hawk 250 big bore kit?

[Megadan]

Originally Posted by alex_in_az

so where did you order yours from?

Aliexpress. I got the second to last one in stock and another member bought the last one. Not sure if the seller has more in stock again as I haven't looked

[XLsior]

Maybe the 18mm wrist pin is a water cooled thing...

I'm just looking up CG300 cylinder kits on Ali X.
2 offerings seem to be the only air cooled options as of searching 8/4/21

https://www.aliexpress.com/item/1005002335946881.html

https://www.aliexpress.com/item/4000872832551.html

[Megadan]

Originally Posted by XLsior

Maybe the 18mm wrist pin is a water cooled thing...

I'm just looking up CG300 cylinder kits on Ali X.
2 offerings seem to be the only air cooled options as of searching 8/4/21

https://www.aliexpress.com/item/1005002335946881.html

https://www.aliexpress.com/item/4000872832551.html

That second link looks to be the one that I ordered mine through.

[drstansbury@yahoo.]

Looking forward to a great video by oddballperformance! I have an extra cylinder I'm going to turn down for.mine. Over the winter I'm going to pull the head and give it a look inside. I have more aggressively ported and shaved head I want to try out on it. I have almost 1500 miles on the build and so far no issues so I think the bottom ends going to be ok

[CheapThrills]

I read this thread and now am interested in learning more. I have the TBR7, and wondering if one of these AliExpress kits would be fun to tinker with? Are all the parts included? Do I have to do any milling? I'm looking for a fun, take apart and rebuild project.


Thx,

[drstansbury@yahoo.]

If you install the cg300 you will have to do a little machine work to make it fit.

[Megadan]

Originally Posted by CheapThrills

I read this thread and now am interested in learning more. I have the TBR7, and wondering if one of these AliExpress kits would be fun to tinker with? Are all the parts included? Do I have to do any milling? I'm looking for a fun, take apart and rebuild project.


Thx,

Only the parts to do a cylinder and piston swap are included. Cylinder, piston, rings, wrist pin, base, and head gasket. If you were going to just do the larger bore cylinder, you would need to swap the cam followers and their shaft (big flathead on the side of the jug.)

As mentioned before, in order to use a CG300 Cylinder either the case halves need to be bored out to match the lower cylinder sleeve, or you can machine down the sleeves outside diameter to match the case or CG250 diameter (73mm).

The "ideal" way would be to machine the cases, but the sleeve has enough material left to be stable, and has already been proven reliable on drstandsbury's engine, which has a cam and ported head.

[drstansbury@yahoo.]

Dan, if you machine the cases on yours be sure to check the oil galley area. I looked at mine visually and looks like it maybe very close if overbored. But we all know the qc on these varies. Just something to check before you go full beans into splitting the case.

[alex_in_az]

what is the plan for modifying the cylinder head, since now the squish band will be different? or is it not enough of a step to make a difference?

[drstansbury@yahoo.]

my current head has had a port and polish treatment. I have one I want to try that is port ed more aggressively, polished, and decked. The cg300 piston has pretty decent valve relief so I don't fear them meeting but I could always mis a gear lol

[Megadan]

Originally Posted by alex_in_az

what is the plan for modifying the cylinder head, since now the squish band will be different? or is it not enough of a step to make a difference?

The deck height of the cg is so big that there is no real effective squish band to take advantage of.

[alex_in_az]

Originally Posted by drstansbury@yahoo.

my current head has had a port and polish treatment. I have one I want to try that is port ed more aggressively, polished, and decked. The cg300 piston has pretty decent valve relief so I don't fear them meeting but I could always mis a gear lol

according to my calcs, the cg300 jug (73mm) on a cg229 bottom end gives us 250cc. is this right?

[TxTaoRider]

Originally Posted by alex_in_az

according to my calcs, the cg300 jug (73mm) on a cg229 bottom end gives us 250cc. is this right?

That's what I came up with too.

[Bill Hilly]

Originally Posted by TxTaoRider

That's what I came up with too.

If the piston is 73mm, I come up with 272cc..

[TxTaoRider]

Originally Posted by Bill Hilly

If the piston is 73mm, I come up with 272cc..

They're actually only 70mm. Comes out to about 250cc.