VF500F bad response beyond 5,500 rpm

Hi all, I have just purchased a 1986 VF500F which has been idle for the last 7 years. I have changed the oil and filter and replaced the spark plugs. The bike runs absolutely fine and smooth up to 5,500 rpm then it starts to splutter and cough.

I have tried spaying carb cleaner into the carbs and also added redex to the fuel. I have done around 150 miles since then and the problem still remains. The max speed is 60mph.

Anyone got any ideas?

 

Firstly hi and welcome to the MadHouse:welcome:.

When you get a chance the folks on here really like to see a picture of your ride, otherwise it won't be long before folks start ragging on you. (Just click the icon 2 to the right of the envelope and follow the prompts.)

I can't really offer much advice on whats going on with your 500, other than to echo your suspicions that if the bike is otherwise running fine, then you have some sort of fueling problem. In good order a 500 should top 100mph with ease.

I vaguely recall comments about some 500's suffering with valve gear issues where the relatively frequent (1,500mile) oil & filter servicing regime was skipped. However as the bike appears to be running OK at lower revs I think your first focus should be on completely cleaning the fuel system.

Anyway, assuming its not something simple like a jammed throttle cable/mechanism, preventing the carbs opening fully then its sounds like you need to check / heavy duty clean the carbs, as carb cleaner is probably not going to clean out the fuel system if the bike has been unused for 7 years.

On the plus side you managed to get it running, however without draining and flushing the whole fuel system I think you will find the problem may just get worse, as old fuel can deteriorate, eventually leaving residues in the tank which with the bike fired up can pass down the fuel lines and block or restrict flow though the carbs.

For now, it may be worth repeating your question in the Mechanics garage on the Forum, as it looks like your post was not been spotted by the technical guys on here. You might also want to review pertinent posts in the 1st/2nd gen area - as you probably won't be the only person endeavouring to resurrect a long parked VFR, and there may be some useful tips.

Good Luck - let us know how you get on




SkiMad