Twinmax on Airhead

[Lean_Angle]

Is it possible (or even practical) to use my Twinmax blaancer on my airhead?

[Bob_Roller]

I've got one and have used it on my R65's, but I'm real enthused about using it, I had Carb Stix before and preferred using it, until it broke and I got mercury all over !!!!! .

Members around this site have made their own 'manometers' from scrap lumber, clear tubing and some sort of colored oil, like BMW fork oil, that's purple, or red ATF, something to give you a contrast .

I'm sure a few photos will appear shortly !!!

[montmil]

... I'm sure a few photos will appear shortly !!!

pdf. file at bottom of this message explains all about the $4.00 manometer. I love it. Use it on both my R65s. Will look for pic later...

[Barry]

Any differential pressure device will work to balance carbs. A twinmax is convenient but ultimately not as sensitive as a U tube manometer filled with ATF.  It would be interesting to do the best balance you could with a Twinmax and then check it with a manometer.

Some say the ATF manometer is too sensitive in that it's hard to get an exact balance. That's because it easily responds to the smallest adjustment that you can possibly make so requires a very careful touch. I'm fine with that even though it means you need to be fairly close to balance before hooking up the manometer or there is a risk of sucking ATF into the engine.

[nhmaf]

Just make sure that you have good/fresh batteries in your Twinmax before you use it - it has no linear regulation in the power supply - unless maybe the newest ones added it - so its accuracy and noise rejection are directly related to the battery voltage.

I really like my Morgan Carb Tune from across the Pond - it works very nicely (and I have the 4-carb model so I can use it on other multi cylinder bikes) - it is quite sensitive and works on the rotameter principle (stainless steel slides in glass tubes) so there is no fluid to leak, etc.   IT isn't cheap though.

[Bengt_Phorqs]

Ditto what Mike said about the Morgan carbtune.  I scored mine from Beemer Boneyard.  I tried the ATF unit but like Barry says, unless the carbs are already close to tune it's guaranteed that you'll suck a whole lot of AFT into the carbs.  No harm to the bike, but frustrating to use.

[EGRG]

Ive used the ATF manometer even after a carb rebuild and have been able to use it without a problem. One must wait a good ten seconds or more between adjustments for the carbs to finish modifying its vacuum levels. If you are too quick you can get lost one way or another. Also check for balance at cruise RPM's.

[montmil]

If the fluid in your DIY manometer is moving too quickly to suit you, as was mine, I added smaller tube-within-a-tube restrictors in the lines about twelve inches from the carb vacuum port.

A slightly heavier fluid is also an effective way to modulate too rapid movement.

[montmil]

[Lean_Angle]

Thanks for the responses. So where could I tap my twinmax into the post carb side, is there a nipple that I can use or would I have to drill for a tap?

[Barry]

The vacuum port is the one nearest the outside of the carb capped with a small screw. This is a right hand carb. On the Left hand carb the position of the vacuum port and mixture screw are reversed.

[montmil]

May have a small screw or a short rubber, closed end, tube.

Have you shared the model year of your R65 or did I miss it? That info is always helpful in providing correct response to questions as their are differences through the production run.

Note that most members have their model and year listed in either a signature line or up with the avatar.

[Bengt_Phorqs]

And be sure to replace the screw or the cap when finished balancing the carbs.  Helps them run smoother.  Right Monte?

[PetrP]

Awesome, was wondering what those little screws were for, noticed them just this morning while setting idle mixture.

[Lean_Angle]

The vacuum port is the one nearest the outside of the carb capped with a small screw. This is a right hand carb. On the Left hand carb the position of the vacuum port and mixture screw are reversed.

Ok, I see a smaller tube and a bigger tube, I assume the screw capped smaller one is the vacuum tap.  What's the bigger one for?  Thanks for the very helpful pic!