1971 CB350 K3 Motor Rebuild - Page 2
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Thread: 1971 CB350 K3 Motor Rebuild

  1. #11
    Member doctorruckus's Avatar
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    Quote Originally Posted by jakec View Post
    If you're rebuilding the engine you have some time to worry about exhaust, I would get reproductions if you want it to run and look the best. As so keeping the engine from spinning you can put a long wrench on the rotor, turn till it hits the ground, and then the engine will be locked.

    where in seattle are you located?
    I'm actually up in Lynnwood. I just put Seattle because it's recognizable and I work downtown.

    I've still got the stator cover on. I don't have a thin enough ratchet except my 1/4 drive that I can fit onto the cam sprocket bolt and I cant get enough leverage to break it loose so I ordered an offset 10 mm wrench. I've been taking this slow because I'm working my apartment garage.

  2. #12
    Member doctorruckus's Avatar
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    Deleted. Double post
    Last edited by doctorruckus; 11-04-2019 at 01:23 PM. Reason: deleted. double post

  3. #13
    Senior Member Boomer343's Avatar
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    Just clamp a large pair of Vise Grips onto the cam to hold it to remove or install the cam bolts. They need to to properly torqued and I would suggest using red loctite on them as well when you get around to installing them.

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  5. #14
    Super Moderator longdistancerider's Avatar
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    I had Schumman Motorworks https://www.facebook.com/Schumann-Mo...9864701915416/ do my head, they're south of Portland off 205. 503-939-7395. Not cheap but very nice work with new bronze valve guides, Viton valve guide seals, SS exhaust valves and conventional intakes.
    Boring the cylinder was handled by a local speed/machine shop
    When I was searching for semi-local vapor blasting I talked with these guys https://www.motoshedseattle.com/#service-restoration and they do engine builds so they'll have some recommendations I'm sure. They were very helpful to me even though they didn't know of anyone down south here. Finally did find one near me so I didn't need to go to Seattle or Grants Pass, OR.
    Last edited by longdistancerider; 11-04-2019 at 02:36 PM. Reason: added link
    Jim O'Brien
    1979 CM400T "road bike" modified for travelling
    1978 CB400T1 restored
    1972 CL350 nuts and bolts restore in progress


    https://www.hondatwins.net/forums/22...d-attempt.html and https://www.hondatwins.net/forums/1-...r-attempt.html
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  6. #15
    Member doctorruckus's Avatar
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    Alright pros. I got it apart. Check out my album and let me know what you think of the pitting on the cam and rockers. Like I said, this is just a weekend bike to mess around on for probably no more than 2-3 hours a week so it doesn't need to be pristine. I tracked down all the compression loss to two of the valves. The yellow-white one leaked carb cleaner like crazy and then the large valve on the other cylinder did the same. I know it's impossible to tell from just pics, but since two are still good...just a clean and hand lap? Is there anything wrong with me trying that and testing for leaks before letting a pro do it? I also saw a piece of thing ring metal next to one of the valve springs. I took a pic of that separately so you guys might have ideas about that.

    Album link: https://imgur.com/a/i51RTyu

  7. #16
    Super Moderator longdistancerider's Avatar
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    The pits you see in the cam and rocker surfaces say they need to be repaired, call Delta.
    The rings in the exhaust ports are copper sealing rings that will pop out, they're pretty stuck in there usually but you can mangle them out.
    Valve? You have 2 known leaking and the other 2 may be in almost as bad condition. Until the valves are out and cleaned you can't determine if they are semi-usable. I say semi because the hard facing of the valve is only @.0002" thick and lapping goes thru that in most cases which leads to premature valve wear. I don't reuse old valves. I replace all of them and have the valve seats cut to get the proper seat width and angles. Valves guides on these engines are always suspect and may need replacement.
    Jim O'Brien
    1979 CM400T "road bike" modified for travelling
    1978 CB400T1 restored
    1972 CL350 nuts and bolts restore in progress


    https://www.hondatwins.net/forums/22...d-attempt.html and https://www.hondatwins.net/forums/1-...r-attempt.html
    Road Trip https://www.hondatwins.net/forums/11...here-i-go.html or "where's Jim now?"
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  8. #17
    Senior Member Boomer343's Avatar
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    Engines that rev to 10000 rpm don't like patch jobs and even though you aren't going to be pushing it long and hard you need to do it right.

    The 2 maybe 3 of the rockers look marginal. One is no good as is. Cam has pitting on the areas of most pressure. Not a good sign.

    That head/valves looks rough with lots of carbon build up and probable corrosion on the seats. Again there is no easy , cheap fix.

    Based on the piston photos you are in for oversize pistons.

    Give up Starbucks for a couple months and save your coins .... it's going to cost you more than you think. It will be worth it for your piece of mind and resale down the road.
    Last edited by Boomer343; 11-04-2019 at 04:26 PM.
    longdistancerider likes this.

  9. #18
    Member doctorruckus's Avatar
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    I don't have Facebook so I'm having a hard time with Schumann. What is not cheap?

    I don't mind shipping these parts out if anyone has a good suggestion on who to use. I haven't measure my bore yet because I'm waiting on my degreaser.

    How much is the Delta service in general? I ask because common-motor does them for $200

  10. #19
    Super Moderator ancientdad's Avatar
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    Delta is less money and they do good work, I've personally used them a couple times
    Tom

    CL450 project reboot, street legal this time
    Budget drag bike project
    CB350K1 full patina project
    Ride along at the drag strip


    running points... because I'm too old for mysteries that begin with pushing

  11. #20
    Super Moderator longdistancerider's Avatar
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    Delta charged me $122.21 July 30, 2019 to resurface the cam and rockers
    Jim O'Brien
    1979 CM400T "road bike" modified for travelling
    1978 CB400T1 restored
    1972 CL350 nuts and bolts restore in progress


    https://www.hondatwins.net/forums/22...d-attempt.html and https://www.hondatwins.net/forums/1-...r-attempt.html
    Road Trip https://www.hondatwins.net/forums/11...here-i-go.html or "where's Jim now?"
    Member Map https://www.hondatwins.net/forums/dcMembermap.php

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