DT125R ARCHIVE

Skintt125 · DTR Senior Member

RE: Air Box mods ??

Calum122 · Guru

That bottle is a restriction that goes from air intake to carb. Like said, as you induct air into the engine some of this air gets pulled into that bottle reducing the amount of air that actually makes its way into the engine itself. The carb has been compensated for this, i.e. its down jetted. So if you wanted to do it you'll want to do the following.

Carbon fibre reeds
240 main jet

and either
block off that bottle or
get an old boot.

Yeah it would struggle since you're now got too much air. I bet if you ran it with the choke on it would run spot on. That tells you it's too much air.

Steady Eddy · DTR Senior Member

As an update on my bike when I first got it running it went well then I sprayed the air filter with proper air filter oil , and for a day or two it seamed to be harder to start , but then it settled down and now starts and runs well so well that I don' t want to touch it , but I covered the holes up that some one had put in the cover , and thinking about it would not the filter be the main restriction rather than the box ?? the box I would have thought is well big enough to cope with the flow providing the filter is looked after , a friend of mine that trials a TY 250 for many years recons that the filter is vital on any 2st motor , so I am going to leave well alone , you know the saying " if it aint broke , don't fix it " it pulls like a train from 5 th to infinity , and is not bad below that , so that will do me one happy bunny

Skintt125 · DTR Senior Member

Calum122 wrote:
So if you wanted to do it you'll want to do the following.

Carbon fibre reeds
240 main jet

and either
block off that bottle or
get an old boot.

Yeah it would struggle since you're now got too much air. I bet if you ran it with the choke on it would run spot on. That tells you it's too much air.

Thanks again Calum aww

Brilliant, helpful information! After my engine rebuild I'm gunna be ordering a TwinAir filter & carbon reed combo from E-bay! I'll block the bottle off then and re-jet to suit! What is the standard main jet size?

Cheers!

Calum122 · Guru

240.

240 is all you're going to need.

Personally I'd stick with the air box. People think that the RAM style works better however even GP bikes use airboxes.

There isn't much to be gained from getting rid of it. Only problems if it's not done properly.

Things you'll want.

Old boot.

Hy tech Reeds

Correct Jet

Skintt125 · DTR Senior Member

Oh yeah I know that mate... I'm not gettin rid of the airbox! I'm getting a hi-flow TwinAir filter that replaces the original, inside the box! I've heard it can be a nightmare to set up a cone filter, that's why I'll always steer clear of them! smile

I'm gunna leave the bike as is until after I do the rebuild and run it in! Then i'll get down to business!! wink

Cheers Calum!! biggrin