Quick engine type question...

[tinysmall]

Ok, so I've got something going on with my bike. Im not sure it's actually a problem, more of an annoyance when it happens. Every now and then when I'm riding I get an odd noise from the engine. It sounds like if you hit a pan with a stick whilst holding the rim to deaden the vibrations, if that makes sense. It normally happens low down the rev range when I just start to open the throttle and the engine sort of skips. It feels like something hitting the underside of the tank making the bike lurch a little bit. Sometimes it will happen three or four times on a ride and sometimes I don't get it for days or weeks at at time and it seems to happen more in the cold weather. Sometimes it's just one 'pop' and sometimes a couple in one go. It doesn't affect performance and there is no smoke or owt. I'm running aftermarket cans but it's not jetted. Anyone got any idea what it is, if it's anything to be concerned about and how to sort it out?

[vtwin]

Sounds pretty normal to me, at least to say mine has always done it too !

It was quite worrying when I first got the bike, sounded like a piston was coming through the bottom of the tank !

Just a trait of a large displacement V twin I believe, although mine does it a lot less since I took the K&N out and put a standard filter in.

[vtwin]

Just to add mine used to do it when sitting in traffic and actually stall the engine, first time it happened I thought It had snapped a rod, until it started right up and ran normally !

[Wicky]

Carb Fartâ„¢

[flak monkey]

Mines done it a few times already. Did make me jump the first time then I figured out what it was

[tony.mon]

They all do it, and sometimes stall afterwards.
Nothing to worry about, and not much you can do about it except fit a -4 degree ignition advancer, and keep the carbs balanced.
But then it runs hotter.
Tickover set to 1400 helps to stop it stalling when it coughs.

[Stratman]

Well, I agree that they CAN all do it occasionally, but mine doesn't very often and I would suggest that mixture and balance need sorting out, together with raising the idle to about 1200.

[tinysmall]

Thanks for putting my mind at rest guys. Carbs are balanced spot on at the minute but I have taken the baffles out so it could do with setting up on the dyno. That'll have to wait till our lass has done her direct access though. Skint until then

[sirch345]

TS, I agree many Firestorms do it, although some owners in the past have said their bikes never do it. I altered the air screws on mine so it runs slightly leaner (after speaking to an expert on this issue), with that and keeping the carbs balanced has reduced this to a minimum. Raising the tick over will help as already mentioned.

As you say getting the carbs set up properly on a dyno will be your best bet.

One thing I did notice I forgot to mention, is that it happened more when the spark plugs needed changing.

Chris.

[pinkyfloyd]

I had this once. I thought something had broken and it scared the bejezus out of me. Hasnt happened since and TBH I'd forgotten about it. Glad it seems normal though. What ever it was!

[benny hedges]

first time it happened to me i almost crapped myself.... i was leaning the bike over, rolling left off a small roundabout at about 20mph then suddenly Pop eheugh.... it popped back and stalled mid lean
quick foot down moment.

as said, raising the idle speed cures it.... you will also find running the idle above 1500 helps smooth out the engine braking too, though does make the fan run harder in standing traffic.
i run my idle around 1750 without problems.