light racing cam chain and sprockets

some of you will recall two years ago i wrote of lightweight racing cam chain and from a sherco that could be fitted. I put up a few photos etc but on my 400 i couldn't make the links work right. Well the same has happened on the 650 engines as well where they are really needed.

i was 1 1/2 teeth out so i needed to add 1mm to the headgasket (etcetra) or take over 5mm off. so i bought two £1 cam bearings that had an OD of 28mm and not 32mm to lower the cam by 2mm. i removed the head gasket (worth another 1.35mm) and even with the 3.35mm off i needed much more off.

so because the top cam sprocket rubs so hard against the CCTB at the pivot i came up with the next best idea i could and that was to go for 17 & 34 teeth. last week i had dummy cam sprockets made that are essentially just 'wheels' and tested the theory. the '219' chain i was trying was still a long way off but the sherco chain came to within 1mm.

now i have 0.5mm too much squish on most of my engines and so to skim the 'block' by 0.5mm will be a godsend for two reasons. firstly the squish will come right and secondly the chain will fit!

so I'm ordering up a batch of 10 sets of cam sprockets. the top sprocket in aluminium and the bottom one in dural.

actual real life chain fitment may alter a teeny bit but hopefully i've got it right.

hopefully with everyone using CNC nowadays, fresh batches can be re-ordered no problem. the bottom sprocket has been altered to align the two sprockets correctly.

now i know you'll be asking me for prices but i don't have any yet. the weight saving will be substantial. 30%.

regards

Taffy

a lot of the info was given to me by other people when i wrote the doc. now i'm in business i see that none of them are worn out and they actually lasted better than the chains. I now modify the original cam sprockets and leave them in for racers and others have a choice.

regards

Taffy

just thought i'd let you see the photos and stuff. this first one is an old photo i took two years ago when i first had the idea of the lighter cam chain.

below are the 4 discs i had made to get the correct PCD and a cheaper way of deciding whether the idea is on or not

below shows a 53 disc in front of a 219 sprocket! you know what the 53 sprocket is off but i won't be telling you what the 219 is off. what a shame it doesn't all work out! but if i can get it going first i may change design in time and go to the 219.

drawings of the 53 sprockets supplied by IWIS. the machine cutters are already there I'm told which saves a lot of money. apparently they already cut this kind of sprog but slightly narrower.

clever buggers aren't they!


regards

Taffy

Damon

Just admit it. I'm still the daddy round here! :twisted: :twisted:

bonegraft: if you were here, i'd put a comforting arm around your shoulder and pat you on the head exclaiming 'bless you!' as i laughed.

I can scarcely be bothered to answer the remarks gentlemen.

go back to your overweight LC pistons and make an ashtray...... :twisted: :twisted:

regards

Taffy

Now ordered and will be with me in the next week. I'm having ten sets made.

do you think i'll get another 'usable' 250 revs out of it bonegraft? i can never make my mind up.

regards

Taffy

well the alloy sprockets had the look of home made while the steel sprockets do look like nice propreitory parts just like all the european manufacturers use now.

open a ktmhusabergshercobetagasgasvorvertamatihusky and you'll see that they are all sharing parts from the same little man named pedro who works very hard somewhere....

nothing to do with vibration damping me thinks.

I haven't finished yet. I also have another idea to do with cam drive that will make your eyes water.

regards

Taffy