MY vfr 400 will not start

[janvfr400]

Hi everyone.. I have a 1982 vfr400 (nc30) with a starting problem. When I bought the bike it was running like a dream.. with just a 1/3 choke from cold she would burst into life.. If I left her to sleep for more than a week she would be difficult to start.. She would cough and splutter and eventually a quite a few goes she would start but ran very rough. Until she was warm. (NOT HOT) If I used her daily she would start much easier? When she was warm she would run like the wind with no misfire or flat spots AT ALL and rev all the way ( a little screamer) However, I haven’t used her for months and now she wont start at all. I have put new fuel in, cleaned the plugs,,(many times) I have good compression (put a little oil down the bores to help) and all plugs are gapped and are sparking well. I have the tank off at the moment and just running a gravity feed to the carbs via a tube full of fuel. When I crank her over after a while the fuel slowly moves down the tube so I think there is fuel getting through (plugs do wet up) now and then I get a pop and a bang (mainly from fuel in the exhaust) Please help what do I look for next,, is there any mechs out there who can bring her back.. I am willing to pay the going rate. I live in North Wales nr Wrexham. CHEERS Janvfr400

[CMSMJ1]

Hello and Welcome!

I would go for the most common culprit for bad starting here and say that your plugs are goosed. Even though they spark out of the bike it is often the case that they get flooded adn mucky and just die.

Also, the fact it has been stood for ages would make me think about cleaning the carbs out and giving all the jets and passages a good dose of carb cleaner.

Am sure others will be along shortly to let you know what they reckon!

[wullvfr]

hello and welcome,first of all....1982 nc30 ,do you mean 1992?

like cm says try different plugs and see if it makes a difference at all.see if you can get some from sum1 as they are not cheap.

you know you are getting fuel to the cylinders especially with the backfire so it seems the most probable cause.



william

[MexicanGringo]

Theres another guy having the same problem right now, iv suggested checking the spark against the frame, checking the fuels flowing properly thru the suction valve, checking the battery is producing at least 12.5v, checking the functioning of the reg/rec by testing charge voltage over the battery at 5k, checking decent air flow with new air&sub air filter, checking float heights cos this can caust lean/rich situation, the pulse generators on the starter clutch could be checked as well, tho i hav to read up how to do this, prob resistance or some such. Like CMSMJ1 suggested you can get a spark but still too weak to do the job properly, you need to clean the contacts & the metal rim round the electrode cos they tend to side arc and spark weird in general. The cdi is also a culprit but you need to check a wiring diag to test it.. Check for a good earth connection to the frame as well, this is very important and there are two main earth connections by each coil.

[janvfr400]

cheers for the advice everyone.. I will look into replacing the plugs and cleaning out the carbs as suggested.. anyone know a good carb cleaner that they can recommend? also i have been told about faulty rectifiers. my friend has a 1992 (same year as mine) rvf 400 is it the same cos if it is he will lend me his to try. and what other bits could i borrow to try and eliminate the parts.?

Cheers Janvfr400

[wullvfr]

if you battery is charged enough to continually try and start the bike then straight away i would rule out a faulty charging system.but to be on the safe side,a simple charge rate check at the battery would rule it out.do this with the bike at 5000rpm.you should get a reading between 13.5-15volts.also check the voltage at the battery before starting.



william

[gothicsanta]

It is very likely that you have been riding the NC30 like an old woman and that is why it is refusing to start for you. It must be given to someone who will thrash the living crap out of it for a while

my friend has a 1992 (same year as mine) rvf 400

82 VFR
92 RVF

mate you really need to start your medication back up again

...as for stripping my ('96) RVF piece by piece you'll have the missus to answer to

I thought that this was a rectifier fault as I know they are often the "weakest link" and I thought if this was goosed then the bike would never start? He has tried to get the bike going off a different battery and via a jump start so it's not that there isn't enough juice there....very lively when turning over - just can't hit the jackpot...

[CMSMJ1]

LMAO @ Al.

Yes..gonna be dad plugs for my 20p bet then..

[janvfr400]

Hi all.. Question for all you techies out there.. what exactly does the rectifier do then????

i know is smoths out the current and converts AC to DC but what effect does that have?

[CMSMJ1]

Simple answer is that it takes the AC current (in pulses from the generator) and recifies it into a DC current so that the battery can be charged.

hows that?

Someof the techy people will come nad bore you now..but you can run your bike without one as long as oyu have a strong charged battery.