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Thread: 1980 CX500 R café racer build project

  1. #21
    Senior Member big1000's Avatar
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    Quote Originally Posted by OCR View Post
    Cylinders look ok to me even with the water staining.
    The valve seats of the one head do need to be cleaned up which will improve the seal which will make it run better.
    Thats encouraging! I dont see any vertical scarring, which is what I was told to look out for. Theres a set of OEM honda NOS rings on ebay for 90$ a side... Ouch! I do have access to a lathe, I read one of murrays's old posts on using a different ring set that required machining out the grooves on the piston head. Any advice or experience about the rings is welcomed it just seems like the logical thing to do would be to replace them since Ill be in there anyways.
    SchyffS likes this.

  2. #22
    Senior Member big1000's Avatar
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    as promised, here's a list of the gaskets and seals I ordered from partzilla:


    Last edited by big1000; 09-05-2016 at 01:05 PM.

  3. #23
    Senior Member big1000's Avatar
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    So I ordered my valve spring compressor yesterday at about 2pm, and it was waiting on my front porch this morning. Gotta love amazon prime

    Valve Seats:

    Left cylinder head:


    Right cylinder head:



    Valves

    all:


    Intake (two rightmost in front):



    Exhaust:







    So I was pretty pleased with the looks of the intake valves, and their seats. However, the exhaust valves look pretty crispy. I'm no expert but I would like to know what you guys think about the exhaust valves. I'm hoping they can be brought back to life and seal nicely after a good cleanup and lapping.
    Last edited by big1000; 09-05-2016 at 06:28 PM.

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  5. #24
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    better check the guide clearance on the one with the carbon build uo
    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


    GET A QUICKSET VALVE TOOL


    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

  6. #25
    Senior Member big1000's Avatar
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    Quote Originally Posted by murrayf View Post
    better check the guide clearance on the one with the carbon build uo
    So measure the ID of the guide or just check the OD of the valve with calipers? is the concern that carbon breaks off and rubs in between the guide and the valve stem?

    Also, I know its hard to tell but do you think lapping the valves will make a big difference for me? I'm thinking my loss of compression was coming from the exhaust valves.

    thanks Murray!

    P.S. thanks for the quote on the carbs. Once I get this engine back together I'm gonna buy those things for sure

  7. #26
    Senior Member Adoom's Avatar
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    Quote Originally Posted by big1000 View Post
    Also, I know its hard to tell but do you think lapping the valves will make a big difference for me?
    Your quest for compression requires a few things. First, start by measuring stuff. Make sure your valves are the correct length (ie they haven't stretched). And size. You don't know what was butchered here before you, but if someone put the wrong gasket in there before (as Murray suggested) than someone's f#$ked with the motor... so nothing is a "given" now. Check for discolouration (sign of overheating).

    Maybe it's the lighting, but your shots of the left/right heads with the valves in place looked very different. On one pic the valves looked deep in their seats, on the other they appeared to be proud. Maybe it's the pic.

    If everything measures okay, start with cleaning all that carbon off, because you should. Then clean all that carbon and crap off the head. Check the valve guides. Once everything is CLEAN. Lap the valves into the head because you took them out...putting them in means lapping them. The lapping compound usually comes in two grits. It takes some time. Do it right and you'll be happy. New Stem Seals? How are the springs? Measure and clean the springs. Check the FSM for spring measurements.

    Piston. Pull the pistons and...measure them. If you're feeling frisky, weigh them too. You can balance the weights if you want to get fancy. If everything weighs out okay then start cleaning. You want the ring grooves to be spotless. Clean the rest of the piston too, because you should, but those grooves are your main concern.

    You can use old rings if they are within spec, or buy new ones. Apparently the rings on these rarely go "bad". Get your gauges and do some measuring for yourself. Rings go into the grooves with a little oil in the groove to help them slip and seal better. Space the ring gaps 120º away from each other. Follow the factory service manual.

    If the valves weren't seating well or your rings weren't spinning in their grooves well, you'll get bad compression.

    I don't have a ton of CX experience, but my other experience has offered me caked up ring spaces and stuck rings in seemingly okay looking cylinders. Since you're already apart, it's a great time to do it right the first time.
    Wannabebuilder likes this.
    1978 CX500
    1968 VW micro bus

  8. #27
    Senior Member big1000's Avatar
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    Quote Originally Posted by Adoom View Post
    Your quest for compression requires a few things. First, start by measuring stuff. Make sure your valves are the correct length (ie they haven't stretched). And size. You don't know what was butchered here before you, but if someone put the wrong gasket in there before (as Murray suggested) than someone's f#$ked with the motor... so nothing is a "given" now. Check for discolouration (sign of overheating).

    Maybe it's the lighting, but your shots of the left/right heads with the valves in place looked very different. On one pic the valves looked deep in their seats, on the other they appeared to be proud. Maybe it's the pic.

    If everything measures okay, start with cleaning all that carbon off, because you should. Then clean all that carbon and crap off the head. Check the valve guides. Once everything is CLEAN. Lap the valves into the head because you took them out...putting them in means lapping them. The lapping compound usually comes in two grits. It takes some time. Do it right and you'll be happy. New Stem Seals? How are the springs? Measure and clean the springs. Check the FSM for spring measurements.

    Piston. Pull the pistons and...measure them. If you're feeling frisky, weigh them too. You can balance the weights if you want to get fancy. If everything weighs out okay then start cleaning. You want the ring grooves to be spotless. Clean the rest of the piston too, because you should, but those grooves are your main concern.

    You can use old rings if they are within spec, or buy new ones. Apparently the rings on these rarely go "bad". Get your gauges and do some measuring for yourself. Rings go into the grooves with a little oil in the groove to help them slip and seal better. Space the ring gaps 120º away from each other. Follow the factory service manual.

    If the valves weren't seating well or your rings weren't spinning in their grooves well, you'll get bad compression.

    I don't have a ton of CX experience, but my other experience has offered me caked up ring spaces and stuck rings in seemingly okay looking cylinders. Since you're already apart, it's a great time to do it right the first time.
    Thank you for the guidance here. I didn't think to check if the valves were stretched- so I will get a height measurement with my calipers once I clean off the carbon (I think its 104mm from base of valve to top?? not sure atm). I will also check to see if the seats have been messed with - i.e. they have been re-ground, lapped incorrectly or something like that.

    That's a very good point about the piston rings being stuck and not sealing correctly. I hadn't heard that the rings on these rarely go "bad". Maybe I will hold off on buying new ones until I take them off. I'm guessing the measurement to tell if they are within spec is the radial thickness of the rings? still learning here.

    I'm not sure if the gasket was OEM or not, so I will try to post a pic of the old HG as soon as I can.

    thanks again.

  9. #28
    Senior Member big1000's Avatar
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    Got the engine pulled today. It came out really clean, and I made a custom little crate for it to sit on which helped. I was going to put wheels on it but a piece of cardboard worked great and caught some of the leftover oil.






    How does the slack on this chain look?






    I think this may be a casting defect on the clutch case: anyone ever seen anything like this:




    I soaked the valves in simple green for about 5 hours, and the intake valves cleaned up pretty good. I think I'll do one more soak before I lap them:








    The exhaust valves were super crispy and I really don't know if they are going to be reusable (lack of experience here, maybe they'll be fine). They are definitely going to soak more overnight. It almost looks like the metal is mis-shapen on the bottom, but I think it may just be really really really stuck on carbon that looks shiny after gently scrubbing with a brass brush.





    I only measurement specs for the diameter of the valve shafts, and my valve are still within the service limit. Someone mentioned measuring the length for signs of stretching but I need to research how to get this dimension. total length of the valve maybe?

  10. #29
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    Simple green is a great degreaser however for cleaning carbon I'd suggest using Acetone. You can also use a light abrasive to remove any of the leftover.

    Here's an example of my X5 diesel EGR valve:


    Last edited by Rupe; 09-11-2016 at 07:46 AM.
    1981 CX500 "RetroModern"

  11. #30
    Senior Member big1000's Avatar
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    Quote Originally Posted by Rupe View Post
    Simple green is a great degreaser however for cleaning carbon I'd suggest using Acetone. You can also use a light abrasive to remove any of the leftover.
    Thanks for the tip. I bought some acetone this morning and it seems to make the carbon a little more brittle. WOW that stuff is really baked on there.

    All of my intake valves look great, just need lapping, but two of the exhaust valves are still pretty crusty. I think I'll be able to get them... I did find two OEM exhaust valves on eBay and made an offer of 45$ so we will see what happens.

    I spent about two hours trying to get an allen head bolt out this morning. It was the bolt that holds the clamp on the hard pipe coolant line coming from the water pump. I broke off two easy outs (#%^&$%!) and then said screw it and cut off the clamp with a skinny disc, and was able to back out the bolt stub with a pair of vice grips. I think thats it for the day, but lots of exciting work on the engine to come.

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