Need alittle guidance on my 84 vf500

OK well i bought a 84 vf500. It has 21,000 miles runs pretty good idles great and rides good except for one thing while riding it and you open it up it hesitates, in neutral its fines but when in ur riding and it goes up over maybe 6000 rpms it hesitates. It has a 4 to 1 exhaust carbs might need to be cleaned but im just learing some of this stuff it gets alittle complicated for me. I figured maybe with the exhaust i might need to get it rejetted.

 

Mine did that, hesitated at 4000-5000, then would spool up and go. CARBS!!! :fear: Be very afraid... lol

 

mine was like that till I shimmed the needles. They were built to run lean in that area for emissions reasons. With the stock exhaust mine (and all V4's I own) were very difficult to maintain speed at that rpm, below and above they were solid. Throw and after market exhaust on them and they get down right doggy in that rpm range because they lean out so bad.

Another ting I did that everyone frowns upon was to drill the holes in the slides a little bit larger. This made the biggest difference in upper rpm throttle response with the after market pipes on my 500 and all V4's.

If you need some shims PM me your mailing address and I'll send you a few. When I ordered them I wanted brass for obvious reasons and the only way to get them was in 100 packs. I generally use 8 shims per bike, 1 was barely noticeable.

 

ok thanks comrad i will pm u thnx man

 

Post some PICS!!!!

 

wow alittle big but its the only pic i have. my daughter stood on the tank and grabbed the handlebars messin with the throttle luckily her legs arent long enough to put it in gear haha lol

 

Try bikepics.com for pics. Enjoy.

 

Hey commrad, I'd like to know more about the needle shims. I think mine is leaning out there as well. Can you share the details?
Thanks,
Jim

 

I covered the basics in the previous post but here's the more detailed version.

when our bikes came into being there were emission controls but no viable fuel injection systems (production costs). As anyone who has cleaned a carb knows there are 2 jets, a slow jet and a main jet. The slow jet handles all the fuel delivery up to about 1/4 throttle then the main jet, which is made variable by the needle, picks up and along with the slow jet provides fuel. Since these bikes had to pass ever increasing emissions standards the shape of the needle was designed so that it causes a lean condition at cruise RPM. This in turn causes that midrange flat spot you feel.

Shimming the needles is the same as the older carbs that have moveable clips. it is the same as the needle thinking your at a higher throttle setting than you actually are so that there is not a lean area in the fuel delivery. It helped on my 500 but the VF750S gave the best response to the shims.

You could get a carb kit but the needles are reported to be very "off", some say they are soft and wear out too fast or they are rough and ruin your carbs.

A few benefits I've seen have been lower operating temperature in the summer, that annoying flat spot was gone and it was 1000 times easier to maintain a set cruise speed and believe it or not my fuel mileage increased, I assume since I wasn't constantly chasing a constant speed by opening and closing the throttle.

Any more question? feel free to ask. I'm sure some one will be along to tell you I'm wrong lol.

Since your in ATL if you want to get together and ride some time let me know, I'm up 85, exit 166.

 

Thanks for the response commrad. I get how shimming the needles would help. What thickness? My carbs are currently apart for the third round of cleaning and I might as well do this now rather than later.

Oh, and I am in Cumming and am going on the VJMC ride on the 27th. I am not sure what bike I will be taking yet. Whichever one runs I guess...

 

VJMC on the 27th? The one in Helen? the website lists it from the 20-22nd. I've got a bag of these things in brass, if you want to swing by and pick some up I live in Toccoa and work in Lavonia. All I remember about the size is that they are metric and brass precision washers sold in a 100 pack. They weren't cheap either. The problem I ran into with regular washers was they were very inconsistent and not suitable for the application.

I'm hoping to ride my baby ceptor to the Helen event and meet a fellow magot or two there.

 

No. The VJMC ride is on the 27th in South Carolina. The National Rally is in Helen on the 22.