Applying vacuum to the fuel tap for balancing carbs? - SV650.org

08-05-06, 01:30 PM

I've read lots of past threads on carb syncing and it appears a fairly straight forward operation. Lots of info to follow and equipment to use.
I don't think I'll have much trouble, apart from accessing front nipple it seems

Question I have is, according to the haynes manual, you need to apply a vacuum to keep the fuel tap open. There doesn't seem to be a great deal of info on this.
Do the kits you buy, carbtune for example as recommended quite often, have the facility for doing this? Or will I need a separate vacuum pump?

I'll probably be able to borrow the carb balancers from a friend..

Viney · 08-05-06, 01:48 PM

To be honest, i have never had an issue with the fuel tap. I start the bike with the tank down, then lift up and remove the rear vacum hose. As for the front, i always just pop off the carbs and slide the tube on. But thats me

Dont worry about the fuel tap thing.

As for the actual job, it takes minutes and make sure the bike is warm.

northwind · 08-05-06, 03:08 PM

You could suck the tap then stick your tongue over the end.

That's the most ridiculous sounding advice I've ever given on here, and it's completely true!

08-05-06, 03:17 PM

You can get to the front vac fitting by slipping the radiator off and down from it's mounts. A squeeze but far easier than taking the carbs off.

I used a crafty trick for the rear one. My scottoiler runs off the other vac tube with a t-piece. Just disconnect the oiler while you're balancing and use the t-piece for the tank pipe, that way your tank is still connected and you can use the rear vac fitting on the gauge.

Viney · 08-05-06, 03:19 PM

Quote:

Originally Posted by haggis

You can get to the front vac fitting by slipping the radiator off and down from it's mounts. A squeeze but far easier than taking the carbs off.

Hmmm, dunno. Depends on how good you are at taking the carbs off. You dont have to take them off, just un pop them from thier mounts and laying on thier sideish.

08-05-06, 04:00 PM

Agreed. I have no real probs taking them off myself. It's getting the blighters back on that causes hair-loss and knuckle shredding.

08-05-06, 04:29 PM

Cut the vacuum pipe from the petrol tap to the rear carb and put a T-piece into it. Put another piece of vacuum pipe onto that and that's your gauge connection point. Block it off when not in use - I have a suitably-sized bolt wound into mine. Front: connect a 6" piece of pipe to it and leave it there, blocking it off like the rear.

Don't drop anything into a carb when you're running it with the airbox off. But you knew that anyway. Just in case, I have a pair of stockings

which when rolled up, stretch nicely over the carb mouths.

08-05-06, 04:41 PM

Quote:

Originally Posted by chazzyb

...... But you knew that anyway. Just in case, I have a pair of stockings

which when rolled up, stretch nicely over the carb mouths.

Yeahhh riggghht!!

Do they fit over your head too!!

Thanks for information, all.
I've done lots more reading today, on it! (To the detriment of my workload)!!

empty · 08-05-06, 06:13 PM

Bike will run for approx 5 minutes with the fuel tap disconnected and it's vacuum feed stolen to do a carb balance.

MT

Sir Trev · 16-05-06, 11:36 AM

You can always clamp the hose. Get the bike running, use mole grips and some wooden strips so the jaws are not ridged/sharp, disconnect from carb and attach gauge in it's place. Vacuum to petcock is maintained that way. Worked for me, although I will probably fit the T-piece and front extension tube next time I do mine after reading the above.

08-05-06, 01:30 PM	#1
kciN Guest Posts: n/a	Applying vacuum to the fuel tap for balancing carbs? I've read lots of past threads on carb syncing and it appears a fairly straight forward operation. Lots of info to follow and equipment to use. I don't think I'll have much trouble, apart from accessing front nipple it seems Question I have is, according to the haynes manual, you need to apply a vacuum to keep the fuel tap open. There doesn't seem to be a great deal of info on this. Do the kits you buy, carbtune for example as recommended quite often, have the facility for doing this? Or will I need a separate vacuum pump? I'll probably be able to borrow the carb balancers from a friend..

08-05-06, 03:08 PM	#3
northwind Moderator Mega Poster Join Date: Jan 2004 Location: In the garage where I belong Posts: 17,082	You could suck the tap then stick your tongue over the end. That's the most ridiculous sounding advice I've ever given on here, and it's completely true! __________________ "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"

08-05-06, 06:13 PM	#9
empty Member Join Date: Oct 2004 Location: at work mostly Posts: 286	Bike will run for approx 5 minutes with the fuel tap disconnected and it's vacuum feed stolen to do a carb balance. MT __________________ Mark T Eagles may soar, but weasels don't get sucked into jet engines.

16-05-06, 11:36 AM	#10
Sir Trev Member Mega Poster Join Date: Jun 2005 Location: High Wycombe, where the chair factories used to be Posts: 1,447	You can always clamp the hose. Get the bike running, use mole grips and some wooden strips so the jaws are not ridged/sharp, disconnect from carb and attach gauge in it's place. Vacuum to petcock is maintained that way. Worked for me, although I will probably fit the T-piece and front extension tube next time I do mine after reading the above. __________________ We are the Goon Squad and we're coming to town, BEEP BEEP!

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08-05-06, 01:48 PM	#2
Viney Member Mega Poster Join Date: Jul 2003 Location: In the shadows to the left Posts: 7,700	To be honest, i have never had an issue with the fuel tap. I start the bike with the tank down, then lift up and remove the rear vacum hose. As for the front, i always just pop off the carbs and slide the tube on. But thats me Dont worry about the fuel tap thing. As for the actual job, it takes minutes and make sure the bike is warm.

08-05-06, 03:17 PM	#4
haggis Guest Posts: n/a	You can get to the front vac fitting by slipping the radiator off and down from it's mounts. A squeeze but far easier than taking the carbs off. I used a crafty trick for the rear one. My scottoiler runs off the other vac tube with a t-piece. Just disconnect the oiler while you're balancing and use the t-piece for the tank pipe, that way your tank is still connected and you can use the rear vac fitting on the gauge.

08-05-06, 04:00 PM	#6
haggis Guest Posts: n/a	Agreed. I have no real probs taking them off myself. It's getting the blighters back on that causes hair-loss and knuckle shredding.

08-05-06, 04:29 PM	#7
chazzyb Guest Posts: n/a	Cut the vacuum pipe from the petrol tap to the rear carb and put a T-piece into it. Put another piece of vacuum pipe onto that and that's your gauge connection point. Block it off when not in use - I have a suitably-sized bolt wound into mine. Front: connect a 6" piece of pipe to it and leave it there, blocking it off like the rear. Don't drop anything into a carb when you're running it with the airbox off. But you knew that anyway. Just in case, I have a pair of stockings which when rolled up, stretch nicely over the carb mouths.