Author Topic: 1972 CB500 - Rebuild Project  (Read 31997 times)

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Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #150 on: March 19, 2016, 06:33:15 PM »
... and a video of the first start up. 

Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline SOHC4 Cafe Racer Fan

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Re: 1972 CB500 - Rebuild Project
« Reply #151 on: March 19, 2016, 09:37:27 PM »
Yes, take 3 was much better, Kiwi!  Congrats!!
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline Bootsey

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Re: 1972 CB500 - Rebuild Project
« Reply #152 on: March 21, 2016, 08:15:14 PM »
Awesome work mate, the pipes look & sound great.

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #153 on: March 31, 2016, 03:45:54 PM »
Right my seat hoop arrived this morning courtesy of Harisuluv...

Anybody have any advice on installing?  Looks fairly straight forward but always keen to hear from those who have done this before.

I know people usually do all their metal fabrication first but I have no experience in welding or fabrication or any equipment.... I also think the back end is one of the hardest things to get right and I wanted to see how the bike evolved before making a decision.

As well as getting the hoop installed I need to consider seat and indicator light mounting points so I might sketch something up this weekend. I also need to decide whether to get the seat pan made out of fiberglass or whether to go for sheet metal.

Lucky for me there is a metal workshop at my new workplace so I can hopefully swap some welding services for beer... usually seems to work.  Failing that my exhaust guy can probably help me out.  The guy who did my tank paint also is does custom fiberglass work so I have plenty of options in terms of getting proper help with the fabrication works.

Photos below of what I'm aiming for the back-end and seat



Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline SOHC4 Cafe Racer Fan

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Re: 1972 CB500 - Rebuild Project
« Reply #154 on: March 31, 2016, 05:38:15 PM »
The seats in your photos are for the most part vinyl covered fiberglass-based seats. 

Go with metal!!  It will hold up better to wear and tear.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline MickB

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Re: 1972 CB500 - Rebuild Project
« Reply #155 on: March 31, 2016, 10:42:37 PM »
Puffin love your air filter screen, you could use it on Alcatraz to lock thieves away who stole Dino's 750.
It'll stop rocks being sucked into the filter.

I love it, it really adds to the bike.

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #156 on: April 04, 2016, 01:22:53 AM »
Carb Sync attempt #1

Ok so made a first attempt at trying to vacuum sync the carbs but I'm having a little difficulty and could do with some help from the carb gurus please.

I can get the bike to run at about 1500 - 1800rpm with the choke fully open however I can't get the bike to idle or run with the choke closed.  At these rpms the guages are showing the carbs to be fairly well balanced.

As soon as you close the choke the bike dies even if you try and hold the throttle open and increase the rpm.

Question - If the bike wont run with the choke fully open that means there is an issue with the idle fuel circuit correct?  i.e. with the butterflies fully open it's getting too much air and not enough fuel?

I'm thinking that maybe the fuel level is too low in the float bowls?  I checked back in this blog and I wrote that the fuel level was about 5mm below the float bowl gasket.

Any thoughts before I start removing float bowls?
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #157 on: April 04, 2016, 02:30:27 PM »
Ok after a nights sleep and a fresh mind I realise I'm being an idiot..! 

Moving the choke lever to 'Open' is the normal running position.  I was getting confused and assuming 'Open' was the cold starting position when in fact the opposite is true.

This is why you shouldn't leave a project for 6 months and come back to it... your brain rids itself of useful information.

Take 2 tonight
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Stev-o

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Re: 1972 CB500 - Rebuild Project
« Reply #158 on: April 08, 2016, 07:32:29 PM »
Choke positions can be confusing to some at times, you got it now, off = open.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #159 on: April 11, 2016, 07:47:52 PM »
Carb Sync attempt #2.

So I had another go at dialing the carbs in last weekend but I was still not happy.  I could balance them ok but the bike just wouldn't idle correctly... it would gain rpms and then suddenly drop and stall and it needed more than 1100rpm to get it running.  Again turning the air screws didn't seem to make any difference.

I decided to go back and make sure everything else was ok before trying to diagnose carb issues.

1)  Checked cam chain tension - ok
2)  Checked valvle clearances - Too much gap, particularly intake valves.... I had set them before the first start of the engine but they needed adjusting now that the engine had run.  I reset them to factory specs and will keep an eye on them.  I guess these will settle down once everything beds in?
3)  Checked timing - Seems spot on.  Test light comes on exactly on the full advanced marks on both 1-4 and 2-3 (Dyne electronic ignition)
4) Spark Plugs - All spark plugs were completely sooted up.  This would indicate rich running condition correct?  I assume that these bikes run slightly rich at idle and I had been idling a long time trying to tune it in but surely this is too much? 
5)  Float bowl levels - Seem pretty good
6)  Compression - All 4 cylinders even at 110 - 115 psi
« Last Edit: April 11, 2016, 07:50:12 PM by Puffin »
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Stev-o

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Re: 1972 CB500 - Rebuild Project
« Reply #160 on: April 11, 2016, 07:51:26 PM »
That plugs appears extreme rich condition, something is not right.  What jets do you have?
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #161 on: April 11, 2016, 07:54:38 PM »
After checking the float bowl levels I think I may have found the problem... 

I noticed some crap come out with the fuel as i drained the bowl.  when I took the bowl off I was pretty horrified to find this...
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #162 on: April 11, 2016, 08:06:33 PM »
If a bit of this loose crappy material has got stick in one of the jets or is clogging up one of the passages it might account for my issues.

Everything was absolutely immaculate when I put it together so I can't believe there is this much crap everywhere.  The carb bodies almost look like a chemical reaction has taken place. Some looks like jelly, some like rust flakes only I don't think it is rust.  I checked the pet-cock bowl and filter and they are both spotless so it's not coming from the tank.

The only thing I can think of is that the fuel has reacted with a chemical cleaner I used to clean the carbs but i'm sure i just used proper carb cleaner or standard engine de-greaser. 

Either that or I used some dodgy old fuel.. I did have some 2-stroke fuel mixed in a can in the garage and I might have done something stupid like run that through the carbs months ago when I first checked the fuel levels in the float bowls.  Would old congealed fuel with 2-stroke oil in it leave this mess behind if you let it sit a few months?
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Stev-o

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Re: 1972 CB500 - Rebuild Project
« Reply #163 on: April 11, 2016, 08:29:52 PM »
2 stroke oil could cause plugs to look rich but not corrosion.  Are you sure your tank is clean? Drain some into a clear jar to inspect. 
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #164 on: April 11, 2016, 09:00:38 PM »
That plugs appears extreme rich condition, something is not right.  What jets do you have?

Everything stock except I replaced the slow jets with aftermarket ones of the same size. 
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #165 on: April 11, 2016, 10:43:11 PM »
2 stroke oil could cause plugs to look rich but not corrosion.  Are you sure your tank is clean? Drain some into a clear jar to inspect.

Yep I'm pretty sure it's not the tank but that is a good idea to rule it out completely. 
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #166 on: April 12, 2016, 05:13:09 PM »
Also, your fuel level is too high according to the picture you posted with the Clear Tube. It should be 3-4MM below the seam. That will cause the rich condition at idle.

Looks like you need to re-clean the carbs  :(

Ok thanks Cal, easy to re-set these now that I have to take the carbs off again for cleaning
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline MickB

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1972 CB500 - Rebuild Project
« Reply #167 on: May 01, 2016, 06:59:52 PM »
Maybe you can just take the bowls off and clean them and pull the jets out and leave the rest insitu, if you take the aircleaner boots off stuff some rags in the throat of each carby or if you prefer each orifice and use  a mirror and a Dremel with a wire brush on a flexible cable like a dentist.

Cal'll have a comment after this suggestion for sure.
« Last Edit: May 01, 2016, 07:19:37 PM by MickB »

Offline MickB

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Re: 1972 CB500 - Rebuild Project
« Reply #168 on: May 02, 2016, 02:45:50 PM »
If it's the photo I've seen with all the corrosion take the carbies off.

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #169 on: May 09, 2016, 09:20:33 PM »
If it's the photo I've seen with all the corrosion take the carbies off.

Yep I elected to take the Carbs off and give them a proper clean.  Whilst off the bike I re-balanced all the throttle bodies and adjusted the float levels as per Cal's suggestion.  I managed to get the fuel level to 3-4mm from the gasket line on all the carbs... at least I think I did, every time I re-checked they seemed to keep changng but I'm fairly confident they are about right.

I knew my old Air Box boots were on the way out and two of them split whilst I was taking the carbs off.  I stumped up and bought a nice new set from 4into1.com.  Whilst I was at it I got another side-cover badge to match the one I already had.  These reproduction badges are quite different from the originals so having one of each just didn't look right.

I think before I put the carbs back on I'm gonna get the rear hoop welded on.  Just need to find some time to cut the end off and plan where I need mounting tabs for the seat, indicators and possibly a small rear fender. 

I'm finding it hard to find the motivation to finish this off which is a shame because I really want to get out and ride it... I think I just need to get a little done and then it will start flowing again.
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline rosewood

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Re: 1972 CB500 - Rebuild Project
« Reply #170 on: May 10, 2016, 06:33:45 PM »
Head up Puffin...

Come have a look in my garage and you will realize how close you are to the finishing line... :)

I have ended up following your foot steps motor is out of the frame being torn down needing new primary chain etc etc..alot more work than I was anticipating

rosewood...

Offline MickB

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Re: 1972 CB500 - Rebuild Project
« Reply #171 on: May 16, 2016, 04:49:01 AM »
Puffin loved the tube with the right angle to check the levels, what about putting it in tips and tricks.

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #172 on: May 22, 2016, 08:53:11 PM »
Got a random email the other day from somebody who knew I was restoring an old Honda so I went down to meet them and I ended up salvaging this old girl out of a shipping container on Sunday....  she is now sitting in my garage waiting for me to finish the CB500.  I hadn't planned on taking on another full scale project but I guess when these bikes turn up randomly you need to snap them up if the price is right.

CB350 Four, first registered in NZ in 1974, 99,500kms on the clock.  She seems to be all there except the left hand switch gear.  I don't think the paint is original as I believe they came in Red just like the spare tank you can see in the back ground, but she'll be getting a new paint job anyway.

She's definately old and tired and is going to be a lot of work again but she turns over ok and was ridden into the container a few years ago.   I expect it will need a full engine rebuild after 100,000k and about 10 owners.  The guy said the starter clutch has definately gone so I'm  going to have to open her up just like the CB500 before I even get it running.

Came with a spare starter clutch, tank and lower triple clamp but given the amount of CB350, 500, 550 and 650 stuff the guy had I'm not going to be short of parts if i need them. Don't actually know anything about the 350's so will need to do my research but looks to be a scaled down version of the 500 so i'm off to a head start.

Thinking full on Black paint job including engine, frame, tank, fork ears and headlight bucket, polished chrome everywhere else, overbored pistons, visually quite stock except for upgrades to electrical system and lights, modern street tyres.  Something classic looking.
« Last Edit: May 22, 2016, 09:04:24 PM by Puffin »
Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html

Offline Tews19

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Re: 1972 CB500 - Rebuild Project
« Reply #173 on: June 14, 2016, 03:22:09 PM »
Not sure if it was covered but check the spark plug cap resistance?
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline Puffin

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Re: 1972 CB500 - Rebuild Project
« Reply #174 on: September 25, 2016, 07:38:20 PM »
Wow so it's been 18 months since I started this project and looks like I've not worked on the bike since April.  I definately got a bit fatigued seeing as I've been at it so long so I've let it sit over winter whilst I tackled some over-due house projects such as a leaky roof and rotten joinery.  Anyways with summer on the horizon and some friends out enjoying their bikes for the Distinguished Gentleman's rides whilst I sat at home with nothing to ride I've decided to pull my finger out and get back into it and get this thing finished off.

I'm going to set myself a challenge to have this done by 1st December

10 step plan as follows:

1)  Chop Back End and de-tab old seat mounting stuff
2) Weld Seat Hoop on
3) Mock up rear end and work out where I need mounting tabs for mud guards, fenders, seat pan, indicator lights etc
4) Weld mounting Tabs on & paint everything back to black
5) Fabricate seat pan out of fibreglass
6) Get seat made by a professional
7) Install rear lights & number plate
8) Tune and sync
9) Get bike re-registered
10) RIDE!



Honda CB500 four
Honda CB350 four (under construction)

1972 Cb500 Rebuild Project - http://forums.sohc4.net/index.php/topic,145835.0.html