Hello, I have a Honda 1983 XR350R that I just picked up. I have an oil leak in the front of the engine where the valve cover and head meet around the spark plug area inbetween the front 2 valve inspection covers. Original owner recently rebuilt the top end. So the valve cover gasket was in good shape. Replace it anyway since you have to pull the motor out to complete this task. Put it back together and still leaking. Not where I found the leak but in the same area underneath the valve cover. It leaks more when the engine is cold. My question to those who know this bike is where could this other leak be coming from? Could the original owner have forgot something when rebuilting? I can't see it. Anyone else have this dilemma? Any input would help. I would hate to pull the motor out again but if I must? Thanks

On my 600, I can take the valve cover off with the engine in the frame. It's not easy to get out, but it is possible. Not 100% sure if this is true for the 350.

I've had a lot of issues with leaks from the head cover to head gasket. Take a very close look for a crack. The other thing to try is make sure everything is completely clean. A tiny amount of crud will lead to a leak. I had to put a film of silicone on the head cover gasket to control the oil. Be very careful if you do this and use an extremely small amount of silicone. Loose silicone inside the engine can block oil passages and cause real problems. I stopped the real leaks on mine. However, it still seeps a tiny amount here and there.

You guys with '80's "vintage" bikes made in the orient make me laugh. Ride the bike , enjoy it, wash the oil off when it gets too unsightly and ride it again! If you had a REAL vintage bike like a BSA or Triumph or a Greeves with an Albion gearbox, or an AJS or Matchless, then you'd know what an oil leak was!

I would remove the valve cover, clean it and inspect it for cracks. If there aren't any, take it to the nearest machine shop and have it surfaced to make it flat again.

(DIY) If you have access to a piece of marble, tape a piece of 220 or 180 grit wetordry sandpaper to it, add a little water to keep the sandpaper from clogging up and lightly move the valve cover in a small figure eight about 5 times. If it's flat, you'll see sandpaper scratches all the way around. Any unsanded areas are your gaps (leaks). Now you have the choice of taking it to the machine shop to finish the sanding or do it yourself if it's minor. You can check the gap with a feeler gauge by laying it on the marble and sliding them under. If you've got knicks or gouges in the surface, you can fill them with JB Weld. Use just enough to fill. Now do the sanding thing. Once it's flat, switch to finer sandpaper (280/320/400 your choice). Using the figure-8 action keeps the wear even on all sides and don't forget the water.

While you have the top off, check the head for dings and goobers in its surface too.

I hope this helps.

Dave

Hey, I was just pokin' fun with my first post.
Davet916 actually gave you good advice, but you really don't need marble for your "lapping" surface. A piece of plate glass would work just as good. !/4'' or 3/8" thick is best, (3/16" thick is actually "float" glass and the surface is a bit more uneven). Most glass places that do mirrors or storefront windows should be able to sell you a 12"x12" or 18"x18" square out of scrap very cheap. Ask them if they'd "seam" the edges and points for you, that means to belt sand the sharp edges and you'll be good to go.

I still say that if it's not a cracked head or cover, and the leak isn't pouring out, ride and enjoy it as is. Leaks never hurt the old Brit iron, I doubt if it would hurt a bulletproof Jap bike!

Old Time Biker is right about that one. Except for the bit of a mess, just think of all the rust you're preventing :p Hunks of marble a darned heavy too.

Dave

Thank you all for your input. Your advice is well taken. I will pop the valve cover off again and go through it, look for cracks and check if I need resurface. But first I need to go rip up some dirt since I just got it. I'll just check the oil after every use till I can get back at it again. Thanks and kick dust. :ride:

I see you have XL 500 if the 350 has a head that is close on design (head cover holds cam in) look At all bolt holes and threads on bolts. My 81 xr 500 weeped due to a bolt hole that needed thread repair. Torque to specs and if metal to metal like the earlier xr and XL use yama bond carefully as the above post about the dangers of silicone is right on the money.

Gentleman, As a rebuilder of several '83,84,85, XR350R's it is Honda factory recommendation to use Honda "Hardening" gasket sealer on the valve cover gasket.

I have found that sanding with #200 grit sandpaper then cleaning with alcahol, break cleaner, acetone will leave all surfaces completely grease and gasket free, resulting in a complete leake free seal.

Maybe this info. will assist someone in a cleaner garage floor.:thumbsup:

ANother thing to look for on these bikes is the rocker pins. They seal with an o ring and I found mine leaking bad after a gear change and gasquet kit. I didn't even know to do the o-rings.Duohhhh! Anyway, its hard to tell that they are leaking but just after a wash, I can see the trail of oil.

TrailTime said:

Thx trailtime. Haven't got to it yet but will take your advice. My XL500 now has started leaking somewhat from the valve cover also. Just my luck. Now I have 2 bikes to deal with. A little more mud action for me then its back to work.

Before you start sanding away get out your feeler guages and lay the valve cover down on a piece of glass etc and check it for warpage. Hey and whats a little oil on your bike, it helps to keep it rust free.:ride: