optimum degree btdc for starting your engine?

Hi

Set up a Boyer on my rust bucket (hack) soon to be ride. Its an analogue MK111 & I, top dead centred the engine took it back 31* & locked up the rotor & set up the pick up plate. It always seems to start pretty well & occasionally I let it dance across the pavement to do fully advanced at 5000 revs. Really not fun on your own. Two people sitting on the seat would help. However? It made me think. With the Boyer, where should you be setting it up for easy starting? How much does the Boyer actually advance?
I would like a bike that starts like Jims old video ie with my hand. The way my knees are going I'm going to need it.

Chris

Each box has a slightly different curve due to variances with the various parts, so fully advanced is the safest way to time a Boyer, I have changed boxes only and the timing was way different by as much as 10 degrees as I had to move the rotor to get the plate to move enough to get back to 31 degrees. If you want to retain 31 degrees and get a curve to suit good starting BTDC then you need something with a programmable curve.

Chris said:

Hi

I let it dance across the pavement to do fully advanced at 5000 revs. Really not fun on your own. Two people sitting on the seat would help.
Chris

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Setting it on the side stand seem to work better. Setting the center stand on a rubber mat or rug will help also.

I think the key to easy starting with these units is a good battery and charging system.

you can't set an analog non programmable Boyer for "easy starting" unless you are trying to eliminate the kickstarter kicking back at you, and you do that by retarding the timing until it just stops doing that

in fact many say the timing is then set and no need to strobe it, you are done, button it up and go ride

the Boyer senses the very low rpm of the motor turning when you are kicking it and retards the timing
for much easier starting and then progressively advances the timing until fully advanced around 5k rpm

My MK3 at 5000 rpm om the centre stand is smooth as glass. It bobs around plenty at idle, but rev it up and everything goes smooth, which is what the isolastics are all about. At 5 k, or anywhere above 3200 rpm you can lay a hand on the tank or seat anywhere and barely feel that it is running. Mirrors are dead still, images are perfectly clear.
650 ss revved up on the center stand, now that is a different story, it wants to leave town! :mrgreen:

Glen

If you set the Boyer at 31 degrees fully advanced,it would be starting at about 12 degrees advance at 200 rpm cranking speed.
I can start a 750 twin with the timing locked at full advance,and it will start easily with a swift kick.With a 1/2-hearted kick it will kick back,especially if you open the throttle instead of having it almost closed.
They'll idle well with 5 degrees advance or 30 degrees advance at idle.

You can't really set your timing by what it does at start-up or idle.It must be right when it's fully advanced.

When I kick any bike over, I always push the piston up until it is about two thirds of the way to top dead centre, then I give it a firm push over the top. If it kicks back and you got firm pressure on the kick start, you will always hold it. If you bounce the piston off compression with the kick -starter, leaving some slack - it can bite you very hard. I've kicked over a racing 1000cc Vincent which was on 13 to one compression, without difficulty. The ignition timing is pretty much irrelevant an long as you keep the firm pressure on the kickstarter. My old 650cc Triumph road bikes always had the ignition locked at full advance 38 degrees. I could always start them first kick without getting bitten. I've only ever had one problem, and it involved my knee injury. I broke the piece of bone off in the centre of the joint. I tried to kick my mates 1963 Bonneville over, it kicked back however I had hold of it. The nerve got pinched in the joint by the loose piece of bone and I ended up on the ground in agony.

A loose bone chip in a joint is called a "joint mouse". I learned to time Boyah once close enough to start by adv till hints of back fire then retard til it don't then put time light on to see what it says for fun, then run adequate octane or use educated throttle hand so no detonation to matter. An optimally timed engine making best power on the octane needed will tend to run with slight detonation you can't hear feel or detect w/o close inspection. After pre-Peel drag strip took out my R knee allowing foot to touch R hip by sideways freedom of crushed joint and torn off ligaments only jeans and skin kept attached to me, I had some non riding time to switch out points for analog boyah the DPO hadn't put in yet. I could kick off w/o hurting R knee within 3 wks of my non medical non attention to local mis-leading mis-guided therapy [but holding together by ace wrap with sheet magnets- till I descided to follow instructions and set to 31-32' while running, then parked bike up on top near edge of slope near house and tried to start it for a back fire that re-crushed R knee lifting me over bike thrown down slope to roll a dozen feet to bottom then whiting in severe pain again - but only for 10 min, then eased up and could gimp away ok, so pleased no end I'd made right decison not to have knee surgery done. Timed back by trial error and was able to kick off and ride though I was called Festus by the local another 6 months before knee completely regrew all surfaces and ligaments *** till taken apart a few times more from deer impacts and goat and dog take downs - but re grew it better than new and can squat fully on it for as long as I want and arise w/o climbing up myself like the rest of you old farts missing out not being in hobot camp that goes against the grain of accepted wisdoms. L knee and both ankles also similarly injured last decade to point i could see bottom of boots while standing , so put good foot on torn open/dislocated ankle to pop back downward facing to gimp around a few months till regrown again better than new. Bones and joints are the ONLY tissue in us that can regrow better than new if nerve and blood and nutritent supply is sufficient. All other tissues only heal with fibrosis/scaring, though can regrow around the scar better than new I've found so my reputation as last resort Dr. keeps em coming a long ways away so I can afford to buy more cycle parts to use up.

Neck traction/stretching plus mutli-minerals above label daily dose has regrown my height almost a couple inches since '99 taking up cycles again, 120 mph hi side with bike on head and worse headlight and helmet deer killing, to point I had to go back to 34" inseam jeans instead of 32" that fit the prior 2 decades. This almost killed me though d/t stroke brain death AWAKING IN SEVERE SUICIDAL INTENSE OUT OF MIND PAIN > SHOULD I PULL TRIGGER NOW OR LEAVE WIFE WITH INVALID to care for that couldn't speak or feed myself, till I realized I was almost 2" longer so had to start with feet near end of bed so pillow pressure on head board didn't choke off brain stem control of brain blood flow. As you slowing die with squirming or seeing friends and family going down with the medical approach remember me in glee on track days to come attempting to take records with a air cooled rubber baby buggy that flat disappears but for road patch harmonics and power steering by slight R wrist action so most the effort is forcing blood to stay in brain to have vision enough to aim as next decision point to jump the rails others are so stuck on.