Bucket Blues

[steve k]

I have finally got around to finishing the matching of my crankcases and proceeded to assemble the gear box and bottom end. I am fitting a mb 50 gearbox into a mb 100 engine and have encountered some problems. With the gear clusters, selector drum and selector forks in place the selector drum can be shifted but it does not sellect all the gears. I have checked the shimming and am sure that all is correct there. The engine is not back together when trying this. the clusters are sitting in one side of the cases on there side. Would puting the cases together and then trying the shifting make any difference. Any advice much appreciated.

Would really like to do some racing this season but this is starting to get a tad frustrating:spudgrr: . Any ideas F5 or Speedpro?

[gav]

Sounds serious, tell ya what, I'll give ya $50 for the lot.......

[ajturbo]

$45.00.......

[dangerous]

forty dollar :spudflip:

My bike already had the 6 speeder in it, so I cant help ya there but I'll ask about.

[speedpro]

I've never tested with the cases apart, too much slop and flopping about to prove anything. You only need the gear shafts and the selector drum and forks and their shaft. How hard can it be to just slide the other crankcase half on. Use a gasket as well when testing as they are thick enough to cause a problem. I'm probably going to run my new motor without one and although it's been a while since I looked at it I recall that it was causing problems with the shafts binding when I tightened the cases up without a gasket.

[steve k]

I've never tested with the cases apart, too much slop and flopping about to prove anything. You only need the gear shafts and the selector drum and forks and their shaft. How hard can it be to just slide the other crankcase half on. Use a gasket as well when testing as they are thick enough to cause a problem. I'm probably going to run my new motor without one and although it's been a while since I looked at it I recall that it was causing problems with the shafts binding when I tightened the cases up without a gasket.

true that. wil put it all together and see what happens. as for you bunch from the si will let you know when i get totally pissed with it and put it on the market.

cheers

[F5 Dave]

You’ll never get it to shift all gears with it half apart. Just leave the crank out to trial so it slips apart easily again.

Just remember to keep turning the shaft as you shift. Obviously at some stage the holes in the gears won't line up so you turn the shaft to help it slip in. Never had any dramas with the MB50-100 gearbox.

[steve k]

You’ll never get it to shift all gears with it half apart. Just leave the crank out to trial so it slips apart easily again.

Just remember to keep turning the shaft as you shift. Obviously at some stage the holes in the gears won't line up so you turn the shaft to help it slip in. Never had any dramas with the MB50-100 gearbox.

Thanks Dave.

[steve k]

well there is definately something not quite right with the six speeder. put the gear box together as suggested and had a go at shifting. there appears to be a neutral where first should be and the whole thing locks up when you get through to where third should be.

I have no idea whats going on there. F5 would you be able to take a look at it if you have the time?

Cheers

[F5 Dave]

Yeah sure, give me a yell next week as off to desert storm this weekend.

[steve k]

Yeah sure, give me a yell next week as off to desert storm this weekend.

Thanks dave. will pm ya next week.

[gav]

well there is definately something not quite right with the six speeder. put the gear box together as suggested and had a go at shifting. there appears to be a neutral where first should be and the whole thing locks up when you get through to where third should be.

I have no idea whats going on there. F5 would you be able to take a look at it if you have the time?

Cheers
$55.... :blip:

[steve k]

$55.... :blip:

for that price ill even throw in a :finger:

[gav]

Speaking of MB100 gearboxes, does anyone know how much oil they take? Using Motul Transoil.

[speedpro]

Take the 6mm bolt out of the clutch sidecover, fill it up slowly whilst holding the bike upright. Stop filling when oil starts running out the bolt hole.

[Sketchy_Racer]

it should say on the side??

[Sketchy_Racer]

or do what speedpro says

[Ivan]

or how about run no oil at all :blip:


:blah: weight reduction:blah:

[gav]

Hey Steve K, how's that gearbox coming along? Got it sorted?

[steve k]

hopefully will have a diagnosis by the end of the week. Still heaps of other stuff to do on the motor. in fact might head out to the shed tonite and get a bit more done.

I have the original 5 speeder but really do not want to conceed and put that in.

will let you all know what the out come is.

cheers

[steve k]

Managed to make some headway on the gearbox thanks to f5 dave. after looking at all components it is looking like the selector forks are not the correct ones. Both gear clusters and shimming look correct and where pretty sure the selector drum is correct.

So its back to the chap I got the gearbox off to see if we can track down the correct selectors.

nothing like incorrect parts to put a dent in ya current bout of motivation to finish the project aye.

[gav]

:gob: Nasty! I've just had a complete MB5 bottom end turn up, it even seems to select six gears as well. After I bought it, had a sudden thought that maybe someone had already swapped it out and fitted a four speed back into the 50, but hopefully should be sweet. But I'm leaving it to an expert to fit, aye DP, cheers mate!

[steve k]

:gob: Nasty! I've just had a complete MB5 bottom end turn up, it even seems to select six gears as well. After I bought it, had a sudden thought that maybe someone had already swapped it out and fitted a four speed back into the 50, but hopefully should be sweet. But I'm leaving it to an expert to fit, aye DP, cheers mate!

Is a bit nasty. Have had a chat to the guy I got it off and he is having a look to see if he can find the correct forks.

in the meantime anyone out there got a spare set of selector forks for a mb5. could always use a cr80 gear box but that wouldnt be in the spirit of bucket racing now would it:yes:

[steve k]

Well theres been a major breakthrough with the gearbox. selector forks have been sourced and tested and i now have a functioning 6 speed box. :headbang: :spudflip: :woohoo:

Big thanks to Peter at Total Motorcycles for sorting out the problem. Also big thanks to f5 dave for helping out to diagnose the prob.

Will have the head and barrel back from the shop this week so wont be long now till start up. Mind you I have been saying that for about the last year. Well motivated now to get the project finish.

will post picies once it is all done.

[dangerous]

Good shit Steve, now get it running and get some race k's up... then regester for the MOTOequip Battle of the Buckets and join Skunk in traveling down and race all day. :Punk:

BOB thread/ http://www.kiwibiker.co.nz/forums/showthread.php?t=29094

[F5 Dave]

Glad to hear it. Rule 1 is once enthusiasm is flowing run with it. If it starts flagging then get the bike running & finish things to the way you want them later.

[steve k]

Barrell and head have now returned from the machine shop so I should really get my a into g and finish the bloody thing. will most likely not be ready for the next bucket meet but will try.

[speedpro]

Assemble it all up using old gaskets and measure squish clearance. I use a bit of thin solder double-doubled and twisted. I poke it down the plug hole with the piston down. With a bit of a bend in it you can get it to go over to the side of the bore. If you now turn the crank gently till the pistons taps the solder and then rock it back and forth till it finally turns right over TDC the solder will be flattened to the squish clearance. Pull it out and measure it with calipers. Be careful as the squish could be cut on a different angle to the piston crown and the squish will therefore vary from inside to outside. Once you've done it once, snip the used bit of solder off and do it again at a different point round the bore. Do it at 4 places minimum, especially if you have the squish down round .7mm. If you've machined for a lot of compression, or even if you haven't, you have to check the compression. I'm lucky enough to have a couple of syringes which makes it easy. The method I use is to get the piston very close to TDC. Mount the motor in the vice with the plug hole on top. Use the syringe to measure in some oil. I use fork oil. Rock the crank just back and forth a tiny bit. Keep squeezing in a little bit more then rocking the crank till the oil is 2 threads up the plug hole. The amount you've measured in is the combustion chamber volume. I use calipers to measure the amount of movement of the syringe plunger. With the bore of the syringe it's easy to work out the volume per cm or movement. Then you add the chamber volume to the measured swept volume and then divide that by the chamber volume to get the compression ratio. Anything round 12-13 is OK, 14 is good, and 15 is pushing it. You need to measure the chamber volume at least twice. If your measurements vary then do it a third time. You have to take the head off and clean it between measurements.

It can be a pain in the arse but can be the differance between a good motor and a VERY good motor, or one that chernobles and one that doesn't.