ET: Engine (Twin) Starting Procedure Twin…Using Chokes or Not?

[CarlHungness]

Even after 30 plus years of owning my twin I can't say my staring procedure(s) are as reliable as I'd like. Having read of
the long-stroke/short stroke and practicing same my method isn't as great as it ought to be. Since installing the B-TH many
years ago I think it has improved but I still don't feel like a journeyman at the process.
I tickle the carbs, 276's, kick the engine through a couple of strokes with the compression lever pulled, try to locate the short
stroke and go just over it, pull in the comp. lever, kick and release simultaneously.
I now ride the bike on weekends and when done with a ride I shut off the petcocks and run the carbs empty so they're not
full of hard-to-ignite fuel.
It usually takes me 5-8 kicks to fire the machine when it's cold, and I've never used the chokes.
After a lunch stop I can usually start the bike with 2-3-4 kicks. I think it ought to be one, max.
When cold, I kick the bike with just a bit of throttle, maybe a quarter. When it doesn't fire I open the throttle all the
way and when it fires, it explodes at full tilt for half a second and I let it back down.
I never have enough confidence that I kick the bike without using the compression release and it often feels as though
I get a phhhht! and not a full swing through. When I do catch it correctly and she swings through a complete revolution, that's
when it starts.
Today I couldn't start it virtually at all. I must have spent ten minutes trying to make it fire and it makes me feel ham-
fisted and not nearly as knowledgeable as I ought to be. I recall the times I've had the valve caps off, plugs in and even out,
and looking and trying to 'feel' piston position so I can position the plot whereby I'm getting a full revolution when kicking.
I think I've seen photos of one using an electric start, with virtually no throttle on at all. I asked John Healy what he does to
start the machine years back, and his procedure was about the same as mine. I recall reading Ron Kemp's method in '40 Years On' where
he just finds a compression, kicks and releases the comp lever at the same time.
I'm still strong enough to kick the engine over with enough RPM's to generate spark and my extended prop stand has a 'cloven
hoof' on the bottom so I can actually let the bike nearly rest on the prop stand to insure power through the motion. Nevertheless, if
I'm on an incline to the right or left, I'll often push the bike to level ground before kicking.
But I've never used the chokes. What's the group's recommendations for this old timer? Trevror Southwell once described
Dave Hills' method of starting his (battery operated ignition) bike as appearing as though he was merely shaking his leg enough
to straighten out the creases in his pant leg. I'm up high on the kick start lever, and even after grinding the first tooth on the ratchet
I find the gears will hit 'on-end' upon occasion, so I try to remember to come down a tooth or so before kicking. I even had an 'expert'
grind the ratchet gear one time and the condition persists, but I can live with that.
While in the UK I resorted to heating the plugs in early morning and that process sure seemed to work well, but I sure ought to
have a process that works without all the aggravation I went through this morning. It's depressing. Even if I had an electric start I'd
still want to kick the bike manually because it was designed to start that way and my forefathers used the method successfully.

 

[greg brillus]

Carl, some engines (twins) are easy to start and others are difficult.........my Rapide has original 276 side bowl carby's, 8:1 pistons new type BTH mag, and some type of high lift/duration cams........these have more duration than Lightning cams........My engine starts well hot but can be a bitch from cold.......I found for a while that I was actually giving the engine too much fuel on a cold start, so you have to go with either no chokes and tickle the bowls, or use the chokes and do not touch the ticklers........I cycle the engine over with the decomp lever but only using it to go past TDC then release it so it can draw fuel in........I feel if you hold the decomp lever in and hold it there whilst turning the engine, this will achieve nothing, as with the exhaust valve lifted off its seat, the piston will draw air back in from the exhaust port. I am 100% convinced that most all engines that are hard to start, and have good carby's and ignition set up and tuned well, that the issue is in the cams.......and/or their timing......I have tried different coil ignitions on mine hoping it would start easier, but this made no difference at all....... The spark from the new BTH mags is not that great at kicking speed, but i'm not convinced that this is affecting mine to any great amount........the problem with big cams is in the overlap........this causes a big portion of the intake charge to be pushed back out of the carby, then this actual "double charge" gets sucked into the engine and is actually very rich.........it is finding a good balance of not enough fuel verses too much fuel.........try turning the fuel taps on, close the chokes.......do not touch the ticklers at all........cycle the engine over a few compressions, then fully kick.......once it fires, then pull the choke levers back to clear the engine.........try not to open the throttle too much as you come down on the k/s lever, this is especially important on a hot engine........these engines like almost nil throttle when starting from hot, as an open throttle leans the mixture out too much........good luck with it.......Cheers. ...Oh one other notable point.......Thick oil makes kicking over a cold engine much more difficult.......I run a 15W/40 Diesel oi in mine and this allows the engine to spin over much better from cold.........thick oil will definitly make the engine much slower to turn.........4 main bearings and all that drag.......all good.

 

[CarlHungness]

Your punctuation, or lack thereof, makes your question extremely hard to read.

Guess I should have proof-read the post, I don't normally make grammatical mistakes, but I dare say the basis of the post still comes through.

 

[CarlHungness]

Carl, some engines (twins) are easy to start and others are difficult.........my Rapide has original 276 side bowl carby's, 8:1 pistons new type BTH mag, and some type of high lift/duration cams........these have more duration than Lightning cams........My engine starts well hot but can be a bitch from cold.......I found for a while that I was actually giving the engine too much fuel on a cold start, so you have to go with either no chokes and tickle the bowls, or use the chokes and do not touch the ticklers........I cycle the engine over with the decomp lever but only using it to go past TDC then release it so it can draw fuel in........I feel if you hold the decomp lever in and hold it there whilst turning the engine, this will achieve nothing, as with the exhaust valve lifted off its seat, the piston will draw air back in from the exhaust port. I am 100% convinced that most all engines that are hard to start, and have good carby's and ignition set up and tuned well, that the issue is in the cams.......and/or their timing......I have tried different coil ignitions on mine hoping it would start easier, but this made no difference at all....... The spark from the new BTH mags is not that great at kicking speed, but i'm not convinced that this is affecting mine to any great amount........the problem with big cams is in the overlap........this causes a big portion of the intake charge to be pushed back out of the carby, then this actual "double charge" gets sucked into the engine and is actually very rich.........it is finding a good balance of not enough fuel verses too much fuel.........try turning the fuel taps on, close the chokes.......do not touch the ticklers at all........cycle the engine over a few compressions, then fully kick.......once it fires, then pull the choke levers back to clear the engine.........try not to open the throttle too much as you come down on the k/s lever, this is especially important on a hot engine........these engines like almost nil throttle when starting from hot, as an open throttle leans the mixture out too much........good luck with it.......Cheers. ...Oh one other notable point.......Thick oil makes kicking over a cold engine much more difficult.......I run a 15W/40 Diesel oi in mine and this allows the engine to spin over much better from cold.........thick oil will definitly make the engine much slower to turn.........4 main bearings and all that drag.......all good.

Pretty good advice Greg. Against my better judgement I did install MKII cams and was warned I wouldn't like them as much as the original MKI's, and that's proven to be true. They're great on the top end, which I don't use much and not as peppy in the lower RPM's. Your description and prior knowledge are convincing. I've never tried to start the bike with just the chokes, and did not consider what happens with the decompressor enacted. I've used Valvoline 20-50 forever. Actually, it's not bad to hear that a journeyman such as yourself has had problems starting the bike from cold and that gives me some solace. I do want to get a set of MK1's for the bike sometime, but I'm no looking forward to yanking the engine out again to do the swap properly. I'm starting a new discipline of panel beating that will take 4-5 years to become fairly proficient at, so my days are really full. I'll try releasing the decomp as you suggest and utilize the chokes. B-TH does have some new coils which I ordered and wonder if they supply a bit more juice at low cranking RPM. Thanks so much for the input and hope my punctuation here is acceptable.

 

[Scout63]

Interesting post and response. I have yet to try to start my new to me Series B twin so am reading what I can. Thanks. Ben

 

[Chris Launders]

I have Mk1 Concentrics and a BTH on my twin, I just tickle the carbs, ease it up to compression and kick it.
It normally starts first kick, however a couple of caveats, it doesn't seem to have a lot of compression and I weigh 20.5st (130kg)
The valve lifter only gets used to stop it.
I don't have chokes fitted.

 

[timetraveller]

.I would not argue with the above advice but on the ex-Cecil Mills bike with M IIs and 9:1 pistons it normally starts first or second kick so I would not worry about changing the cams for some time. There are no chokes on the Monobloc carbs so I flood it generously. Kick it over a couple of times to make sure it is out of gear or that there are no other problems and then just boot it, letting the valve lifter off half way down the kick start stroke. My experience leads me to believe that one needs a good spark (I have coil ignition and get a really decent spark) and just let the inertia of the flywheels do the work. No messing about with trying to find the long or short stroke, no trying to get the engine into just the right position, just a good strong kick and a good spark. If it does not start first or second kick then either I have flooded it too much or not enough. If too much, open the throttle fully, kick it over several times, and let the spark burn off any excess from the spark plug. A good spark will do that. I am 200 lbs and five foot seven or eight so no superman type physique.

 

[CarlHungness]

I have Mk1 Concentrics and a BTH on my twin, I just tickle the carbs, ease it up to compression and kick it.
It normally starts first kick, however a couple of caveats, it doesn't seem to have a lot of compression and I weigh 20.5st (130kg)
The valve lifter only gets used to stop it.
I don't have chokes fitted.

I got lousy mileage with the Mk1 concentrics and changed to the original 276's.

 

[CarlHungness]

Interesting post and response. I have yet to try to start my new to me Series B twin so am reading what I can. Thanks. Ben

If you have a stock magneto I'm pretty sure your bike wants to be started on the rear cylinder because the magneto was originally made for a vertical twin and it does not put out a full spark at low kicking revs when installed on the Vincent. If that's the case, and I had a stock mag for many years, I'd suggest you opt for the B-TH which puts out equal spark on both cylinders. Thus if it has to be started on the rear cylinder you'll have to fiddle and figure out where that compression event is as you operate the kick-start lever. I did so for several years and was much happier with the B-TH, a very simple and inexpensive conversion. It'll idle better as well.

 

[CarlHungness]

.I would not argue with the above advice but on the ex-Cecil Mills bike with M IIs and 9:1 pistons it normally starts first or second kick so I would not worry about changing the cams for some time. There are no chokes on the Monobloc carbs so I flood it generously. Kick it over a couple of times to make sure it is out of gear or that there are no other problems and then just boot it, letting the valve lifter off half way down the kick start stroke. My experience leads me to believe that one needs a good spark (I have coil ignition and get a really decent spark) and just let the inertia of the flywheels do the work. No messing about with trying to find the long or short stroke, no trying to get the engine into just the right position, just a good strong kick and a good spark. If it does not start first or second kick then either I have flooded it too much or not enough. If too much, open the throttle fully, kick it over several times, and let the spark burn off any excess from the spark plug. A good spark will do that. I am 200 lbs and five foot seven or eight so no superman type physique.

I don't know for certain, but I'm speculating the coil ignition puts out a much healthier spark than any magneto, stock or B-TH. The result of course is easier starting, but trouble if you have a dead battery.