Assistance needed - tempremental VFR400

[JediGoat]

Ok, it's not about an SV...and it's not even my bike, but a good friend of mine is at the end of her tether with a bike she has just bought.

Bex got a 1994 Honda VFR400 NC30 about 6 weeks ago. As she is on a restricted licence it is restriceted to 33BHP.

Since then she has barely been able to ride it due to constant problems. These include:

1. Difficulty starting - will start with the choke out, when choke is cut off and bike is idling, any throttle will cause bike to cut out. Bike is then a pain to restart.

2. Cuttting out when engine is warm - same thing as above, cut off seems to occur on throttle opening.

3. Excessive heat - when riding in town, the bike produces what appears to be an excessive amount of heat from the engine. Temp guage has once plopped right over into the red - on this occassion the battery seemed almost drained immediately after, and would not start.

So why am I asking all the questions in here? Well, Bex has trawled through some VFR forums (fora?) and been given dozens of potential causes - rec/reg, ignition coil, pulse generator (is this from star trek?), but as she is non technical she took it back to the dealer for it to be checked out (more than once I have to add). They say there is absolutely nothing wrong with the bike, and it is down to how she is riding it....but she doesn't know what it is she is supposed to be doing wrong.

Is anyone able to offer any advice....or better still, have a look at the damn bike to see if they can work out the problem (be it mechanical or riding style?)

Thanks in advance

Jo

[yorkie_chris]

Something blocked in the carbs, maybe a pilot jet making it run lean on one or more cylinders.
Thats where I'd start anyway, then take a timing light to it and check its not advanced too far.

[fizzwheel]

Originally Posted by shop_addict

They say there is absolutely nothing wrong with the bike, and it is down to how she is riding it....but she doesn't know what it is she is supposed to be doing wrong.

Meh utter rot, sounds like the bike is at fault not the rider here IMHO.

I cant give specific advice, but something sounds not right.

Definately shouldnt cut out when the throttle is opened, that sounds like a fueling problem. I think that batteries do get knackered if they get to hot, as it boils the battery acid ( but I might be talking rubbish ) Again the starting problem could be fueling related or the fact that the batteries toast or its not charging properly. The only way to fix any of this is for somebody who knows what they are doing to take a systematic approach and isolate things one buy one till the root cause of the problem is found.

Can you friend take the bike somewhere to a different mechanic and get a 2nd opinion. Let me guess the dealer she's been going to is the one that sold her the bike... Did they fit the restrictor kit ? It could all be related to an improperly fitted restrictor kit perhaps...

[JediGoat]

Originally Posted by fizzwheel

Can you friend take the bike somewhere to a different mechanic and get a 2nd opinion. Let me guess the dealer she's been going to is the one that sold her the bike... Did they fit the restrictor kit ? It could all be related to an improperly fitted restrictor kit perhaps...

I think that is the only solution. The place that is doing the checks is the place that sold the bike and fitted the restricter. Although she is not getting any joy there, at least she hasn't had to pay for the checks.

The nearest Honda specialists that I can think of are Slocombes in Willesden, but if it is a case of numerous potential faults it could cost more than the value of the bike to find the fault.

If it were my bike, I'd return it as not fit for purpose, but she really loves the old thing (when it works).

How much do you think it would cost to have the fueling checked out....or is that an impossible question to answer?

Jo

[yorkie_chris]

An MOT station will have a gas analyser and will usually have a gander for a fiver or so

[squirrel_hunter]

I would go for carb related problem. I'd take them off for a bit of a clean first. Or you could try the Redex approach. However also check out the fuel filter for blockages.

I remember Strechie telling me his VFR had a similar problem that was due to the fuel tap IIRC and is a known fault. For more information try 400 Grey Bike I'm on there for my NC23.

Finally the running hot could be due to the temperature sender if the fan is not coming on or just a dead fan (this can easily be checked by wiring it directly to a battery). As for the poor starting/ draining the battery the reg/ rec is most likely as due to the age of these bikes they are starting to become a weak point. However I'd get it running right first.

Isn’t the 1994 gonna be a NC35??

Anyhoo,

I don’t think it is just one problem here … I think you have a number if different ones here …

First thing to do is lift the tank off/up this will reveal the airbox, give it a reasonable tug/wabble to establish if the carbs are seated – getting the carbs back on a V4 is a pig!!! I am presuming the restrictor was blanking plates in the inlet, hence the carbs have been disturbed.

If the carbs seem to be ‘on’ then check the vacuum pipe from the engine to the fuel tap. Also take this off the tap and with the fuel pipe off the tap, get another little pipe and provide a vacuum by sucking on the end … fuel should come p1ssing out of the tap.

Unless she is sat around for ages or going <20 for ages, I think the engine overheating can only be down to a sticking thermostat or not enough fluid in the rad/system.

I simply reckon the carbs were not replaced properly …

OK, I have very little mechanical knowledge, but I do have an NC30

Even when mine was fully healthy the fuelling could cause similar issues to what you describe. Ie I always had to start on choke, but once it had warmed up for 5 minutes it would stall if you didn't turn the choke off. Restarting when warm had to be done with no choke. It ran fairly hot, the frame would be hotter than you'd want to touch with no gloves.

So, not much to offer except that I'd guess it just a fuelling problem and not worry about the electrics till you've eliminated this.

Also
>They say there is absolutely nothing wrong with the bike, and it is down to how she is riding it

Is just utter rubbish.

[21QUEST]

Jo,

I think the guys are more than probably on the right track in saying it's very probably a fueling problem.

Anyhoos spoke to a mate of mine who has quite a bit of experience with VFRs/pocket rockets. His initial thoughts were carbs/fueling from what I explained to him.......jets in general and air/fuel jet in particular.

When I brought to his attention the fact that carb restrictors were in place, he also said with those bikes it is important that the air/fuel screw is adjusted to take into account the carb restrictors.

Is the fan not coming on at all seeing as you mentioned the temperature going into the red zone at one point. The fan should have kicked in well before that.

Mentioned a couple of things that may or may not contribute to the various symptoms you mentioned ie shims, coils........

One thing I would say(IMHO) is that sticking it into a Honda garage won't necessarily mean they'll be able to sort it out quickly and without costing more than it should.

I'll PM you in a wee bit with a suggestion later with regards the above.


Ben

[JediGoat]

Originally Posted by squirrel_hunter

I remember Strechie telling me his VFR had a similar problem that was due to the fuel tap IIRC and is a known fault. For more information try 400 Grey Bike I'm on there for my NC23.

Squirrel

I think Bex has looked at that site, and she is aware of the four thousand known faults with the VFR, but she does still like it. She's gonna go back on there for more info.

Jo