Cold air intake

Ratt_Bones · Sep 17, 2013

I was thinking about constructing a cold air intake. I have not seen any yet on these bikes, well I have, but not many, and usually poorly done. My concern is more about air cleaner mounting. Typically, on motorcycles you don't want to be more than 3" away from the carb with the cleaner. However, air is air. It doesn't change from 3" to 13" in distance. So I'm wondering if I should leave the cleaner on the carb and run an elbow & hose to my desired location. Or, do the same, and have my air cleaner at the end.

Either way, I don't think it could do anything but good seeing as that the carb is mounted behind the engine, and the air it breathes comes directly off of the engine's heat sink.

I'm just looking for pros and cons/opinions here.
I went back 15 pages, and did not find any discussion on this.

-Thanks!

Oh, and my muffler is fixed. Haha, the thing was just shot. Funny story too.

2door · Sep 17, 2013

It is doubtful that you would see any measurable benefit from routing "cold air" to the carburetor. The level of sophistication of our little engines doesn't require the pre-cooling you might see on a high end, turbo or supercharged automotive/racing engine. The air that enters the carb isn't as heated as you might think and the few degrees difference isn't going to make much, if any difference.

This isn't to say that you shouldn't experiment but but don't expect anything substantial in the way of performance gains. The most noticable effect might be a decrease in intake noise so common with a piston ported 2 stroke engine.
Good luck.

Tom

Ratt_Bones · Sep 17, 2013

2door said:
It is doubtful that you would see any measurable benefit from routing "cold air" to the carburetor. The level of sophistication of our little engines doesn't require the pre-cooling you might see on a high end, turbo or supercharged automotive/racing engine. The air that enters the carb isn't as heated as you might think and the few degrees difference isn't going to make much, if any difference.

This isn't to say that you shouldn't experiment but but don't expect anything substantial in the way of performance gains. The most noticable effect might be a decrease in intake noise so common with a piston ported 2 stroke engine.
Good luck.

Tom

I wasn't so much looking for a performance gain, but more or less worrying about hindering the performance, or changing the mixture accidentally, etc., etc.

Ratt_Bones · Sep 21, 2013

Not really cold air intake, but I did some tinkering around. Managed to gain a slight power increase. I'm not completely done with this mod yet. Aside from making this more of a forced air intake, and noticing that overflow on these carbs seems to want to go back out through the filter.... >.< Just underneath the filter connection I added an overflow tube that drains into a miniature whiskey bottle (true rat rod fashion).

I also got sick of the clutch being ****ty, so I added a linear teflon slick cable, and used an "L" bracket with a 500lb cable pulley mounted to the clutch cover.Pulls butter smooth with just two fingers now.

2door · Sep 21, 2013

The pully method is a popular one. It has been tried and used successfully by several members here and one even markets his own design in the 'Swap & Shop' section.
There has been some very innovative ideas displayed here with regards to clutch cable routing and the ways to decrease clutch lever pull pressure.

If I might make a suggestion you might want to explore a simple modification to the clutch actuator cam and bucking bar that will make your clutch motorcycle easy to pull.
I use a Dremel with a sanding disc and smooth the contact areas of those two components then polish them on a bench buffer. As they come from the factory the bar and cam are rough and a little smoothing and polishing will achieve wonders as far as the reduction in friction between the two parts. Of course ample lubrication is also required.

Good luck with yours. Thanks for sharing your design.

Tom

Ratt_Bones · Sep 23, 2013

2door said:
The pully method is a popular one. It has been tried and used successfully by several members here and one even markets his own design in the 'Swap & Shop' section.
There has been some very innovative ideas displayed here with regards to clutch cable routing and the ways to decrease clutch lever pull pressure.

If I might make a suggestion you might want to explore a simple modification to the clutch actuator cam and bucking bar that will make your clutch motorcycle easy to pull.
I use a Dremel with a sanding disc and smooth the contact areas of those two components then polish them on a bench buffer. As they come from the factory the bar and cam are rough and a little smoothing and polishing will achieve wonders as far as the reduction in friction between the two parts. Of course ample lubrication is also required.

Good luck with yours. Thanks for sharing your design.

Tom

Did this today.
Thanks for the tip!
Noticeable difference for sure!

Much appreciated.

ivan H · Sep 24, 2013

Hi, for those using an SBP shift kit, there is a really simple way to fix the clutch cable problem. I made up a small metal bracket, 2 1/8" high. It has a small tab with a hole drilled thru it bent at 90 degrees to the main body of the bracket that mount under the nut at the top right shiftkit mount on the down tube. The main body of the bracket then tapers to a width of 1 1/4" at the bottom where it rests against the tab on the shift kit that is bolted to the motors reduction gear housing. I drilled a hole thru the bracket, ran the clutch cable thru a teflon lined 90 degree brake cable noodle & passed it thru the hole in the bracket & across to the clutch actuator arm. Its now a dead straight pull from the bracket to to the actuator arm & lightened the clutch pull considerably. The cable runs along side the reduction gear housing because of the noodle. SBP should probably incorporate something like into the shiftkit. Cheers

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Cold air intake

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