NC30 Carb Balancing trickery.

[royster81]

RVFhooligan ,don't get confused as the front coils on the vfr are on the other side to the rvf

[Jon]

The drill bit method is very simple;

With carbies off the bike and upside down and using the smallest drill bit you can find;
1. Use the idle adjuster open #2 butterfly so that you can slide the drill bit throught the opening with the slightest drag.
2. Use the same drill bit adjust the synchronising screw for each carburettor so that you get the same drag on each butterfly.
3. When all butterflys are synchronised open the throttle a bit and let it snap closed a couple times using the the throttle drum.
4. Recheck with drill bit and make sny adjustments required.
5. if any adjustments are required repeat steps 3 & 4 until when checking they are all the same.
6. Adjust idle screw until butterflies are fully closed, then wind in about 1.5 turns.
7. Refit carbies, warm up and adjust idlespeed.

I use the vacuum balancing method as used to work on older bikes with multi cable pull carbies, with them you have to balance each carbie on the idle stop and then crack the throttle a bit and adjust each cable to get it synchronised while on throttle.

regards
jon

[britaxcooper]

The drill bit method is very simple;

With carbies off the bike and upside down and using the smallest drill bit you can find;
1. Use the idle adjuster open #2 butterfly so that you can slide the drill bit throught the opening with the slightest drag.
2. Use the same drill bit adjust the synchronising screw for each carburettor so that you get the same drag on each butterfly.
3. When all butterflys are synchronised open the throttle a bit and let it snap closed a couple times using the the throttle drum.
4. Recheck with drill bit and make sny adjustments required.
5. if any adjustments are required repeat steps 3 & 4 until when checking they are all the same.
6. Adjust idle screw until butterflies are fully closed, then wind in about 1.5 turns.
7. Refit carbies, warm up and adjust idlespeed.

I use the vacuum balancing method as used to work on older bikes with multi cable pull carbies, with them you have to balance each carbie on the idle stop and then crack the throttle a bit and adjust each cable to get it synchronised while on throttle.

regards
jon

Sorry this is a late reply to this thread but Im only just ready to do my carbs...

What size drill bit are you talking, Ive got 1mm and 1.5mm to hand. Ive got a vaccum gauge handy so it seems silly not to use it but I dont have one of them silly bevel screwdrivers!

[RVFHooligan]

What I noticed when doing mine with the carb tubes is that because the VFR/RVF is a small motor with a high redline is that the motor doesn't produce much vacuum pressure so the readings were only a few marks from the bottom of the tubes. They didn't rise up that much. At idle the Mercury was just barely visible popping up from the bottom. Anyone else notice the same thing? Maybe it was just the set of tubes. I'm sure a much larger displacement bike produces greater pressure and really sucks the Mercury up high into the tubes. It really is all relative, just an observation.

Also, I leaned my bike slightly over against the wall on the right side, on the bar end, to be able to get a better view and access the screws from the left side.

This is the unit I get to use this weekend, I'll let you know if it's any better/easier than the tubes.

http://www.phatperformanceparts.com/Pro ... Code=TS-71" onclick="window.open(this.href);return false;

[RVFHooligan]

3. How do you not lose the adaptor screws in the V when taking them out to put the vacuum gauges in?

I used one of them telescoping magnets and held it right below the screwdriver tip so that if the screw and washer fell off they attached to the magnet. It helps to use a new or newer screwdriver as the edges are sharper and hold the screw better and they don't fall off. Or use a magnetic tip screwdriver. I might even have one, I just never looked.

[fumb]

I don't know why a few people have had a pop at the 90 deg. screwdriver. I bought one for £30, used it and sold it on for £30. It wasn't too fiddly to use. It made adjusting the screws very easy and i had the bike balanced in about 30 minutes. The hardest bit about balancing is getting your head around the order and setting up the carbtune. A little spent here makes for easier and more accurate settings.

A note just to point out as someone said they are going to do their valve clearances after the balancing. You should balance your carbs after you have done your valve clearances not before.

[viper_biker]

Would it benefit the forum if there was a set-by-step guide on how to do this with pictures.

[RVFHooligan]

Viper, I will take pictures this weekend and post them up using the digital carb tune which is essentially the same setup, just the unit that is different.

btw, my last name is Farrell, was O'Farrell a few generations back, know any of my distant relatives in Ireland? :D

[viper_biker]

I know a guy called Colin

There are a few methods of balancing carbs, by eye, the drill-bit methog, the carb-tune guages, I'll do as many of these as I can over the weekend.

[britaxcooper]

Im watching this space