Valve timing

I've attached the drawings for A11 and 4C vernier cam sprockets. I haven't done them for the 120 cams, but will do if anyone needs them. The only difference is the location of the timing marks, which is not really important for drilling the sprockets. It just helps to identify which sprockets you have.

The tooth spacing is 12o and the hole spacing is 25.71o, so the indexing increments at the cam wheel is 1.71o (one hole shift - two tooth shift). That equates to 3.42o at the crank, which is quite a coarse adjustment, but there isn't enough room on the cams to drill more holes. Fine adjustment between the 3.7o can be obtained by slotting the holes in the camshaft flanges. A 1mm slot is sufficient because that gives near enough to 4o change at the crank, so you don't need to remove heaps of metal.

Note that if you have A11 sprockets on 4C cams (as I did) you may not need to drill more holes. I just flipped the inlet cam over and slotted the cam flange holes to get them right.

Phil Todd has said on several occasions that the bolts won't slip in the slots. This is also confirmed by ny experience. I've done about 3000km since slotting my cam flanges, and the timing has stayed put. One thing I probably could have done (but didn't) is loctite the bolts. But they weren't loctited originally and they do have lock washers anyway. I'll check them next time I do the valve clearances just to make sure nothing has come loose.

Edit: Hole set 0 on each drawing is the original hole set. Sprockets are marked "A" and "S" for inlet and exhaust respectively (Aspirazione e Scarico)

Cheers,
Cam
 

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Dellortoman said:
Hi Paul

I'm happy to draw up whatever you need, but I'm not sure whether you want a vernier sprocket, a degree wheel, or a degree wheel with valve timing markings on it.

Cheers
Cam
Click to expand...

Hi Cam

since I don't even know what a vernier sprocket is, how about a degree wheel with valve timing markings for an RGS 120 F1 cam set... Pretty please?

Paul LeClair
 
My cams are in the bike, but I've been looking at adjustable sprockets and would really like to see if an adjustable one could be fabricated cost-effectively. There's a manufacturer located near me (Falicon, the crankshaft people), and although they're very Laverda-unfriendly I'm still tempted to see if they have an adjustable sprocket on the shelf that could be modified to work on our bikes.
Does anybody have a detailed drawing of the sprockets showing dimensions (centre hole size and drilled hole radius are the only ones that count, oh I guess sprocket thickness, number of teeth and chain pitch too).

Ken
 
Here you go Paul

Valve timing disks for F1 and Axtell camshafts attached as a pdf.

They're sized to print on A4 paper at 120mm diameter so you can cut it out and glue it onto a CD. I've found CD size is adequate, but if you want bigger, just enlarge it in your printer's page setup.

Timing disks for the 180 motors need a 22mm dia hole to fit over the crankshaft's alternator rotor thread. I assume the 120 motors are the same.

Cheers,
Cam
 

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Hey Cam

Good timing...... excuse the pun.........

I am planning to start looking at my valve timing this weekend............ F1's into a 120 so will use your CD  I've also got a set of 4C's to try ..........  ;)

I'm a newbie to valve timing so I'm looking forward to the challenge.

                              Cheers
                                    Matt
 
Dellortoman said:
Here you go Paul

Valve timing disks for F1 and Axtell camshafts attached as a pdf.

They're sized to print on A4 paper at 120mm diameter so you can cut it out and glue it onto a CD. I've found CD size is adequate, but if you want bigger, just enlarge it in your printer's page setup.

Timing disks for the 180 motors need a 22mm dia hole to fit over the crankshaft's alternator rotor thread. I assume the 120 motors are the same.

Cheers,
Cam
Click to expand...

thanks very much, Cam, really appreciate it. When i am eventually finished my present garage cleaning/organizing poproject and finish painting the KZ 650, I'll have a go at checking the timing of the cams in the RGS and see if i got it even close at all last attempt.....

Paul LeClair
 
Hi Nick7

Ye the beastie is up and running I'm now refining the bike and have the valve timing on the list along with others mods............... Specials are never finished.......... :)

                        Cheers
                              Matt

 
Hi all been off the forum for a bit. I have made up a Vernier cam Jig if you want just send me the wheels and I'll drill and tap them. I have a XL spread sheet with the movement per hole and tooth. 4 deg change. Considering the number of teeth and the meat left between the new drilling's it was the best compromise I could find. you still need to file the holes very slightly on the cam to give you the sub 2 deg movement. Its not much more than a couple of strokes and I have taken one to 5 deg with no harm and they have never moved.

JugsS
 

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good news Matt,
I sent my bike to Keith and among other things, he sorted the valve timing, drilled sprockets etc.Don't know exactly what difference that made as too much other stuff(new ignition etc) done together ,but its bloddy fab now! You know how you ride a bike and think it would be great if had that extra 10/15%...well it does :D
Look forward to seeing yours in action..have you been round to Clem's yet? You should have come to the ILOC AGM..
Nick7
 
Er , Keith DID re-fit them :-[ so i reckon there's 10% more to come when I whip 'em out :D Not that I am going anywhere near those carbs again if I can help it..
hey,Keith, if you are reading this, can you (I am useless at IT stuff) post a piccie of my c/head when you were playing with it..showing the drilled polished cams/billet cam blocks etc?
Nick7
 
well, all that kit  was in action yesterday...absolutely 'uckin amazing....goes like i don't know what, steams through 120 with ease, did a nice 100miles to south coast(Lewes) and back. Never had to back off before...now I do, until I learn to recalibrate.No oil used (pipes nice and dry) and so quiet at tickover(primary chain  merc duplex job now properly aligned. Can surprise some modern stuff too, which is always fun :D
Nick7
 
I had sent cam and sprocket drawings to my local hot rod bike bit maker, Falicon, to see if they had an adjustable cam sprocket design that could be adapted to our antiques. The idea was to find something that could be modified to work by individuals, rather than putting the obligation on one of the people here who works on Laverdas for an actual living. I never even considered contacting Wolfgang to se if he's interested until I started typing this email...

Anyway, turns out they're pretty sure they can adapt one of their existing designs that they do manufacture locally in house. They want to see a head and camshafts to be sure, so this weekend I'll pull my cams and bearings out, and take them plus my spare head over to their shop. Initially I'm talking 4c/7c cams ('cos that's what I have drawings for and my cams are 4cs), but the basic design should be adaptable fairly easily to A11s or even Axtells. Don't know if they'll work on 120s, though. :D

If you're interested, take a look at http://www.faliconcranks.com/sprocket_price.html. I think the $74 items are just slotted sprockets, so we'd probably be looking in the $200 price range for a sprocket with a "carrier" that bolts onto the existing holes and fits in the available space. A bit more expensive than drilling a bunch of holes in the existing sprockets, but this does give you unlimited adjustment, which the holey sprocket (Batman :D) system doesn't give you. I'm in no position to front for these. Falicon would need to SKU them up, so you could buy direct from their web site. Probably on a special order basis (which usually means they wait until they have enough orders to make up a batch). Doing it this way also means dealers could buy them too, if there's enough demand.

They have asked me how many of these they're likely to sell, which will obviously affect the price. I told them off the top of my head that "we" would probably end up taking about a dozen. So, if you think there's at least a fair chance that you might want to buy adjustable cam sprockets if they're not too expensive, could you let me know via this forum or PM or email (mcnicol_at_ij.net) so I can give Falicon a bit better idea of immediate demand. I'm planning on buying a set, SWMBO permitting ???.

Ken
 
I don't recon there is enough room in there for them.... can get to within a degree (camshaft) with drilled wheels, how much "better" do you want it?


      Keith.
 
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