XRV750: Adjusting the mixture/synchronisation: How? - Horizons Unlimited

**cornepol** · #1 8 Sep 2003

Hi there,

I'm having a little trouble with mij AT. It runs very unregularly, and when I pull the choke it stops. Also the exhaust is black from the smoke, so it would seems to me that it's running too rich, and if I pul the choke it really chokes... My repair manual sais there's is a mixture adjusting screw on the carburators. I think I found it, but I'm not sure...

So does anyone know which screw to turn and in which way (right = leaner mixture?)

And does anyone know how to check the synchronisation of the carburators without the fancy workshop tools?

Thanx,
Corne

**mcdarbyfeast** · #2 9 Sep 2003

It's unusual for the mixture or the carb balance to need adjustment on an AT. This may sound daft, but have you checked the air cleaner. If it's clogged the mixture will be too rich.

**bayonet** · #3 10 Sep 2003

Check your choke cables as they can sometimes stick at the carb end. Take the tank off and remove the carb end of each cable which is only held on with a plastic nut. The choke plunger and spring is part of the cable and should be a certain distance out of the end of the cable (see manual for distance). This is why the choke cable has an adjuster halfway along it before it splits into two.

I've had my bike running rich on one cylinder because of a sticking choke but a quick squirt of WD40 on the plunger sorted it. The symptoms were one cylinder with sooty sparkplugs and uneven low speed running when warmed up, which got worse the longer you rode at low speed. Didn't seem to affect high speed running at all.

Motor

**LordStig** · #4 17 Oct 2003

Yes, I've had the same problem on my transalp. It seems that with bikes that are left on the sidestand all the time (obviously not when they're being ridden) it's possible for water to find it's way into the cable for the front carb, even though the rubber sealing boot is in good condition. Eventually the cable, cable outer and spring corrode. Mine became so bad that the whole choke mechanism seized! Recently, I've started to have more problems and will be replacing the cable assembly.

**mmaarten** · #5 20 Oct 2003

And here the easy way to check the carb. sync. in the field.

You need two pieces clear plastic fuel-line of about 2.5 meters.

Connect the end to the vacuum-outlet on the inlet-manifold and let the line's go up about 1 meter. attach them there to something (a tree?) and let the ends go down into a little bottle (or jerycan for all I care) with fuel so the ends are submerged.

Now start ther bike and you'll see something wonderfull hapening... the fuel get's "sucked" up into the line's and stay at a certain level... Ofcourse the levels must be the same... that's all there is to it.

One tip: Use fuel in the bottle... just in case it get's sucked in by the engine

Have fun

Maarten

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