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Discussion Starter #1
I'm thinking about installing two vacuum gauges up in the cluster, one for each cylinder. Part of the reason is that I get pretty good vibration in the foot pegs at cruising speeds/rpms. Handlebars used to shake too, but I synced the carbs with a home made differential manometer and that took care of the bar shakes. Foot vibration is less but I'd like to see what the carbs are doing at speed under load. Revving from idle in neutral sent the front vacuum way up, but I don't like cranking her up in neutral. Also could have been that one slide was slower than the other to lift.

Just wondering if anyone has tried mounting vacuum gauges before? I'll end up sticking a volt meter in there too... kind of really want to get all matching white face red needle gauges just to keep the cluster consistent.

Anyways, anybody have any experience with this? Support/shoot the idea down? My fuel tap does have a Pri position so fuel delivery/distorted readings shouldn't be a problem.

Also wondering if there is some sort of differential gauge already out there, or if I could make one, and reduce it down to a "carb balance gauge"
 

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Because you asked, and with all seriousness aside....

Sounds like a waste of money to get what amounts to useless information. Perhaps you can put a clock on the bike that tells you what the time in Istanbul is?

IF you synced the carbs already, what's the point in doing this? What are you going to do, try and "sync" the carbs for 5,000 rpm and above ...while making it idle like crap?

Aren't there always slight differences in cylnder performance (not to mention gauges) that would make trying to do anything about any discrepency almost impossible anyway? Aren't CV (constant velocity) carbs supposed to solve this issue to begin with?

I would guess it would look cool to have some more guages tossing out readings while the bike goes along, but I think a good voltmeter is at least something that will give you usefull information rather than something cool to look at.................


(and what's wrong with cranking her up while she's in neutral? Isn't this safer than having the bike in gear?)

;) Thanks for letting me "shoot it down"...

KM
 

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Shoot Low

I know hes a distance away from you Sheriff,, but shoot LOW, hes ridding a Shetland Pony! Just punning !!!
 

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Discussion Starter #4
I knew it would be you, KM. And no, I wouldn't say useless. Not if I want to see if there is a bad cylinder balance at upper rpms. I could settle for a rougher idle if it ran smoother up high... I dont ride my bike at idle.

Yes, CV carbs are supposed to be smooth, but mostly because you can't dump on them, choke the engine with air like on a slide carb, and then rocket away. The butterfly valve is still the ultimate determinant of how much air can pass through the carburetor, the diaphragm and slide just keep the action smooth. If a butterfly wont let enough air through at upper rpm's, the slide is not going to slide up as high.

And no, I don't like useless gauges. This would mostly be a diagnostic tool that I could use while riding.
 

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If only it had 6th gear..
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Ok now that i've recovered from km's ribbing ;) I'll throw in my marbles for what they're worth.

The nature of a V twin is to vibrate. Our engine's are balanced pretty well but there's always gonna be some vibes. So,
I think permanently mounting vacuum gauges is a waste and a pita because of the hoses etc. But... I do like you're idea. If I were concerned about it I would probably stick a good vac gauge on one side at a time and tape it to the gas cap for a few rides, record the data and go from there. If ya really want to seewhat both are up to the stick two on there, why not.
The only thing I've found a vacuum gauge useful for permanent mounting is fuel economy .
A- I don't care on my bike, and B- I don't want to see how uneconomical my riding style is, lol.
Vac gauges do look cool flicking this way and that tho I'll give ya that. ;)
 

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Discussion Starter #7
Ah KM, I knew you were half-screwin with me. But I'd say that really you can do with just a speedo, like in my car. Ticks on the speedometer indicate redline in each gear, and then you get two gauges in one. That is, if you're not just using you ears

Nevertheless, I'm wondering if anyone has mounted vacuum gauges with a useful result? I've spent plenty of time on the Vulcan, and this one is vibrating more up top than the last, which had a bad balancer to boot. I don't care about the thing looking cool, otherwise it would be shiny and the R/R wouldn't be in place of the helmet lock. I care about smoothing out the engine, but rather wouldn't spend 50 bucks on gauges if someone has mounted them and can tell me that it's not worth it.

And still, I'd like to hear some discussion on butterfly valves vs slides. I still maintain that the purpose of the slide in a CV carb is to smooth out air/fuel flow, not be an ultimate determinant of total air/fuel volume/flow.
 

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Nevertheless, I'm wondering if anyone has mounted vacuum gauges with a useful result? .
Seriously doubt you are going to find anyone here that has done that... Because , as mentioned, it sounds like a silly idea.;)

Well , I'm not going to go on pointing out reasons while it is so... But rather tell you to go for it. You should get some kind of prize for at least coming up with the idea. Even if we think it is silly....what do we know.

You can be the first to prove us wrong. Take photos, tell us what results you get and what they mean.

Butterfly valves? Wow, maybe you can mount a Weber carb to the bike if your balancing adjustments prove to fail.

Thank God for fuel injection,
Knifemaker
 
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