Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.

My "New to me" CB500

NFortySeven
NFortySeven
Squiddy
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My "New to me" CB500 Empty My "New to me" CB500

Post by NFortySeven on Tue 14 May 2019, 1:39 pm

Afternoon all!

I bought my first bike a couple of weeks ago, never heard of the CB500 before this one came up at a bargain locally.  It's a '94 CB500R with 35k from new, partial service history, 2 keys and 2 original owners cards.  Story is, the previous owner accepted as a trade-in at the motorcycle dealership he works at and had planned to turn it into a cafe racer, he then loaned it to his friend for a couple of weeks last year, but it just laid up in his friends yard until a couple of weeks ago.

Here she is in all her glory:

My "New to me" CB500 Img_6811

My "New to me" CB500 Img_6810

I bought it knowing that it was going to be a project, and a labour of love as the bike is a non-starter.  The bike was fully serviced before it laid up last year, which included a battery, plugs, oil, fork seals etc. 

Originally when I got it home the bike was dead, not even click when engaging the start button.  I took a gamble and bought an oximizer for the battery just incase it could be recovered - and according to that it's fine and holds charge, I then changed the fuses in the started solenoid which were rusted, drained the tank and carbs of old fuel and replaced with new, got rid of any crud on the side stand and clutch switch connections.  Now the bike will turn over slowly 3 times, pause for a couple of seconds, turn over once, pause for a couple more seconds, and the turn over 3 times again etc.  I've tried rocking the bike back and forth in 2nd gear aswell to try and loosen the starter, but still won't fire up.  I thought it may be caused by the battery not supplying enough power, as it was only turn the bike over if it's above 12.5V, any lower than that and I just get a click.  Would a new battery be worth picking up?  I've yet to check the plugs, so wouldn't rule those out yet either.

Any advice is much appreciated!  Also, if this is in the wrong section please feel free to move.
NFortySeven
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Post by NFortySeven on Tue 14 May 2019, 2:37 pm

Update!

Got the battery up to 13.9V and the bike started!

Idling around 2.5k, revved it up to 4k but it took a while to return to 2.5k.  Shut the bike off after letting it run for a few mins and then started it again, no revs but it is now idling at 4k.

Possible vacuum leak?
wrighty
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Post by wrighty on Tue 14 May 2019, 7:24 pm

Check carb mounting rubbers for air leaks between carbs and head. It happened to me years ago on my mz. When i shut throttle it kept going at full revs, when i turned ignition off it still revved at full revs. I put it in 2nd gear and dumped the clutch to stall it. This was a race day at cadwell park and the spectators looking on thought it was highly amusing. When i eventually pushed it up the hill to the paddock i got a big cheer. Anyway  the carb rubber had a huge split and it was sucking fuel through regardless of my efforts. I guess even a small air leak affects carburation.
NFortySeven
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Post by NFortySeven on Tue 14 May 2019, 8:01 pm

@wrighty wrote:Check carb mounting rubbers for air leaks between carbs and head. It happened to me years ago on my mz. When i shut throttle it kept going at full revs, when i turned ignition off it still revved at full revs. I put it in 2nd gear and dumped the clutch to stall it. This was a race day at cadwell park and the spectators looking on thought it was highly amusing. When i eventually pushed it up the hill to the paddock i got a big cheer. Anyway  the carb rubber had a huge split and it was sucking fuel through regardless of my efforts. I guess even a small air leak affects carburation.

Hmm, I could switch my ignition off and that would kill the engine, just when it was running the RPM would come down slowly after revving it, and then when it restarted it wouldn't go down below 4k RPM.  I will definitely check the mounting rubbers though!

Left the bike alone for a few hours and it no longer starts, even with the battery charged above 14V.  I get maybe 2 or 3 attempts to get it firing up before the battery's voltage falls too low to turn the engine over.  Half tempted just to throw it up to my mechanic and have him get it running, maybe this isn't my forte!
Jameshambleton
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Post by Jameshambleton on Wed 15 May 2019, 7:44 pm

stuck choke /choke cable
cb500rider
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Post by cb500rider on Fri 31 May 2019, 5:54 pm

It's notorious for bikes of that age for the fuel tank to rust, and that's when fine particles of rust can enter the Carbs to finally clog up your pilot & main jets. Also, surface inside the carbs can become coated too where the float needle needs to freely move too.

So, it's time to get a large type inline fuel filter to attach in middle of your fuel line, a can of compressed airduster like used on computer keyboards, a can of decent quality Carb Cleaner not the cheap crap and a 'G' string guitar wire because it's slim enough & obviously strong enough to poke through hardened up crap within the jets.

Having clogged jets can cause you fuel starvation but also it plays havoc with your fuel mixture too causing the revs to die out on you if it's sucking in more air than fuel into the combustion chamber.

You may find that the Carb bowl's screws maybe not wanting to loosen up, but they can be easily stripped because they are made of not strong metal. So, having an impact driver always helps to turn stubborn screws without damaging them.

Also, I would clean & re-oil the pull & push throttle cables while you've got the carbs out to clean, as they too can get a build of crud/rust within them making the cable stick. The effect you mention about the revs still higher than normal when turning the bike off could be due to the push & push cables being clogged up. So, when you let go of the throttle you should hear a loud 'bing' sound almost right away telling you the throttle has fully returned, but if you get 'bung' sound then it's not free moving enough. If it doesn't or takes a second or so to happen then that means it is clogged up or the throttle movement isn't moving freely enough so try pull on the throttle's rubber grip and pull it away till you get about 2mm gap between it and the right hand switch unit, and see if it moves more freely.

Also, like the other person mentioned double check your choke cable as that too can can get rusted/clogged up over time.

So, for maintenance on your cables buy a cable oiler device and clean them out with WD40, BUT REMEMBER to use cable oil after it to prevent it sticking in the future because WD40 does dry out completely which can make things seize up over time even locks/ignition barrels if not re-oiled.

Depending if you're working with a fully charged battery you should be getting a few more attempts than that in trying to start it. So, your bike's battery could be nearing it's way out in not being able to hold a full 100% charge like when it came out of the factory. Only smart battery charger will tell you if it's still good or not.
NFortySeven
NFortySeven
Squiddy
Squiddy

Posts : 14

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Post by NFortySeven on Mon 24 Jun 2019, 10:57 am

@cb500rider wrote:It's notorious for bikes of that age for the fuel tank to rust, and that's when fine particles of rust can enter the Carbs to finally clog up your pilot & main jets. Also, surface inside the carbs can become coated too where the float needle needs to freely move too.

So, it's time to get a large type inline fuel filter to attach in middle of your fuel line, a can of compressed airduster like used on computer keyboards, a can of decent quality Carb Cleaner not the cheap crap and a 'G' string guitar wire because it's slim enough & obviously strong enough to poke through hardened up crap within the jets.

Having clogged jets can cause you fuel starvation but also it plays havoc with your fuel mixture too causing the revs to die out on you if it's sucking in more air than fuel into the combustion chamber.

You may find that the Carb bowl's screws maybe not wanting to loosen up, but they can be easily stripped because they are made of not strong metal. So, having an impact driver always helps to turn stubborn screws without damaging them.

Also, I would clean & re-oil the pull & push throttle cables while you've got the carbs out to clean, as they too can get a build of crud/rust within them making the cable stick. The effect you mention about the revs still higher than normal when turning the bike off could be due to the push & push cables being clogged up. So, when you let go of the throttle you should hear a loud 'bing' sound almost right away telling you the throttle has fully returned, but if you get 'bung' sound then it's not free moving enough. If it doesn't or takes a second or so to happen then that means it is clogged up or the throttle movement isn't moving freely enough so try pull on the throttle's rubber grip and pull it away till you get about 2mm gap between it and the right hand switch unit, and see if it moves more freely.

Also, like the other person mentioned double check your choke cable as that too can can get rusted/clogged up over time.

So, for maintenance on your cables buy a cable oiler device and clean them out with WD40, BUT REMEMBER to use cable oil after it to prevent it sticking in the future because WD40 does dry out completely which can make things seize up over time even locks/ignition barrels if not re-oiled.

Depending if you're working with a fully charged battery you should be getting a few more attempts than that in trying to start it. So, your bike's battery could be nearing it's way out in not being able to hold a full 100% charge like when it came out of the factory. Only smart battery charger will tell you if it's still good or not.



Thanks for the post, plenty of valuable information there!  All above my head though so it may be a job for my mechanic neighbour lol.

Just to update as I haven't been on in a while due to moving house:

I bought a new battery and the bike now starts first time.  There is a rattling noise though when the bike is idle, however this goes away when I pull in the clutch cable - after doing some reading I believe this is quite common and could be the clutch basket?

I've changed the enormous indicators for some smaller halogen numbers and not only has it freshened the bike up no end, but it has resolved the rapid flashing issue that was apparent in the older indicators! Very Happy

Since then I've been mainly doing a couple of cosmetic things.  I've sanded down the chrome headlight surround to get the surface rust off and painted it black.  I've bought a brand new tail section in black as my current red one is cracked and poor condition.  I've removed the screen off the front as I prefer the naked look.  I'm waiting on a set of Renthal Ultra-Low in Silver arriving so that I can replace the current set and then fit my new LHS switch, due to mine being quite faded and the markings having rubbed off.

It's going in for MOT this coming Saturday (29th June), so I'm hoping that it passes.  The only issues I can forsee (touch wood) would be the headlight alignment being off, or the tyres.  The tyres were brand new last year, but since it laid up for a year and not having been moved they are cracked in places.

Once the bike gets through the MOT I'll focus on making it a bit more presentable.  Plans are to have the tank powdercoated black, and then the wheels powdercoated in Ferric Grey or a bright Silver.  Maybe change the exhaust from the Motad to something a bit smaller, but I quite like the sound of the Motad and I've yet to look at replacements.
NFortySeven
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Squiddy
Squiddy

Posts : 14

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Post by NFortySeven on Sat 29 Jun 2019, 8:03 pm

Well, the old girl failed it’s MOT on headlight alignment and a wobble in the swingarm. Their alignment machine couldn’t recognize the headlight for some reason, the examiner said it could be to do with the alignment or the bulb but that he’d never seen it happen before. The play in the swingarm may be down to worn bushings, so I intend to get these both remedied before the retest next weekend 🤞🏼

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