Hawk 250 Top end rebuild. New piston and rings
 

Hello everyone! Im looking for a new piston and ring set for the Hawk 250.

I know the Hawk engine is an upscale honda 125 but I cant find any information on these parts.

Does anyone have any experience rebuilding this engine or finding parts for it?

Thanks!

Welcome!


The engine is referred to as a CG250; use that as your search criteria on eBay. Measure the bore of your engine to ensure that you're ordering the correct parts.

The easy way is to get the parts from CSC (California Scooter Co.). The piston and rings are the same as in their TT 250...ARH ;)

Thanks Guys! ill take a look at some parts!

So heres an update guys. I got a used Hawk 250 off craigslist and started troubleshooting why it wasnt running. The odometer says it has 638 miles on the motor. Did a compression check and it only has 60psi which is way too low. I assumed it needed a piston and rings but after I took the head off the cylinder wall is marked up. So im thinking Ill just buy a new block from CSC for 44.50 and a piston and rings for 12.50

http://www.cscmotorcycles.com/TT250-...MBLY-s/311.htm

My question is I just wanted to make sure that this block will work on the hawk 250 motor?

Thanks!

Just out of curiosity, did you make sure the valves were adjusted properly before performing that compression test? I ask because the number one most neglected and overlooked thing with these bikes when they are assembled is that the valve clearances are never checked or set, and they almost always come from the factory with no clearance at all, or even tight. After a little bit of riding, the valves will actually stretch a little during break in, and cause all sort of issues from not sealing with the head. A poorly adjusted valve can cause all sorts of issues, including extremely low compression.

That's a great thought! I haven't checked the valves yet but I will do that after work today. Thanks for the suggestion!

What do you mean by the cylinder wall is marked up? If it sat for a while with dirty oil in it, the cylinder often gets stain marks where the piston comes to rest. 638 kilometers (bikes odometer reads in kilometers) is not even broken in, really. Cheaters break in new rings by starting the engine and feeding a pinch of Bon-Ami through the carb and then ride it for a short time, immediatly changing the oil when getting home. That's known as a FWIW....ARH

I second what Dan Said, Practice the K.I.S.S principle before going off all half cocked wanting to rebuild the top end. You just may get lucky and find out it was something simple. It may very well need a top end rebuild, but for now lets hope not. These engines are notoriously tough as nails. But there are folks buying these bike that don't know much about maintaining them. Keep us posted on what you find. AND, round here we LIKE PICS!

Sounds good. Im going to work on the bike some tomorrow and ill be sure to take some pics!

So I did the value adjustment and it still only has 60 psi.

I think at this point I'm going to have to work on the top end?

Here are some pics

Inside the head

Wear?

There is definite cylinder scuffing going on, but what interests me more at this point is the oil and grime all over the top of the cylinder jug, and signs of oil seepage around the head gasket. Was all of that there when you first pulled the head after your first compression test, or is that oil from sticking the head back on and testing it again? If it was there from the start, I would almost wager the head got loose and the head gasket essentially failed.

I think at this point you might want to pull the jug and inspect the rings and piston. Since you have come this far, it's not much more work to get the jug off.

Yes I was thinking the same thing about the oil around the head gasket. It was there when I started.

I'll take the jug off and send more pics!

Thanks for all the help guys!