[Luke_Yallop]

Looks really good. A good thread to read too. Just out of interest, how long have you guys been riding 2 strokes? Looking through various posts it seems like a lot of you have done lots of performance mods and you seem prepared to put a lot of effort into trying things out!

I'd agree with this.

Although if i ever tried.. it would ALWAYS go horribly wrong

 

[lizard821000]

steve mate, id say unless you got enough dollor to burn id try a few designs and give up, i bet its a lengthy and costly process deffining tthe correct shape,size etc box. thats prob why APRILLIA gave up.

 

[rabbit8dude]

Pego, I think ram-air was just a term thrown about in the nineties by the bike manufactures for the 'technology' of running a duct from the front of the bike to the air box. I was gutted reading Robinson's comments on 'ram-air' in his book on four stroke tuning as my FZR 400 only did 140-ish mph!

I agree that a duct that tapers out from it's opening to a large sealed area would slow the air down and create a nice still and calm pocket of air for the engine to feed from.

A bike accelerating through the atmosphere isn't conducive to 'making power' IMO so I reckon that an air box is reducing losses more so than 'creating' power. However there might be a mph threshold that once exceeded creates a situation that a well designed duct/box actually will add a little barometric pressure above and beyond the particular atmospheric conditions that one happens to be riding there bike in on that particular day. Probably why carb bowl vents have to be vented into the air-box.

Of course the Helmholtz effect mentioned earlier in this post is something different altogether and would probably need some laborious experimenting with to see gains.

 

[oktrg500]

I would have made the box seal tight around the tank. And fed the box with fresh air from front of the bike. And added something for bleeding the box, to make sure the jetting conditions are as stable as possible. Are you going to do any back to back testing in the dyno?

...Just out of interest, how long have you guys been riding 2 strokes?

29 years. Road and track. Aprilia RS125, RG250, RG500, RD350, RD500, TZ250.

 

[AF1 Replica 91]

Long time then, some nice rides listed there.

 

[Gregowicz]

I would have made the box seal tight around the tank. And fed the box with fresh air from front of the bike. And added something for bleeding the box, to make sure the jetting conditions are as stable as possible. Are you going to do any back to back testing in the dyno?

you mean somethin like this dont you, this is only the mk1 version, will get some more fibreglass and possibly some carbon and im gonna take my time with the next one as I only spent 2 days making it.

 

[Gregowicz]

Looks really good. A good thread to read too. Just out of interest, how long have you guys been riding 2 strokes? Looking through various posts it seems like a lot of you have done lots of performance mods and you seem prepared to put a lot of effort into trying things out!

thanks, this is my first bike. have had it for 4 years and have been tinkerin since i got it lol

 

[Gregowicz]

heres a few pics of stefanos airbox, his isnt closed and doesnt seem to be hurting his power (around 40hp)?

this is what I based my box on

 

[ryancook1993]

I'm rubbish when it comes to airboxes, why is the carb inside the airbox.

 

[rabbit8dude]

".....why is the carb inside the airbox."

So that the same atmosphere/ barometric conditions are present at the carb bell-mouth and float chamber.

It's also easier to get the carb on and off for jet changes I'd say.

What are you using for a mold Gregowicz?

 

[pego30]

heres a few pics of stefanos airbox, his isnt closed and doesnt seem to be hurting his power (around 40hp)?

this is what I based my box on

and your port work lol

and my bore job lol

i still do a little wee when i see the size of that spanny

 

[oktrg500]

Long live old threads

Has anyone tried extending the air intake tube so it goes A) to the opening of the snorkels or B) connects to the air box? I can't understand why Aprilia ended the tube in the frame. For sure, it is not desirable to get the fresh cold air mixed with warmer air from the engine and the radiator. Extending the tube so it terminates near the snorkels will be something I'd like to test one day. It will most likely be much more hassle connecting the tube straight to the box. My guess is this could upset the jetting, but I'm far from sure. So, have anyone had ideas like this before and perhaps done some testing?

 

[rs125plus]

the reason aprilia didn't connect it was they wanted a cold air feed-
not pressure feed.....pressure fed would add another variable (ie -seize-)

cold air for power
hot air for economy

 

[monty16v]

I had a go at extending the air feed pipe
Didnt connect it to the snorkels, just brought it closer

 

[ApriliaChris]

Sorry to go off topic here guys, but quickly what rad is stefanos running in that pic as it looks massive and what is that what would appear to look like a hydraulic damper bolted to the frame and running up to the front of the bike .

 

[Rs125 crazy]

Think it is a r6 rad. And that will be a streeing damper.

 

[ApriliaChris]

Is there any benefit to the bigger rad apart from running good with temps, is the steering damper beneficial ?

 

[rs125plus]

no - extra weight

if you are running hot your jetting is wrong - lean-

even with more cooling you will still seize

 

[rs125plus]

on the steering damper - its good if you are 50 pencing a corner
helps to teach better leaning skills

the rs125 doesn't need a steering damper - its quite an easy bike to ride
quite slow turning for a 125

 

[ApriliaChris]

Fair enough, I won't bother with the possibility of a steering damper. Only reason I was wondering with rad was because I need a new one and just seeing what options I could go with.