Balancing Carbs

[dr nosh]

Took the ST for a run out this morning before the late afternoon showers.

Got the engine nicely up to working temperature.

Time to balance the carbs.

Recently purchased 2 gauge set up from M&P Accessories to add to the workshop tools.

Connected via the stubs underneath the carbs.

At tickover, the gauges were fluctuating wildly. Is this normal?
Managed to watch each gauge long enough to get a mean of the 2 and then set up tickover.
Result better, smoother tickover.

Next ran the engine up to 3K rpm. Again gauge needles flutuating wildly, and watched the needles for long enough to get a mean and cable adjustments were made to get the mean needle novement for each cylinder closer.

Result. dont know need to go out for another ride to test.

What an excuse to ride the bike!!

Anyway, is this needle fluctuation normal, and have I used the gauges correctly?

Thoughts/ comments please.

 

[cookie]

The needles fluctuate because they need damping. There may be some adjustment on the dials, possibly a restrictor or a clamp of some kind for the tubes.

I've used G clamps in the past on undamped gauges.

 

[Rob Farmer]

The M&P site's down so cannot see what type of gauges they are. As Cookie says there should be some form of damping. The older Heine Gerike ones had a brass collar that you either tightened or loosened to adjust the damping. The problem with some of the generic ones is they're set up for jap bikes with conventional carbs.

You can use those little clamps you get from Aquatic centres to compress the tubes slightly. These Ebay link

 

[D6]

the guages are blue?
if so u should have got some little white plastic valves, and instructions where to fit em

 

[Captain Black]

I'm interested in this as well. I was going to look for a set of these gauges and try to widen my knowledge base to just over a fraction of an inch.
This (the carbs) is part of the service my own airhead i've not learnt about yet.
Cleaning pet cocks/filters and carb balancing are my next milestone!

What gauges would be the best to buy??

 

[cookie]

What gauges would be the best to buy??

I think I'd be looking at the digital unit Steptoe has been trialing recently. There's a thread about it on site somewhere. Dunno how much they cost though.

 

[Rob Farmer]

The Carbtune II units work very well. I went through a whole pile of different gauges trying to find something that worked well. To be honest the best I found was the home made manometers but obviously they don't fit in your panniers.

If you have a hand vacuum pump and rig them up to most of the vacuum gauges using a T Piece you find that the majority of the dial type gauges, even the expensive ones, are a mile out to start with.

 

[Steptoe]

you find that the majority of the dial type gauges, even the expensive ones, are a mile out to start with.

And they constantly need adjusting to be usable - dial guages on an airhead are shite.

In the past i've ended up using the carbs to balance peoples dial guages.

 

[fayeslane]

To be honest the best I found was the home made manometers

Me too.

 

[D6]

The Carbtune II units work very well. I went through a whole pile of different gauges trying to find something that worked well.

i ended up with these, as good as my old mercury ones, and a bit better than guages(wich are ok, but takes more care to do )
they are simple, and compact, and do the job v well

 

[Redboots]

After trying by ear - deaf in one so no good and various mercury/rod/dial gauges that all proved to be too much of a fiddle or pfaff, I got a Carbmate

I have to say, it just works. No fuss. Does what it says on the box.

Cheers,
John

 

[(RIP) maverick]

Been using the Twinmax for couple of years now. As long as the battery is fresh it works fine.

I have tried to set the carbs by ear several times and sometimes you can just hear it being exactly right. Unfortunately 99% of the time I fiddle with it so much end up setting it way out so just resort to the twinmax and get is as close as possible

 

[Beemerboff]

Cant find the link but I have a STE Synchrometer flow meter which I prefer.

I have balanced with a twinmax or carbtune , then checked with the flow meter, and they are balancing different things, as the readings are always different.

I think my bikes run smoother and better when set with the flow meter.

They are a good bit cheaper too.

Flow gauges were the original factory way to balance carbs, and when a set of the OEM meters comes up on Ebay they go for 4 or 5 times the price of a new set.

 

[MattW]

Cant find the link but I have a STE Synchrometer flow meter which I prefer.

I have balanced with a twinmax or carbtune , then checked with the flow meter, and they are balancing different things, as the readings are always different.

I think my bikes run smoother and better when set with the flow meter.

They are a good bit cheaper too.

Flow gauges were the original factory way to balance carbs, and when a set of the OEM meters comes up on Ebay they go for 4 or 5 times the price of a new set.

Interesting.

You can get them (in the UK) from Dellorto:
http://www.dellorto.com/merchandise/products.asp?CategoryID=8&PartsectionID=17

I guess I could use one of these to reset the butterfly stops on my oilhead throttle bodies (I've a suspicion they were messed with by a previous owner).

 

[cookie]

after watching steptoe balance a couple of bikes at the wee-kend, i now just use the gauges to get the carbs in the ball park, then fine tune by ear. it's not difficult.

slavishly tuning to gauges, does not seem to produce such a good result.

 

[dr nosh]

D6.
You are absolutely correct.
Totally overlooked these in the 'corner' of the box, under the bubble wrap.

Will retry at the weekend.