Running Problems

[IgorVigor]

Hello People...

Been a while since I logged on :S

Got a problem with the Firestorm...

The engine starts and runs when stationary.
It will rev to the red line quickly and happily...

When moving though, its fine to roughly 4.5k rpm, and then beyond that it just bogs down and misfires like mad...
If I keep the throttle pinned, sometimes I can get it to pick up and continue for a short distance, and then it happens again...

I have checked the carbs arent leaking around the manifolds etc
I have tried bypassing the sidestand switch
I have double checked that none of the pipes to the tank are blocked/pinched and are definitely connected to the right places...

Now I have discovered that the bike has been tuned in the past, and has had the standard Honda restrictors removed, so it should have its full potential
and it ran fine the other day, when I went out in the morning. It then started playing up when I went out on it again.

I have replaced the air filter (with stock Honda) and I have fitted new plugs (that do spark and are gapped correctly)

Any ideas what it could be?

The only things I could think are:
Fuel tap diaphragm (most likely?)
Fuel starvation (need a fuel pump?)
Carb diaphragm (I dont think it is, as the last time I had one tear (on a different bike, it wouldnt run right at any RPM, not just over a set RPM)
Timing out (least likely)

It makes no difference if I pull the 'Choke' on or off...

I wondered if the fuel tap diaphragm is leaking (no fuel is coming out of the drain hole on the tap)
If it is, do I need to drain the tank?
I havent done it before so I dont know if the fuel tap is located before or after the diaphragm? :S

Also, do you think it could be fuel starvation?
The bike is obviously upjetted a bit as it hasn't got the stock Honda restrictors in it, I have debaffled the stock cans (not holes drilled, the baffle and tube is out) and with a Honda paper filter runs a about right...

Anyone got any ideas?

thanks..

Igor.

[IgorVigor]

Just wondering, seeing that the VTR suffers from fuel starvation, would it be possible to do the Vacuum fuel tap bypass like they used to do on the NC30/NC35 (VFR400/RVF400)?

http://www.akhara.com/nc30/fueltapmod/index.html

might solve the fuel starvation problems (both when pushing the bike, and when the damn diaphragm is damaged...)

[tony.mon]

What "standard Honda restrictors"?
Sounds like a seller's line.....

I'd guess that the cam timing is out 180 degrees, matches your symptoms well.

Not unusual that a bike is sold after a CCT failure/repair and the timing's not been done properly.

The good news is that it's not a huge job, and no damage will have been caused, assuming I'm right.

So the question is:
Has it ever run right since you had it?(I.E has it revved out to the redline (or above eight, anyway, if you're not a speed freak) since it was last "tuned"?

[IgorVigor]

the standard honda restrictors in the intake...
I have seen the pictures on here showing them cutting the intake size down a little

well I can see that the ones in my intake have been cut out (the metal band is still in the rubber, but its not protruding into the intake)

and it isnt a sellers line, the seller (a dealer) never said a thing about them...

I would be surprised if the cam timing was out as before these troubles started it would rev to over 8k rpm, and always has done...

it started the other day when I went to go out on it again :S

And its hasnt had a CCT failure...

the previous owner had them replaced often (got the receipts)
and I have fitted a Manual CCTs

Thats why I wondered if its the fuel tap diaphragm...

it revs ok when stationary.
it runs fine on the road up to 4.5k rpm
past that it misfires, judders etc...
sometimes, it will clear its self and be ok for a few seconds and then it starts again...

EDIT:
The restrictors like this:
http://www.billzilla.org/VTR1000-restrictor.jpg

mine is a UK bike, but seems to have these :S

[benny hedges]

those intake restrictors, you can pry them out easily.
it appears some have them, some dont.
mine did, but hasn't now :d

that wont make it misfire tho.

how long have you had the bike btw?? if you bought it from a dealer, maybe you should take it back and get them to sort it?
are you sure you have enough fuel in the tank?
might sound daft, but if its been on its sidestand and you only have like 2L in the tank....

or plugs might be blacked up if youve been lugging it low rpm low gear?
check the basice first, unscrew the carb drain at the bottom of the bowl and check its full of good clean juice - might just be a bit of crap / water got in the tank.
did you jetwash it when you put it away last time???

also you say you think it's been 'tuned' in the past, and doesnt have original jets, but you have put a std air filter on...
was this when the problem started?
if it had a k&n on before you just wash it, dry it and oil it with k&N filter oil.
you should never need to replace a k&n.
see k&n site for cleaning info, unless you have thrown it away?
they do look very similar to the oem filter but pass a LOT more air.
and as well, did you remove / refit the oil breather caps in the airbox?
have you got airstacks fitted?
when you fitted new plugs, did you just drop them down the plughole? cos you may have damaged the gap when they hit the bottom - and are the plug caps fitted properly?
simple things to check but could just be a simple problem!

[IgorVigor]

the intake restrictors have been filed on mine (before I got it)

I have had the bike for a year now...

its got almost a full tank
the fuel is good and clean.

the plugs have been replaced.
the old ones that came out were a nice tan colour so it was running nicely...
the new plugs are a bit black, because of starting it with choke...

tried the old ones again, but doesnt fix the problem...

I havent jetwashed it.

the tank isnt pressurising (makes no difference if the tank is open or closed)

the carb diaphragms are fine
the needles look relatively new

its getting a good clean spark at both plugs

the cam timing is definitely fine, as before these troubles started, it would rev to the red even in 4th (:P)
nothing has been fiddled with.

literally, the other day I used it in the morning and all was fine.
took it out that evening and this problem showed itself...

still think it could be the fuel tap diaphragm...

[benny hedges]

still think it could be the fuel tap diaphragm...

remove it then - well, cut a big hole in it and remove the internal gubbins out the tap.
if the tap is fkt i might have a spare one in the garage somewhere...
look at the fuel pump mod on the front page for details of removing the diaphragm.

theres obviously something wrong, you'll just have to work through it til you find the problem.

before you take it to bits tho, start the engine, pull off the tank vac pipe and make sure it's pulling air...

[IgorVigor]

when I took the tank off yesterday, the pipe does seem to pull air, and the engine note changes when you clamp it...

I know how to do the fuel tap mod, I had a look...

only thing is I dont like the fact the fuel can just run as it wants :S
I havent got a fuel pump to stop it...

I will have to order a fuel tap repair kit...
I also need to get a choke repair kit...

I took the choke assembly out of the carbs only to find that the back one never opens, because the cable just slides around.
the cable lug is missing, the front one looks worn...

Anyone know where to get a new set?
I need the needles, and needle holder (with the cable lug on it), the plastic threaded casing...

[benny hedges]

Anyone know where to get a new set?
I need the needles, and needle holder (with the cable lug on it), the plastic threaded casing...

somewhere in the workshop section is a parts fiche for the storm - i think it was posted by seb

might be worth looking on wemoto too as they do a lot of kits in the fuel section...

a dodgy choke plunger would cause the problem you state imo..
if you cant find a repair kit you can have my old fuel tap - it works fine.
but it will cost you a pair of your grandma's soiled panties

[IgorVigor]

I had a look on Wemoto...

I hope that the price they have listed is for both :S

~ £37 :O

if the price is each I will not be happy :S...

The only thing concerning me, is if the plunger is dodgy and letting too much fuel in, it means that the bike will be jetted too lean

I dont think the choke is the problem though...

Will have to check the fuel tap diaphragm...

which is a pain to do really...

got to find a container to drain all the damn fuel into (its got almost a full tank, perhaps 1/2 a gallon gone from it :S)

just going to list what I have checked, and what the problem isnt:
spark plugs (old and new make no difference, nice big spark on each one)
timing (it cant be the timing as it was fine the other day)
Carb diaphragms (checked them today and they are fine, both slides drop down at the same speed, no tears or damage)
no pipes kinked, and are all fitted correctly
sidestand switch is bypassed so its not that


I need to get the carbs balanced once I can get it running properly again.
the butterfly valves open fully and smoothly at the same time.


So I suppose the only possible problems it can be are:
fuel tap diaphragm (seems the most likely now doesnt it?)
choke plungers (seems unlikely, as it was a sudden problem, not a gradual one)

[rumpleforeskin]

I had similar symptoms on my last bike and that was caused by a damaged choke cable.

the cable had birdcaged so even when the choke knob was fully in the cable was still holding the choke on a little.

[IgorVigor]

fair enough...

the cable on mine is the other way, its got a bit of slack

the rear carbs choke doesnt work.
the front one works...

will have to spend out and replace them

[IgorVigor]

Ordered a pair of choke assemblies today...

£74 for the pair :S...

Hope that sorts the problem :S...

while I wait for them to arrive I will drain my fuel tank, and remove the tap and check the diaphragm and clean the filter...
probably never been done so might help ...

[IgorVigor]

Bit of an update...

I have fitted the new choke assemblies and they are much better than the old ones...the old ones I think have been leaking, as riding with the choke on 1/4~1/3 is the same as no choke before...

it has however, still got the problem...

I will drain the tank and check the tap diaphragm and the filter...

it will now misfire above 4500rpm even when stationary...

but I know the timing is correct....

[benny hedges]

seems like 2 of you with the same problems - maybe compare notes with gilson & see what you haven't tried yet - i suspect a few things -
dodgy cdi unit / wiring...
dodgy pulse generator - does it pick up from the metal contacts in the flywheel??? if so, are they clean?
iffy spark advance gear?
faulty rev limiter - or wiring - not sure how that works yet but will check after.