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Old 10-24-2014, 01:02 PM   #1
hect75   hect75 is offline
 
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Replacing gaskets

Hi, , I need to replace the leaking gaskets (cylinder head and cylinder) but I am not sure if draining oil before taking off the cylinder head is needed. Screws at the cylinder head are loose and learned that oil is leaking slowly since I cleaned an oil spot under the bike. I know Spud drained the oil when rebuilding the engine but not sure if needed when doing the cylinder gaskets.

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Old 10-24-2014, 08:50 PM   #2
Le_Thon   Le_Thon is offline
 
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If it were me, I would drain the oil. Oil is cheap and you probably need an oil change any way!


 
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Old 10-24-2014, 10:27 PM   #3
SpudRider   SpudRider is offline
 
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It isn't necessary to drain the engine oil when removing the cylinder and cylinder head, either to rebuild the top end of the engine, or to replace gaskets. However, I suggest you try tightening the bolts first; you might stop the leaks without the need to replace the gaskets.

Use a torque wrench when tightening the bolts. You can find the torque specifications in the the Yamaha TW200 Service Manual, which you can download at the following link.

http://api.viglink.com/api/click?for...0Manual%20(PDF)
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2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
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1998 Kawasaki KDX220

Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894


 
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Old 10-27-2014, 10:44 AM   #4
Weldangrind   Weldangrind is offline
 
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I agree with Spud; just try tightening the fasteners first. Please let us know the result.
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Old 11-02-2014, 11:45 PM   #5
hect75   hect75 is offline
 
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Quote:
Originally Posted by SpudRider View Post
It isn't necessary to drain the engine oil when removing the cylinder and cylinder head, either to rebuild the top end of the engine, or to replace gaskets. However, I suggest you try tightening the bolts first; you might stop the leaks without the need to replace the gaskets.

Use a torque wrench when tightening the bolts. You can find the torque specifications in the the Yamaha TW200 Service Manual, which you can download at the following link.

http://api.viglink.com/api/click?for...0Manual%20(PDF)
I was gonna do the top engine rebuild but after watching spud´s thread I felt a little bit overwhelmed. I will pay someone to do it for me (any shop willing to take my money)I will drop by or call available shops to find out which is better and cheaper. Replacing gaskets will cost me around $73. After two months of oil change and 300 miles, I check the level and added about 100 ml for the proper level. I think the engine leaked too much oil after 2 months and want to fix it ASAP.
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Old 11-03-2014, 12:05 AM   #6
SpudRider   SpudRider is offline
 
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You can probably save a lot of money by purchasing a complete gasket set from Taobao.

http://item.taobao.com/item.htm?spm=...cket=19#detail
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"Never argue with an idiot. He will drag you down to his level, and beat you with experience." Mark Twain

2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220

Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894


 
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Old 12-26-2014, 10:09 PM   #7
hect75   hect75 is offline
 
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Hi guys, long time I haven´t post it here. I have time to do the top end rebuild but I can´t remove the bolts. I follwed Spud´s advice but the bolt won´t go any futher (see the pic). I don´t want to remove the engine, please help.

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Last edited by hect75; 12-27-2014 at 02:00 AM.
 
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Old 12-27-2014, 01:19 AM   #8
SpudRider   SpudRider is offline
 
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If you reduce the photograph in size by 50%, it will be much easier for us to view it.

I suggest you remove the nuts from the ends of all four bolts. Then remove the difficult bolt last. You can tilt the cylinder, if necessary.
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"Never argue with an idiot. He will drag you down to his level, and beat you with experience." Mark Twain

2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220

Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894


 
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Old 12-27-2014, 01:58 AM   #9
hect75   hect75 is offline
 
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I will try, Thanks Spud.
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Old 12-31-2014, 11:55 PM   #10
hect75   hect75 is offline
 
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I had to remove the engine because I learned that bolts have a flange (not sure if about the right name) on the low position. This made it impossible to remove it (sorry for the crappy pic).


Then, I remove the engine and found valves are dirty


piston same as valves




Also I found a hole in the cylinder head (upper right side). Probably, this is affecting the performance of the engine and don´t know if the hole must be fixed.



Finally, I went to the shop asking about rebor and the machinist said yes but will do it until next Monday due to holidays.



Feedback is welcome.
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Old 01-01-2015, 12:48 AM   #11
SpudRider   SpudRider is offline
 
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I don't see a hole in the cylinder head. Are you talking about the chip/indentation located at 1 o'clock in the photograph below?



If you actually have a hole, you can patch it with JB Weld, et cetera. Otherwise, you don't have any problems.

Have the machinist bore and hone the cylinder to match the smallest oversize piston you can find. You can order a piston for the Yamaha TW200. Besides the oversize piston, I suggest you order new piston rings, gaskets, and valve stem seals. I also suggest you have the machinist clean the cylinder head, and lap the valves for you.
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"Never argue with an idiot. He will drag you down to his level, and beat you with experience." Mark Twain

2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220

Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894


 
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Old 01-01-2015, 02:26 AM   #12
hect75   hect75 is offline
 
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Quote:
Originally Posted by SpudRider View Post
I don't see a hole in the cylinder head. Are you talking about the chip/indentation located at 1 o'clock in the photograph below?



If you actually have a hole, you can patch it with JB Weld, et cetera. Otherwise, you don't have any problems.

Have the machinist bore and hone the cylinder to match the smallest oversize piston you can find. You can order a piston for the Yamaha TW200. Besides the oversize piston, I suggest you order new piston rings, gaskets, and valve stem seals. I also suggest you have the machinist clean the cylinder head, and lap the valves for you.
Yep, at 1 o´clock. I will patch it. What kind of valve stem seals do I need? Only the tw200 piston will fit or any other piston fitting the pin? (obviously same size of rebore).

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Old 01-01-2015, 03:03 AM   #13
SpudRider   SpudRider is offline
 
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All the parts are TW200 parts. Every recent model year of the TW200 should be fine, but you can select 2006, Yamaha TW200 parts, if you like. I would also order a new piston/wrist pin.
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"Never argue with an idiot. He will drag you down to his level, and beat you with experience." Mark Twain

2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220

Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894


 
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Old 01-01-2015, 04:23 PM   #14
Weldangrind   Weldangrind is offline
 
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Is the cylinder scored? Is there a ridge at the top that you can catch with a fingernail? If no, then you might not need to bore the cylinder. Just buy a cylinder hone (meant for an automotive master cylinder) and hone it as is. Install new rings and gaskets and enjoy the bike.

It's rare to need to bore a motorcycle cylinder, until there are several thousand miles on it.
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Old 01-01-2015, 04:27 PM   #15
Weldangrind   Weldangrind is offline
 
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Quote:
Originally Posted by hect75 View Post
Also I found a hole in the cylinder head (upper right side). Probably, this is affecting the performance of the engine and don´t know if the hole must be fixed.
That might just be an oil drain-back hole.
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