3000rpm flat spot

[mb4807]

I've got a standard bike (year 2008) but with an Akro end can, which I run with the baffle out. There's a noticeable flat spot around 3k to 3.5k revs. Is this common/normal, and what can be done about it without going to great lengths, like a de-cat or full exhaust system?

 

[robb]

yes it is

 

[Bendy toy]

The Akra system potentially gives more power at the expense of making the flat spot worse. In the meantime, Pending the remap, a £10 universal baffle will soften the flat spot and make next to no difference at the top end.

A remap will make full use of the exhaust system and fill the flat spot.

 

[Pukmeister]

The bikes run about 17.5 to 1 air/fuel ratio up to 4500rpm, then richer to about 14 to 1 above 4500 rpm.

I'd wager yours is running even leaner, which is probably why you can feel the flat spot and loss of power.

 

[Bendy toy]

In most engines, the ambda signals are used to keep the mixture at 14:1 air:fuel ratio. Does the R1200 actually use the Lambda signals under 4500 rpm? Or are they only used when it taken above 4500?

 

[mb4807]

Popped the baffle back in

Popped the baffle back in for my 1500km trip last week and the flat spot has very significantly reduced - to the point where I only really noticed it when I remembered I should be looking for it. And the exhaust note is not that much quieter with it in, so that's how I'll ride it from now on! - A nice easy fix!

 

[Pukmeister]

In most engines, the ambda signals are used to keep the mixture at 14:1 air:fuel ratio. Does the R1200 actually use the Lambda signals under 4500 rpm? Or are they only used when it taken above 4500?

If you look for a dyno graph of the R1200 showing A/F ratio you'll be able to determine the answer to your own question. Try the Remap thread, you should find plenty on there.

 

[Sot1200]

That's what I found as well. Baffle out peaky and dead midrange. Baffle in and a nice fat midrange and do not think that there is anything missing at the top either.