Conference noted::motorcycle

	With the help of the guy at the local Bike JY, I've now located the
fuel mixture screws on the Virago 750. (yup, right there in plain sight!).
Good news is that they've already been drilled out so I don't need to remove
the carbs to perform that little task. Bad news is that while the left carb
(rear cylinder?) adjustment will kill the bike when closed all the way I'm
not sure the same is true for the right. I'll need to pick up one of those
works-around-corners screw drivers to make sure, cuz I was just using a real
short one which was kinda difficult to handle in the restricted quarters....

	But, if this is the case, it means I must have an air leak somewhere,
right? Is some movement of the carbs when the bike is running considered
acceptable? I can visually see (at least the right one) moving, I didn't look
that close at the left.

	BTW: The fuel mixture screws are located right beside the carb bowl,
they face downward inside a sort of tube shaped portion of the carb body on the
intake side.

thanks,

Rick

Re: .30

> Bad news is that while the left carb
> (rear cylinder?) adjustment will kill the bike when closed all the way I'm
> not sure the same is true for the right. I'll need to pick up one of those
> works-around-corners screw drivers to make sure, cuz I was just using a real
> short one which was kinda difficult to handle in the restricted quarters....

>	But, if this is the case, it means I must have an air leak somewhere,
> right?

Ahh, what if the carbs are not perfectly synchronized and the front cylinder
is doing most of the work at idle?

Just wondering.

Keith

>               <<< Note 369.31 by GRANPA::KMAYES "Starboard!" >>>
>                                -< What if ... >-
>
>Re: .30
>
>> Bad news is that while the left carb
>> (rear cylinder?) adjustment will kill the bike when closed all the way I'm
>> not sure the same is true for the right. I'll need to pick up one of those
>> works-around-corners screw drivers to make sure, cuz I was just using a real
>> short one which was kinda difficult to handle in the restricted quarters....
>
>>	But, if this is the case, it means I must have an air leak somewhere,
>> right?
>
>Ahh, what if the carbs are not perfectly synchronized and the front cylinder
>is doing most of the work at idle?

	Played with the right carb/front cylinder fuel mixture screw last night
and it appeared that I *didn't* have it turned in all the way. So I may
be OK on both carbs with repsect to the turn it in all the way and have
the bike die test. Maybe I'll run it tonite and find out for sure.

	Having a tough time finding a "works-around-corners" screwdriver,
though. Auto Phalic and Sears Hardware had them for GM carbs with a tip
called a double-D, but none with just a standard screw head driver. I tried
a flexible 1/4 extension from Sears but it really didn't flex enough to
work well. (I turned the right screw in with the new screwdriver tip for the
flex directly on a 1/4 rachet, it works, but not too well either). Any ideas
where to pick up the proper tool?

	Also, any thoughts on initial settings for the mixture? I've counted
the revolutions from where they *were* set, so I know where it was running OK, 
but what's the formula for this short of the Yamaha dealer's exhaust analysis
machine?

thanks,

RIck

    Hi.
    
    1) disconnect one spark plug
    2) start the motor (you might have to turn the idle up on the active
       cylinder
    3) turn the idle down
    4) adjust the mixture to produce the highest idle
    5) turn the idle down
    6) adjust the mixture to the produce the highest idle
    7) repeat.....
    8) do the other carb.
    9) reduce idle the same amount on both cylinders until you have
       the idle you want.
    
    to really get the idle set correctly, you need carbstix or a variant.
    
    /Charlie

	Played with the Virago yesterday.....

	I tried the test below but couldn't get the bike to run on only
the front cylinder.... Other problems, maybe....
    
>    1) disconnect one spark plug
>    2) start the motor (you might have to turn the idle up on the active
>       cylinder
>    3) turn the idle down
>    4) adjust the mixture to produce the highest idle
>    5) turn the idle down
>    6) adjust the mixture to the produce the highest idle
>    7) repeat.....


	With that in mind, I tried the test of closing the fuel mixture
screw all the way on the front cylinder, now that I have my new flexible
screwdriver.... The bike DID NOT die. Does this mean that I have air leaks
elsewhere? For instance, all that movement I see between the carbs and the
intake flanges *isn't* normal?

thanks,

Rick About_to_give_up_and_take_it_to_the_dealer_OUCH!

ps. Sat on a V-Max yesterday... What a mistake! The Seca could get traded
	Real easy for one of those! 

pss. Where the heck is the gas tank filler on a V-Max?

    I would be easlier to use a vacuum gauge. Max vacuum is almost always
    max tune (about 2% c0) 20-22 inches of mercury. If you have emission
    testing you have to check to see if 2% co is ok.
    
    I do had a crude gas analyzer, from England. It works I needed to get
    my volvo to pass emission. I have used it on all of my cars and my
    virgo and it does read about the same as the state testing site. I just
    takes patience, it is slow to responde to changes in co %. 
    
    You can borrow either the vacuum gauge and/or the gas analyzer. 
    
    You can check for vaccuum leaks with a propane torch. Blasting the leak
    with unlite propane will increase the idle speed.
    
    Before you use propane I would suggest you read an old maintenance book
    for an english or foreign car. Their are good with the step by step
    instructions as well as the theory.
    
    It is not hard it just takes care. 
    

	The '82 Virago 750 is running *NICE and SMOOTH* now, thanks
to all that provided input on it's woes. In thinking about the idea
that "extra" air was being allowed in somewhere causing the lean mixture
and the bike's decelleration "popcorn" pops, I thought hmmmm... There is
that funky Mixture Control Valve attached to the front cylinder, I wonder
what would happen with it unhooked. This frame mounted valve runs off the
intake vacuum which is shared with the front cyclinder petcock and returns
to the same intake.

	I ran a direct, unshared vacuum line from the intake to the fuel
petcock and plugged the control valve return on the intake. I then adjusted
the mixture screws as described in an earlier note looking for the highest
RPM on each cylinder, while continually turning down the idle back to the
right setting. Took the bike for a ride after this, nice and smooth! No 
discernable pops, it ran GREAT!

	Of course this does bring up a few questions.....

	What is the intended purpose of the Mixture Control Valve?

	If it does indeed control the mixture, why only on the front cylinder?

	If the vacuum lines to/from the valve are new, does this mean the valve
	is NG? Should I bother to replace it?

	After the successful ride, I hooked the MCV back up and the bike was
back to it's old popping ways.... Does this indicate a bad valve or would the
fuel mixture need to simply be reset *again* cuz it had changed by hooking it
back up?

thanks,

Rick

ps. Both bikes will see Florida in only 13 days!

>	Of course this does bring up a few questions.....
>
>	What is the intended purpose of the Mixture Control Valve?
>
>	If it does indeed control the mixture, why only on the front cylinder?
>
>	If the vacuum lines to/from the valve are new, does this mean the valve
>	is NG? Should I bother to replace it?


	Talked to the mechanic at the bike shop yesterday and asked the
questions above...

	Seems the MCV is intended to allow more air when the throttle
is quickly closed to inhibit backfires. Also, it's apparently a "usual"
fix to unhook them and leave them unhooked and the bike runs fine. (the
Virago sure is!) Guess I'll just hunt around for a more graceful plug
for the remaining intake manifold line than a vacuum hose with a golf
tee in it. :-)

Rick

ps. Both bikes will see Florida in only 7 days!