!
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Tue Oct 22, 2019 5:35 pm    Post subject: Reply with quote

Need to get some new tires on it, so I can do some proper shake down runs.
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