Put the bike in for new downpipes and an MOT (not cheap!) and have picked it up today. Sounding a hell of a lot better, in fact had forgotten what it was meant to sound like!! However, it feels like I have lost a little power when pulling away in 1st. Almost like there is a little delay before it kicks in with the pull…is this possible after major exhaust surgery?!
Can’t race people off the lights any more ;):w00t:
I’m no expert in such things but I would guess the replacement downpipes are different to the originals in that they provide more resistance to the exhaust gases perhaps by being narrower or double-skinned, thereby increasing exhaust backpressure and draining some of the power of your engine by virtue of the fact that it has to work harder to open up your exhaust valves.
So - were the downpipes standard, or aftermarket?
Is it just a sound thing?
In the 70’s and 80’s it was a well known fact that if you took your Lotus in to be tuned up, all they would do is knock a baffle out of the exhaust to make it louder, hence you’d think it was quicker
What bike do you ride, is it injected?
If it is perhaps look at getting the ecu sorted might not be mapped properly.
Alternatively give it more gas…
I thought back pressure was good for low end pull?
Probably the above, pipes allow more airflow so lower end is sacrificed for an improvement in top end.
I had similar with my old exhaust, putting the baffle in reversed the power delivery.
I have the same, without the baffle in my bike is a tad weak low down, but revs for england at the top end. Baffle back in gives bit more at the bottom
It’s all about flow of gases going in and out of the cylinder, and many factors affect it. A baffled exhaust will always be less efficient due to greater resistance to the gas flow. However, what is being described here about the loss of drive at lower revs is probably due to the fuel/air mixture. This will be important throughout the rev range, but you are just noticing it more at the lower revs, which is why you should have it checked on a rolling road, in case it needs new jets/mapping to suit the new dynamics of your system. Quite often it can be too lean, which can be extremely detrimental to an engine, so it’s worth having it checked out.
On your earlier post a couple of us mentioned the link pipes that some of the CBR600 replacement downpipes don’t have. Sounds like you make not have these, as the result’s genrally seem to be a low end flat spot??
At the risk of sounding stupid I don’t really understand!! What does ‘too lean’ mean and the fact that it is detrimental to an engine is scary…is this something that needs doing soon or have I got the miles to ride it back to norfolk and get it sorted after exams?
If its just a straight replacement off the downpipes can’t see an issue needing a remap -assume you have a fuel injected cbr? If so this will make minor changes to fueling anyway, would be more of an issue imo if you fitted a whole new performance exhaust.
Still think the loss of low end is prob down to aftermarket downpipes that lack the balance pipes. If you look behind the front week under the rad, you will see the down pipes and look for small horizontal pipes linking them.
Cheers guys - reckon I will just bring her to a meet at the Ace or BMM as obviously not mechanically minded - so long as there is no risk of her sponteneously combusting in the meantime!!
