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Cribbs74

M151 engine teardown

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Finally was able to split the 151 cases today. What a horrible mess inside. I think this thing sat outside for quite some time. I sure hope the 125 internals from my other engine will swap into this case.

piston is still stuck in the cylinder, so will have to remedy that. 

Anybody know where I can find a parts catalog for cheaper than the $100 they want on Ebay? A photo copy would work fine. I have a Haynes manual coming, but it’s not model specific.

I am attaching a couple pictures of inside the cases for fun...

 

 

ABC12B34-673E-4040-B784-FBF67FE0A47D.jpeg

33361EE3-0C24-484D-AA54-793243EC7E4B.jpeg

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InMotion in the U.K, have very good quality copied part manuals for well under that price. I bought one and it's just as good as the originals from the factory.

Best of luck with the rebuild

 

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Looks like everything needs to soak in diesel or Gunk for at least a month. With careful cleaning many of the parts will be reusable apart from the bearings.

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Thanks for the parts manual info. Definitely cheaper, shipping will cost the same as the manual I am sure.

Some of it looks useable, hoping nothing is too pitted. I’ll soak it and see.

So, I removed the piston. I was able to save the piston, but the sleeve is cracked at the bottom. It was bored over .075 so it was pretty thin. Not sure if I broke it or it was already broken. My 125 Engine has no sleeve whatsoever, so I guess I need a new sleeve and piston. Any suggestions? Thank you for the help and replies.

 

Ron

Edited by Cribbs74

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Hi Cribbs, yes, diesel is great for soaking motors in that state. For parts Lynn Mobley in Nevada is a great source of parts. Let us know how you get on.

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The Haynes manual should give you all of the info you need for your bike as the early 70s 5 speed models are pretty much the same. The bike pictured on the front cover is actually a 151

If you look for another cylinder it has to be from the early 325,  models 92, 125 or 151. The cylinder was a new design from 159 onwards and won't interchange with the earlier engines

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Thanks for the info John and Woody, 

If the Haynes has an illustrated parts breakdown that would be great, but part numbers would be very helpful so I can cross reference.

Both cylinders are in really good shape externally. A new sleeve would be the best course of action, but can’t seem to find any online.

Nothing on the Bultaco Classic website or any of the other usual sources. 

Ron

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Being in the states have you tried www.bear-sports.com  The list of manuals they have on their site is just a fraction of what they have, I've bought several of their manuals for CZs & they're well worth the $18. I see 27 different Bultaco manuals in the list that came with my last manual but none showing on the site

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