cutting out

[andyd76]

bought my first firestorm a few weeks ago and loving it. Sorted some bits and pieces out and its much nicer to ride now but i still have a problem with it cutting out. It starts and idles perfectly, but the revs dip very low brefly while riding if i release the throttle and pull the clutch in at the same time and occasionly cuts out. Only happens at about 5k. Above and below that it seems ok, a little unnerving as it locks the back wheel up on the lower gears if i'm slow to change gear. Any ideas where to start looking?

[benny hedges]

yeh m8 first thing to check is is the fuel lines are kinked or twisted under the tank causing fuel starvation.
this is quite common when the tank has been taken off and placed on the subframe, then put back wrong.

you could also raise the idle speed a bit... i run mine about 1500rpm (sometimes 1700) this eliminates most of the severe engine braking and stops the annoying cough at low rpm.

does the bike rev clean to the redline usually though??
im assuming you have only recently got the bike?
wondering if the cct's have been changed or other head work and the cams have been timed up wrong... usual symptom is the bike will cough and die 6500+ rpm, just wont pull proper to 7k...
easy to sort though.

[andyd76]

Thanks for the reply, will take a closer look at the fuel lines but i was sure to check them when i had the tank off to change the plugs. The fuel lines do seem really short, i struggled to lift the tank up far enough to disconnect them!...and yes the problem was there before i removed the tank

CCT's look fairly old, doesn't look like the bike has had any engine work done recently. Pulls clean up to the limiter and runs fine apart from the revs dipping when releasing the throttle from 5k. It doesn't do it at standstill, only when riding. I'm thinking its a fuelling issue, the bike has an ohlins rear shock and maxton stickers on fairing so i would guess this bike has had cans and been jetted at some point in its life. Would this cause the problem?

[tony.mon]

Not much to go on from your description, where in the country are you, maybe you're near someone who can help?

The revs are, of course, meant to drop when you close the throttle, but you would have to be pretty slow at changing gear to let them drop to an engine stall, which I think is what you're saying....

+1 on tickover speed, 1400 is about right for most people, Benny rides his like a racer and needs those extra few revs to stop it dropping too quickly and locking up with the lightened flywheel fitted

[Wicky]

i would guess this bike has had cans and been jetted at some point in its life

You need to describe more fully if it has aftermarket cans, airfilter (stock or K&N and what condition are they in) as there a quite a few variables that could account for your symptoms. Could it have had different afore mentioned bits then been altered before it was sold to you. When was it last serviced etc

[andyd76]

Not much to go on from your description, where in the country are you, maybe you're near someone who can help?

The revs are, of course, meant to drop when you close the throttle, but you would have to be pretty slow at changing gear to let them drop to an engine stall, which I think is what you're saying....

+1 on tickover speed, 1400 is about right for most people, Benny rides his like a racer and needs those extra few revs to stop it dropping too quickly and locking up with the lightened flywheel fitted

I'm in portsmouth, and yes you're right with normal riding it isn't noticable but i know the problems there now. Just wondering whats causing it. Tickover in about 1400 already, I'll post a reply if i find the cause.

i would guess this bike has had cans and been jetted at some point in its life

You need to describe more fully if it has aftermarket cans, airfilter (stock or K&N and what condition are they in) as there a quite a few variables that could account for your symptoms. Could it have had different afore mentioned bits then been altered before it was sold to you. When was it last serviced etc

The bike currently has a stock filter and cans, filter is clean and plugs looked good but were the wrong ones so I've replaced them with the recommended ones. Not sure on the history, but with the bike having an ohlins shock i'm sure the bike would have at least had a set of aftermarket cans on in the past. I'm gonna have a good read up and have a play, just thought i'd post here first incase someone else has had the same problem. I'll keep you posted!

[tony.mon]

Give the carbs a clean, in particular the emulsion tubes.