Hawk 250 New piston and rings

[Wolftrax]

Originally Posted by zach3697

Well I think this story is coming to an end. I went ahead and replaced the sparkplug and the ignition coil and it fired right up. Finished buttoning it up and took it for a ride! I know I have a little ways to go, like jetting and tuning the carb. Does anyone know where I can get cheap platics for the bike?

I have used black plastics you can have for the price of shipping.

[zach3697]

Originally Posted by Wolftrax

I have used black plastics you can have for the price of shipping.

That sounds great! How much do you think shipping would be?

Also thanks to everyone thats helped get this bike up and running again! I appreciate everyone's help!

[bogieboy]

as an fyi, it may have just been your spark plug.... jut had a BRAND NEW ariens snow blower come into the shop for a no start.... spark plug sparks, but weak....LOL slaped an NGK in (stock was a chinese Torch brand due to the ariens using LCT chinese engines) and fires right up.... i am a big advocate of getting rid of the stock spark plugs and switching to NGK or even champion (dont like them as much though...)

[SecondHandHawk]

Hello everyone.
Old thread but a project I am just about to do myself.
I have read the entire tread and still a bit confused on the ring gap. The final numbers were never actually stated other than compression rings were ok at .016in.

My new compression rings measure at .015in and new oil rings at .010in
It seems as though I will have to shave quite a bit off of the oil rings to meet the .12in through .035in spec.

Is this correct or am missing something. Could someone verify if i have this right? Or even provide numbers that actually have been used?

Thanks in advance.

[Megadan]

Originally Posted by SecondHandHawk

Hello everyone.
Old thread but a project I am just about to do myself.
I have read the entire tread and still a bit confused on the ring gap. The final numbers were never actually stated other than compression rings were ok at .016in.

My new compression rings measure at .015in and new oil rings at .010in
It seems as though I will have to shave quite a bit off of the oil rings to meet the .12in through .035in spec.

Is this correct or am missing something. Could someone verify if i have this right? Or even provide numbers that actually have been used?

Thanks in advance.

Again, as stated in this thread, there is no real official factory stated numbers for these motors. There are however some general rules of thumb for ring gap.

On a liquid cooled engine it is .004 times the cylinder bore in inches. For air cooled this is often opened up to .005 or even .006 times the bore in inches.

.005 x 2.638 - .145" gap and .006 x 2.638" = .158" gap. So basically anything around .15 to .16 will be fine.
That amount of gap should also suffice for the second ring since these aren't exactly high performance motors.

The oil control rings will not suffer as much from expansion, and most ring manufacturers typically state all oil control ring gaps at around .015 inches. The CG125-150 engines spec the ring gap tolerance as .2mm to .5mm, aka .008 to .019 inches. I would just file them to reach .015 inches and call it a day, that is only shaving 5 thousandths off, which isn't much at all and well within spec.

[SecondHandHawk]

Megadan.
Thank you for clearing things up. I had done some research along with reading this thread.
I had read bore x .004. but with .005 the numbers seamed closer. I would never have guessed bore x .006 though.

So I was on the right track with a little filing on the oil rings. And I was guessing that .015 would be a safe bet but wanted further verification.

Thanks for your reply and I hope it will benefit others in the future.

[Armycopter]

What an interesting thread! I hope I never need the information contained here but I am subscribed now just in case. These pictures are great along with all the specification info.