Valve timing

Not an oversight Piet, just a lack of knowledge! I've got a few mates with Nortons and have never heard mention of a cam chain so I just assumed they were driven off the crank.Same with the Matchless! Always good to increase the knowledge base... :D


Perhaps we could substitute Beezers and Vincents instead....
 
I guess I was thinking of the honda twin and four cyl ohc bikes which run in the pre ?73 "true classic" classes and neither was I aware that these brit bikes used chains.
Cam?s work is something any of the more competent fiddlers on the forum could manage. It can have very noticeable benefits and is just one step above Lothars mantra of carb setup and valve clearance. I know that production endurance teams in Oz set up motors ready to install for different characteristics, fuel consumption for less pit stops, midrange for wet race etc by installing every cam in the importers parts store and recording its timing, as they weren?t allowed to modify anything. A bit of research for what you want to achieve and you can have lots of fun in the workshop.
 
Tippie, the cam timing on my race motor has been significantly altered from the original factory settings with very successful results, our plan was to build a motor with more mid range than the normal peaky power delivery of an F500 spec motor. The difference is incredible.
 
Never mind anything else, I want to know what cam thinks has improved via a seat of the pants report!
 
OK. Here's the seat of the pants report. I took the bike for a short blast - about 3000km.

Compression is up from 150 to 180 psi

The motor feels more responsive in the mid-range and possibly a bit in top end too.

Throttle reponse is better when lifting the slides off the idle position - no hesitation before the power comes on (which it did do before)

Exhaust note is different - kind of sharper and louder, especially when in the resonant rev range of the pipes.

Fuel consmption has improved dramatically. Before adjusting the cams, I was having to turn on the reserve tap at about 140km after filling the tank. On the trip to Sydney, I was regularly doing over 200km without having to go onto reserve. That's at least 60km additional range, or a 40% improvement. It may even be more because I have yet to discover how far it will go before reaching the reserve.

Cheers,
Cam
 
That's a great result Cam, wonder how many Lavies are out there running less than optimum performance cause the valve timing is out!!
Last night I read through all the different valve timing topics as well as Phil T's Laverdamania artical and I'm now pretty comfortable I sort of know what I'm doing :-\
All I need now is my head back from the Ceramic coaters to check how inacurate it'll be.
 
I dont fancy my chances playing with cam timing but it looks like the benefits of getting it right are well worth having. Thanks for the feedback Cam.
 
Dellortoman said:
Fuel consmption has improved dramatically. Before adjusting the cams, I was having to turn on the reserve tap at about 140km after filling the tank. On the trip to Sydney, I was regularly doing over 200km without having to go onto reserve. That's at least 60km additional range, or a 40% improvement. It may even be more because I have yet to discover how far it will go before reaching the reserve.
Click to expand...

Cam

That's stil pretty thirsty though. Mine gets 130-135 miles (210-219 km) before I have to switch to reserve, and I've still had petrol at 180 miles (~290km), although not much! I have RS36s and a digital ignition. but I did get a 40+% decrease in fuel consumption when I ditched the Dells and the HKZ system. If I degree the cams, I wonder if I'll get another 40% boost? With the way petrol prices are going here (about 75% increase in price in 6 weeks), that would be a nice thing to have.

Ken
 
After all the stuff just done to my Jota, including cam timing by Keith  and new ignition, I have 165 miles so far  and reckon on at lest 20 more to empty. Sure does make life easier on a longer trip, apart from saving a few quid.
Nick7
 
  I have seen so many owners so pleased that their cams had been degreed in - citing stories just the same as Cams - especially in the Uk where so many 4/C cams were fitted on A11 wheels. - Which exaggerated the "rich shift"  that most triples have to some degree as mid range RPM ( Where a lot of everyday use is) - thus causing high fuel consumption.  - With fuel so expensive now - it's even more vital not to waste it -Go get those degree discs out - Regards - Phil
 
mcnicol said:
That's stil pretty thirsty though. Mine gets 130-135 miles (210-219 km) before I have to switch to reserve
Click to expand...

G'day Ken.

I haven't yet found where reserve is. I think the furthest I got was 208 km (without reaching reserve) before filling up. It may indeed be as good as yours. Hopefully better  :D

Actually, I expect it would go quite a bit further because Tim and Russ generally took a bit more fuel than me when we stopped to fill up. We all have identical tanks and they hadn't reached reserve either, so there was probably a litre or two still to go in my tank until it reached reserve level. So I'd guess maybe 220 to 230 km.

One thing I haven't tested is whether it makes any difference to how far you can get running with one fuel tap open or both open. The theory being that using only one tap will leave a bit extra in reserve in the other side of the tank. But I suspect not. I reckon the fuel probably sloshes around enough to cross the centre barrier in the tank.

Cheers,
Cam
 
Dellortoman said:
OK. I'll see what I can do to get it sorted. I don't like the idea of filing out the holes in the camshaft "ears". But I dunno how hard the sprockets are to drill and tap. Anyone want to sell me a set of vernier sprockets?

Phil, I checked the crank phasing. It's perfect. I couldn't detect any misalignment within my ability to measure with a timing disk.

Speaking of timing disks. I'm too stingy to buy one so I made my own which I've attached to this post as a pdf. I sized it to print out at 120mm diameter - the same size as a CD. Print it, cut it out carefully with scissors and glue it to an old CD. The CD is a bit smaller than most commercially available disks, but plenty large enough to read to within half a degree or so. I did two versions - one with 4C and one with A11 valve timing marks. If anyone wants anything different I'm happy to oblige. The centre hole in the CD needs to be bored out to 22mm to fit the alternator thread on the crankshaft. If you don't have a reliable way to bore it out (I used a lathe), just glue the paper on first and then use the printed circle as a guide to file it out. Best to use a rap music CD - they're no good for anything else  :D

Cheers,
Cam
Click to expand...

Hi Cam

how many beers would it take to convince you to do a timing wheel pdf for a 120 motor? I have no idea how to do it on a computer for myself. Pretty please? 8)

Paul LeClair
 
one of these?
http://www.tavia.com/free_degree_wheel.html

or the pattern for drilling holes in the sprockets?

the std bolt holes for A11 180 and the F1 120 are the same
4 degrees off of tooth peak
only difference is the marking for lining the cams up to the bearing

4C bolt holes line up with tooth peak
 
I must point out that, even making the tappings for the camwheel holding bolts in exactly the right place on the camwheel, it is no guarantee that timing will be correct. It depends as much on the relationship between the teeth on the non modifiable crankshaft sprocket and the position of the crankpin on that web. Of course crank needs to be perfectly phased as well. I did have a customer who had bought a complete  genuine factory4/C camset (Wheels and cams) that was miles out. So, once again, get those degree discs out!! - Regards - Phil
 
"One thing I haven't tested is whether it makes any difference to how far you can get running with one fuel tap open or both open. "

Cam, I've never had a triple that would run well on only one fuel tap.  They wouldn't flow enough fuel.
 
Cam, I've never had a triple that would run well on only one fuel tap.  They wouldn't flow enough fuel.
Click to expand...

What he said  ;)

These big old triples with biggish carbs and pump jets can consume vast amounts of fuel at certain times (like when you cane it  :D )

I took a triumph T595 around Snetterton for a track day and got around 16mpg  :o  That's a modern - light(ish) bike with fuel injection. Bet you could get a Lav close to 10mpg in the same conditions. That means, at an average of 100mph you need to flow a gallon of fuel in 6 minutes - won't happen through one tiny hole (tried it when I wanted to fill the mower - takes ages  ;) )  Even if you could just get enough, the furthest carb would be starved on occasion - not a good plan....

Of course, if you use it to go shopping, you should be fine  :P :P

Italians are actually pretty good engineers - if the bike only needed one tap, that's what they would have fitted  8)

Pete
 
I usually open both fuel taps, but one day I only opened one for whatever reason (probably got interrupted while starting the bike) and the bike ran fine. I didn't know it was only running on one tap until I shut it down at the end of the day. I wasn't caning the bike though, just cruising along through flat country at the speed limit without using much more than half throttle. So flow wouldn't have been an issue.

At one stage on the climb up the Monaro Highway into the mountains, Tim said his 3C was running out of steam when he was giving it bit of stick to catch up after dropping behind. I think Russ and I both asked at the same time whether he had both taps open - he didn't. After opening the second tap, no more top end power loss.

Cheers,
Cam
 
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