Built a diy Manometer...

[weasel01]

I saw Monte's post about the manometer and read on the net how to do it.
So a quick trip to homey-d and wham-o I have this thing built.
I followed the instructions to the "T" and was able to perfectly balance at
1050rpm and 2500rpm with the throttle stops on the idle side and cable adjustments on the higher rpm side.
What it wont do is any change at all with the idle mix screw?
I just set each one at 3/4 turn and set the rest from the other 2 adjustments.
Should the vacuum change with the mix screw adjustment or am I ok at 3/4 turn?

[montmil]

Jeez, Ampy. Give it a rest and go ride your bike and have a couple beers  [smiley=1drink.gif] You're gonna wear out your toolbox, man!  

You're probably fine at 3/4 turns out. Changes to the air mixture screw usually require a short blip of throttle to get things going. It will alter the manometer position but it's kinda a slow deal. Air screws are the first item to be adjusted, then throttle stop screws, then back n' forth until you wantta puke, then cables.

Ideally, the throttle cables should not have tension on the carb levers and the throttle stop screws should be just b-a-r-e-l-y touching the arms. In other words, neutral carb throttle levers.

By the third time -honest- that I hooked up the manometer, I felt like I was pretty sure I had it right. Road test reveals all.

Monte

[weasel01]

Thanks again, Monte!
Sorry for my OCD I am going nuts on this bike because next month there is a local BMW motorcycle rally that I have been going to for the last 10 years as a spectator slobbering over all the beautiful beemers and wishing like hell I had one .
Instead of buying a bike I've been growing a small business so I've just been a spectator.
This year however I am hoping to attend as a participant and really want to get this bike running as good as I can but unfortunately I 'm about to run out of time as I have some traveling coming up over the next few weeks.

[montmil]

Just raggin' on you, bud. Been so hot 'round here that I get sweaty just thinking about being on a bike. Hope your trip comes off.   Monte

[Barry]

Adjusting Idle mixture with a manometer... I've been thinking of trying this approach.

If the manometer is tall enough not to suck the fliud into the carb ( a very big IF perhaps and may need a different type of gauge) connect to one carb only and leave the other tube open.  What this will do is measure the absolute pressure on that carb which will enable you adjust the idle mixture for max idle revs. Then swap to the other carb and adjust it's mixture.

This is how old fashioned vauum dial gauges were used.
 

[weasel01]

I think if you only hooked up one side of this thing you would definitely suck fluid into the carb.
The way this works is each end of a 20 foot tube plugs into the vacuum line holes the center of the line is mounted to a yard stick.
The fluid just rests until the engine is started then the fluid shifts towards the side that sucks the most just make the carb adjustments till it's equal
the fluid moves slow.

[Barry]

Ampliflyer your right. I wasn't thinking or maybe thinking too much!

I just worked out that the manometer would need to be at least 16ft high which is hardly practical.  

The old type of dial gauge that measures up to 25 or 30" Hg would work.

[montmil]

Ampliflyer your right. I wasn't thinking or maybe thinking too much! I just worked out that the manometer would need to be at least 16ft high which is hardly practical.

Dang... I need to raise the ceiling in my shop! Motorcycles! One thing always leads to another.

With the DIY manometer hooked up to both carbs and, if you start tuning badly out of synch carbs, you will eat some fluid if you rev the engine. That's why I use lightweight fork oil as it won't harm the engine if a bit is ingested.

Get the Bings synched properly at lower rpm, all cables, needles, levers, everything just right then you can bring the revs up around 3500 to see what the manometer levels look like.

Have a fairly good sized fan blowing cooling air over the engine while doing all this. Spend too much time and you risk overheating the stationary bike.

While tuning, I hang my manometer from the paint tray of a 6-foot stepladder 'cause that's what I got. [smiley=thumbup.gif]

Monte

[Bob_Roller]

That manometer had me confused, until I saw that each end of the hose was connected to the vacuum port on both carbs at the same time .

I had the mercury Carb Stix for about 20 years, and in that application, the end of each hose was connected to each carb, and the fact that mercury was so heavy, it would only raise the level of mercury about 12-16 inches when the engine was running .

[weasel01]

20 feet sounds like a lot but I hang mine from a nail in the rafter of my gararge about 6' of the clear hose is mounted to the yard stick
(3' on each side of the yardstick with the center at the bottom of the yardstick which leaves 7' of hose hanging down from my rafter which perfectly reaches my carbs.
I just pull my bike right up to it and the fluid is directly in front of me.
I took Monte's tip and used fork oil which is blue so if I do have a mishap it wont ruin anything ...at least I hope.
It took a lot of vibration out of my bike at speed.

[montmil]

I left the vinyl tubing extra long so I can run it under the bike with enough room to avoid the exhaust pipes. The longer length also gives me additional working space. I can get clumsy sometimes.  

BTW, I leave the oil in the manometer tubing and cap the open ends with vinyl Screw Protector Caps available at Ace Hdwr and other big box stores. Saves reloading every time.

Monte