TwinMax I Carburetor Synchronizer

Suzuki VX800

Suzuki VX800


"It all starts with the certainty that my engine no longer responds properly to acceleration, that the RPM no longer matches the one before / speed and higher fuel consumption. I'm driving in the city but 8L/100 is too much!"

"So by dint of pushing it back, you have to go for it as the investment is worth it: between 100/150€ for the synchro at the mechanic's versus three hours (for the first time, or one hour next time) and 99€ all inclusive: The TwinMax is delivered with the two M5 end caps, the O-rings and the 9V square battery. In addition, the possibility, to learn (always important) and to redo at will, as much for me as for others if need be".

"I wanted to start from scratch, so I first checked both carburettors: tank level, interior and nozzle cleaning, condition of the perforated membranes that I had repaired two years ago, following grandpa's advice (sewing + glue) and which are still good. Thank you !!!!!"

"I also wanted to adjust the synchro cable, carburetors fitted. Not to be done, it's a big hassle to pass the keys. I should have done it when dismantling the two carburetors, but I did it one by one."

"So a little time and a rather empty tank allowed me to get started! So I took all the topics, known, including the German one, the RMT, the workshop manual (both giving only an idea of the settings) and the technical data sheet of the device. Everything is useful the first time".



Locate the two holes (cross-head screws + seals) for the two M5 end caps on the left side for the rear and on the right side for the front. As I don't have the hands of a midwife, I saw one of the bits to screw it in with a flat screwdriver.

For the front, don't connect to the plug fixed on the intake pipe, it is fundamental for the depression of the rear carburetor or do like the Germans by using a Tee on this pipe, which seems more judicious to me, but hey, I didn't plan it!

It is necessary to dismantle the balancing box of the air filter housings, (let it hang down)



Dismantle the tank, and pass the supply pipe over the frame so that it can be lifted to pass the cross-head screwdriver at the front cylinder idle setting and the 8 spanner to tighten the locknut.



I taped the device to the top of the tank so that my hands are free and it is always easy to read. I connected the two hoses to the carburetors. I chose the left outlet for the rear carburetor and the right outlet for the front carburetor.

This choice influences the settings: increase or decrease the front or rear carburetors, since the aim is to synchronise the two carburetors at 0. The needle goes left or right depending on this choice. It is according to this choice that you will have to grope to find which action is the right one.



The TwinMax data sheet is self-explanatory. So first of all set the zero of the device: Sensitivity (left button) to max and zero adjustment (right button). This important adjustment is very sensitive.



Turn the engine on. To start the idle adjustment, I did it without the sync cable being properly tensioned, which by the way calls into question its real function (the only one I see is to adjust the front cylinder idle if you increase the idle on the adjustable screw on the rear cylinder).

This is where it becomes useful to lift the tank for access to the adjustment screw on the front carburetor. Eventually, I plan to change it for either a "knurled" screw like at the rear, or a BTR.

Adjust both carburetors to reach zero with increased sensitivity or even max. The device is sensitive enough to detect the variation in pressure between the two cylinders and therefore the needle oscillates left and right very quickly. It is therefore necessary to find and consider its own fineness of adjustment.



Once the idle was set, I adjusted the tension of the sync cable (and now it's a mess). Go up to 2000, 3000 rpm and adjust the synchro with the two accelerator cables.

Here too, it is difficult to pass the 8 and 10 spanners for the lock nuts. I recommend using eyebolts that will have to be sawn off to pass them through the accelerator cable!

For ripening choose your own tolerance because max. 1/8 turn of tension. On the cables deflect the needle to one side or the other, this is very precise and sensitive.



You have to have done it once and fumble around a bit to realise that it's not rocket science. I haven't been able to control the consumption yet but I have reduced the number of engine revs/speed. I can feel the engine breathing better and above all reacting better to the throttle, it's really nice.