Race modified CW air cleaner question

[Larry S]

I have reeded my Combat Wombat and now want to modify my air cleaner for better air flow. I got a race modified filter element from Terry and now need to drill the element cover. I know there are pictures on the net showing how to do this but I can't find any. I need someone to post a picture of a race modifier element cover.

Larry S

[matt glascock]

Go to Hodaka Parts, open the library, go to the tech tips book, open the hot tip titled "Increased Breathing" and....BOOM! There it is.

[viclioce]

I looked at that tech tip. Is the drilling done on the inside filter retainer? The part I don’t have? Then you add additional foam under it? I may cut a metal cover for it. I’m just using a clear plastic cover right now. Been trying for months to twist Nate’s arm to sell me one of his. He calls items like these ”Unobtainium!” Victor

[Larry S]

Thanks Matt. Found it.

Larry S

[Larry S]

Vic, yes I am drilling a bunch of holes in an Unobtainium part. Your CW is piston port so I don't know if you need to make this mod.

Larry S

[Bullfrog]

Larry, while doing this modification - keep in mind the following two cautions:

1. Be sure that that the main air cleaner foam element does not have an outer profile which goes appreciably "outside" the shape of the inner cover. An element which does go appreciably "outside" the contour of the inner cover (whether from thickness or from compression deformation) will encroach into the volume inside the main enclosure which allows air to flow to all parts of the element. Encroachment on that "flow volume" can reduce flow.
2. Be cautious about the foam you use on the inside of your modified inner cover. A balance must be achieved. The foam must be thick enough to properly clean the air - but it must not be so thick that it encroaches too much into the volume available to flow air on the carb side of the element. Note that every increment of thickness on this new flat piece of foam, reduces the area of the normal element which can flow air by the same increment (a strip all the way around the normal element - which can be a significant issue).

Ed

[viclioce]

Larry. I just acquired a Reed Valved Complete Combat Wombat motor. Still need the Unobtainium, but I plan on putting this motor in a Model 94 roller I acquired with this motor. So it will get a round Wombat air box, and hopefully a custom pipe too! Victor

[viclioce]

Ed. It would seem that buying an extra Uni filter & cutting it open and into 2 pieces would provide the same air flow and provide the same filtration as well. Probably worth the $28. Victor

[Dale]

Here is your filter element...

http://hodaka-parts.com/item.asp?PID=11040

[Larry S]

Drilling the Unobtanium part full of holes made a BIG difference in power. This is a fresh engine and I've been running it rich during break-in. Rod Liddle built the top end and set up the carb for me. I don't know the size of the pilot jet - the needle is in the center notch and a 250 main. I would foul a plug every twenty or thirty minutes of riding time. (That's better than melting a piston).

I have about two hours of riding since drilling the inner cover. I'm still running the 250 main, but the bike is running GREAT. I did multiple plug chops and the plug is a beautiful medium brown. My butt dyno is telling me I have more power. I'm happy with the way it's running.

PS. I vapor blasted the fouled plugs and they look new. I plan to re-use them.

Larry S

[Bullfrog]

Larry, that is one fine looking job of modifying the inner cover of your CW air cleaner. And you have quite decisive evidence that the mod is indeed making it easier for air to flow. You were running a 250 main jet (which was providing evidence that it was actually a bit rich with the standard air cleaner set up), then you did the air cleaner mod -- and that same 250 main jet doesn't seem to be quite so rich (it sounds like it is just right now). That's the way the air cleaner mod is supposed to work.
Ed
PS: The photo shows that you do NOT have air cleaner element "pooching" out to the sides and encroaching into volume needed for air flow around the element. That type of concept must be adhered to in ANY air box. i.e., if air is restricted from flowing freely around the outside of the air cleaner element . . . the element simply can't pass through as much air as it has capacity to do.

[viclioce]

I’m guessing if you don’t have the Unobtainium Filter cover that you can cut a metal cover and then drill the holes wanted. I currently just have a plastic cover in mine which I made out of clear plexi. But it was indeed just to be temporary until I could get some flat sheet metal & cut a metal element cover.

Larry, what are the total specs for your carb setup? Besides the 250 main, what other deviations from stock did you do on your carb? Thx! Victor

[Bullfrog]

Larry, I'm guessing about your CW set-up, is it:
1. Stock flange mount 28mm carb?
2. Stock CW exhaust system?
3. Reed modified cylinder without extra porting tweaking?

Just curious.
Ed

[Larry S]

When I bought the CW it was equipped with an Enduro/Cross kit. It never ran well. I discussed this with Ron Liddle. I told him my MX days are behind me, but I still race cross country.

I sent the entire top end of the engine to Ron. He bored it, ported it, changed the reed pedals and set up the carb. It has the 28mm carb with a 40 pilot jet and 250 main jet. I don't know about the needle and slide. I'm running the stock pipe. The engine is not pipey. It pulls strong throughout the power band. Ron told me this engine will run with Super Combats. I think it will.

Vic, you could easily make a cover from flat stock. If you do, that cross piece that is tack welded is important. It keeps the cover in place. Without that, the cover (and air filter) could vibrate out of position and you could suck gravel into your engine. Rather than modify my foam filter, I just bought a racing element from Terry.

Larry S

[viclioce]

Thanks Larry!!! Victor