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Discussion Starter · #1 ·
Hello, I must ask again for some advice from all of you. My 1972 Honda CL350 K4 is in trouble again. I took it out not to long ago and ran it for about 3 hrs, before I realized that oil was leaking (a lot) from the right side of the engine. My boot and the entire right side of the bike was covered with oil when I finally got it back to the garage. I thought that I would reseal the right points case because it seemed that was where the oil was coming from. So, I resealed the points case and the top head gasket, because I took a look inside the top half of the engine. Now, the engine starts fine however it is blowing some major white smoke from the breather tube and a little bit of smoke from the right exhaust pipe only ( left exhaust pipe looks fine, no smoke). So, I guess my question would be where would you all start? Should I start taking the engine apart?? Do you think a ring might be broken on the left piston thus the smoke?? or Do you think the smoke it a condition from the oil leak and should stop once the oil burns off?? Any thoughts are always welcome, and thank you all in advance. :(
 

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Sensei
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Ok... The points are on the left side of the engine.... Tach drive is on the right....
What you need to do first, (after you clean the oil drips off) is run a compression test.....
 

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Yup, listen to Steve on this. Run a compression test and post the results.
 

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Discussion Starter · #4 ·
Ok, the first thing is that you are right, I have my left and right switched :roll: . I meant to say that the left side was the problem side. So, after the compression test I have determined that the left side is in fact the problem side. The right side has a nice strong 150 psi, while the left has a mere 60 psi. So, what would you say would be my next move?? Do you think that so much oil leaked out as to damage the left rings?? :cry: This just blows. By the way, thanks all for the quick response.
 

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Even your "good" side is marginal, not "nice strong", sorry.
You're looking at a top end job, might as well tear it down and do it while the weather is bad......

 

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Yep...Definately time for at least a top-end rebuild.....
150 is the MINIMUM recommended compression for a 350 engine....
 

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Discussion Starter · #7 ·
Hey, I was wondering where you got that page. My Clymers book said that spec should be between 140-170 psi. Another note: When I went back and read the book, it said to test the compression by using the kick start and leaving the key in the off position. When I did that, the right side topped at 170 psi and the left was 90 psi. Anyway, I suppose I do need to rebuild the top side. Do you guys think I should replace both piston rings or just the left side?? Since I'm opening the engine up is there anything I should look for to avoid any further problems?? Once again, Thanks a lot for all the advice.
 

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There is NO way to be certain just what will need replacing until you
disassemble, measure, and compare everything to specs.....
We can only guess, having nothing absolute about
what the specific problem/cause is yet....
There may be multiple problems, you'll pretty much have to check everything....
 

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Whatever I did to this engine I would do to both cylinders. Valve job, rings, pistons, bearings, whatever. I wouldn't care to run an engine with one cylinder brand new and the other with X miles worth of wear on it.
 

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R_O_M173 said:
Hey, I was wondering where you got that page. My Clymers book said that spec should be between 140-170 psi.
That page is from the Honda factory manual - I have two of them on my personal website, the links have been posted here many times.
But here they are again - an older one and a newer one - both contain errors, so you need them both......
http://home.comcast.net/~tbpmusic3/CB_CL_SL_250_350.pdf

http://home.comcast.net/~tbpmusic3/CB_CL250_350RepairManual.pdf

The Clymer makes good toilet paper, that's about it........

When you check your compression, make sure you do it with warm engine, throttle wide open, NO CHOKE.
Do it a couple of times to make sure the numbers are consistent.
then add a little oil down the spark plug holes and check it again.
If it jumps considerably, you have bad rings. If not, then bad valves.
 

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Discussion Starter · #11 ·
Hey, thanks again for the advice and help. Also, a very big thank you to tbpmusic for the links to the 250/350 manuals. Those were really hard for me to find and now that I have those, I will tell Clymers to stuff it :p . I will give the bike a once over and post a final pic when I'm done, now that I have the exhaust wrapped and everything is mounted. Thank You all and keep on riding. :D
 

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Discussion Starter · #12 ·
Hello again all, I thought I would write a sort of update to see if anyone had any thoughts about my dilemma. Ok, first I continued the engine compression test and after a warm up the right side began to read 170 psi, the left side still read 60 psi. I thought I would pour a tablespoon of oil down the left side and it still only read 60 to 65 psi. So, I now believe that it must be my left side valves that are not seated right......right?? I opened the tappets and readjusted the rocker arms just to be sure that the intake was .002 and the exhaust was .004. Put the tappets back on and tried the compression test again....still 60 psi. I assume I should now take the engine out and begin a rebuild, what should I be looking for as far as the valves and do you guys think that there is a chance that my rings may still need to be replaced?? Any other thoughts well appreciated, Thanks a lot guys. :D
 

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Sensei
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Could be valve seating, could be a slightly bent valve not fully closing.....
You won't know for sure what you will need to fix it until you tear it
down and measure/check everything....
 

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R_O_M173 said:
Hello again all, I thought I would write a sort of update to see if anyone had any thoughts about my dilemma. Ok, first I continued the engine compression test and after a warm up the right side began to read 170 psi, the left side still read 60 psi. I thought I would pour a tablespoon of oil down the left side and it still only read 60 to 65 psi. So, I now believe that it must be my left side valves that are not seated right......right?? I opened the tappets and readjusted the rocker arms just to be sure that the intake was .002 and the exhaust was .004. Put the tappets back on and tried the compression test again....still 60 psi. I assume I should now take the engine out and begin a rebuild, what should I be looking for as far as the valves and do you guys think that there is a chance that my rings may still need to be replaced?? Any other thoughts well appreciated, Thanks a lot guys. :D
Get someone to "mike" the cylinders, go with what that data shows. If the cylinders are still within specs, hone them and put in new rings, won't cost a lot.
Yeah, sounds like the valves. Let a competent machinist evaluate them - maybe you can just lap them, but maybe they need new seats cut in.
 

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Steve, you keep beating me to the punch tonight !!!!
What are you doing here this late? Get a life !!!!!

Wait, I'm here too.........
 

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Apparently we are reading/replying in the same order...You usually beat me to the punch....LMAO!....
 

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Discussion Starter · #17 ·
OK, so I started to take the engine apart ever so gingerly as to not miss anything. First, there is a lot of oil throughout the engine on every layer. Nothing in the upper half of the engine is broken, and it doesn't get interesting until I get under the valves and found this torn gasket. :shock: Also, if you notice the left and right side of the pistons and the underside of the valves, right side is dry while the left side is wet. I am going to take the valves in for inspection tomorrow, do you guys think there is anything else I should look into?? Thanks, all.

P.S. There are some pics of what I found.
 

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Sensei
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Well, that trashed head gasket would explain the low compression and the oil smoke problems..... Could be, that is all that's wrong, but as long as it is apart, might as well check everything else.... You already know you need new rings at minimum as the "good" cylinder was nominal.........
 

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Discussion Starter · #19 ·
Hey guys, I have a question?!?!! When I go to reassemble the engine what would you recommend using to reseal the gaskets? I had previously used the little brown bottle of schlack but I have heard that maybe something that does not dry hard would be better. Also, I was told that I should not totally seal the head gasket and just seal around the rods. Anyone have any thoughts on this??? Thanks, once again to everyone. :p :p
 

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I've never used anything extra to seal head gaskets. Other gaskets I only use something if necessary to hold gaskets in place during assembly or sometimes to stick the gasket to one part or the other for dissassembly/easier cleanup.

Will be interested to see what Bill and Steve have to say.
 
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