93 750 carbs torn apart

To start with, thank your for all of the patient responses so far. For those who havent seen any of my other posts... I have a 93 vfr that keeps fouling plugs. The airfilter is clean, I had a new set of plugs in it, ran sea foam, carb cleaner, fuel additives, octane etc through it and still ran rough and fouled out cylinders off and on, then all plugs eventually to where it would only pop and not start. I would pull the plugs off and they would be wet and then once dried a nice black soot. Leads me to believe the bike is running too rich. This bike has never been modified other than a twin bros pipe. Other than that the carbs look like the had never even been off. I took the carbs off today and opened them up cleaned the floats, all needles, seets, main jets etc checked the diaphragms. My first question: The honda shop says that taking it apart and cleaning all parts with spray carb cleaner and high psi air isnt enough. They said it must be soaked. Question 2: I am lead to believe that what would make most sense to explain this fouling would be mixture screws. My manual calls for 1 7/8 turns from fully closed. So given that the bike has a pipe and is running rich would you recommend more turns out that that? Turning the screws out leans the mix correct? Any other ideas and tuning tips would really help. I have had the worst week of luck with this bike. IT WAS SO PERFECT. Until I let it sit outside one cold night, lost the key and started turning my motorcycle life into a country song. THANKS!

 

You need to ge a hold of Jamie Daugherty at Jamie Daugherty Racing. Mr. Daugherty seems to be the accepted pro around here when it comes to earlier VFR's. Here is a link to his site:

http://www.daughertymotorsports.com/

He will be able to help you out.

 

my suggestion , after all the work you've done, is to get the engine warmed up and start adjusting the mixtuire screws one at a time by slowly screwing them IN (leaner) until that cylinder cuts out....then open up again about 3/4 to 1 turn from that point. Do all 4.
IF you have a screw all the way in but the cylinder is still working, you have a BIG problem......like a damaged mixture screw.

Did you set float levels, because it's normal for fuel level to rise slightly as carb parts age and should be readjusted as necessary and will cause excess richness at all rpms if not reset.

 

A soaking is recommended because carb cleaner cannot get to the small myriad passages inside the carb that you cannot even see. If sea foam doesn't get it, spray carb cleaner is one step next up on the cleaning scale. Dipping is the best/last step. A dipping cleaner + can is usually about $35 at Autozone. If you go this route, make sure all plastic/rubber is removed.

What condition did you find the carbs and their respective parts?

Do the float level adjustment and get fresh gas.

Set the pilot screws to the factory settings. Then I would richen just a tad. The bike comes lean from the factory to meet EPA regulations.

Because of the aftermarket muffler, I don't think you would need to richen it up much - if at all.

How's your air filter?

 

Yamaha makes an excellent carb cleaner that mixes with water and won't harm rubber components. We used to mix 3 parts water with one quart cleaner. It comes in a quart bottle. You may want to make sure your enrichner (choke) is operating correctly as well. I doubt the problem is with your idle mixture (pilot screws), but there is a procedure for adjusting those as well in the Honda manual called an idle drop procedure. Carb adjustments are very difficult to do via computer and word of mouth without seeing the bike and knowing it's overall condition. How many miles on the unit? Has anyone done a compression or leakdown test on it?

 

Here's the Yamaha stuff.

 

Do everything you can before soaking the carbs because you will then need to separate the unit into 4 separate carbs, deal with lots of springs, o-rings, other stuff. It's a mess!

Avoid soaking if possible, but use high-pressure compressed air and carb spray on passages.

 

De-banking is not required.