Topic: Splittin' the cases - 500 four

[hummbug]

So the time has come to split the cases on the CB500. The bike has been sitting idle since this happened...

http://forums.sohc4.net/index.php?topic=69328.0

I have a gasket kit, a new kickstart mechanism, a manual and a sense of adventure.

My plan is to pull the engine, split the cases to get into the gearbox and replace the kickstart mechanism.
I will inspect the gears but I'm not sure exactly what to look for - hopefully there won't be any probs in there.
Anyone have any handy hints for splitting cases and replacing the kickstart spindle??

I'll be hitting up the forums in a couple of weeks when the process begins. I'm hoping to do it all in one weekend

[lordwhimsey]

It's quite straight forward if you follow the manual, unscrew bolts in the right sequence and take lots of photos. You should also disassemble and assemble it upside down. Once you're in there it's very easy and quick to change the kick start mechanism.

Take the opportunity to change the primary chain if it looks a bit floppy and check it hasn't started sawing through the cases (It doesn't matter if it has, as long as it's not through to the oil way).

I think a weekend might be a bit optimistic; I find my time estimates are always ruined by unforeseen difficulties (stripped threads, loosing a tiny component, not having the right spanner etc.)

[hummbug]

thank you lord.

I have found shavings in my oil previously so I guess the primary chain should be changed. From what I can see in the manual, the top end has to come off to do this...
How much more work then to replace the cam chain?? I am restricted a bit with time because I'm using the workshop of a friend of a friend and I don't want to stretch the 'friendship'.

That said, I want to get as much done as I can while I have the bike in bits.

Also, when removing the shaft, will I need the shaft puller illustrated in the manual or is there a more backyard way of getting this done??

thanks

[dave500]

youll need some external circlip pliers for the kick shaft interiour circlip.err,im not familiar with the puller?ive done them by hand,,is that to pull the kicker lever from the shaft?if so just wedge it open a little with a chisel,gently.let me know if you need any bits,i have a good spinning /selecting 500 bottom end here on the gold coast.or maybe "puds four parts" can help out in victoria.

[hummbug]

Thanks Dave. I think the puller is a weight hammer. If I need any bits I'll be sure to let you know. There aren't that many 500 owners here in Oz, its good to hear from another one.

[Fritz]

Also, when removing the shaft, will I need the shaft puller illustrated in the manual or is there a more backyard way of getting this done??

If you are referring to the primary shaft for changing the primary chain: I've read that you can use on of the rear motor bolts to pull that shaft. It's supposed to slip out quite easily.

[dave500]

i always have got the primary gear off easy enough with a brass drift,if it was tight a puller like that is ideal,you dont need one for the actual kick shaft,make sure you dont forget to remove all the case bolts,especially the 6mm x about 400mm one from inside the gear box by the oil pickup screen .you might need to buy an impact screw driver if you dont have one,i replace all those pesky phillips(jis=japanese industry standard)with allen head bolts.once the motor is out drop the bottom pan and have a good look for other damage and take some photos.

[fantino]

Make sure to take a long, hard look at the shift forks and engagement dogs on the transmission gears. This was a real weak point of the 500 design and experiences a lot of wear. Mine were pretty trashed when I cracked the cases. Also a great opportunity to replace your oil seals since they're cheap and you're in there.

If you're already replacing the primary chain, it literally adds another 30 seconds of time to replace the cam chain as well. You could endlessly find things to replace or upgrade when working on a motor, but it's good maintenance to replace your chains and seals while you're in there!

Good luck!

[CBJoe]

Whatever you do, please take some pics and post 'em..... I'd love to know what the root cause was for the kick starter lever to do what it did.  

Joe

[lordwhimsey]

Also, when removing the shaft, will I need the shaft puller illustrated in the manual or is there a more backyard way of getting this done??

If you are referring to the primary shaft for changing the primary chain: I've read that you can use on of the rear motor bolts to pull that shaft. It's supposed to slip out quite easily.

Screw one end of the engine bolt into the end of the primary shaft, leave the foot peg on the other end and tap it away from the engine with a soft faced hammer. You don't need to use much force, it should come straight out.

[hummbug]

All good advice - thanks. I have been thinking way too much about the how, what and why of this recently so it will be good to open her up and see it for real.
I have also decided to wait and see what's in there and needs changing before buying parts. It could take a bit longer this way but I have the workshop for longer now so I'm going to take my time.
I will take photos as I go and post them, stay tuned. Two weeks and counting. It's raining more in this part of the world than it has done in years - which is a good thing. When the sun comes out the bike should be ready to go!!

Thanks for the picture Fritz, I'll need a new footpeg as well, it was bent when the bike tried to throw me off.

[dave500]

man!you were lucky,and some skill involved aswell,im keen to see the autopsy results aswell,,thats one strange phenomenon you had!,i used to live in glen wayverley,and mooroolbark,and belgrave sth,and clayton,and coldstream not all at the same time though.

[bryanj]

Dont need the puller, remove the oil pump and tap the other end of the shaft with a soft metal drift

[CBJoe]

Updates    I'd love to know what the internals looked like.

Regards, Joe

[hummbug]

Quick update with pics to come in a day or so...just got home.
Long day but  - with a lot of help - we managed to get the cases apart and find the broken bits.
The copper coloured gear on the kickstart mechanism has seized and welded onto the shaft - no sh**. It took an angle grinder to get it off and remove the whole kickstart mechanism.

There was also a disintegrated bearing from the end of one of the gear shafts. There was quite a bit of shrapnel.

So now there are decisions to be made  - is it worth it fixing......anyone?

Dave500 you said you might have some spare parts, I'm working out what I need tomorrow - I might give you a hoy once I know exactly what I'm looking for...

[dave500]

no sweat humbug,i have a good kick shaft here.try puds parts down your way,save you some postage,ide like $30 for this.the bearing should be easy to find at say cbc bearings or similar,just get the number from it.

[hummbug]

Here are some pics of the 20mm needle bearing from the transmission counter shaft and the kick starter pinion. Both have failed but I'm not sure which order it happened in...
The needle bearing was all throughout the gearbox and the pieces kept appearing as we dug deeper. No signs of it up in the top end.
The pinion was literally welded onto the shaft from excessive heat.

The theory is that the bearing failed dramatically, putting a huge load onto the pinion,thus creating the heat that slowly seized it to the shaft. You can't really see in the pictures but the inside of the pinion cog shows signs of extreme heat and you can see where it bonded to the shaft. When it finally seized, it engaged with the counter shaft and flung the kickstart lever around with all the force from the engine and stopped the back wheel dead.

There could be a few causes of this and it would seem that lack of oil would be the main one...There is no sign of low oil though, there was plenty in the bike at the time and I am pretty adamant that it didn't ever get low enough to do this.
There is an oil leak from the gear shift shaft and it looks as if the PO (or even further back) made some attempts to cover this up with some little foamy o-rings to soak it up. The oil was welling inside the sprocket cover and leaking from the bottom of that.

The next step is to find replacement parts and get her back together. This won't be happening for a few weeks though.

Dave500 - I already have a kickstart mechanism - thanks for the kind offer, I wish I'd known months ago, it was the first part I bought after it happened! I paid about $70 for it from the States.
I'm looking for a replacement counter shaft though - complete and with bearings intact.

Then I'm going to replace as many bearings and oil seals as I can. The primary and cam chains both look in very good condition, as does the cam chain tensioner. The top end stays as is - it was running well before this, I see no need to change it....just could do with a clean up on the outside.

I could have taken more pics but at the time, it was all about doing the job.  The bloke who helped me was a bloody ripper! I couldn't have done it without him. He pulled the front axle out of his CRF to use as a puller for the primary shaft and wore down two discs on his angle grinder getting the pinion off amongst other things...

[dave500]

those needle bearings are discontinued from honda,bummer,you might find some nos somewhere,the normal ball type can be replaced,counter shaft one is 91022-286-004,the mainshaft is 23931-323-004  http://www.motoretro.com.au/index.html   try here.the "286" number indicates that bearing was first used in 69 cb250 i think,other models might share these,you might be better of finding a new bottom end or complete motor if the bearings are going to be impossible to find.

[hummbug]

Thanks Dave, I'll chase up the bearings.
In the meantime, I've just purchased both trans shafts, complete with all bearings and cogs from eBay. That solves the needle bearing and counter shaft problem and gives me spare parts if I need them.
Off to the bearing shop and then onto the oil seals....
Thanks for all your help mate, I appreciate it.

[dave500]

no worries,the seals are best to get genuine,theyre odd ball sizes like 13.7 x 3.7 or some weird shyte,david silver should have them,the honda dealer will want your soul for them.no damage to the cases?look real close.while its apart reseat the valves and replace the valve stem seals.

[bryanj]

Was the bearing correctly located on its peg? Never in lots of years seen a bearing go like that, i would avise changing the shaft with bearings as the inner race for the rollers is the shaft itself. I agree with your conclusion about the welded gear tho'

[hummbug]

bryanj - do you mean before or after it smashed into a hundred bits? I can only assume it was beforehand but it was all through the case when we pulled it apart so I doubt it stayed there for very long.
I don't know much about the oilways and the manuals illustration is a little hard to decipher. Do you think it's possible the oilways were blocked to that bearing and its surrounds, causing a lack of oil?

[dave500]

the improvement incorporated into the 550 was a little trachoid oil pump on that bearing,that bearing is only splashed in the 500,if the engine wasnt started for years that area could have dried right up and if condensation attacked the needle surfaces that might have been a cause?was the little peg present?the outer may have spun reducing the splash effect?

[hummbug]

I don't know if the peg was in place, the bearing was all over the place when we split the case....hard to tell.  It does seem like a lack of oil to that part of the tranny so I'll make sure it's all put back together properly and make sure the oilways are clear, not much else I can do really.

The engine certainly wasn't sitting idle - I had been riding regularly on long and short trips and it was running well.  I won't be getting back to the bike until October...

[dave500]

ok i doubt the peg got smashed,try and find it,you should have one for your reassembly.