Low speed riding - gearing

[Supermofo]

Hi Guys,

Right had the Storm a while and still having the same problem and I'm not sure if its just me So let me know your thoughts.

Basically ridden under 50mph the engine is a bit of a pig. Acceleration even slow acceleration is fine as long as the throttle is positive, but trying to maintain a constant 30 or 40 is just a complete pain in the 'arris :mad2. Riding through towns and down through the Hatfield tunnel where there is a ave. speed section (I know the camera's face the front but don't wanna take the pi**) I find that both 30 and 40 seem between gears no matter what I do. In second at 40mph its around 4,000rpm and coincides with a flat spot in the fueling so the bike intermittantly goes to cut out and small throttle changes have the bike pogoing back and forward. In 3rd its smoother around 3,000rpm but is just at the bottom of the flat spot and feels a bit poop and the engine doesn't feel happy. Have simular problems with 30's but can't remember the rev's but either way no sweet spot that I can find. Under 30 is fine and over 50 is perfect no matter largely on gearing/revs I can fine a sweet spot. Wouldn't be so much a problem if there weren't so many camera's about but don't want to have to try the 'But officer my bike don't work under 50' line

Is this just my bike or me? or are they all like this?

I have a 2 teeth more Renthal ready to go on the back, will this help? I have lowered gearing on all my bikes but this is the first time I'm hoping that it will help cure an actual problem rather than just for fun.

I have had the bike dyno'd etc when I had the cans fitted and there was a massive hole in the fueling which was largely sorted on the readout but on the road I still find it

Any ideas?

[Stratman]

Have to disagree with Timbo there.

I really can't say I have any flat spots at all - I have open Scorpion cans, standard jets and stock airfiliter. I have a 2 tooth larger rear sprocket. I actually find the Storm a joy to ride at low speed (except for wtists and neck if for any protracted period) as she will filter along at tickover in 1st and unlike my fuel injected TDM doen't hunt or suddenly snap on the power as the TDM does when on slow corners/roundabouts in second, meaning a clutch slip is sometimes needed.

I think you need to check what is standard and what isn't, get the carbs balanced and air filter/plugs changed and then see how it feels, but changing the gearing will not change these characteristics.

[Supermofo]

Low speed running/filtering is fine. Its constant throttle at 30's - 40's around 3-4000 rpm. Up to say 25 is good and above 45 is good, but thats not good when you need to do a dead 30 or 40.

With standard cans on the bike wasn't great, but with Motad Venom cans the problem got more noticeable. Had the bike Dyno jetted and new air filter (standard) and carb balance. Bike run better but not perfect at those rev's. Dyno showed up a big hole in power/torque beween 3200 ish and 4800 ish (emissions test I would think?), work on the dyno gave me an extra 6lbs and 4-5bhp in this spot but its the constant throttle thats the issue, if you ride through it you will never know its there.

I know change of gearing won't impact on engine running, but hoping it will move the speeds I'm having issues with out of the problem zone in the rev range. Plus I can't help but feel that the bike is massively overgeared as standard it will pull 70 odd in top at 4000rpm and often feels better in 5th rather than 6th if under 80 ish.

[sirch345]

I'd fit the + 2 rear sprocket, I think you'll find that will definitely help.

I have the same set-up as Paul (Stratman) and I like him have no flat spot's either.

Something doesn't sound right on your bike to me. When you fitted back the standard filter did you notice if it was still there, or put back the channel that the standard air filter's up-stand sits in, it's attached to the air box lid (see first pic in link below). If that is missing you could be get a turbulence problem which is causing a flat spot.

http://www.burniemorgan.com/firestorm/airfilter.html

As Stratman suggests, get the carbs balanced and air filter/plugs changed if you've not done so for a fair time.

Chris.

[Supermofo]

Something doesn't sound right on your bike to me. When you fitted back the standard filter did you notice if it was still there, or put back the channel that the standard air filter's up-stand sits in, it's attached to the air box lid (see first pic in link below). If that is missing you could be get a turbulence problem which is causing a flat spot.

http://www.burniemorgan.com/firestorm/airfilter.html

As Stratman suggests, get the carbs balanced and air filter/plugs changed if you've not done so for a fair time.

Chris.

Dyno guy did airfilter so I don't know, I'll have a look, but he came fairly well recommended and seemed to have done a decent job so can't see him not fitting the filter properly but as I said I'll have a check.

Carbs were balanced and filter changed when I had the dyno jet kit fitted in March. Will change the plugs when I service it next.

[seb421]

im on standard sprockets and mines a dream at low speeds and at constant speed's, it will happy pull along bellow 3,000 rpm when im trying to save fuel on the run's home from work at night

saying that having the carb's sorted by that Damien Hill defo made a difference before they was put right it was using more fuel and wasn't so smooth at low rpm are at constant rev

[stormingjoe]

this also could be to do with the ThrottlePositionSensor out of adjustment, this controls the base ignition settings in the ECU, I would check this and balance carbs, something that shoould have been done at dyno time! My bikes standard except for viper race cans, now with db killers fitted,and down one tooth on the back sprocket, pulls like a train from 2,000 no glitches at all.

[IgorVigor]

My bike is completely standard apart from 33bhp restrictors, and I havent noticed the problem...

Well, I did have a running problem because of the vacuum hose being connected to the wrong tap connection, but once that was discovered its a joy to ride :S

pulls from tickover to 6k rpm nicely (then the restrictors really kick in )

TBH though, I might not have noticed it because my last bike was a 650cc single cylinder, which was strangled for the emissions so ran rough and had 1,000rpm of smooth running :S

[warby221]

3500 to 4000 revs is the transition point for the carbs were they go from the slow speed running jets to the main jets so my guess would be carb settings
have a look here
http://www.factorypro.com/tech/carbtun.html

a lot of tuners don’t do anything with the bottom end if nothing is said about a problem there and when they sort the main jets it upsets the slow running settings

[gilson]

Let's see your dyno... Do you have manual CCTs?

[seb421]

3rd gear with a hand full of throttle between 4 - 6 thousand RPM how good does that sound!!

"MOVE OUT THE WAY PEASANTS IM COMING THROUGH!" haha

[Supermofo]

Will try and post up dyno chart but have to remember to bring it in to work and scan it. The curve looks good though and on paper the hole is filled.

Having said all that I went out for a hundred odd mile ride yesterday and didn't have the problem once, which makes me think it might be me doing something your not The bike will roll along nicely at 3k or under and will pull great at all revs from nothing. Its just the contant throttle thing at 3.5-4k ish.

Sadly I don't ride much anymore, never owned a car till I was 28 biking all year round from 18ys old, but combinaton of longer commute, getting soft and a big off when I hit a car 2 years ago meant I gave up the communting so weekends and the odd ride to work only so maybe I'm just not getting enough practice in and riding the bike odd. On longer rides I seem to ride round the problem to the extent its not noticeable. Whereas after a couple of weeks lay off and in area's where I'm trying to say on the speed limit I have the issue, so that could be it? Have to say I've owned 2 smokes, in line 4's and a couple of singles and a twin is the one I've struggled most with. Odd. Then again now I'm old(er) and more senseable ( ) I pay more attention to limits whereas before I use to just ride so again could be me being more anal about speed/revs etc.

[Supermofo]

Do you have manual CCTs?

Not as far as I am aware (unless previous owner did it which I doubt as he didn't even change the original tyres it came with from new in 9500miles/5 years!). I listen for cam chain rattle but nothing as yet so gonna leave it. I've read the pro's and con's and for the moment sticking with the standard unless something goes amiss.

[Stratman]

Won't make any difference whether manual or OEM CCTs are fitted.

When you get this symptom, what speed are you doing and in what gear? Not saying you do, but you can't let the Storm chug along in high gear at low revs, even if it is a V twin.

[Phil-VTwin]

Won't make any difference whether manual or OEM CCTs are fitted.

Have you seen Gilsons Dyno chart when the manual CCT's were too tight? - Big hole in power and torque