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Author Topic: Two engines, which to fix?  (Read 685 times)

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Offline hs2k007

  • 1972 Honda CB350F
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Two engines, which to fix?
« on: January 20, 2010, 08:12:13 PM »
I have a 1972 CB350F with a engine in the bike that is running but leaks oil.  I also have the original engine that came with the bike.  This was my grandfathers bike and I bought it back from another owner.  Not sure why the original engine was yanked out, possibly because the bike sat for a while in my dad's garage without running before he sold it.  The engine off the bike looks in better condition, (most of the original yellowing clear coat is still on the case).  The engine on the bike runs and runs pretty good, but leaks oil.  My questions are this.  What would I need to do to clean/drain the internals of the motor that is off the bike without opening the case?  How can I bench test the motor off the bike?  If this can not be done, would it be better to fix the leaking engine or tearing the "off bike engine" down and rebuild it?  Is anyone interested in rebuilding a 1972 cb350F engine?

Steven
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Offline wingman

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Re: Two engines, which to fix?
« Reply #1 on: January 20, 2010, 10:06:49 PM »
I just started my rebuilding tonight with my tear down of my 7000 mile 350f.  Should be fun. 

Sounds like you are going to need to do at least a compression test on the bike out of the frame.  Probably want to change the oil as well (if there is any in there).


A simple rebuild - barring any horrible discoveries - are as easy as getting a gasket kit and some new rings, assuming that everything is in spec.  There are a boatload of NOS gasket kits for our bikes on ebay and the rings are pretty cheap as well (35-40 a set).

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Offline Hush

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Re: Two engines, which to fix?
« Reply #2 on: January 20, 2010, 11:10:01 PM »
Try this, change the filter on the engine that is in the bike, remove the sump and strainer unit and clean all that out, new oil.....see if it still leaks?
Did this to my 650 (was told motor was shot and leaked oil everywhere) and it hasn't leaked a drop since. :)
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Offline hs2k007

  • 1972 Honda CB350F
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Re: Two engines, which to fix?
« Reply #3 on: January 21, 2010, 06:16:33 PM »
Thanks for the suggestions.  I never thought about just draining everything.  I did think about cleaning and degreasing at a "do it yourself" wash to determine where it is leaking and just replacing the leaking gasket.  The motor on the bike runs well.  I have had the bike at 90 mph without issue, just oil on my pants.  I did have the motor get hot on a ride on the highway, and the bike slowed down.  I stopped and let it cool and it ran fine after that.  Not sure if the bike was still breaking in.  I have started working on the bike tonight.  I am relacing the wheels and spokes so I will drain everything while it is in the garage.

Steven
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