CG250 Head - A Closer Look.

[Megadan]

Personally, for my goals I don't believe a camshaft is necessary. I just want to get an honest 20-22hp out of one of these engines. No doubt it would help, but when you start changing cam profiles, you start to effect the powerband of the engine more, and I want to keep it happy in it's current operating range.

[pistolclass]

How about this ?
http://www.ebay.com/itm/MOTORCYCLE-Q...-/401311496266

[Megadan]

Don't tempt me lol

[JerryHawk250]

Originally Posted by pistolclass

How about this ?
http://www.ebay.com/itm/MOTORCYCLE-Q...-/401311496266

I've been looking at them for a while. They are proud of those little turbos. I have bought full size turbos for less. So being here in south Louisiana there are lots of jet ski parts at the outboard repair shops. I'll find a good use one eventually to experiment with.

[JeremyC]

I'm eager to watch this play out! And yeah, that exhaust port is nasty.. makes me want to tear mine down just to do it myself. The intake port doesn't look too bad to me, until you hit the valve guide area. This could make an interesting winter project if you get the results we're all drooling over!

Take lots of pics as you go! We're all going to want every detail.

[Megadan]

Originally Posted by JeremyC

I'm eager to watch this play out! And yeah, that exhaust port is nasty.. makes me want to tear mine down just to do it myself. The intake port doesn't look too bad to me, until you hit the valve guide area. This could make an interesting winter project if you get the results we're all drooling over!

Take lots of pics as you go! We're all going to want every detail.

I will do the best I can to take pictures, but I tend to have a hard time stopping once I start working to snap a shot unless I deem it worthy lol.

While I was assembling my bike I went ahead and checked my stock ports, and they are more or less the same. I was wondering if maybe it was just this particular casting that was kind of crap, but it wasn't.

This most likely will be a winter project for me, but I want to try and get started sooner rather than later. My biggest problem is, I have other obligations through the year that require my attention more, so if I do get any work done it will either be in spurts, or all at once.

[Ariel Red Hunter]

Originally Posted by JeremyC

I'm eager to watch this play out! And yeah, that exhaust port is nasty.. makes me want to tear mine down just to do it myself. The intake port doesn't look too bad to me, until you hit the valve guide area. This could make an interesting winter project if you get the results we're all drooling over!

Take lots of pics as you go! We're all going to want every detail.

Yes, I'm very interested in this as well. I have, in the past, recommended leaving the ports alone, because it is way too easy to screw the job up if you don't know what your doing. Not the case here. Megadan has a well thought out process in mind. I particularly like the ceramic coating idea. Should reduce oil temperature....ARH

[humanbeing]

Originally Posted by Megadan

...ceramic coating applied to the piston top...

Coated piston (<$5) is the standard item in workhorse trike...

[Megadan]

^I wouldn't trust that coating to do much of anything that I am talking about. If you want to try it go ahead. I have my limits on things I would cheap out on.


Speaking of coatings. As much as I would love to do so, I am not going to dive that far into this. This exercise is literally just a matter of porting the head to see the results. I intentionally bought a second head for this so I can not only enjoy the bike while doing this on the side, but also have the factory head to switch back to if I discover I don't like the nature of the bike after doing said work.

The whole ceramic coating idea was part of a "if I were to go all out" discussion. I wanted to keep this as pure as possible and not introduce anything to skew the results of what just simple port work can do with a more "high performance" carb.

[ben2go]

I just looked at the head again. It has a hemispherical combustion camber, so your bike will have a hemi in it.

[Megadan]

Originally Posted by ben2go

I just looked at the head again. It has a hemispherical combustion camber, so your bike will have a hemi in it.

They should all be hemis. Not uncommon on old Japanese engine designs.

[Ariel Red Hunter]

Originally Posted by Megadan

^I wouldn't trust that coating to do much of anything that I am talking about. If you want to try it go ahead. I have my limits on things I would cheap out on.


Speaking of coatings. As much as I would love to do so, I am not going to dive that far into this. This exercise is literally just a matter of porting the head to see the results. I intentionally bought a second head for this so I can not only enjoy the bike while doing this on the side, but also have the factory head to switch back to if I discover I don't like the nature of the bike after doing said work.

The whole ceramic coating idea was part of a "if I were to go all out" discussion. I wanted to keep this as pure as possible and not introduce anything to skew the results of what just simple port work can do with a more "high performance" carb.

I don't know what high performance carb you have in mind, but in a round slide carb, Mikuni makes ANOTHER VM26, costs about 80 bucks, but has an enriching circuit instead of a butterfly choke with shaft hanging in the air stream...ARH

[Megadan]

Looking at a 32 or 34mm flat slide style carb with an enrichment circuit similar to what you just mentioned. I am open to, and welcome all ideas.

[Ariel Red Hunter]

Originally Posted by Megadan

Looking at a 32 or 34mm flat slide style carb with an enrichment circuit similar to what you just mentioned. I am open to, and welcome all ideas.

Wow. Bigger than 1 1/4 inch on a 250? Other than an Italian single cylinder road racer? My 22 hp AJS 250 CSR only had a 1 1/8 inch carb on it, for what ever that's worth...ARH

[Megadan]

As I said, just considering at this point. There are a lot of variables to consider,