Bloody annoying flat spot

bob the builder · Post by **bob the builder** » Tue Mar 27, 2007 9:24 pm

Does anyone else have a bloody annoying flat spot on their VTR at about 2500 rpm? Using the bike daily including town riding i spend a lot of time in this rev region. It is now starting to annoy me, I was going to go for a dynojet kit, will this help?
I would appreciate any feedback
Cheers

LotusSevenMan · Post by **LotusSevenMan** » Tue Mar 27, 2007 9:54 pm

Assuming it is a carbed FireStorm have you tried balancing them? Cured a mates flat spot in about ten minutes doing this!

Zer0Zer0 · Post by **Zer0Zer0** » Tue Mar 27, 2007 10:25 pm

ALL storms are carbed

Post by **kevg** » Wed Mar 28, 2007 7:29 am

YUP, i've got it, only started after i had a jet kit and my blue flame cans fitted, makes the bike real hard to ride slowly in town, nearly stalls all the time, and manouvering around mini rounda-bouts is a nightmare. the dyno guy said it was set up perfectly, the curves were good and if you crack open the throttle it can really pull, but sitting at below 3000 revs in any gear is hard going.

i've posted about this a few times in the past and you seem to be the only other person that has had this trouble.

i'm in the middle of stripping my bike down to change a few things and took the exhaust off last night, i found that the front gasket has gone completely, there was road grime on the inside of the exhaust at this point. so i'm hoping that when i put everything back together that this might help, the other ones seemed ok, and the usual one at the back was fine.

Kitch · Post by **Kitch** » Wed Mar 28, 2007 9:03 am

I have one too, but mine's a bit lower, like 2100 rpm.

I can sit at 2.5k quite happily, but below that gets lumpy.

I put it down to huge carbs and pistons, my fuelling is spot on too Kev.

V-Thump · Post by **V-Thump** » Thu Mar 29, 2007 9:33 pm

It shouldn't be there on a standard bike. Airfillters and race cans reduce air/gas speed which reduces torque at lower revs.

my bike is noticably stronger and happier below 3k rpm if my Scorpion race cans have the road legal baffles inserted (increases back pressure). Trouble is smooth abundant power starts from 4k rpm so I rarely go below!

bob the builder · Post by **bob the builder** » Fri Mar 30, 2007 10:10 pm

Thanks folks, I have a pair of Art cans on the bike this may have some relevance to the flat spot.

LotusSevenMan · Post by **LotusSevenMan** » Sat Mar 31, 2007 11:43 pm

Zer0Zer0.
Yeah OK, but the FireStorm family of 'V' twins includes SP1's and 2's and these are fuel injected so not technically carbed but throttle bodied!
Well that's what I meant OK?

http://www.honda.co.uk/motorcycles/Disp ... #focusHere

bob the builder · Post by **bob the builder** » Tue Apr 03, 2007 10:51 pm

I should have also said that when the bike is running on choke i have no flatspots at all. Would this be down to the bike not being starved of fuel or am i talking pish!!
I was going to go to Drysdales and ask them to dynojet it and put it on a rolling road, waste of money?

Cheers

LotusSevenMan · Post by **LotusSevenMan** » Tue Apr 03, 2007 11:35 pm

If it runs OK with the choke pulled out then it IS a fueling problem with it running too lean (The choke basically cuts off some of the airflow).

Dangerous situation as easy to overheat and burn valve seats etc. You need to get it seen to if you're not doing the work yourself asap!!!!
Might be something as simple as some small particles of tank rust in the jets restricting flow, or an air leak bypassing the filter weakening the mixture. Would have the same effect.
Had that once on a Suzuki so....................good luck.
To sum up:-
A rich running engine will waste fuel, run poorly, and if extremely rich, can cause engine damage.

An engine running lean for an extended amount of time will almost always result in engine damage.

bob the builder · Post by **bob the builder** » Wed Apr 04, 2007 11:17 pm

thanks for that, i now need to find a decent place to put the bike as i do not have the relevant skills to fix.
All feedback was much appreciated.