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01-19-2018, 11:01 AM | #1 |
Join Date: Jan 2018
Posts: 43
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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! Last edited by zach3697; 01-22-2018 at 02:54 PM. |
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01-19-2018, 11:06 AM | #2 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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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.
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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01-19-2018, 11:06 AM | #3 |
Join Date: Jun 2016
Location: akwesasne, NY-13655
Posts: 2,220
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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
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01-21-2018, 12:28 PM | #5 | |
Join Date: Jan 2018
Posts: 43
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Quote:
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! Last edited by zach3697; 01-21-2018 at 01:17 PM. |
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01-21-2018, 01:42 PM | #6 |
Join Date: Apr 2017
Location: Omaha, NE
Posts: 8,109
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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.
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Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124 |
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01-21-2018, 01:57 PM | #7 | |
Join Date: Jan 2018
Posts: 43
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Quote:
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01-21-2018, 08:31 PM | #8 | |
Join Date: Jun 2016
Location: akwesasne, NY-13655
Posts: 2,220
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Quote:
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01-21-2018, 09:37 PM | #9 |
Join Date: Oct 2013
Location: Leesville SC
Posts: 835
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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!
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01-22-2018, 12:30 AM | #10 | |
Join Date: Jan 2018
Posts: 43
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Quote:
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01-22-2018, 10:07 AM | #11 |
Join Date: Jan 2018
Posts: 43
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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 |
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01-22-2018, 01:21 PM | #12 |
Join Date: Jan 2018
Posts: 43
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Inside the head
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01-22-2018, 01:23 PM | #13 |
Join Date: Jan 2018
Posts: 43
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Wear?
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01-22-2018, 03:31 PM | #14 |
Join Date: Apr 2017
Location: Omaha, NE
Posts: 8,109
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There is a little evidence of some debris scuffing going on, and maybe a little evidence of some mild overheating as well, but the fact that the cross hatch is still visible in the cylinder wall where the scuffing occourred tells me that this wear isn't that severe and shouldn't contribute to such a drastic loss in compression. The rings look to be in decent shape as well.
What interests me more is the evidence of poor valve sealing, especially on the exhaust valve. If it were me, and I didn't have the proper gauges to check the cylinder, then I would likely take the cylinder to a local shop, have them check and hone the cylinder. Either get a new piston and rings, or clean up the current piston and get new rings - the difference in cost is pretty small between the two. The last thing I would do would be to clean up the head, check the head to ensure it isn't warped, and lap the valves. The poor valve sealing doesn't surprise me. The head I bought and ported showed very poor valve to seat contact from the factory, and I had to lap the valves starting with a coarse grit to get a full seat contact, and then finished with a fine grit compound. This is a good affordable little kit of tungsten carbide lapping compound, comes with a small amount of 100 and 240 grit, which is still way more than needed for this head (you could probably do 50+) https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 Beyond that, new base and head gaskets obviously. |
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01-22-2018, 05:36 PM | #15 | |
Join Date: Jan 2018
Posts: 43
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Quote:
The only thing im concerned about it the warped head. If it is warped can it be fixed myself or would a machine shop have to get involved? Excited to get this motor running! here are some pictures of my cylinder wall |
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