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vm carb tuning 78 gs 1000

  • Thread starter Thread starter lrgguy
  • Start date Start date
L

lrgguy

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Just wondering if anyone has any tips on setting up throttle cables on vm carbs ? Tips ? Tricks ? Etc

Thx
 
Use Suzuki cables, the Motion Pro ones suck. They will work for a while but not as nicely.

Little bit of slack on both cables. Tighten the locknuts. Keep the adjusters up by the handlebars short. Lube the cables up if they're sticky. Make sure they aren't kinked, and don't get pulled when you turn the handlebars. Make sure it's not getting pinched in the steering stop. Some guys remove the cable that pulls it shut, but I like to keep it there as a spare for the one that pulls it open. Or a spare for someone else's bike.

That's about it.
 
tkent02 said:
Use Suzuki cables, the Motion Pro ones suck. They will work for a while but not as nicely.

Little bit of slack on both cables. Tighten the locknuts. Keep the adjusters up by the handlebars short. Lube the cables up if they're sticky. Make sure they aren't kinked, and don't get pulled when you turn the handlebars. Make sure it's not getting pinched in the steering stop. Some guys remove the cable that pulls it shut, but I like to keep it there as a spare for the one that pulls it open. Or a spare for someone else's bike.

That's about it.
Click to expand...

So that cable that pulls the carbs shut isnt required ?
These cables were on the bike when I purchased it , and seam to work fine . Just going to lube em up ...
Beginning to like these carbs more then the cv carbs on the 650..
 
I removed my return cable. The newer bikes have cv carbs and dont have them.
 
That Big ass spring on the front of the carb should be enough to pull that throttle back .. lol
But I like Tken idea of having a spare caple there for back up ..
 
Yeah, the two are identical, and the return one isn't really required to be there. It's not under any stress, so it should be in great shape when you or your buddy needs a spare cable.

I carry a spare clutch cable on some bikes, already routed and sealed on the ends. If the cable breaks it's super easy to replace. Don't generally bother with that on the street bikes, it's so easy to ride without a clutch on pavement it's not worth doing.
 
tkent02 said:
Yeah, the two are identical, and the return one isn't really required to be there. It's not under any stress, so it should be in great shape when you or your buddy needs a spare cable.

I carry a spare clutch cable on some bikes, already routed and sealed on the ends. If the cable breaks it's super easy to replace. Don't generally bother with that on the street bikes, it's so easy to ride without a clutch on pavement it's not worth doing.
Click to expand...

Huh ?? Ride with out a clutch ?? Do explain ...
 
Clutchless shifting is easy. A lot of people don't use the clutch to shift at all. With a little practie it's even smooth. Try not to stop but if you do it's easy enough to get going. Either push the bike a little and drop it in first with the engine idling as it's rolling, or kill the engine, put the bike in first gear and push the starter button, it will go.

I broke a cable in Texas Saturday afternoon of a long weekend, rode to Seattle before I could get a cable.

Probably easier on a highway than in a city with steep hills, but it can be done. Easiest is to replace the cable before it breaks.
 
Any suggestions Tken on adjusting screws on my vm carbs ?
Have had them soaking in pinesol for almost 24 hrs now , removed all jets etc .
Now I believe that screw below the bowl gets turned out 1 - 1 1/4 turns it was previosly set at 2 turns out by Po , and the air screw on the side of carb should be at 1 1/4 - 1 1/2 turns out ?
There is little marks on rim of carb where screw goes in , factory setting ...
Below carb the factory mark is at 1 turn out 1 1/8 on 2 of the carbs actually ..
The markings for the air screws are all at 1 1/4 turns out 1 carb actually is marked just a little more then 1 1/4 ..
Any suggestions on a good starting point for those 2 screws would be appreciated..

Bike has stock exhaust & airbox
 
Fuel screws 3/4 to 7/8 as a start, air screws twice that. You will fine tune from there but that's a good starting point. DO NOT turn the fuel screws in tightly, the tips will get stuck and break off usually ruining the carburetor. I put them in while I'm looking for the tip to show in the little hole, then feel for a VERY slight increase in tension, that's it. Any tighter and you risk breaking it off.
If the spring is making it move in jumps take it out and find out why.

If you just spin them in like a normal mixture screw it will get stuck for sure. They are about ten times easier to ruin than the mixture screws on CV carbs.
 
Pilot screws ( bottom ) at 7/8 out and mixture screws ( side ) at 2 out is where I have found is where all my 1000s like it. You dont adjust the bottom once its set for tuning..you fine tune at the mixture screws. Turning in will RICHEN the cylinders and out will LEAN the cyclinders.
 
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chuck hahn said:
Pilot screws ( bottom ) at 7/8 out and mixture scrwws ( side ) at 2 out is whjere I have found is where all my 1000s like it. You dont adjust the bottom once its set for tuning..you fine tune at the mixture screws. turning in will RICHEN the cylinders and out will LEAN the cyclinders.
Click to expand...

Thanks Chuck .. ill let you know how it runs with those settings , the previous owner had the pilot screws on bottom almost 2 turns out .. would that have caused the engine to run very hot ? He had the air screws at 1 1/2 turns out ..
 
Dont know about making it run hotter than normal, but anything over the 7/8 ( from what I have found ) is way to rich on the pilot circuit and a waste of fuel and it also makes the adjustments with the mixture screws harder.
 
Chuck,

from your previous posts, it appears that the fuel screws (bottom) richen the mixture when turned out, whereas the air screws (side) lean the mixture when turned out, correct?

This would make sense, as opening the screw would either allow more fuel or more air...
 
The bottom ones richen the pilot circuit only. But Like I said before, thats all the circuit really needs as a maximum setting to stay a tad rich. Below 3/4 I find its too lean. How do I know this you may ask...I used my colortune and watched the color change as I made some investigative adjustments.

Now, like I also said before, once i set them at 7/8 I have found absolutely no need to dick with them ever again..why?? Because when I put the colortune in and start turning IN the side ( mixture screws ) I watch as the color goes to the orange / yellow color which indicates a too rich fuel to air mixture. Turn the mixture screws back outward and the the flame returns to the bunson burner blue as indicitive of the proper fuel to air ratio.

These are my findings as the colortune bears the evidence. Take whatever advice your inclined to. All I do is report my exact findings as I have found thru using the tool to tell me what the carbs are doing and why.

Set the bottom pilots ONCE and forget about them.....again heres how the side ( mixture screws) work. Turning them in cuts off air being mixed with the fuel which makes the mixture RICH. Turning them out adds more air to the mixture which makes the mixture more lean. Picture a water faucet and a sink. The sink full of air is the cylinder with fuel in it. As you OPEN the faucet ( side mixture screw in this case ) more water rushes out ( more air goes into the fuel mixture ).. Just the opposite if your closing the faucet..right?? Same as with the mixture screws..turn them in ( closing them ) takes the air away. Its just as simple as that really.
 
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And yes I note that every engine is its own animal due to wear, mileage, how it was or wasnt maintained etc etc. But i assure you my settings will get you so so very close that youll have to do very little adjusting.
 
Unfortunately not done by carb dip, but after 28 hrs in pinesol these carbs look pretty darn clean !!
I set up the pilot fuel screw and air screw exactly as Chuck suggested !!
Fingers crossed all goes well , going out to install them now ...
Keep you posted .. and again thanks tken and Chuck both your opinions I value !! & appreciate ...
 
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