Questions on exhausts and fuelling!
 

Hey all

I've been reading the site for some time but it seems that there's so much information now that I'm not entirely certain which is the most up to date, so bear with me while I try to find the latest answers in one place...

I'm going to order 2-1 header pipes from Off The Road to increase ground clearance for my XTR, and source a can to save weight (probably a GPR can - buying the whole kit from OTR is just far too expensive but the Metal Mule headers seem to come with problems and require adjustments), then shove in DNA stage 1 and 2 filters. Now I've had bad experiences with singles running too lean after an exhaust change in the past (burned a hole in the piston head).

I gather that DNA filters with a new can will cause the bike to run too lean, is the Kev O2 mod alone enough to handle this? Are there other adjustments to make? It's a lot to change so I don't want to risk it until I know, and nost threads on the mod talk about reducing surging rather than preventing lean running. Also, does the fuel mod still exist, and what was it for? It seems to have vanished from eBay. Is it a requirement for these additions?

Also wondering if going from 2-2 to 2-1 increases back-pressure and reduces output / risks damage.

Any takers?

Cheers :icon_rabbit:

I kind of have the same question.. I want to fit custom exhaust cans (haven't done any filter adjustments yet) and asked a mechanic if this will cause my bike to run lean. He said it won't do much harm and will probably operate fine.
On this forum i read various stories regarding his topic. I'm quite confused on what to believe now.

You said you burned a hole in your piston before.. on what bike did this happen? XT engines are a lot more bulletproof than most other singles though..

I run twin Akra's 1 and 2 filter snorkel out and the required number of holes in the airbox I've run that set up with both Kev's fuel mod and then a PC and have run the latter for some years now.

Re the difference in pipes there is a post by me somewhere on here about I always wanted a 2/1 set up because it makes the bike look 100lbs lighter(at least) the way the bike ran was like chalk and cheese if you have the R and intend off-roading green laneing then I'd go 2/1 but if your running X and every bit of HP you can get then it's 2/2 mine runs really well could just do with more weight off.

That 'mechanic's' statement doesn't exactly inspire one with confidence! ;)

Seriously though, just fitting exhausts alone (custom or otherwise) will NOT cause you or your bike any issues/problems. You certainly aren't going to hole a piston! You'll be fine. Go ahead...

Haha that's actually not what he said, i was tired when writing that. I have them fitted now, runs lean as hell. PC will be here soon, expensive though. Carburated is so much easier.. :(