Carb sync

[Black 550 L]

I just got a older motion pro from a gentleman that had a 2 cyl. bike. He only had hoses on 2 of the 4 tubes. 1 hose is 5 foot long the second is 6 foot long. How long are the hoses suppose to be and do I need hose restrictors in them? There were none in them now. I also need the adapters to hook them up is this something I can make or should I try and buy some?

[chef1366]

Is this the mercury type? If yes you need the restrictors.
The adapters are for sale. Check Denniskirk.com

[Black 550 L]

yes it is the mercury type

[Steve]

The hoses need to be long enough to reach from the tool to the bike. I don't think the actual length really matters.

Restrictors are nice, but not always necessary. What is the fluid in the tool? If it's mercury, the need for restrictors is minimized because the weight of the mercury does its own damping.

You can get a set of adapters from Z1 Enterprises for under $12. If you tried to make your own, you would certainly put at least that much into material and effort.

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[Black 550 L]

Thanks Steve I'll order the adapters. Yes it is mercury.

[KiwiGS]

Steves right the length of the tube doesnt matter.
Watch the first time you use it, if the sync is way out you could suck the Hg into the head.
Cheers

[Steve]

Steves right the length of the tube doesnt matter.

Yeah, it's my opinion that the tube length does not matter, but a guy I have been working with for the last four weeks says that he was told that all the tubes had to be exactly the same length. Personally, I don't see why, maybe someone can explain that to me.

[KiwiGS]

Yeah, it's my opinion that the tube length does not matter, but a guy I have been working with for the last four weeks says that he was told that all the tubes had to be exactly the same length. Personally, I don't see why, maybe someone can explain that to me.

I built a manometer a while back and assumed the length would have to be the same, but I asked one of the physics lecturers here at work and he said the length wasnt important. He did explain it in physic talk but the gist is you are measuring a pressure not a length or volume. Once the air is extracted the pressure is the same no matter how long the tube is. The only difference will be the time taken to pull a vacuum. Assuming the tubes are quite small diameters then the time diff would be quite small.
Cheers

[chef1366]

Everyone knows length doesn't matter

[Black 550 L]

Ok I Think I understand how to sync the carbs. but, can I adjust the idle with the motion pro to get the best idle before I do the sync.

[Steve]

... can I adjust the idle with the motion pro to get the best idle before I do the sync.

No.

Well, not really. If the sync is way off, it won't idle worth a hoot. Your best bet is to do a bench sync first, if you already have the carbs off. That is a process that merely sets the sync visually, by looking at the sliver of light coming through the carb throat. If you are lucky (or just good), you will be close enough that only minor tweaking might be necessary when you connect the vacuum gauges.

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