hawk 250 big bore kit?

[alex_in_az]

Originally Posted by TxTaoRider

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

that's right, 73mm is what we have to turn the o/d of the skirt down to

[CheapThrills]

Any advice on where to get a pre-turned big bore kit?





Tried AliExpress, they processed my payment, but cancelled my order. Good news, paypal refunding money.


Thx,

[XLsior]

There are still a few CG300* kits on Aliexpress.

there is this 73mm skirt option but it comes with a 16mm pin, however they say "please contact for 18mm pin"
Dynop official
https://www.aliexpress.com/item/1005...70240.html?spm

Cheaper store:
https://www.aliexpress.com/item/1005...13236.html?spm


I got 1 of the 16mm pin 76mm skirt options a while back before 73mm were being listed...prices were cheaper in AUD back then.

Haven't got it machined down yet to fit....but I'm thinking about getting done soon. though if the machining quote is near $100aud i might just get another pre machined 73mm kit :/

[XLsior]

Just out of curiosity anyone have any idea how safe is it to deck the jug and if so by how much?

If I am going to get the skirt turned down to 73mm I might as well get the top face skimmed too...

When i see these kits installed there seems to be about 3mm of TDC piston gap to the cylinder mating face.

That seems somewhat excessive.

But how much is a safe skim with all the other components taken in consideration...

is 1mm to much?

[XLsior]

Ok I just watched the Motocult perfomance hawk kit YT video being installed.

From what I can see they deck the cylinder 2mm and provide shortened locating dowels and a rocker assembly spacer plate that looks about 2mm thick. Cant remember if the washers under the head stud torque nuts are stock...

Going by this assessment I think 1mm should be safe.

[Zapkin]

stage 3 for cg250

https://motocultparts.com/products/s...43139496870087

[XLsior]

those "deluxe" gaskets look pretty standard to me...

Even with a $200 on sale discount...that's a lot of cheddar.

[Thumper]

That looks like a new pushrod cam too. Interesting kit. I wonder how much it bumps hp. And durability.

[Megadan]

The Motocult parts are pricey, but they aren't unreasonable. The cams they sell are WGK, the same as the one I put in my bike. $75 is actually quite a fair price and only a few dollars more than what it cost me to get mine directly from Brazil.

The jugs are decked with a mill to set a tight squish gap and have the base machined to 73mm. $250 is reasonable considering the machine work. You can buy a cylinder on Aliexpress with the 73mm base already finished for about $160 delivered, but it does not have the deck milled down.

$250 for the ported head is again, pretty reasonable.

Also, the kits come with a rocker arm shim to correct the rocker angle if you get the cylinder. That's a nice detail.

I wouldn't hesitate to buy the Motocult stuff if I didn't want to invest in a lot of time and tools to do all this work.

[stoppre12211]

Just want to bump this thread to see if 223cc zs165mm-l cg250g-d have had any new big bore kits. I wsa hoping 72mm to 75mm bore Thanks

[XLsior]

Originally Posted by stoppre12211

Just want to bump this thread to see if 223cc zs165mm-l cg250g-d have had any new big bore kits. I wsa hoping 72mm to 75mm bore Thanks

No


I'm not sure a 70mm would even work in a 165fmm as it does in a 167fmm


You'd have to measure the OD cylinder skirt.


And i'll be honest doing the 70mm bigbore kit on my CG250 didnt gain much.


If you want a real performance uplift look into getting a bigger engine...


like a 175fmm if it will fit.