Author Topic: Understanding the decompressor  (Read 13896 times)

0 Members and 1 Guest are viewing this topic.

ivantheterrible

  • Bulleteer
  • ***
  • Posts: 145
  • Karma: 0
Reply #15 on: December 06, 2018, 12:07:37 am
You use the kick start pedal to bring the piston to the place on the compression stroke where you feel compression resistance at the kick start pedal.
Then, push in the decomp to release pressure and hold it down while you SLOWLY and GENTLY move the kick start pedal to bring the piston up to TDC. You can determine the correct position by watching the ammeter deflection to indicate that the points have opened.
Let off the decompressor so that it returns to the closed position.
Then, let the kick start return spring bring the kick start pedal all the way to the top. Get a good strong position to kick, and kick it once good and hard, and follow thru all the way to the bottom.
If that doesn't start it, repeat the procedure.

does the ammeter trick work with electronic ignition? Mine doesn't seem to deflect, or move much at all.


If it takes more than 5 kick attempts, then investigate what is wrong. Don't wear your leg out trying to kick start a bike that isn't going to start.
2007 sportster 883, yamaha vino 125, 2005 Nfield sixty 5 military with Hitchcock 612 kit


ace.cafe

  • Grand Gearhead
  • *****
  • Posts: 14,457
  • Karma: 1
  • World leaders in performance/racing Bullets
Reply #16 on: December 06, 2018, 12:55:00 am
If your ammeter doesn't move, listen for the sound of the air going out the exhaust pipe to stop.
You will get a feel for how far to move the pedal after doing it a few times. It isn't super critical. Just get it up around TDC or a little after, and then kick.
Home of the Fireball 535 !


Bilgemaster

  • Just some guy
  • Global Moderator
  • Grand Gearhead
  • *****
  • Posts: 3,251
  • Karma: 1
  • 2005 Bullet 500ES in "Mean Green" Military Trim
Reply #17 on: December 06, 2018, 05:17:20 am
If your ammeter doesn't move, listen for the sound of the air going out the exhaust pipe to stop.
You will get a feel for how far to move the pedal after doing it a few times. It isn't super critical. Just get it up around TDC or a little after, and then kick.

Thanks for the kudos! Just to add my two kopecks to Ace's explanation, the little ammeter swing he describes, and which is also explained in countless "How to Start a Royal Enfield Bullet" checklists and also YouTube videos, is caused by the electrical draw of the ignition points closing and opening. Mine was fitted with an electronic ignition by a previous owner, and so does not do this little ammeter dance. I've gotta guess that with all your bike's fancy gimcracks it's even money that you may also have an electronic ignition. So don't get too hung up on the ammeter thing if nothing's going on there. Just get the kickstarter through until it's really FIRM, and then a little steady pressure until it just isn't (you don't really need a decompressor to get it there in the stroke--it just helps make it easier), and with the choke lever on the carb down, a nice solid gentle kick may get her sputtering. Mine likes the very faintest wisp of throttle when cold, but try first with no throttle at all. They flood easily. But you know, each is different. You'll get it down to second nature in no time.

One other thing: Before commencing your whole "12 Lords A'Leaping Tribute" for this holiday season, you might do well to pull in that clutch and kick it through a few times to free up those clutch plates a little to make things easier. Your right leg will thank you.
« Last Edit: December 06, 2018, 05:58:07 am by Bilgemaster »
So badass my Enfield's actually illegal  in India. Yet it squeaks by here in Virginia.

 


Unlucky_soul

  • Scooter
  • **
  • Posts: 27
  • Karma: 0
Reply #18 on: December 06, 2018, 12:58:49 pm
You could remove the decompressor and fit in another spark plug there. Dual spark plug ignition for more responsive power and milage. Have done it on one of my bikes


ivantheterrible

  • Bulleteer
  • ***
  • Posts: 145
  • Karma: 0
Reply #19 on: December 06, 2018, 04:05:43 pm
You could remove the decompressor and fit in another spark plug there. Dual spark plug ignition for more responsive power and milage. Have done it on one of my bikes

Really?! I had no idea, that's very interesting.
2007 sportster 883, yamaha vino 125, 2005 Nfield sixty 5 military with Hitchcock 612 kit


ivantheterrible

  • Bulleteer
  • ***
  • Posts: 145
  • Karma: 0
Reply #20 on: December 06, 2018, 04:13:10 pm
Thanks for the kudos! Just to add my two kopecks to Ace's explanation, the little ammeter swing he describes, and which is also explained in countless "How to Start a Royal Enfield Bullet" checklists and also YouTube videos, is caused by the electrical draw of the ignition points closing and opening. Mine was fitted with an electronic ignition by a previous owner, and so does not do this little ammeter dance. I've gotta guess that with all your bike's fancy gimcracks it's even money that you may also have an electronic ignition. So don't get too hung up on the ammeter thing if nothing's going on there. Just get the kickstarter through until it's really FIRM, and then a little steady pressure until it just isn't (you don't really need a decompressor to get it there in the stroke--it just helps make it easier), and with the choke lever on the carb down, a nice solid gentle kick may get her sputtering. Mine likes the very faintest wisp of throttle when cold, but try first with no throttle at all. They flood easily. But you know, each is different. You'll get it down to second nature in no time.

One other thing: Before commencing your whole "12 Lords A'Leaping Tribute" for this holiday season, you might do well to pull in that clutch and kick it through a few times to free up those clutch plates a little to make things easier. Your right leg will thank you.

Thanks, that's helpful. Mine does have electronic ignition. I figured that the ammeter thing wouldn't work with electronic ignition.

I've had a few kick only bikes (srx600, sr500, klr250, xr650) and I had no problem with it, (this is in no way meant to be a claim of expert status) but I'll admit that I've been kicked back a couple of times on this one.
So after I hear the huff from the exhaust, that's when I'm good to kick?
2007 sportster 883, yamaha vino 125, 2005 Nfield sixty 5 military with Hitchcock 612 kit


Unlucky_soul

  • Scooter
  • **
  • Posts: 27
  • Karma: 0
Reply #21 on: December 06, 2018, 06:43:16 pm
Really?! I had no idea, that's very interesting.
Pretty simple. you have to re-thread the decompression part to match the one in the sparkplug. then get two ignition coils... wire the second one in series i.e + from first coil goes to - of second coil.


Bilgemaster

  • Just some guy
  • Global Moderator
  • Grand Gearhead
  • *****
  • Posts: 3,251
  • Karma: 1
  • 2005 Bullet 500ES in "Mean Green" Military Trim
Reply #22 on: December 06, 2018, 08:17:25 pm
[...Snip!]
So after I hear the huff from the exhaust, that's when I'm good to kick?

It's not so much a "huff" on mine, as an almost imperceptible "hiss" with decompression. (Did I miss something? Is your decompressor sorted out now?) Like I said, move the kickstart to until it's VERY FIRM...and then just a tad past that until it just softens up (with or without operation of the decompressor). Let the kickstart lever ratchet back up, and then give her the boot.
« Last Edit: December 06, 2018, 10:24:39 pm by Bilgemaster »
So badass my Enfield's actually illegal  in India. Yet it squeaks by here in Virginia.

 


Adrian II

  • Grand Gearhead
  • *****
  • Posts: 4,143
  • Karma: 1
  • Sharing my ignorance with anyone who needs it
Reply #23 on: December 07, 2018, 03:28:03 pm
Pretty simple. you have to re-thread the decompression part to match the one in the sparkplug. then get two ignition coils... wire the second one in series i.e + from first coil goes to - of second coil.

No, the Bullet decompressor valve has the same 14mmx1.25mm thread as the spark plug, only the outer body of the plug might need to be turned down a bit to fit the outer recess in the head, and the little hole in the head that allows the decompressor to vent into the exhaust port will have to be blanked off. The normal spark plug in the iron barrel Bullet is a long-reach plug, you will need a short reach plug of the same heat value for twin plugging.

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


ivantheterrible

  • Bulleteer
  • ***
  • Posts: 145
  • Karma: 0
Reply #24 on: December 11, 2018, 02:14:02 am
that's all interesting, but for now, I'm just focused on riding, which I've yet to do. unfortunately, this bike is a project that is behind a few other projects. But I'm going to make it happen.
2007 sportster 883, yamaha vino 125, 2005 Nfield sixty 5 military with Hitchcock 612 kit


ace.cafe

  • Grand Gearhead
  • *****
  • Posts: 14,457
  • Karma: 1
  • World leaders in performance/racing Bullets
Reply #25 on: December 11, 2018, 12:45:31 pm
that's all interesting, but for now, I'm just focused on riding, which I've yet to do. unfortunately, this bike is a project that is behind a few other projects. But I'm going to make it happen.

It is much easier to just leave the stock decompressor there, and just operate it however you wish.

I have done every kind of decomp mod that is possible on various Bullets, and while it doesn't do any harm, there is no measurable power gain in twin-plugging. If there is any other benefit, we haven't noticed any.
Home of the Fireball 535 !


Bilgemaster

  • Just some guy
  • Global Moderator
  • Grand Gearhead
  • *****
  • Posts: 3,251
  • Karma: 1
  • 2005 Bullet 500ES in "Mean Green" Military Trim
Reply #26 on: December 11, 2018, 02:52:43 pm
It just seems to me that twin-plugging gives you twice as much to go wrong.  I do admire folks coaxing every last pony out of whatever they're riding, but if I were really interested in eyeball-flattening power I wouldn't be plonking around on an old Bullet. I embrace the languid tedium. It soothes me.
So badass my Enfield's actually illegal  in India. Yet it squeaks by here in Virginia.

 


cyrusb

  • Kept man
  • Grand Gearhead
  • *****
  • Posts: 3,616
  • Karma: 2
  • There's a last time for everything
Reply #27 on: December 11, 2018, 08:56:14 pm
Ahem, She understands it....   https://youtu.be/LD7ooOumfBM
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shock springs,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


Bilgemaster

  • Just some guy
  • Global Moderator
  • Grand Gearhead
  • *****
  • Posts: 3,251
  • Karma: 1
  • 2005 Bullet 500ES in "Mean Green" Military Trim
Reply #28 on: December 12, 2018, 03:16:06 pm
Ahem, She understands it....   https://youtu.be/LD7ooOumfBM

As she rides off for the Bangalore Arm Wrestling Semi-Finals...
So badass my Enfield's actually illegal  in India. Yet it squeaks by here in Virginia.

 


Adrian II

  • Grand Gearhead
  • *****
  • Posts: 4,143
  • Karma: 1
  • Sharing my ignorance with anyone who needs it
Reply #29 on: December 12, 2018, 07:11:26 pm
A 350 Electra 5S, she could just have used the electric start. Or am I missing the point?  ;D

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...