Topic: Cam followers, buckets and shims - what's it all about?!

[lordmoonpie]

Having played with a lot of early 70's Honda race bikes, I'm familiar with the tried and tested cam, rocker arm, adjustable tappet, valve setup. I've started looking at designing a head from scratch and all the modern race tackle talks about cam buckets, followers and biscuit or top hat shims. I haven't a clue what they're on about and can't visualise a setup with these parts that I can relate to the old honda valvetrain.

Can anyone point me to a reference source that explains the more modern setup or better still, pictures so I can figure it out in my own head?

Put me out of my misery please.... 

[mlinder]

That's for direct overhead cam, where the cam lobes apply lift directly to the valves. The bucket fits over the top of the valve stem. Some are bucket over shim, some are shim over bucket. the shim is how you adjust them.
Doesn't apply to a SOHC with rockers.

[BLUE71TURBO]

Moonpie, yer not familier with the early KZ900/KZ1000 heads with the shim buckets ?  Here's a picture of the cams and valve train.
This is a early version with the shims on top of the bucket. Later versions put the shim ( smaller ) on the top of the valve retainer.
With way bigger cams the early version had a tendancy to spit the shims out, so racers would go to the shim on the bottom.
    Draw back to the later version was that you had to remove the cams to do a valve adjustment.     A.P.E. has pictures of all of
the parts on thier website. I hope this helps ya. 

                     

[simon#42]

simon , its about time you came roaring into the 80s , bucket and shin tappets will be the thin end of the wedge. before we know it you will be getting rid of that betamax video!

[Yoshi823]

That's for direct overhead cam, where the cam lobes apply lift directly to the valves. The bucket fits over the top of the valve stem. Some are bucket over shim, some are shim over bucket. the shim is how you adjust them.
Doesn't apply to a SOHC with rockers.

And then there are the forked followers like on the ZZR1100 where there is only one cam lobe operating the follower...this then operates onto two valves with shims under each fork. This is the same way that BMW have engineered the new S1000R.

[BLUE71TURBO]

simon , its about time you came roaring into the 80s , bucket and shin tappets will be the thin end of the wedge. before we know it you will be getting rid of that betamax video!

 First he has to drop the draw bridge, leave the castle, fight the Knights of Nii, then stop at the Castle of Anthrax before the long journey to town. The only problem is he never gets past the Castle of Anthrax !!   

                     

[Sam Green Racing]

He'll be asking about roller tappets, hydraulic tappets and desmodromic valve gear next, he's such a wind up.  

Question for his Lordship, what do you do when your tappets are TAPPIN

Sam.

[BLUE71TURBO]

He'll be asking about roller tappets, hydraulic tappets and desmodromic valve gear next, he's such a wind up.  

Question for his Lordship, what do you do when your tappets are TAPPIN

Sam.

   Why he get's to dancing..................

               

[lordmoonpie]

Well I did think about straight to pneumatic valves but you can't boil the ocean so direct action cams will do for a start. Thanks for the pic Blue71turbo - that helps my wee brain a lot 

I just started kicking some ideas around about building a vee-twin again which is where the question came from (Obession? I think so!). I had set off down a route of replicating Judd V10 pistons but as they seem to be like rocking horse doo-doo I moved to thinking about the head and cams. All this dreadful daytime TV is bad news you see - gets you thinking all sorts of stuff. I woke up at 2am last night and couldn't get back to sleep with thinking about optimum conrod lengths...

I'm aiming for a 102 bore x 68 stroke but I want to work out the best conrod length for that combination. I'm thinking based on Ducatis that it'll be around 14cm long but there must be a table or formula to work this out surely?

I have a 102mm piston from a ducati supermono to play with but conrods for the same are like the holy grail and I ain't going on no crusades with the Knights of Nii!

Betamax - is that better than Blu-ray Simon? I still can't work the menus on my new blu-ray player 

Sam, oh streamlined one,  - my tappets are dead quiet, proper engine setup you see 

[Sam Green Racing]

I've stopped worrying about your back, I'm more concerned about you wearing out your fingers and keyboard with all this excessive posting.

Sam.

[lordmoonpie]

I'm enjoying it while I can Sam 
As soon as I'm half way fit I'll be recuperating in the garage LOL!

[Sam Green Racing]

How long will it be before you'll be able to return to work Simon?

Sam.

[lordmoonpie]

Another 6-10 weeks and then to reduced hours to begin with. 

[simon#42]

 conrod  length is normally twice the stroke or slightly longer , not very specific im afraid but you wont be to far wrong !!

relax and enjoy the time off , you will be back slaving away before you know it

[Sam Green Racing]

Good morning your Lordlyness, stickers arrived last night,  what do IOU.

Sam.

[lordmoonpie]

Thanks Simon - that's a good rule of thumb to get me started 

Sam - are the stickers OK? You owe me the princely sum of nowt - call it swapsies for the photos 
Actually, when you're at Thundersprint, get Ben to take a nice snap of the tank for me so I can shove it up on my tarted up website at www.moonpie.co.uk

[Sam Green Racing]

Thanks Simon - that's a good rule of thumb to get me started 

Sam - are the stickers OK? You owe me the princely sum of nowt - call it swapsies for the photos 
Actually, when you're at Thundersprint, get Ben to take a nice snap of the tank for me so I can shove it up on my tarted up website at www.moonpie.co.uk

Cheers Simon, you're so kind. I'm sure Benny will do the honors, and we'll see you at the Thundersprint.

Sam.

[Bill/BentON Racing]

LMP,you got me worried now,you sure it's a DVD,I'm getting or an EIGHT TRACK ? ,Bill

[lordmoonpie]

Oh it's a nice modern DVD Bill.....of a grainy old 8-track movie LOL!