Two bearing bottom end...

Here a pic of drive side crankcase, for you to look ponder and ask why?

Derek I assume you what to see something not in the photo??

exactly ! i want to see the sprocket from the rearof the sprocket is it a taper does not look like it is ? , and why is the seal the wrong way round please enlighten us Mike.

but a very interesting shot.

Great redirection Mike - !

hope it goes well for you the week end-

sadly I have my money on Ian winning a few at pembry he was un-catchable last year

Interesting indeed - Seals put in this way round primary compression is higher...

Std taper on sprocket - taper just nearer crank.

Yes Ian was un-catchable except for the two races I beat him in, and another one
where we had to wait for the results to be published before we knew who won...

Yes other than that - un-catchable!!

hi all hope you all have a great time, sorry i can not be there, but i have a more important celebration but i will be amongst many friends you know too, so i will pass on your hello's like are you comming out to play.

Anyway - Mike pack it up will you, you sound like a right prema dona" - I still recon Ian will win more this time espcially if his bike has no issues, with reliability, I watch his commitment into the righthander onto the straight, were i stopped my heart last year, I was very impressed. I have to say I think he had a much wider entry and later appex than you, anyway I hope you all stay up and its dry for a good weekend for you all.

photo Mike photo's, can we see the back of that sprocket, - on the bike not loose in your hand ?

kind regards Derek

on that seal you sure it is'nt a RD 250 TIMING SIDE SEAL"?

Regards Derek.

No Derek its not a 250 LC seal its a TZ350 seal !!

where do you get these from, and whats the part number.

Derek

Webbs of Lincoln 01522 528951/513193

Try to get Steve or Andy

Part Number 93103-20076-00

Same as LC except 20mm inner diameter

you mean its an LC ?

Perhaps you know more than me Derek???

Seals I've used are these sizes:-

TZ seal 40x10x20

LC seal 40x10x25

Hi Mike,

I'm probably gonna ask a stupid question here, why has the case been machined round by the bearing and what are the five small bolts for?

Apologies in advance.


Eddie

Hi ed Mike has a machined aluminium plate/ boss screwed to the other side that holds the ball bearing as opposed to bronze bush, brilliant mod, Not sure who did this first on a bantam, I think it may have been Tom Miller Ever the Engineering ideas. but I could be wrong, we were running neddle rollers on both sides before this but the beraing allows better control on the layhaft, Ithink that the reason, but also frictional and high speed rotational support/stability is better.

on the seal Mike not sure what the model is but 40x10 x20 is correct for the LC my friend a timing side job mate, Iknow this as I was running them on my 19mm bantam shaft, thats how I know they are 20mm, as 25 on a 19mm shaft will not start because of blow by round the shaft,but ok with no seal above 5,000 ? but not recormended.

Anyway on the seal we usto use an LC Engine on a dyno to test our Go-kart and squeeze cast pistons. many times to distruction at Goetze formely AMAC, then A.E.Piston Products.
so they came FOC AT THE TIME AND IMPORTANT FACT WHEN RACING A BANTAM.

WE TRIED ONE GAVE AN EXTRA 800 rpm because of the lower frictional losses, we had a seal manufactures engineer because we kept blowing seals on the 1000 ton rams / on the rams he explained that all !(i will correct all in a minute) seals have dies made smaller if you measure a seal inner diameters it will be 1.25 to 1.5mm smaller then the shaft diameter, even though its made for the same size, now try your engine with a seal made for a shaft 1mm bigger, !!! the difference is unberleavable, this is absolutly top secret -

(now for that correction on all seals )- not all seals are as flexable, it depends on the application and design of seal rubber used, smome are rigid so made closer to the shaft diameter like in F1 engines-it is at all costs a design criteria to have no protruction comeing out side of the cases were a seal is going to be required, ? even though they produce close to 1000. BHP at the crank.

Now viton lipped seals are great but a viton tipped seal designed for a shaft at 20mm on a 19mm shaft ? you would not beleve the difference between the readings on the dyno, just
minimum of 15 to 20% improvement its also an increasing reduction as the revs rise
RPM'S

its certainly something i have found you can feel, at the seat of your pants, especilly the difference in top gear on a bantam.

But please no law suits, i'm not suggesting you try this as I always purchase 10 seals and try them on the same dummy shaft first, you would be amazed at the difference as you rotate the seal with your fingers, between them then try them on a 19mm shaft ?? just turning in you hand before fitting, the risks -the seal will not last? - NO actually it lasts longer????? , as most of the time it does allow some blow by on a piston ported, but be carefull on a reed motor, it sucks not sure why this is, the theory is above my knowledge.

frictional losses great subject - thers a s lot more to seals than meets the eye!.


regards Derek