Hi all, have just completed fitting some spanking new stainless downpipes only to find that my bike now has the most terrible flat spot ever between 6k-7k.

Is there a cure for this? Will i have to live with it? Why does it occur?

Regards,
Wattsy

 

Guessing here but... If you didn't create an exhaust leak (not changing the crush gaskets on the headers might do it) you may have significantly changed the exhaust profile. If you did, then you'll have to get her tuned.

 

Hi!
How did you solve this? My CBR600f41 2002 has this stainless downpipes on and I can see this flat spot starting at 7k ending at 8.5k, VERY ANNOYING!

Please, let me know.
Thanks

 

Im assuming downpipes means headers? And these aren't stock? If so I'd bet money you bought cheap *** no name ebay headers that didn't have any actual tuning/design work done to them, sobody just fabbed them up in a garage. If thats the case then no, theres nothing you can do to fix it except get stock or properly designed headers.

 

Yes, these are not stock ones. The thing is that I did not fit them. Bike had them when I bought it. I don't even know the model or brand...
I guess replacement will be the only solution to this.

 

what's a flat spot?

 

A flat spot is when it feels like the bike just stops making power all a sudden then starts making power again further up in the rpm range.

 

Hi Hebbo,

Yes i did finally cure this.

I originally replaced my rusty ones with a stainless set from sanybikes (recommended to me!)
I then also tried a set from delkevic...same problem, not quite as bad.
From what i could tell, both sets had great finish and the fit was almost spot on (heard lots of internet horror stories about aftermarket downpipes being a pig to fit.)

I then went to a local motorbike tuner to speak to him about tuning out the flat spot, he told me to first get rid of the delkevic set and get a Motad set. They were only a little bit more money, but when they came i was blown away by the quality compared to the other 2 sets. The pipes must have been 50% heavier through the thicker guage metal.

Anyway , fitted this set (new gaskets between every set) and the flat spot not only disappeared but the bike sounds and feels better than ever with these fitted.

David silver spares are the cheapest supplier of motad pipes, even calling motad directly couldn't get me a price match to david silver spares due to the contract they have with motad!

I took some pictures for reference. Hopefully you can tell which is which.

 

Hi,

thanks for your reply Wattsycbr.
I think I have seen these pictures in another forum. so getting new Motad ones is the solution. Looks like these small balancer pipes make a difference.

BTW, did you manage to get your cash back for the "faulty" downpipes? Or you have got a collection at home? XD

 

Yes, I did post this on another forum sometime.

The tuner said the balancer pipes were important. The pics are actually of the sandybike ones, not the delkevic. The delkevic pipes also had balancers but still gave a flat spot...

I got a full refund on both sets. One of the 2 suppliers wouldn't refund the original postage mind, but oh well...not a big loss. A big lesson learnt though...