Topic: Papp's 1971 CB500 Rebuild. *LOTS O PIX!* Updated 5/08/09

[DCopp]

I took it apart 'cuz the complete motor is too heavy to ship...not sure on the gaskets ask around here.  Mileage is around 17k if the speedo from the bike I had was correct.  It should be a direct bolt in...the 550 was just a revised 500 motor anyways.

[papp101]

So I got the new (to me) head in that I bought off ebay which had 9k on it. It could use a cleaning, but it's all there. I plan to use one or two valves from that head in mine if I go with my original head, OR use that head with my valve springs that have 3k on them and put new stem seals on. Either way, I'll be lapping the valves on whichever one goes in.



Started the cleanup on the top of the cylinders.
Obviously BEFORE:

Obviously AFTER:



The number 1 cylinder has some serious pitting issues.



DO YOU THINK THE PITTING ON THIS VALVE SEAT MEANS I SHOULDN'T GO ANY FURTHER WITH THIS HEAD?


Just for practice, I cleaned the rest of the ports with a small wire tip dremel tool.

[martino1972]

i think you should go with that other head,unless you feel like putting new valve seats in this one,that pitted seat will never work this way...

[papp101]

Well I'll just keep posting because I need to get these pics up to get everyone's opinions on my next two steps.

Would you scrub this chain in kerosene? Or just buy a new one? Trying to stay cheap but realistic as always.




EDIT: I found the 20.00 motorcycle chains, and it's worth it to me to not have to screw with the solvents and such. New chain on the way.

Cleaned up all the pistons, I need 2 sets of rings, as the other two are in good shape, yet currently removed for inspection.




The big question is the cylinders. I plan to use the stock pistons and hopefully new stock rings. 3 of the 4 cylinders look good, but one has some crud stuck to the wall. Would you try to hone it out or go at it with fine steel wool? And is that stuff around the very tip of each cylinder a concern?







Lastly, I'm attempting to clean up the freakin calcification of whatever is on these valves, and I actually ran the wirewheel I have into the ground. Gotta pick up another, along with the right tools for porting/polishing. Any recommendations on where to find those for cheap?

[martino1972]

no steelwool on the cylinders,go to a cheap tool store and get urself a set of honestones,they fit in ur drill and have 3 legs under spring action with each a stone on it,chase that up and down ur cylinders and they will look like new with a nice cross patern in it,perfect for seating new rings...
and you said you needed 2 sets of rings??? NO,u need 4 sets of rings....

[martino1972]

heres a link to show u a cylinder hone..

http://cgi.ebay.com/ebaymotors/Cylinder-Hone_W0QQcmdZViewItemQQ_trkparmsZ72Q3a543Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem330284123274QQitemZ330284123274QQptZMotorsQ5fAutomotiveQ5fTools

[Artfrombama]

I prefer a ball hone but whatever method you use to refinish the cylinders, go easy. It doesn't take long to remove .001-.002" with a stone. May push the cylinder out of tolerance.

[papp101]

Thanks for the replies guys. I can rent a 2" to 3" cylinder hone at the local auto parts store for free, I'll just do that.

As for the rings, it's just so damn expensive! 4 sets for 30 a piece, or I could just buy that overbore kit for 150! Any ideas here?

[bsa101]

We can hone it here at the shop!  <G>  I have one!  Are there press-in valve seats in that head???  I think they are.

Dad-O

[papp101]

We can hone it here at the shop!  <G>  I have one!  Are there press-in valve seats in that head???  I think they are.

Dad-O

LOL this has what family communication has come down to. Hilarious! I still may go rent one so I can assemble as soon as the rings are in from whatever bastage place charges me rdiculously for them.

[Hush]

Way to go noobie, lookin good.
Cylinders 1 and 2 probably look worse cos lazy previous pwners leave these bikes on side stand for 20 odd years with no plugs in ha ha.
Ever wondered what a bike would look like if the owner abandoned it completely sealed in plastic after draining all the fluids?

[papp101]

LOL hush, yes, somehow I think this would have cost slightly more than 175 wrapped in plastic, but that would be PERFECT! Maybe I'll do that once it's normal again and let is sit for 20 years just to see?

My father had a great revelation yesterday why this bike, purchased and run from 1973 to 1976 was in the condition it was:

FLOOD BIKE!

There was severe GUNK in the exhaust ports, yet the exhaust was never off the bike. The carbs were basically FULL of water as well! And both coils are shot, which may or may not have to do with anything, but normally coils that sit that long are fine. I'm sure I'll get a name and address from the plates once I try to chase down the lost title. Hopefully there's a story to go with it!

Does anyone know the correlation between CB500 pistons and CL125's? I can't find the stats on a CL/SL125 and would like to know if those rings are another option for me.

[papp101]

Rented a Cylinder Hone, and went at it.



Slow speed, back and forth while adding a medium light oil, getting the nice Cross-Hatching marks. Even though one cylinder still has remains of the pitting, I'm satisfied with it and it doesn't feel any different than the rest of the cylinders any longer. The all seem like "paper" to the touch.







Then I removed the valves/retainers etc on the replacement 550 head.






Went to take another crack at cleaning the bowls.. . . . and how the hell will I fix this?





I could attempt to match it back up, and solder it, or drill it out and tap/epoxy or tap/solder another in.

Help!

[dagersh]

I know solder has worked for cracked drains, perhaps try JB Weld?

[papp101]

JB weld sounds like a good idea, any 2nd opinions on that?

[Artfrombama]

JB weld sounds like a good idea, any 2nd opinions on that?

I tried it on cracked overflow tubes, no go.

[papp101]

Yes, I'm quite f'd on this one.

Best I could do is ask if anyone has a spare carb bowl for the cb500/early cb550.

Help if you can gents! Thanks!

[mrbreeze]

I'd take the drill it out and replace it route.A bit of patience and the right tools(probably a Dremel) and it should be fine.If not....there are plenty of replacements out there(money and time to find/aquire).
You'll get it one way or the other!!!

[papp101]

Sounds like a good idea, but i'm not sure where I can find a brass tube like that. I've been searching all morning to no avail, so help would be appreciated if anyone's got a good idea on this one.

[Artfrombama]

Maybe this will help

[dagersh]

Hey Papp,

Alright, hopefully not strike 2!  Try a hobby shop or hobby supplier.  I know you can get lengths of brass tube that diamerter.  Model train supplies too.

Keep us appraised!

Gersh

[StrongPerf]

Papp,

I'm leaving on business travel for 2 weeks but shoot me a PM and when I get back maybe I can hook you up. Let me know what carb number it is. I have some spares but not all. I already helped someone so I'm down to 3.

Later

[Tom in Newcastle......Ontario]

Yes, I'm quite f'd on this one.

Best I could do is ask if anyone has a spare carb bowl for the cb500/early cb550.

Help if you can gents! Thanks!

If you can post the number on your carb I will see If I have some,I think some of the bowls are different but not positive,

[bunghole]

I've bought all types of brass tube from Ace Hardware.  I seem to recall them having some small diameter tubing.

[CBGhia]

JB weld sounds like a good idea, any 2nd opinions on that?

I tried it on cracked overflow tubes, no go.

I used JB Weld on my overflow tube and i have never seen it leak another drop.  You have to give it a day to cure before you put it on, and make sure you use the old fashioned JB Weld, not JB Quick.