Twin plugging and other options

andrewinuk, I would be interested to hear what instructions Cray provided for running with twin-plugs and a modified bean can.

My bike is now having a good going over up at Roy Gardner's where he discovered that the dry drive shaft was rather wet :blast
 
Some guys who have tried including RM only set ignition timing on a dyno as they have found a 6 degree difference in optimum timing between bikes.
I have the Boyer twin plug set on my G/S up which works well and has been fit and forget,but the max advance mark is not anywhere to be seen over around 3500 revs so I dont know what sort of timing I have.
It was set be trial and error as at the time the bike didn't have a rev counter and I didn't have a timing light.
I try to keep the revs 500 either side of peak torque as much as possible, and if you do the ignition curve doesn't matter much as the ignition will be at full advance most of the time anyway.
 
Ok... I have an idea. When I get a moment in the next month or two I will take the GS to my local dyno for the morning and try an experiment, just for curiosity's sake and because I can.

1. Run with twin-plugs, existing timing which was optimised on dyno and the bean can modified by Andrew Sexton
2. Disconnect the 2nd plugs and run with single plug, standard timing and a standard bean can
3. Run with my new twin-plug Boyer and timing optimised on the dyno

I'll of course keep an eye on the fuelling via AFR meter but would change carburation settings only if necessary. However, to do this I would need loan of a standard bean can for a while. Anybody interested enough to lend me one?
 
Sean Kelly said:
andrewinuk, I would be interested to hear what instructions Cray provided for running with twin-plugs and a modified bean can.

My bike is now having a good going over up at Roy Gardner's where he discovered that the dry drive shaft was rather wet :blast
Click to expand...

I'll have a dig in the shed tonight but i last saw the little bit of paper a long while ago :-/ but it was basically altering the timing to suit what ever modification he made in the bean can along with the compression change and twin plugs. Thinking anyone more technically minded than me and familiar with this mod could advise on where the mark is supposed to be!

Good luck though and looking forward to hearing how you get on.
 
As I cant see the full advance mark on my twin plug bike it must be well down, round about 24/ 25degrees advance.
If you have lost the timing altogether then set the can in the middle of the adjustment and get it started.
Then adjust the can until you have the fastest tickover, then back the advance off to just short of the point where the motor starts to slow down. Mark this point well with a couple of centre punches
if your luck is in it will run well there, but there is probably a little more to come if you take it to a decent sort of hill where the motor is pulling hard and experiment with a little more advance.
This was much easier back in the day when distributors has a adjusting knob and one degree click either way was easy, but it isnt too hard on an airhead as long as you have heat resistant wrist protectors - the exhausts get real hot if the timing is a little retarded!
 
Bike back from Roy Gardner's and running lovely. Hardly seems worth messing about with the ignition but I am a curious soul. No offers yet of loan of a standard bean can so maybe a straight comparison of Boyer and tweaked Bean can will suffice.

Roy runs slightly larger valve clearances as he believes standard clearances account for some of the hot, high tickover issues. I'll see how this works out. I'd forgotten completely that the bike is running a k&n air filter of which I'm not a big fan. I'll consider whether to swap to OEM and rejet for the South America trip.

My strobe lamp has a knob on the back for checking advance retard so will have a look at what that reveals about the a Sexton tweaked bean can.
 
Sean Kelly said:
Bike back from Roy Gardner's and running lovely. Hardly seems worth messing about with the ignition but I am a curious soul. No offers yet of loan of a standard bean can so maybe a straight comparison of Boyer and tweaked Bean can will suffice.

Roy runs slightly larger valve clearances as he believes standard clearances account for some of the hot, high tickover issues. I'll see how this works out. I'd forgotten completely that the bike is running a k&n air filter of which I'm not a big fan. I'll consider whether to swap to OEM and rejet for the South America trip.

My strobe lamp has a knob on the back for checking advance retard so will have a look at what that reveals about the a Sexton tweaked bean can.
Click to expand...

I have a good, spare bean can you are welcome to try. Would pop it int the post to you if you want a loan for a couple of months.
 
Thanks for the offer warmshed that sounds great, just what I need. I might delay the test until after I get back from South America at the end of January. Following the delays with the gearbox leak I'm not convinced I want to change much so close to the 'off'. The Boyer is sitting on the workbench though and it is so tempting to have a play.

Also realised that I must have fitted a K&N air filter at some point, so with that, the Y-piece and the twin-plugging I reckon I might need the dyno for a week. My local dyno chap is up for the experiment although his rates have gone up somewhat.
 
You would be welcome to take it with you if you think a spare might be handy, not something you can source locally out there.
 
That's a very generous offer, thankyou. I wouldn't take it to South America as I'm travelling light but if it was at home, it could be posted to me quick if I needed it. I might still get a chance to try it on the dyno before I go too. I'm not a subscriber here so can't accept PMs but maybe you could drop me a line through my website email, info (at) sunbeamland.com should work ok.

Many thanks
 
FYI I just checked my existing timing with modified bean-can using a Gunson strobe with the adjustable advance dial which I imagine will be reading double because of the wasted spark ignition. At tick over I estimate it to be actually 4 degrees advanced, maybe a little less than a tooth. Over 3000 rpm the Z mark is pretty much lined up.

The new Boyer information suggests dialling in 3-4 degrees retard at full advance which sounds reasonable.

The timing was originally set by Andrew Sexton, fiddled with by me on the dyno (should have kept notes!) and may then have been reset I suppose at some point when the bike has been serviced in the last 10 years.

Current status : baffled.
 
Bought a cheap-as-chips strobe from eBay which suggests that my Gunson strobe with the adjustable advance dial may be playing up. The new strobe gives me standard timing at tickover and a few degrees less advance than standard over 3000 rpm with the Sexton bean-can. This is what I "want" to believe of course but if you tilt your head a little you can line the marks up any where you want. Mr. Warmshed of this parish has kindly offered to lend me his standard bean-can for comparative purposes and also as a spare for the upcoming trip.

In the meantime as I decided to ditch the K&N for this trip I thought I'd get some baseline results and fuelling data against an OEM filter. Removing the K&N improved initial throttle response and required a size down on the main jet to cure a slight richness as expected. Also the cheapest 3hp boost I ever had. The bike has a problem with sustained high-speed (well 90mph plus) at the moment, maybe fuel starvation and will require further investigation. Also, tickover has always smelt a bit rich and leads to sooty plugs around town so I also went from a 45 to 40 pilot which I think is now too weak. I think a 42.5 would be perfect if they made one.

Next step is to sort the starvation issue and to try the Boyer out.

 
Not sure if it makes much difference but if you are standing when doing the dyno run then you will not be compresssing the rear spring and lining up the shaft with the gearbox in same way as you would when riding. Is it possible that some power could be sapped by the UV joints if the shaft is not lined up in straight line? All the adjustaments will show their relative gains if you are consistently standing when doing the dyno runs but nonetheless would be interesting to see if being fully seated would effect readings.
 
One float height was really quite low, I blew some air down the breather, added some more fuel to give a head of pressure as the HPN tank carries the fuel low and the bike now holds 90+ no problem. 80mph is my normal, comfortable cruising speed on the bike.

Hadn't thought about the effect of drive shaft alignment on power but if the shaft soaks up much I suspect it would be getting hot pretty quick. We can certainly look into it but consistency on a dyno on different days or even different times of day is hard to achieve. It's always interesting though and can throw up some surprises.
 
Sean Kelly said:
Hadn't thought about the effect of drive shaft alignment on power but if the shaft soaks up much I suspect it would be getting hot pretty quick. We can certainly look into it but consistency on a dyno on different days or even different times of day is hard to achieve. It's always interesting though and can throw up some surprises.
Click to expand...

...but at the end of the day, it isn't a Honda Fireblade we are tuning !! :D
 
Good point and well taken. My standard 'blade is terrifying enough thankyou very much.
 
The problem with the angle of the driveshaft joints on a paralever is that whatever power loss there is is transferred into heat in the joint and this heat can result in the joint loosing it's lubrication.

Monolever joints are cooled and lubed by splash by the oil in the shaft and dont suffer as much.

If the para joints loose their grease, then joint life is greatly reduced - drop the suspension on a Datsun 260Z and the previously bulletproof rear end won't last 20 hard miles. 240Z rear ends weren't bulletproof, if you wondered-------.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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