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.

:thanks:

If it were me, I would drain the oil. Oil is cheap and you probably need an oil change any way!

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 agree with Spud; just try tightening the fasteners first. Please let us know the result.

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.

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

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.

http://i123.photobucket.com/albums/o...1.jpg~original

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. ;)

I will try, Thanks Spud.

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).
http://i123.photobucket.com/albums/o...2.jpg~original

Then, I remove the engine and found valves are dirty
http://i123.photobucket.com/albums/o...a.jpg~original

piston same as valves
http://i123.photobucket.com/albums/o...8.jpg~original

http://i123.photobucket.com/albums/o...6.jpg~original

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.

http://i123.photobucket.com/albums/o...0.jpg~original

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

http://i123.photobucket.com/albums/o...e.jpg~original

Feedback is welcome.

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?

http://i123.photobucket.com/albums/o...0.jpg~original

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).

:thanks:

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.

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.

That might just be an oil drain-back hole.