Honda CR167 that is only used for Iceracing. It's a '92 cylinder on 99 cases, 2000 frame. The only option I've ever had was a production 125 pipe. I'm sure there's power to be had with a pipe designed for it, not a 125. Bore is 60 mm. not sure stroke but certainly could measure.

Any Ideas on making a 125 pipe work better or a custom pipe?

all depends on the cylinder porting and your needs.

Odds are you should bump stinger size 1mm at a minimum.

Naturally and I can get a port map layout, volumes would be more difficult. All things equal, is the volume of the expansion chamber likely too small?

36MotoMarc said:

In short answer, yes.

BUt most likely because the pipe is too short. IN order to lenghten it...the diameter would get larger using same cone angles....

Just an update and inof others could use.....

I had a custom pipe made with 250 silencer adapted to it, custom fit to the 2000 frame, for $340!! It is a custom, individual-cone-welded pipe, very beefy. I can't believe how cheap it was, Williams and a few others were quoting aroud a grand!!!!!!

I provided them with the port timings, and gave them the bike to fit it. This is not feasible for everyone but good for people in the midwest.

I used Aaen performance, well known in the sled industry. Olav Aaen is one of those guys who has forgotten more than a lot of us will ever know. They are in Racine, WI.

The pipe appears longer, fatter in the chamber, larger stinger, with a CR250 shorty silencer.

Thanks for the info! I wonder if I could make up a jig for my 'CR175' pipe to hold the manifold and top pipe mount in the proper relative locations, and then send them just the pipe for mods (it will basically need to be extended down towards the ground, both header and diffuser/center sections). Even if I needed to do a little final tweaking myself it would be worth it, at that price.

Ray

36MotoMarc said:

So did you notice a performance gain? Did you look into pipes designed for Kart applications? Some of the pipe builders for Kart are making HUGE power.

I have a CR250 as a dedicated ice race bike. I bought an RCE Racing pipe for a Kart and with a few cut and rotate welds it will be fit and mounted as a down turn pipe which is fine or ice or dirt track.

you can play with stinger diameter with consideration of how long a wfo pull your making on the ice, 55-70% of the headpipe diameter 55 being tight short pull.

Since your on the ice you could also experimental with wrapping the pipe belly or making a snowmobile type clamshell for it.

If you have a real serious race effort going on then a custom pipe would make sense, but if I were doing it I'd want your motor too to develop it.