Another VF500C idle problem (1984)

Hey all, I'm hoping some of the VF experts here can help me with an ongoing problem on my 84 VF500C. I've had this bike since last year in May. It's in really good shape overall (around 11,600 miles on the odo), but I'm chasing a few little engine issues. The bike had been running really poorly when the ambient temp was above around 80º, and it doesn't like to idle at those temps either. Yesterday I pulled the carbs and cleaned them out. Now the bike runs a lot better. It pulls really well all the way to redline, but it's still reluctant to idle. It will still slowly die at idle. What should I look at next? I haven't synced the carbs or adjusted the valves, but I want some opinions before I move forward. I appreciate any input.

Suomi

 

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It may be running too rich, just check your plugs.

I'd suggest double checking float levels or playing with mixture screws by turning them clockwise just a bit.

Also, synch the carbs.

 

from all the work iv'e done to mine...im willing to bet its the rubber boots for the carbs. they get real hard from sitting around a get small cracks and well... just stop sealing all the way. these bikes, and from what i understand especally yours are very suseptable to even the slightest vacume leak. try spraying some carb cleaner underneath the carbs if the idel goes up you have a little vacume leak. replace the boots and i bet youd be suprised. And for sure get the carbs synced.

dts

 

I suspected the carb insulators, but when I soaked them in WD40 it didn't affect anything. Then again, I might just replace them to be sure.

 

I forgot to mention that I did replace all of the vacuum lines on the carbs. I'll try adjusting the fuel mixture tomorrow.

 

Hey Suomi

I have the same problem with my 84 500F, I have to run it slightly rich just to get it to idle when hot, when it is cold it idles great. Of course running rich makes the idle jump around from 1300 to 2000, quite frustrating when pulling into corners as you dont know if the engine is going to stop or try to pull through.

I have been over the carbs with a fine tooth comb but have not tried to replace the insulators. Can you let us know if it helps, I agree with the statement that these are very susceptable to vacume leak. I could not get it to idle at all until I replaced what looked to be a perfect hose going to the fuel shut off valve.

In the end I replaced everything rubber where I could get hold of the parts, I am still looking for insulators in Aust. The result was a bike that is fantastic to ride just have to watch comming up to lights as it still likes to stall sometimes and is a 'mungrell' (aust for hard) to start when it is hot.

 

I'll be ordering new insulators tomorrow. I'll report back once they're installed, which should hopefully be by next weekend.

 

As a 2nd generation vintage V4 owner, I got one solution for you- Sync the carbs. They are the heart and soul of the bike and once they are set up properly, the bike will run like it is new.

 

A carb sync is in my very near future.

 

how it going

Hi Suomi

Not sure if you are still having problems with yours but I recently discovered I was setting the float levels all wrong on mine :redface:, the result was too rich and this caused hard starting once warm.

There is a line in the manual which says to measure the float level with the carb held at 45 degrees, so the float just rests on the needle, if you don't use the angle then the float depresses the pin in the end of the needle and you get a wrong reading, Using the correct method made huge difference to my bike. Of course mine has now developed an electrical problem but that is a whole new story I am working through. Once the levels were right I was able to balance the carbs and get her running better than she ever has, for me anyway.

I have also recently replaced the insulators which although they looked OK on the bike were full of cracks once I got them off, worth replacing anyway.

Lots of luck, I hope you have fixed your problems and dont actually need this post.

 

hows it going

Hi Suomi

Not sure if you are still having problems with yours but I recently discovered I was setting the float levels all wrong on mine :redface:, the result was too rich and this caused hard starting once warm.

There is a line in the manual which says to measure the float level with the carb held at 45 degrees, so the float just rests on the needle, if you don't use the angle then the float depresses the pin in the end of the needle and you get a wrong reading, Using the correct method made huge difference to my bike. Of course mine has now developed an electrical problem but that is a whole new story I am working through. Once the levels were right I was able to balance the carbs and get her running better than she ever has, for me anyway.

I have also recently replaced the insulators which although they looked OK on the bike were full of cracks once I got them off, worth replacing anyway.

Lots of luck, I hope you have fixed your problems and dont actually need this post.

 

Where did you get the insulators?