Carbs all done --- still having problems (high idle, can't sync)

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Paul S Wilcox

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Thanks for everyone’s help in getting my '88 VMAX carbs MOSTLY sorted out. (Special thx to Sean @ Morleys Muscle for sending my new jets so fast.)

After putting the completed carbs onto the bike (with stock airbox and no air leaks) there’s still a very high idle and I’m unable to get my left and right banks synched very well. The vacuum on #3 and 4 is weaker than #1 and 2, regardless of how much I fiddle with the sync screws.

I seem to remember that someone has a "test bed" engine they use to evaluate and synch rebuilt carbs. Can anyone tell me who that is — and how much it would cost to send my carbs to them for fine-tuning?

So close, yet so far!

Thx

Paul
 

Paul S Wilcox

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Hey folks, I finally got the carbs bench-synched and vacuum-synched right on the money.

The problem last time is that the #3 vacuum hose adjustment valve was blocked, leaving the needle frozen in one place, making it impossible to match #3 to any of the other carbs.

Now the bike idles fine, runs great, and is much faster than I was expecting (first time I've had this beast running).

Next on my V-list:

-- Take plug readings (I suspect the mixture is rich)

-- Make air/fuel screw adjustments

-- Tightening up the steering head bearings

-- Attempt to quiet down all that rattle-y valvetrain noise

-- Attempt to address the loud gear whine in the final drive (or middle gear??)

Onward!
 

Fire-medic

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Your problem was the carburetor synch tool, and not the bike? Did you try switching that hose to another carb to see if the 'bad carb synch' reading also changed to the new location? That's the type of thing people have been suggesting on-here for years. Bad firing cylinder? Try switching one-thing at a time, from that cylinder to another, and see if the engine miss follows the switch: spark plug, coil wire, spark plug cap, ignition coil.

Anyway, sounds like your issue has been solved. Keep at the other stuff.
 

Paul S Wilcox

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Thanks, Fire-medic,

Turns out it was human error ...and I was the erring human. When I was setting up the vacuum gauges -- turning the little knobs that keeps the needles from shaking -- I turned one too far, causing that one needle to freeze. o_O Doh! No wonder none of the other gauges synched with that one!
I like your one-thing-at-a-time approach. Exactly what the medical community suggests when trying to cure various illnesses.
 

Paul S Wilcox

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Finally!

The bike now runs so strong it scares me!

This being my first VMAX, I had read about V-Boost over and over, but had no idea that the rush of power would be SO intense.

Talk about truth in advertising!!
 

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C2protect

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Hey folks, I finally got the carbs bench-synched and vacuum-synched right on the money.

The problem last time is that the #3 vacuum hose adjustment valve was blocked, leaving the needle frozen in one place, making it impossible to match #3 to any of the other carbs.

Now the bike idles fine, runs great, and is much faster than I was expecting (first time I've had this beast running).

Next on my V-list:

-- Take plug readings (I suspect the mixture is rich)

-- Make air/fuel screw adjustments

-- Tightening up the steering head bearings

-- Attempt to quiet down all that rattle-y valvetrain noise

-- Attempt to address the loud gear whine in the final drive (or middle gear??)

Onward!
Definitely at the very least, make sure you don't have a tear in the diaphragm. They are very thin and easily cracked. Also assure you have lubed the spring and resistant springs so they can adjust freely. With corrosion or road grime they can easily add to the friction and sync ability is out the window.
 

Paul S Wilcox

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Thanks, C2protect. Your advice, along with the other guys, has gone to good use.

The bike back together and running great.

From here it's all detail stuff.IMG_3014.jpg
 

Denci

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Thanks, C2protect. Your advice, along with the other guys, has gone to good use.

The bike back together and running great.

From here it's all detail stuff.View attachment 71789
Nice Vmax! Im right where you are now with my 98. It runs great scary as hell but seems to be noisy to me. Nothing to compare it too here in Vegas to see if the sounds she makes are normal
 

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Denci

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Your Max is looking great, too. The photo confirms that I'll be painting mine black -- the sun has faded much of my red paint to some weird shade of pink. If you want to compare engine noise to another Vmax in the Las Vegas area, I believe that EuroSports has a '95 in their used bike inventory. https://www.eurocyclelasvegas.com/search/inventory/query/vmax
Thanks for the info I will go down and check it out I see theirs has forward control conversion wonder how much if any that improves comfort on the Beast Max? Mine is original paint too and the PO had a tank bag on it but I was able to get nearly all of the scratches out so it looks amazing now nearly like the day came from the factory. Ill be polishing the Scoops this evening when it cools off a bit.
 
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