[Redline]

Put on a local made (Thai) pipe yesterday which looks and sounds great.

But it's killed the little kick or burst of acceleration at 6000rpm. On a bonus though it's made the engine braking much smoother and lass dramatic. But I'd rather my acceleration.

The downpipe is very fat coming onto the muffler.

Am wondering if I got something made to fix the muffler onto the original downpipe might it help?

 

[Aufitt]

Look at that size of pipe! no wonder why... fit the baffle if it came with one.

 

[Redline]

It didn't actually.

They have a race and street version, this is the street version.

What about the downpipe idea? Or is the connecting end of the muffler still too big?

Only cost $200 and the dealer said they'd sell it on for me if I wasn't happy with it. Which I will if I can't fix the acceleration bog. So those in the know, is it probably just the size of the downpipe, or the muffler as well?

Cheers.

 

[sendler]

pipe

How big is the header pipe at the top section? The bottom section right before the muffler being a steady flair instead of the two big steps that we see usually see with the adapters that come with slip ons should actually be better. Are you sure it's slower? did you ever time it? Most dyno print outs show an increase in torque from 3-4000 rpm which then goes back to stock from 4-5800 where it then gains 1.5 horsepower from 6-8700 rpm. Maybe you gained a lot of power from 3-4000 which makes the transition to 6000 less of a jump. The only way to know is to dyno. The Two Bros dyno shots show that remapping doesn't help much. The left shot is with a remap and the one on the right is their slip on without any remapping. If your check engine light doesn't come on after a couple trips, it might be safe to say that the control unit has corrected itself without any further measurements.

 

[Redline]

tbh it feels about the same in the low revs, I haven't timed it but just going from the ol' seat of the pants test. Seems the same low down but from 6k+ rpm it bogs and goes up slowly, which is a bit of a disappointing when you're used to it kicking a bit. Makes the ride kinda dull.

I prefer it the old way, but want to keep the pipe and sound.

If I can find a way to get the performance back to the stock feeling, with the pipe I'd be happy.

 

[Rossman]

Mapping

Probably need to remap it in order to benefit from the new pipe.

 

[Redline]

They might have a CDI available soon-ish. But without touching anything but the downpipe/muffler is there anything I can do? Taking it back isn't a problem but I'd rather keep it if there's a way to adjust it, like changing back to the original downpipe as this one is way thicker?

 

[sendler]

diameter

like changing back to the original downpipe as this one is way thicker?

Is the header pipe a larger diameter all the way to the head or just as it changes size to meet the muffler? Is the original header pipe double walled at the top? The inside diameter might be much smaller than it looks on the outside. You might be better off to have someone try to fit the muffler to the stock header pipe. The muffler inlet doesn't look any bigger than the TwoBros or Yoshi and they measure great with no remap. Is the manufacturer local to you? They might be interested in improving their product with your input.

 

[Redline]

I think the headerpipe is probably what I've been calling the down pipe. In which case it's not the same size all the way to the muffler but gets a lot bigger quite a bit down from the muffler, probably down by where my toes would be.

I forgot about the cat converter on the stock pipe, so would probably still have the same large pipe section leading up to the muffler if I connected it to the stock.

I'll go talk to them about it early next week I think and see if I can connect the two that way and see if it makes any difference.

Cheers.

 

[sendler]

toes

I think the headerpipe is probably what I've been calling the down pipe. In which case it's not the same size all the way to the muffler but gets a lot bigger quite a bit down from the muffler, probably down by where my toes would be.

I forgot about the cat converter on the stock pipe, so would probably still have the same large pipe section leading up to the muffler if I connected it to the stock.

I'll go talk to them about it early next week I think and see if I can connect the two that way and see if it makes any difference.

Cheers.

The inside diameter of the pipe for the first .5 meters or so has an effect on the gas flow velocity and pulse tuning out the exhaust valve but after that the job of the muffler is to let the gas expand and to cool it. Both of which make it quieter. The increasing size by your toes as the pipe gets larger to meet the muffler is normal for any of the slip ons and yours is a nice, steady expansion. Unlike many of the other slip ons which accomplish the size change in two clumsy steps. And they show good numbers. Of course, the dyno runs are done at full throttle so who knows, maybe all of these slip ons kill part load power.

 

[Redline]

Cheers.

Reset the ECU and the difference is amazing.

Aftermarket Pipe: Make sure to do this: - Honda CBR250R Forum : Honda CBR 250 Forums

 

[CAM]

How do you go about resetting the ECU , does it done at the dealership or can you perform these task yourself. Just in case i need to do on my when i install my full system.

Cheers Cam...

 

[Redline]

The link in the above post has most of the info (that's available now).

See the last few posts I made in it, with info from my dealer.