DIY carb sync tool revision
- Injected
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DIY carb sync tool revision
17 Dec 2025 08:52 - 17 Dec 2025 08:55
I made this manifold for vacuum syncing carbs as my old mercury unit is a bit finicky (low mercury level?)
When I was drilling the holes in the acetal plastic I screwed one up and it got oversized (smallest hole) so one gauge bounces erratically even if the flow knob is dialed right down (SMC flow controls)
I bought some 6061 so I could replace that manifold log and have redesigned the outputs to be at 90 degrees to the gauges so there will be no way the tiny link hole (.032") will get messed up this time.
Looking to get on this before Spring comes.
When I was drilling the holes in the acetal plastic I screwed one up and it got oversized (smallest hole) so one gauge bounces erratically even if the flow knob is dialed right down (SMC flow controls)
I bought some 6061 so I could replace that manifold log and have redesigned the outputs to be at 90 degrees to the gauges so there will be no way the tiny link hole (.032") will get messed up this time.
Looking to get on this before Spring comes.
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
Last edit: 17 Dec 2025 08:55 by Injected. Reason: sp
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- Warren3200gt
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Re: DIY carb sync tool revision
18 Dec 2025 03:26 - 18 Dec 2025 03:30
After accidentally running over my mercury set back in the early 2000's I tried all the usual suspects and concluded they're all pretty rubbish in comparison to the old school mercury set.
This prompted me to make up a fool proof tool that relies solely on simple physics.
The center ball bearing is the datum point and the outer is open to vacuum from the carb. There is a small restrictor in each side to prevent the ball from getting sucked where it shouldn't go.
Use carb three as the sync dataum then adjust so the inner and outer balls are directly aligned and those two carbs are perfectly balanced.
This prompted me to make up a fool proof tool that relies solely on simple physics.
The center ball bearing is the datum point and the outer is open to vacuum from the carb. There is a small restrictor in each side to prevent the ball from getting sucked where it shouldn't go.
Use carb three as the sync dataum then adjust so the inner and outer balls are directly aligned and those two carbs are perfectly balanced.
Last edit: 18 Dec 2025 03:30 by Warren3200gt.
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- kevski
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Re: DIY carb sync tool revision
18 Dec 2025 04:30After accidentally running over my mercury set back in the early 2000's I tried all the usual suspects and concluded they're all pretty rubbish in comparison to the old school mercury set.
This prompted me to make up a fool proof tool that relies solely on simple physics.
The center ball bearing is the datum point and the outer is open to vacuum from the carb. There is a small restrictor in each side to prevent the ball from getting sucked where it shouldn't go.
Use carb three as the sync dataum then adjust so the inner and outer balls are directly aligned and those two carbs are perfectly balanced.
Mine is hanging up in the garage alongside the redundant morgan carb tune.
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- kevski
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- Cra-z1
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Re: DIY carb sync tool revision
18 Dec 2025 07:09 - 18 Dec 2025 07:13
I have used them all but my homemade mercury ones have been the best. Just have to be extremely careful with the mercury. I store the bottle in a secure place when not in use. I was an HVAC tech and the mercury is from many old Honeywell thermostats I had replaced over the years. The ball bearing idea is interesting.
Last edit: 18 Dec 2025 07:13 by Cra-z1.
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- Bloobaba
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Re: DIY carb sync tool revision
18 Dec 2025 12:04
Simple and effective. I made a digital device, and it works well. It can be powered independently with a 12/24V converter or by mains electricity with an adapter. I can also measure the rotation angle of the crankshaft or camshafts with an accessory, an incremental encoder. If needed, I can write a program that can be used for another application.
Z400F 84 (ZR400B1)
Gpz900R 84
500 H1 73
Gpz550H1
Gpz900R 84
500 H1 73
Gpz550H1
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