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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: Wed Oct 09, 2019 8:34 pm    Post subject: SB6R Fueling Issues? Not wanting to REV in gear. Reply with quote

Having some issues with my SB6R.

Went to ride it for the first time and it would not rev out in gear.
Low RPMs around town were fine. Pulls well, no hesitation, shudder or issues.

Pull onto the highway, and it just hits a wall.
About 5k RPM. Seems to be the same in every gear
Parked I get WOT with no issues.

Carbs were just cleaned. They actually were in good shape, I just went through them because the bike had sat. I have done many carbs in my time, but could have missed something.

Fresh fuel, air filter, oil, plugs, coolant.

Could there be an issue with that fuel pump in the airbox?
How can I test that?
Something that can be cleaned, or rebuilt?
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Evilchicken0



Joined: 12 May 2010
Posts: 2996
Location: London

PostPosted: Wed Oct 09, 2019 10:03 pm    Post subject: Reply with quote

You're using the 40mm CV carbs ???
The SB6 uses gravity feed fuel to the carbs .... ask JonnyB but I think he ditched the pump.
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Jaguar



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

PostPosted: Wed Oct 09, 2019 10:34 pm    Post subject: Reply with quote

OEM carbs.

Pump looks like a simple pulse style unit, what causes them to fail?

I didnt replace the fuel filter yet, probably should do that.

Is there also a screen in the tank as part of the auto petcock?
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Evilchicken0



Joined: 12 May 2010
Posts: 2996
Location: London

PostPosted: Wed Oct 09, 2019 10:47 pm    Post subject: Reply with quote

Do the fuel filter first
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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Thu Oct 10, 2019 7:40 am    Post subject: Reply with quote

Hi Jaguar.....what causes the pumps to fail? Same as on any fuel pump fitted to a Bimota or other bike...inactivity primarily or the bike being "drained down and stored"....the rubber seals in the pump dry up and break apart and thus no more pump....still makes the noise but wont suck fuel without effective seals....New fuel can kill the seals also.....As others have said....pull the hoses and connect up an inline fuel filter in lieu of the pump and see if it revs out then......and...if you want to...buy a stock pump with same connecter and in and out sized lines......readily available.....Pumps seem to last longer if they have fuel in them in my experience so bikes with them on I dont drain them down over winter...I top up the tank instead to decrease air in the tank that the fuel can suck water vapour from/ethanol separating...
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GeeKay



Joined: 29 May 2009
Posts: 1767
Location: West Yorkshire

PostPosted: Thu Oct 10, 2019 8:21 am    Post subject: Reply with quote

I removed the fuel pump from my SB6R for that very reason. I didn't replace it and it ran just fine. I have the spare pump if you want it (though I recommend that you do not replace it)
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Bimota SB6 and Benelli TNT 899S road bikes.
Beta Techno trials iron. Project bikes:- Suzuki V4 500, TS185 cafe racer, XR11/71, Kettle/Katana, TDRGV250, OR50, Gag125,Triumph T595 and a Triumph X75 Hurricane replica.
Too many projects...............
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Jonny B Bad



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

PostPosted: Thu Oct 10, 2019 9:42 am    Post subject: SB6R Reply with quote

As Chuckie says, that fuel pump needs to go in the trash - doesn't seem to need it, unless you spend a lot of time on the back wheel, and makes it difficult to get the fuelling right.
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Jaguar



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

PostPosted: Thu Oct 10, 2019 11:39 am    Post subject: Reply with quote

I took the pump apart last night.
Zero dirt inside.
The check valves were perfect. Normally I see these have a "fold" when they fail. But honestly I have only seen a pulse pump on a two stroke.
The one end of the signal line (vacuum) had a tear in it, so I replaced that.

At some point someone replaced the fuel lines inside the airbox. They were too long and slightly pinched the line. I corrected that.

I pulled the fuel solenoid and it is clean.

Bike started and idled, but too late to take it for a rip.
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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Thu Oct 10, 2019 1:09 pm    Post subject: Reply with quote

a tear is all thats needed for it to go awol…..you have to remember....all the rubber items are nearly 25 years old....and you wouldn't ride around on 25 year old tyres would you?
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Jaguar



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

PostPosted: Fri Oct 11, 2019 12:01 am    Post subject: Reply with quote

Back from a spin around town.
Still has an issue with the new fuel filter and checked over pump.

Dug into things a bit deeper.
-tank vent is good.
-fuel tap is clean and flowing well.
-vacuum to pump is good.
-pump is clear and appears to be pumping.
-fuel filter is new.
-plugs are all even and good color. All are new NGK as well.

Checked to see if there was a cracked coil. None that I can see.
Will check the spark quality latter.

When Reved in the garage with the airbox on, I don't see the slides moving. Unsure if the vacuum system is hooked up 100%.

Plates rotate to full open with no issues.

Fuel is new high test.

At least I, getting good at taking the tank and seat off....
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Jaguar



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

PostPosted: Fri Oct 11, 2019 10:51 pm    Post subject: Reply with quote

I bypassed the pump and it is still doing the same thing.

Ended up moving the air box boots to seat better and the slides now move when rev'ed in the garage.

At my whits end.
Cant remember the last time a bike was fighting me this hard.
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Evilchicken0



Joined: 12 May 2010
Posts: 2996
Location: London

PostPosted: Sat Oct 12, 2019 8:53 pm    Post subject: Reply with quote

Ive said it on farcebook but it needs a dyno.
Ghe only last thing I can think of is the is the float seals - mine went hard and shrunk semi flooding the bike. I replaced them with vitton seals but they were a tad too think so the floats wouldn't seat properly. I put them on a drill bit and used wet n dry until they sealed properly.
Might not be it but it's the last shot ...
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Jaguar



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

PostPosted: Sun Oct 13, 2019 3:19 am    Post subject: Reply with quote

Evilchicken0 wrote:
Ive said it on farcebook but it needs a dyno.
Ghe only last thing I can think of is the is the float seals - mine went hard and shrunk semi flooding the bike. I replaced them with vitton seals but they were a tad too think so the floats wouldn't seat properly. I put them on a drill bit and used wet n dry until they sealed properly.
Might not be it but it's the last shot ...


Does have new seals.
Didn't notice and issue with the bowls.

Would think that would cause idle issues as well though.

I saw some talk about a dyno, but that really isn't a thing here in the states.
Any local shops are either 100% Harley, or 100% new sport bike service.

Wish there was something that would accelerate this process too, and let my new bike accelerate too.

I checked for intake leaks and a few other things today.
Plan to test ride in the morning and see.
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Jaguar



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

PostPosted: Sun Oct 13, 2019 5:04 pm    Post subject: Reply with quote

I set the mixture screws to 2.5 turns out and it was slightly better.
But still not right.

Rode the the bike with the gas cap opened for a pull, and that didn't help.

Checked the compression
120-120-180-120
Tested a few times to confirm.
Seems like I might have some crud on a couple of valves from sitting.
While uneven, I would have thought the motor could over come that to rev.

Whats it take to do a valve lash check on one of these?
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Bud977



Joined: 03 Mar 2013
Posts: 525
Location: Sydney

PostPosted: Sun Oct 13, 2019 9:13 pm    Post subject: Reply with quote

Check the temp of the pipes as soon as you start the bike to check if it's running on all cylinders evenly.

If you do it soon enough, you can check with a wet finger. Otherwise you can use one of those common infared temperature guns.
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