hi all i have recently purchased a 1986 VFR400 NC21 and i am discovering a few issues which i was needing some help with.

I am a new rider with no experience so i apologise if this is repeated,

the bike doesn't seem to start, the battery seems to hold a charge at around 13V and that doesnt seem to drop if unused, the bike turns over but seems as though it dies upon actual fire if i miss the first catch it seems as though its dieing. i have been told that the carbs may be caked up and need a clean as they think it sounds like its not gettin fuel. Once i have taken it for a ride the problem still occurs, the bike does seem to bump start though? So i am a bit stumped as to what it could be?

another problem is that the water in the radiator seems to expand as it should into the expansion bottle but when the bike cools down it doesnt retract back to the radiator. i have bought a new radiator cap as i thought it might be pressure related and i bought a new radiator fan sensor as the one on there was broken for the fan to kick in but i know the fan works. is this the right thing to do?

any help is much appreicated, thanks luke

First question: How are you starting the bike? Should be FULL CHOKE and NO THROTTLE.

Second question: Have you looked at the cooling system since changing the rad cap? Just to confirm it was that.

Third question: Have you checked that fuel is getting to the carbs? I.e dodgy fuel tap/vacuum hose.


For what it's worth it's probably a good idea to clean the carbs out whether they are at fault or not.

I am starting the bike with no throttle and full choke!
I haven't been out on the bike since the radiator cap change was just seein if I was on the right track ha
How can you check the fuel is getting to the carb? Where do I look for this?
What sort of price am I looking for a carb clean? With no mechanical knowledge seems quite complex to clean otherwise
Thanks

No worries mate, it's just these V4's like their choke

You're probably on the money with the rad cap change.

Don't know if there's any big differences between the NC30 and NC21 in how the fuel flows, but it seems strange that you've been out on the bike one day then the next it isn't getting fuel.
Make sure you're vacuum hose is intact and connected properly.

Don't know what the price of a carb clean is, but I shouldn't expect it to be too high.

Usual old neglected bike issues.

Strip and clean carbs, check everything is in the right place and jets are ok.

replace carb rubbers as they are most likely shot.

Check / replace vaccum hose as its important and most likely old and shot too.

adjust valve clearances while carbs are off, no shims on the 21 so no need to buy anything just time.

check plugs / air filter and replace if necessary along with engine oil if unknown.

reinstall carbs and balance.

Should run like a swiss watch after that. Really simple and easy to do just time consuming to get the carbs off and stripped.

If you follow the above in that order you shouldnt have any problems with the bike.. valve clerances are often neglected and important to the bikes health. With prpoer valve clearances and clean balanced carbs you should get a superb idle.