Using Carbtune - SV650.org

04-04-05, 10:18 PM

Just done my carbs tonight using Carbtune.
Never used or seen one used before & it was dead easy to get them balanced.
I'd like to pick the brains of anyone more experienced using vacuum guages.......before I started to balance them the difference was about 6cm/Hg........is that slightly out, or miles out

The bike's done 11,500mls & it could be the first time they've been checked.......

Sid Squid · 04-04-05, 10:21 PM

It's far enough to notice the difference, but not far enough to cause any real trouble.

embee · 04-04-05, 10:53 PM

I'd say 6cm is a lot out, and you should certainly notice much nicer idle and off idle ("tip-in") behaviour!

Bear in mind at idle the vacuum is of the order of half* an atmosphere (Bar), or around 40cm Hg, then 6cm is a pretty significant proportion. You should be able to get it to a few mm quite easily.

(* not simple to describe for a single cylinder, much easier for multi cylinder manifolds)

05-04-05, 09:12 AM

Having used both types, carbtune and vaccum gauges IMHO I'd sling the carbtune in the bin. From experience I never managed to get repeatable readings using the carbtune - laden with inaccuracy. Put em on e-bay and look out for a set of vaccumm gauges or morgan balancers.

Hope it helps.

ps 6cm of Hg is a big difference

northwind · 05-04-05, 04:09 PM

Is there anything as simple to use as the Carbtune that'll give better results? I don't really fancy all the monkeying around with vacuum tubes etc, but then again I also don;t fancy setting up my carbs with what seems 'to be a random number generator

05-04-05, 08:12 PM

[quote="embee"]I'd say 6cm is a lot out, and you should certainly notice much nicer idle and off idle ("tip-in") behaviour!

Dead right Embee. Changed oil last night after doing carbs & started bike tonight to circulate oil & top-up.

Bike started easier, & with less choke than last night & was able to close choke after only a few seconds. Idles more smoothly, & revs pick up more cleanly.

As far as Carbtune goes,- mine's the Mk 2 version........the obstacles presented by the SV are far worse than actually using the Carbtune.

The Haynes manual says a vacuum needs to be applied to the fuel tap.......I'd given this some thought & reckoned by using a small syringe I could get enough suction. I'd read somewhere (Haynes?) that with more experience it was possible to do the job with only the fuel in the carbs.
This was what happened with me first time doing it.

Doddle.

The Carbtune comes with metre-long hoses, & I've just left one hose permanently attached to the front carb with the rubber cap off the front carb spigot over the exposed hose end.

I also did the job with the airbox insitu. The breather tube catchtank gets in the way of access to the balance adjuster screw so I ditched it.......permanently.

Any engine experts got a view on this.......& why do Suzuki specify the carb balance should be done with the airbox removed....

Thanks for the advice chaps. Gary

04-04-05, 10:18 PM	#1
GDBD59 Guest Posts: n/a	Using Carbtune Just done my carbs tonight using Carbtune. Never used or seen one used before & it was dead easy to get them balanced. I'd like to pick the brains of anyone more experienced using vacuum guages.......before I started to balance them the difference was about 6cm/Hg........is that slightly out, or miles out The bike's done 11,500mls & it could be the first time they've been checked.......

04-04-05, 10:21 PM	#2
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	It's far enough to notice the difference, but not far enough to cause any real trouble. __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

05-04-05, 04:09 PM	#5
northwind Moderator Mega Poster Join Date: Jan 2004 Location: In the garage where I belong Posts: 17,083	Is there anything as simple to use as the Carbtune that'll give better results? I don't really fancy all the monkeying around with vacuum tubes etc, but then again I also don;t fancy setting up my carbs with what seems 'to be a random number generator __________________ "We are the angry mob, we read the papers every day We like what we like, we hate what we hate But we're oh so easily swayed"

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04-04-05, 10:53 PM	#3
embee Member Mega Poster Join Date: Jul 2003 Location: Warwickshire Posts: 2,804	I'd say 6cm is a lot out, and you should certainly notice much nicer idle and off idle ("tip-in") behaviour! Bear in mind at idle the vacuum is of the order of half* an atmosphere (Bar), or around 40cm Hg, then 6cm is a pretty significant proportion. You should be able to get it to a few mm quite easily. (* not simple to describe for a single cylinder, much easier for multi cylinder manifolds)

05-04-05, 09:12 AM	#4
John Burt Guest Posts: n/a	Having used both types, carbtune and vaccum gauges IMHO I'd sling the carbtune in the bin. From experience I never managed to get repeatable readings using the carbtune - laden with inaccuracy. Put em on e-bay and look out for a set of vaccumm gauges or morgan balancers. Hope it helps. ps 6cm of Hg is a big difference

05-04-05, 08:12 PM	#6
GDBD59 Guest Posts: n/a	[quote="embee"]I'd say 6cm is a lot out, and you should certainly notice much nicer idle and off idle ("tip-in") behaviour! Dead right Embee. Changed oil last night after doing carbs & started bike tonight to circulate oil & top-up. Bike started easier, & with less choke than last night & was able to close choke after only a few seconds. Idles more smoothly, & revs pick up more cleanly. As far as Carbtune goes,- mine's the Mk 2 version........the obstacles presented by the SV are far worse than actually using the Carbtune. The Haynes manual says a vacuum needs to be applied to the fuel tap.......I'd given this some thought & reckoned by using a small syringe I could get enough suction. I'd read somewhere (Haynes?) that with more experience it was possible to do the job with only the fuel in the carbs. This was what happened with me first time doing it. Doddle. The Carbtune comes with metre-long hoses, & I've just left one hose permanently attached to the front carb with the rubber cap off the front carb spigot over the exposed hose end. I also did the job with the airbox insitu. The breather tube catchtank gets in the way of access to the balance adjuster screw so I ditched it.......permanently. Any engine experts got a view on this.......& why do Suzuki specify the carb balance should be done with the airbox removed.... Thanks for the advice chaps. Gary