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Carb synchronization bolts

2760 Views 9 Replies 7 Participants Last post by  Desmo Stu
What are the bolts I need so I can sync my carbs? From what I understand it's the same bolt that goes into the intake manifold, but it has a hole through it so I can put my vacuum gauge on top of it.

The dealer in bellevue said they didn't have any in stock, then that they might, then that theyd call me back but they never did. Would they carry this in an automotive shop?

I suppose I also need vacuum caps.
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The vacuum nipples that were origionally on your bike for the evaporative cannister will work. If you still have the cannister they are still there, if not many Duc techs have a bunch laying around If you need to buy them the thread is 5 mm.
I ordered a set from these guys. They make a great gage but sell the accessories in case you only need the parts you are asking for. Once I put the nipples in the intakes, I leave them in place and use vacuum caps to seal them off until the next time I decide to check the sync,.

I was planning on buying a vacuum gauge, but it turned out that my stepdad happened to have one that he hadn't used in 15 years. It's now sitting in my garage, waiting for some nipples. I've been thinking though, since I already planned on getting one, when not have two vacuum gauges? This way I could hook them both up at the same time, and basically sit on front of the sync screw, gauges in sight, and turn until they both equal each other. No putting gauge on, taking gauge off, putting gauge on other side, adjusting sync screw, taking gauge off, putting on other side, adjusting, taking off, putting on other side, oops went too far, adjust, take off, other side, and so on.

Hows that?

Is it ok to put the vaccum gauge(s) on first, then start her up? And is it cool to just leave the caps on like J_C when youre driving around?

BTW thanks for the link but those are pricey!
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The PIA with any gage is that the pulses from the intakes have the gages bouncing all over the place. Whicever way you go (jumping back and forth with one gage (pain in the ass factor just multiplied by 10 IMO), two gages at the same time, or a real sync gage like the carb tune) you will want to either pinch the hoses until the pulses smooth out or buy a reducer to put inside of the hoses (another accessory available from the Morgan Carb Tune)

As far as leaving the nipples in, the only precaution I could see might be to use some blue locktite on them and to be sure the rubber caps you use are in good shape otherwise they may dry out, split/crack and leak.
Hmm I new I bought that pair of vice grips for a good reason
I have the CARBTUNE it is brilliant , very easy to use , today I balanced my S$ with it and used my Fluke multimeter to set TPS, all I need to buy now is a set of techno research leads and software and a Gunson gas tester and i wont ever need the dealer.

I made this gauge setup. Bought the gauges from AutoBarn. Pop riveted to aluminum strap. You can see the pulse dampers in the lines. If you like I can get you the Mercedes part number for the vacuum dampers. These gauges were made so I can work on two CB750's that a friend has. Of course when I'm working on Ducati's I only need to hook up two of them.

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I ended up buying a real carb tuner too a couple months back, bought the electronic Twinmax sync tool.

Really pretty darn nice and easy to use. It's electronic and small enough that you can actually mount it on the bike and set your sync under load while riding up and down a deserted street (I haven't done this yet, but I have rolled the throttle to check sync)

It measures the two cylinders against each other instead of having two separate gauges that you pair up.

It was really a great investment for me and I can use it to sync up multiple cylinder engines too [thumbsup]
This might help........ [thumbsup]

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