Topic: Bringing her back to life - '73 CB500 - with questions

[vintage_mpg]

So I pulled this old gal from a dusty barn (does it count as a barn if there are no doors?) and am in the process of bringing her back from the grave...any and all advice appreciated!

Here's the "on the way home" pic:

[Trav-i]

First off download the shop manual for your bike, which can be done here.  As always, regardless of the miles on the bike a 3,000 mile service is in order.  Also a complete carb cleaning will also be in order, which invlolves removing all the jets and cleaning all the passage ways with cleaner and compressed air.  Then there are also the other things as well such as tires, and possibly fork seals ect...

That should get ya rolling, the 500 owners will help with more of the specifics.

Travis

[vintage_mpg]

So - a quick update on what's been happening with her...

A pull of the carbs revealed the nastiest, slimiest, grimiest gunk in the carb bowls.  Floats were stuck wide open, and fuel was POURING out of the overflow tubes.  After much wrestling, I was able to get them out, clean them up, and re-install.  Major improvements, and she fired up.

Front brake was frozen in place - gripping that front wheel like a leech.  Worked her over, and she's rollin' freely with great brakes.

Clutch was frozen and unresponsive.  Pulled it apart, recoated everything with fresh oil, adjusted and cleaned it - and now have a working clutch. 

I've readjusted the valves, set the points, checked the timing, and lubed this and that.

Still have a few issues, though: fuel is leaking from the petcock.  The brass downtubes/nipples are pulling right out of the petcock, with no seal.  This has to be addressed.

Also, she's running GREAT at low RPMs and idle speeds - however, much past 3000 and things start kicking and spitting and sputtering like mad.  She simply refuses to rev over about 4000, and even that's a fight.

I'm in the process of chasing down a dwell meter to verify that the points are set to what they need to be at.

I'm in the process of running some Seafoam through the fuel system, but am not getting far with that as the darn petcock is losing fuel so quickly that it takes constant monitoring.

Anything I'm missing?  What would you be looking for?  I'm mostly concerned with the poor running condition at higher RPMs right now, along with the petcock.  Any suggestions for either of those problems?

[vintage_mpg]

First off download the shop manual for your bike, which can be done here.  As always, regardless of the miles on the bike a 3,000 mile service is in order.  Also a complete carb cleaning will also be in order, which invlolves removing all the jets and cleaning all the passage ways with cleaner and compressed air.  Then there are also the other things as well such as tires, and possibly fork seals ect...

That should get ya rolling, the 500 owners will help with more of the specifics.

Travis

Thanks, Travis -

I've downloaded the bike, and have enjoyed accessing it.  Tons of great info there.

While I had the carbs out/apart, I cleaned all the main and pilot jets, but I did not do a complete disassembly and rebuild.  I was/am hoping to keep from having to separate the whole carb bank, but it may be unavoidable in the long run.  I'm hoping a little time with the Seafoam will be helpful as well.

The other big pieces are on the list (i.e., tires, fork seals, etc.), but if I can't get her mechanically dialed in, I don't want to pour tons of money down the drain.  I'm hoping that we'll get there soon, tho.

[Trav-i]

The last few items I mentioned are just sort of a check and see what condition they are in.  If the forks don't leak ride on, I might suggest at least changing the fluid in the them.  I didn't change the seals in 78F 750, and finally popped one in the mountians a couple of weeks ago so now I get to do them anyway.  Tires are the same thing check 'em at least.  I'm willing to bet they're dry rotted, tires aren't too expensive especially for safety reaasons.  Being a 73 I'm pretty sure that petcock should be rebuildable, kits are readily available for them.

Good luck,
Travis

[bryanj]

Sometimes you can "glue" the spigots in otherwise its a new petcock (dave silver) dont forget the special fibre washers under the heads of the retaining screws or it will never turn off.

The high rev not running right could be a naff battery or charging system, i have had both before, could also be emulsion tubes in carbs

[vintage_mpg]

Sometimes you can "glue" the spigots in otherwise its a new petcock (dave silver) dont forget the special fibre washers under the heads of the retaining screws or it will never turn off.

The high rev not running right could be a naff battery or charging system, i have had both before, could also be emulsion tubes in carbs

brayanj - what would you use to glue them in place?  JB Weld?  Anything else?  Thanks for the dave silver referral; I'd rather not drop the $60+shipping for that piece, but it's nice to know that it's there if all else fails.

I have a new battery, but have no idea if the charging system is working or not.  Any idea on how to test that?

The carb emulsion is VERY likely.  There was so much crap in the fuel bowls that I'd not rule out ANYTHING involving those things.  I'm hoping the Seafoam will work some magic on those carbs, if I can run/ride it long enough to let that stuff work.  It's a long shot, but I'm lazy.

[vintage_mpg]

So while I'm trying to generate enough momentum to jump into the petcock issues, I thought I'd crack into the right hand headlight switch and see what's going on.  The switch won't do anything; can't switch from low to hi, and off is completely out of the question.

Here's what I found:



Anyone know where I can find the tiny little replacement sliding piece?  The piece that actually makes the contact between the wiring harness and the switch?  It's all busted up into pieces, and the tab that fits into the sliding switch is completely broken off.  Any ideas on the replacement?

[dave500]

check the ignition advancer isnt frozen.

[Johnie]

I have used Lock-Tite to glue a petcock nipple back in place. One thing I did not see you address unless I missed it is did you check the gas tank for crapola? I bet there is some in there. And if you run that into your nice clean carbs you will have to start that cleaning all over again. It may look good, but I would be suspicious of that tank if your bowls were that dirty.

[vintage_mpg]

check the ignition advancer isnt frozen.

I checked the timing last night with a timing light; everything seemed to look OK, at least according the Clymer manual.  I verified the timing at both idle and 2500 RPMs, and all was well.  I may be wrong, but I figured I could scratch that from the list of potential problems.

[vintage_mpg]

I have used Lock-Tite to glue a petcock nipple back in place. One thing I did not see you address unless I missed it is did you check the gas tank for crapola? I bet there is some in there. And if you run that into your nice clean carbs you will have to start that cleaning all over again. It may look good, but I would be suspicious of that tank if your bowls were that dirty.

Thanks for the tip, Johnie.  I'll be chasing down a new tube of Lock-Tite tomorrow.  Probably the red, yeah?  Isn't that the "always and forever" version?  I can never remember.

I think the tank is pretty clean - I THINK.  I flushed it with clean fuel, and let her breathe for a good bit.  Surprisingly, the PO thought he'd drained all the fuel (and I believe that he HAD - from the tank).  However, he failed to utilize those really cool carb-bowl-draining screws, and stuff really got nasty in there.

[bryanj]

Before you refit the spigots use something like the taper on a centre punch to open out the end that fits in the casting, that switch part isnot and never was available seperately you will have to get a complete switch, don't forget to check the european and UK e-bay as that switch was on all of ours not just the early ones

[MoMo]

You need to remove part #3 and clean  http://www.mrcycles.com/fiche_section_detail.asp?section=122903&category=MOTORCYCLES&make=HONDA&year=1973&fveh=2937    Welcome and safe riding...Larry

[Johnie]

Red or blue Lock-Tite will work. I used some blue because that was all I had here. But you are correct, the red is the permanent stuff. I put a little grease on each nipple when I put the fuel lines on. That way I do not pull the nipple off. If it is an old line on a new bike I usually slice it with an Exacto knife so I do not pull the nipple out.

[vintage_mpg]

OK all - I'll try the punch idea as well.

Found a few right hand controls on eBay, but am hoping a cheaper one might turn up here on the parts for sale section.  I'm watching...

[vintage_mpg]

OK, boys...it's been a while, but I'm slowly getting back on track.

Spent some time on the fuel petcock last night; pulled the tank, pulled the brass drain/petcock tubes, cleaned them and soaked the ends in blue loctite.  Let it cure for the night, and reassembled this am.

She's been running for 30 minutes solid - not a single fuel leak.  Still early to declare total victory, but so far, I'm feeling good about it.

I'm going to try and push some fuel/seafoam through her and see if that won't jazz up the carbs a bit.

It's still doing this: when I rev it up with the choke open (after warming her up), she's good up to 3500 rpms or so.  Close the choke, and she'll run right up to 6500 rpms.  Why does it do that, you think?

I give it LESS air, and it runs stronger/faster.  That would indicate it's running lean, right?  Which points me BACK to the clogged/dirty carbs.  Is my line of logic reasonable?

[vintage_mpg]

You need to remove part #3 and clean  http://www.mrcycles.com/fiche_section_detail.asp?section=122903&category=MOTORCYCLES&make=HONDA&year=1973&fveh=2937    Welcome and safe riding...Larry

Hey Larry - thanks for the suggestion.  I meant to ask you this earlier, but forgot: which part #3?  There are a couple of parts labeled #3 in the link...

[MoMo]

You need to remove part #3 and clean  http://www.mrcycles.com/fiche_section_detail.asp?section=122903&category=MOTORCYCLES&make=HONDA&year=1973&fveh=2937    Welcome and safe riding...Larry

Hey Larry - thanks for the suggestion.  I meant to ask you this earlier, but forgot: which part #3?  There are a couple of parts labeled #3 in the link...

I only see one #3 but it is the midrange/emulsifier tube(the slide needle goes into it). Every 400 four I have restored(seven) had the holes clogged. You will need to remove the float bowls, top caps and slides to get at it.  The manual if you do not have one should be able to be downloaded from this site...Larry

[vintage_mpg]

OK, Larry - I'm with you.

That's a fun-filled afternoon of carb-bank pullin', right?

Oh man...here we go again.

Give it to me straight: you think I can run enough Seafoam through her to clean that old crap out?  Is there enough Seafoam in North America to do that job?

I've yanked those carbs once, and am not looking forward to doing it again.  If I have to, then I have to.  Otherwise, I'm going to push a tank of fuel/foam through her and see what happens.

It's the lazy man's approach, I realize.  Just being honest.

[vintage_mpg]

Well, she's been in the driveway purring for an hour - and nothing's changed. 

She still revs solid up to 3500ish, and when I close the choke, she'll push 7000 - coughing and spitting occasionally.  Purrs like a CHAMP up to 3500 - then chain smoker cough.  Also, start getting some  blow-by pushing out the breather tube at the higher rpms, but not much.  Can't imagine she's loving the revving right in the driveway, with the sun beatin' down on her.

Some of this also feels like a mechanical advance issue.  I set the timing using a light and the Clymer recommendations (at both idle as well as 2500), and she was really looking solid.  Can I assume that it the mech advance works to manual settings that it's working fine up to the redline?  Is that a reasonable assumption?  If she's solid on the bottom end of the tach, will it work all the way up?

I'll chase down a dwell meter and confirm things with the points, as well.  Still haven't done that - just set 'em with a feeler gauge at this point.

[MoMo]

OK, Larry - I'm with you.

That's a fun-filled afternoon of carb-bank pullin', right?

Oh man...here we go again.

Give it to me straight: you think I can run enough Seafoam through her to clean that old crap out?  Is there enough Seafoam in North America to do that job?

I've yanked those carbs once, and am not looking forward to doing it again.  If I have to, then I have to.  Otherwise, I'm going to push a tank of fuel/foam through her and see what happens.

It's the lazy man's approach, I realize.  Just being honest.

I think you're in for another carb pull.  If you did not remove the midrange/emulsifier tubes first time, I think you're right that there is not enough Seafoam in the world to get where you  need it to go...Larry

[vintage_mpg]

Carb-pullin' time it is, then!

Larry, can I pull the carbs, yank the float bowls, top caps and slides all without separating the carbs? 

Breaking them apart has me all sorts of worried, honestly.  Once I get that far, then I may as well rebuild each individually, which means re-balancing them all, etc...  That's a giant can of worms that I was hoping to avoid.  I'm a bit intimidated by all that, to be truthful.  I've read/seen too many bike projects that crater right there at that one hurdle.

What do you think?  I know the float bowls can be pulled while they're all together - but what about the top caps and slides?  I didn't see anything about separating the carbs in the shop manual, so maybe I'll have a shot!

Would the plugged jet make it act as I'm describing?

[MoMo]

The problem is poor performance in midrange, right? If so and the bike had been sitting for awhile the midrange has to be clogged.  I've never seen otherwise on 7 bikes.  You do not need to separate the carbs.  The slides are a bit tricky to remove and reassemble though.  You can pm me if you get stuck...Larry

[vintage_mpg]

OK Larry - I'm back in town and about to yank the bank.  That's the bank of carbs...

When (not if!) I run into a jam, I'll shoot you a PM.

Sound good? 

Here goes nothing...