Stuck air mixture screw

[Venturous Randy]

While at Vogal, I had my carbs synced by the professionals and it ran better and smoother on the hand grips. But, I knew my carbs needed to have the air mixture setting adjusted because at idle the richness would bring tears to your eyes.

Without starting the bike, I started around the carbs and found two was about two turns out and one about one turn out. When I got to the front carb on the right side, I tried to turn it and it was pretty tight, but moved a little. When I bottomed out, it would not move and in the process of trying to make it move, I broke off the two raised edges that are on each side of the slot, therefore no more slot.

I have another set of carbs I bought cheap off ebay, so I knew at worst, it would take pulling the carbs off and breaking them apart and cleaning them all and putting a spare on. So, if I really screwed the carb up on the bike, it would be ok.

What I ended up doing was I used a drill bit that fit the hole with minimal slop and drilled a dimple in the head of the screw. I then used a small drill bit that fit the easyout, or screw extractor as some would know. I was able to drill deep enough to get a hole without drilling so deep that I drilled to where it shanked down to the step area. By tapping the easyout and seating it, I was able to unscrew the adjustment screw. I used a piece of rubber hose on my shopvac to pull out any debris. I was then able to put in one of the spare mixture screws from the other carbs and I was back in business.

I then hooked up my son's carb syncing outfit and synced them myself. It took a few minutes, but I got them all the same. Now the bike is again running good and don't bring you to tears when idleing.

randya

[Yammer Dan]

Congrats, I lost one of the screws out of mine when playing with them to see where they ran the best. Replaced it as you did an it has never turned as it should. It turns but is a lot stiffer than the others. Another thing to be taken care of with the 2nd gear.

[Squidley]

Randy...your always full of good practical info Bud! That would be a steady hand to drill that small screw...glad it worked out for you!

[Russ]

I think this may be what a lot of my problems are... 93 Venture mentioned that he could smell gas pretty strong when riding behind me.. and seeing as how I can't get over 90 mph going downhill with a good tailwind, I'm wondering if my stuck screw is causing more problems than I previously thought... never really thought about it until you mentioned that yours was running rich at idle... problem is I"m a little scared of doing much to my bike... I depend on it heavily for my daily transportation and I really don't want to make it unridable. don't suppose anyone wants to make a weekend trip to Central Illinois and help me fix this thing do ya? I'll make sure there's cold brews in the fridge and somethin' burnin' on the grill.

[FROG MAN]

Randy glad you got it wooped. My 86 Max was set to lean about 1.5 turns. I opened it up to 2 turns with a big improvement. Now set at 2.5 and just starting to get to rich.

[Venturous Randy]

Gerald, you have brought up a good point. I was of the opinion that you are leaning it out by increasing the turns out. Mine was rich when they were turned in too far. Also, I don't believe fuel goes thru this point, but air. If fuel went thru it, it would need more than threads to keep the fuel from leaking out, especially with this being about the lowest point on the carb.

Let's do a poll here and see what others think.

randya

[FROG MAN]

Randy here is a copy of a link i was using. I have a picture of the carb diagram fuel air flow at home. This piece is for the vmax but i think it is the same for venture.

 

Low speed Carb tuning - Justin Lassy

 

The fuel mixture screws are indeed located behind the brass plugs. The brass plugs must be removed to access the screws. Be *very* careful about drilling out the plugs-use a drill stop. If you hit the screws with the drill bit, even for a moment, you risk running the screw down hard against its seat, destroying the screw and possibly the carb seat. Bad.

The fuel mixture screws deal w/ mixture at idle and a little bit above idle. They will determine off idle throttle response and extremely low idle cruising. Turn screws in to lean the mixture out, turn them out to richen the mixture.

 

 

Here are some rough guidelines to determine if you are running rich or lean at various RPM's. Examining the plugs is really the best way to get accurate results, but these guidelines will help you shoot for a direction (leaner or richer).

Idle and off idle:

Lean conidition: Poor off idle throttle response, idle that flutters a little after a throttle blip then slowly returns to the idle that you've set, popping back through the carbs when the throttle is blipped.

Rich condition: Off idle response may be good unless plugs are fouled from a way too rich mixture. After a throttle blip the motor will dive down below set idle and will either die if way too rich or may return to set idle if it can recover.

 

http://vmaxoutlaw.com/tech/images/vmaxcarb.jpg

[Venturous Randy]

I just checked with my trusted independent motorcycle shop and he said the same thing you did. He also noted this is a fuel/air mixture that is being adjusted just like the schematic shows. He also stated that about three turns out appears to be best on the average Venture.

He charges $20 for a carb sync and says he can make money on that.

randya