airbox mod 250 hawk

[Goshawk]

I do not wish to appear lazy but I cannot find the airbox mod that is frequently referred to. I come up with an adjustment to the tabs that hold the rear of the airbox to the frame but that hardly qualifies as a modification, more an adjustment. Sorry to be a PITA but I have made a diligent effort to find it

[imapdog]

http://www.chinariders.raptorrefuge....d.php?p=207520

[Megadan]

All you do is open up the plastic blocking half of the snorkel path. Follow the above link to see what I am talking about.

[roundhouse]

I did it. super easy.

[Goshawk]

Originally Posted by imapdog

http://www.chinariders.raptorrefuge....d.php?p=207520

thanks guys, it's done.

[AresROC]

Hmmm, since the subject title maybe appropriate please excuse me for hijacking the thread =]

I am thinking, the factory flaps are there to restrict air flow, for more low end torque. Opening it up will get you higher output at higher RPM, and cost of low to mid-end torque. Anyone with personal experience care to share? Thx.

[Megadan]

Originally Posted by AresROC

Hmmm, since the subject title maybe appropriate please excuse me for hijacking the thread =]

I am thinking, the factory flaps are there to restrict air flow, for more low end torque. Opening it up will get you higher output at higher RPM, and cost of low to mid-end torque. Anyone with personal experience care to share? Thx.

It has zero impact on the low end. I ran with no lid and a foam filter sheet on the top just to experiment a little bit, still no change.

Installed a foam pod filter right on the end of the carb, no loss of low end.

In fact, you gain a ton of mid range. Top end, if there is a change, is miniscule (this engine is choked off pretty bad). Until the cat is removed from the exhaust, or an aftermarket exhaust is installed, the gains from an intake upgrade are fairly small, and almost unnoticeable.

a majority of the power restrictions in this engine are actually on the exhaust side. Starting with the sorry excuse of an exhaust port in the head, followed by the weld bead that overlaps the inside of the stock head pipe right out of the head, followed up with a hilariously restrictive catalytic converter, and then piped into the worlds largest and overly baffled muffler.

Want to get the most bang for your buck? do an exhaust. Then you will make the most of an intake upgrade. Want the biggest bang for your buck? Invest in a rotary tool and port the head, especially the exhaust port, and then lap the valves in better than the factory did - this will still not affect the low end, but really opens up the higher RPM range of this engine, where it normally falls on its face well before it's rev limit.

[Goshawk]

I may be wrong, but I was of the opinion that the orifice that counts when deciding where the torque curve gets strong, is the intake side of the carb. A smaller intake = torque lower down the rev. range, but will restrict the top end as the engine runs out of breath. A large orifice will allow the engine to breath better at high revs but will bog down at low revs.
The airbox is unlikely to affect the volume of air at low/mid range revs, but it is possible it could strangle the engine at higher revs, an unlikely scenario with the Hawk engine in its stock tune.
I am in the process of removing the Cat. material from the exhaust and am frankly surprised the engine would run at all. The Cat. material is comprised of a corrugated, lightweight aluminium sheet, rolled into a very tight 3" plug. It is so dense I had to hammer a screwdriver into it to get a start for a drill bit when trying to drill it out. This mod. has to be one of the most effective in allowing the engine to breath. By far the best,"Bang for your buck".

[Megadan]

Originally Posted by Goshawk

This mod. has to be one of the most effective in allowing the engine to breath. By far the best,"Bang for your buck".

It is, which is why I called it the best bang for your buck mod you can do. That cat is ridiculous.

[timcosby]

ihave always been skeptical of the airbox mod. the openings are already twice the size of the opening at the carb.

[imapdog]

not sure how much better mine is bc of it. i can say i did it during assembly with vm26 mikuni 120jet exhaust. and barely turned idle. nothng else and it runs great. i am leaving mine right where it is. the midrange advantage makes sense though.

[Megadan]

Originally Posted by timcosby

ihave always been skeptical of the airbox mod. the openings are already twice the size of the opening at the carb.

It does make a difference, just not a huge one. I would consider it more of a supporting mod to an exhaust than anything else.