Hi from sunny Scotland

[NINJA]

@nottsbiker I would be very surprised if that exhaust had a negative affect on power. Just from those pics the pipe's bore off the head looks larger, it has a smoother flow to the bends and the tail-pipe looks shorter too. I would say that it also has very little restriction from end to end as well, so all-in-all it should add power and not deduct it at all!!!

@Glynn123 Can you upload a vid showing some revs, so we can here the beast in action please dude???

[Calum]

@cyber-ninja Oh yes, but then it's not a four stroke so....

[NINJA]

@calum So.... - Please elaborate???

[Calum]

@cyber-ninja So the shape of the pipe very much has a make or break scenario for the performance.

[NINJA]

@calum Ie. The straighter the pipe the quicker the expulsion of burnt gases aka more power is achieved by the cleaner airflow? Is that what you mean dude???

[Calum]

@cyber-ninja No.

I didn't want to make it sound like I'm teaching you to suck eggs.

I'm talking about the taper of the expansion chamber causing the temporary reverse flow of the exhaust gases causing lost charge to be forced back into the combustion chamber for a momentary supercharger effect. That is, by nature, the two stroke engine.

[NINJA]

@calum AAAHHHHH!!!!

Thank you for the clarification.

[Calum]

@cyber-ninja Fascinating subject if you haven't read about the physics of it.

[NINJA]

@calum Reading - I'm more of a looking at 'pictures' type of guy. You know lots of curved bumps in all the right places etc. LOL

[Calum]

@cyber-ninja said in Hi from sunny Scotland:

@calum Reading - I'm more of a looking at 'pictures' type of guy. You know lots of curved bumps in all the right places etc. LOL

Nuff said

[NINJA]

@calum So do under-slung exhausts increase or decrease this 'Supercharger effect' then???

[Calum]

Basically, that effect you see in that picture is a direct result of the expansion chamber. Now the taper, angles and lengths, determine when and how long that pulse goes on for.

So you could have a savage pipe that creates 100000BHP, but at 20K RPM, which is unuaable for a DTR.

So yes, it can have a massive effect.

[Calum]

@cyber-ninja Increase. Which is why I went with one.

A wrap around pipe is a compromise, for ground clearance and to still keep this forced induction.

An underslung can be better tuned to give a wider band.

For performance, it's all about underslung/

[NINJA]

@calum Cool - G2K!!!

[Glynn123]

Hi guys, sorry for the really late reply, there was an unbelievable difference from changing the pipe and upsetting my main to 250, the bike pulls very strong through low end and has a big kick at high revs, it also absolutely screams way higher than my old stock expansion chamber with dep end can. Here's a video I took a while ago of a quick acceleration with the pipe, although it doesn't have quite the kick it has now that I've put my boost bottle back on, I had it off for a while to see if there was a power change.
The overall speed and power of the bike is about the same as my mates 2016 CRF 250x, both accelerate about the same and top out roughly the same, but the Dt suspension isn't quite as good
https://youtu.be/KQQ217FyGFE

[Calum]

Quality bud!