Author Topic: Finding TDC  (Read 9480 times)

0 Members and 1 Guest are viewing this topic.

tooseevee

  • Grand Gearhead
  • *****
  • Posts: 3,705
  • Karma: 0
  • A Simple Twist Of Fate
on: September 28, 2016, 04:32:54 pm
        I've reached a point where my EDS, scoliosis, arthritis and muscle loss have pretty much made me useless.

         The other day I decided to do my valves (although they are probably right where they ought to be) and found that it is just totally impossible for me to turn the engine over with either the kicker (by foot OR hand) OR the rear wheel and at the same time watch the TDC tool (which in itself contributes to the difficulty of turning the engine to a precise position because it replaces the spark plug you've removed to make it easier. It's the perfect Catch-22).

          Plus the engine is VERY reluctant to STAY at TDC and always manages to go "just over" and "just past" where I want it to stay. VERY frustrating and to be perfectly blunt: It pisses me off and I have to walk away to avoid looking for a sledge hammer  >:(  :o

             And yes, I know I should be able to watch the pushrods and see when they're both slack at TDC, but I can't. 

           I'm thinking of pulling the primary off and turning the engine over with the crankshaft nut like I do my harley (open primary) on which I can set both points gap, ignition timing and the valves in about a half hour.

            So - question for those who have done it: Can I turn the engine over with this nut (at the crankshaft) with the plug out or will it just unloosen? Or do I just have to go ahead and see what happens?

             PS: What's the Part# of that nut? I can't seem to find it in the Parts Book. 

             PPS: Before someone asks, the last time I set the valves was when the head came back from ACE and I KNEW I was at TDC because I was looking at the piston and could tell by the positions of the lifters that I was on compression stroke. 
'08 Black AVL Classic.ACEhead 9.8:1/manifold/canister. TM32/Open short bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades


Chasfield

  • Grand Gearhead
  • *****
  • Posts: 1,583
  • Karma: 0
Reply #1 on: September 28, 2016, 05:18:08 pm
Here is my method. I use a reference pointer wire with french chalk on the back wheel.

Set the wire so that it sits over the back tyre side wall like a pointer.
Engage top gear. Rotate the back wheel forward until well past TDC, say 10 mm marked on the finder. Mark the back tyre under the wire with French chalk.
Wind the back wheel well back then, going forward, establish 10 mm before top dead centre and mark it on the back tyre.
Now find the point half way between the two chalk marks on the back tyre.
Wind the wheel well back again and go forward till you have  that centre point under the pointer wire.
Voila, TDC.

This way you are never trying to judge the vague area when the piston is very near TDC.

All the wheel movements must be in one direction to take the huge transmission backlash out of the equation.

Incidentally, in top gear (direct drive), about 0.4 of an inch BTDC measured on the back wheel is good for static ignition timing.
« Last Edit: September 28, 2016, 05:20:38 pm by Chasfield »
2001 500 Bullet Deluxe


malky

  • Grand Gearhead
  • *****
  • Posts: 2,758
  • Karma: 0
  • Team Rough Inferior.
Reply #2 on: September 28, 2016, 06:58:14 pm
   
            So - question for those who have done it: Can I turn the engine over with this nut (at the crankshaft) with the plug out or will it just unloosen? Or do I just have to go ahead and see what happens?
 

Yes. That is the way I have always done mine and never encountered any problems.
I was Molly Sugdens bridesmaid.

Spontaneity is the cure for best laid plans.
‘S Rioghal Mo Dhream


tooseevee

  • Grand Gearhead
  • *****
  • Posts: 3,705
  • Karma: 0
  • A Simple Twist Of Fate
Reply #3 on: September 28, 2016, 07:25:22 pm
Here is my method. I use a reference pointer wire with french chalk on the back wheel.

Set the wire so that it sits over the back tyre side wall like a pointer.
Engage top gear. Rotate the back wheel forward until well past TDC, say 10 mm marked on the finder. Mark the back tyre under the wire with French chalk.
Wind the back wheel well back then, going forward, establish 10 mm before top dead centre and mark it on the back tyre.
Now find the point half way between the two chalk marks on the back tyre.
Wind the wheel well back again and go forward till you have  that centre point under the pointer wire.
Voila, TDC.

This way you are never trying to judge the vague area when the piston is very near TDC.

All the wheel movements must be in one direction to take the huge transmission backlash out of the equation.

Incidentally, in top gear (direct drive), about 0.4 of an inch BTDC measured on the back wheel is good for static ignition timing.

             That's brilliant!  :) :) :) Double ++ and thank you. Malky, too.

             I feel so stupid and my only excuse is that this never came up doing harleys either because of open primaries or the simplicity of finding your place using the kicker lever and watching the pushrod positions (I didn't use TDC to set valves on harleys especially kick onlys). 

              I may not get to this today (it's 2:30 already and I missed lunch :(), but I WILL get back to you.
« Last Edit: November 09, 2016, 09:37:38 pm by tooseevee »
'08 Black AVL Classic.ACEhead 9.8:1/manifold/canister. TM32/Open short bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades


Arizoni

  • Grand Gearhead
  • *****
  • Posts: 7,409
  • Karma: 2
  • "But it's a dry heat here in Arizona
Reply #4 on: September 28, 2016, 07:34:56 pm
If all your doing is adjusting the valves, if the piston is within ±15° of TDC the adjustment will be fine.  Both the exhaust and inlet valve are totally closed in this range and the cams are not even close to starting to lift a valve.

If you were sitting the ignition timing it would be another matter.
Then, every degree counts.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary


REpozer

  • Grand Gearhead
  • *****
  • Posts: 3,275
  • Karma: 0
  • Royal Enfield Let the good times roll.
Reply #5 on: September 29, 2016, 07:13:41 pm
You can also .....
Remove the fuel tank, remove spark plug...,
Slow crank the engine. Use a wooden dowl/ stick to take measurements through the spark plug hole . Mark the dowl/ stick with the highest point . Check push rods to see if loose. If not , crank engine 180deg more.TDC
Chasefield 's way  to TDC is smarter.
2008 AVL Classic Bullet in British Racing Green
REA # 84 ( the first time)


tooseevee

  • Grand Gearhead
  • *****
  • Posts: 3,705
  • Karma: 0
  • A Simple Twist Of Fate
Reply #6 on: October 01, 2016, 02:15:28 pm
You can also .....
Remove the fuel tank, remove spark plug...,
Slow crank the engine. Use a wooden dowl/ stick to take measurements through the spark plug hole . Mark the dowl/ stick with the highest point . Check push rods to see if loose. If not , crank engine 180deg more.TDC
Chasefield 's way  to TDC is smarter.

             Thanks, but I already Have a TDC finder finder that screws into the spark plug hole. It's even indexed in tenths between whole numbers.

              But you Are right: the big wooden dowel would be easier to see  :) :)

              I still haven't gotten back to the bike. It's been raining for 4 or 5 days now and I'm a hurtin' MFer :o  it's too damp down there :'( Waah!
'08 Black AVL Classic.ACEhead 9.8:1/manifold/canister. TM32/Open short bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades


tooseevee

  • Grand Gearhead
  • *****
  • Posts: 3,705
  • Karma: 0
  • A Simple Twist Of Fate
Reply #7 on: October 14, 2016, 01:05:56 pm
           
              I still haven't gotten back to the bike. It's been raining for 4 or 5 days now and I'm a hurtin' MFer :o  it's too damp down there :'( Waah!

            Well, I 'spose I should bring this thread to a close. To tell the truth, I forgot all about it.

             I dragged the better half down one day when the rain finally dried up. I 'splained what she needed to do and she watched the TDC finder go up and down with a good light while I turned the engine over with the rear wheel in 5th gear.\

              We found that TDC was exzackly 4.0 on this particular TDC finder. The valves were perfeckly OK when I checked them as I thought. 

               I had had a shitty running experience previous to this and had dropped the bowl, checked that the needle was shutting off properly and removed the mixture screw and the pilot jet to blow everything out. I took the pilot jet out in the sun and looked with a magnifying glass and lo and behold there was a tiny piece of grit inside the jet in one of the holes. How it got through the super-fine filter in the tank and my inline filter I'll never know.

             It started up OK on the third crank of the ES which is why I still have a love/hate relationship with this TM-32 Mikuni. I HATE the way the engine will just NOT stay running the first time no matter how many times I have tried to tweak the carb to make it so. I have made a hundred tiny mixture screw tweaks from the sweet spot and it's still the same story the next day. It will run a couple revolutions and no matter how quick and delicate I am with the throttle it will die and sometimes it dies with one of those horrible sprag clanks that slams into my brain like getting hit with a baseball bat and makes me want to just say F! this and get rid of the bike. If it does it twice I get so pissed hearing that sprag clank I want to smash the whole F-ing bike with a sledge hammer and just be done with it.

         And I will go to my grave hating the fact that this engine will NOT kickstart cold. Period. And I'm convinced it's something to do with the characteristics of this carburetor on this particular engine (ACEhead with 9.8 comp). There is no tweaking I haven't tried and it still won't kickstart cold or get past those first 10 seconds after electric starting and keep the mu**rf**ker running on the first ES. 

         But then it runs so good out on the road and is an instant starter warm (both kick and electric) that it's like a dog that bites you once in a while, but you still love the dog.

         Yes, I've gone one up and one down on the needle. Ran like shit both ways from the middle groove. And the richener is useless. It Will Not start AT ALL with ANY use of the enrichener.   
'08 Black AVL Classic.ACEhead 9.8:1/manifold/canister. TM32/Open short bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades


Adrian II

  • Grand Gearhead
  • *****
  • Posts: 2,621
  • Karma: 0
  • Sharing my ignorance with anyone who needs it
Reply #8 on: October 14, 2016, 06:59:11 pm
It sounds like you and Mikunis Just Don't Get Along... I'm sure you have been in touch with ACE about this, so consider the alternatives, though (re-)check that your carb hasn't got an air leak around the mounting rubber flange, it sounds a like the way mine was behaving a while ago, tightening up the hose clip sorted it.

Amal Concentric Mk 2 - Bullet Whisperer swears BY these carbs rather than AT them, he's the go-to guy for tuning these.

Dell'Orto PHF 32, 34 or 36 with the accelerator pump, the carb of choice for the UK importer's original go-faster kit for the Electra-X, there's a Malossi flage rubber for it with the correct 60mm centres. Don't worry about the black spaghetti in the photo, that's just small bore tubing from the overflows, which can be trimmed to suit.



Other carbs might be suggested, possibly our host's JRC Kehin copy.

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


tooseevee

  • Grand Gearhead
  • *****
  • Posts: 3,705
  • Karma: 0
  • A Simple Twist Of Fate
Reply #9 on: October 17, 2016, 02:00:38 pm
It sounds like you and Mikunis Just Don't Get Along... I'm sure you have been in touch with ACE about this, so consider the alternatives, though (re-)check that your carb hasn't got an air leak around the mounting rubber flange, it sounds a like the way mine was behaving a while ago, tightening up the hose clip sorted it.

Amal Concentric Mk 2 - Bullet Whisperer swears BY these carbs rather than AT them, he's the go-to guy for tuning these.

Dell'Orto PHF 32, 34 or 36 with the accelerator pump, the carb of choice for the UK importer's original go-faster kit for the Electra-X, there's a Malossi flage rubber for it with the correct 60mm centres. Don't worry about the black spaghetti in the photo, that's just small bore tubing from the overflows, which can be trimmed to suit.

Other carbs might be suggested, possibly our host's JRC Kehin copy.

A.

            Adrian,

                    I did some bitchin' and moanin' over on DanB's thread. I shoulda done it here. I just can't deal with everything that's involved in learning yet another carburetor at this point and getting it dialed in.
'08 Black AVL Classic.ACEhead 9.8:1/manifold/canister. TM32/Open short bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades


finbullet

  • Scooter
  • **
  • Posts: 80
  • Karma: 0
Reply #10 on: October 17, 2016, 07:36:03 pm
If you have tried everything allready with the carb, you could try to retard your ignition by 1 or 2 degrees. I think it would reduce those backfires when cold.

I have heard those mikuni carbs are really sensitive about their jets. If you want an easy carb I would suggest a PWK carb. I bought one from China and it was basicly free (35$ if I recall) but it works like a charm. Got it jetted with the jets witch came with it.
« Last Edit: October 17, 2016, 07:54:33 pm by finbullet »


Adrian II

  • Grand Gearhead
  • *****
  • Posts: 2,621
  • Karma: 0
  • Sharing my ignorance with anyone who needs it
Reply #11 on: October 17, 2016, 07:54:19 pm
Unlike the cast iron Bullets, the AVL classic and Electra-X have fixed ignition, there's no provision for changing the firing position apart from using offset rotor keys.

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


finbullet

  • Scooter
  • **
  • Posts: 80
  • Karma: 0
Reply #12 on: October 18, 2016, 04:26:41 am
Unlike the cast iron Bullets, the AVL classic and Electra-X have fixed ignition, there's no provision for changing the firing position apart from using offset rotor keys.


A.
Sorry I tought it was the same as CI but with no points.
Anyways now that i have read you posts on this thread and from the other thread. I really think it is not a carb related issue but a weak spark because of the high compression. The spark could look OK on the open air but it can be weak on the compression chamber where the compressed air is more denser.

First you have to check you don't have resistors on both the plug and the plug cap. If the plug cap shows 5 kohms then use b9es or b8es plug.

I would recommend you to get a better coil (bosch blue or pertronix flame thrower 40511), good quality ignition wire and a resistor plug cap if you use plugs without resistor (b9es or b8es) or a plug cap without resistor if you use plugs with resistors ( br9es, br8es or iridium br9eix or br8eix)
« Last Edit: October 18, 2016, 04:29:20 am by finbullet »


tooseevee

  • Grand Gearhead
  • *****
  • Posts: 3,705
  • Karma: 0
  • A Simple Twist Of Fate
Reply #13 on: October 20, 2016, 06:27:07 pm
Sorry I tought it was the same as CI but with no points.
Anyways now that i have read you posts on this thread and from the other thread. I really think it is not a carb related issue but a weak spark because of the high compression. The spark could look OK on the open air but it can be weak on the compression chamber where the compressed air is more denser.

First you have to check you don't have resistors on both the plug and the plug cap. If the plug cap shows 5 kohms then use b9es or b8es plug.

I would recommend you to get a better coil (bosch blue or pertronix flame thrower 40511), good quality ignition wire and a resistor plug cap if you use plugs without resistor (b9es or b8es) or a plug cap without resistor if you use plugs with resistors ( br9es, br8es or iridium br9eix or br8eix)

             I've had compression blowout in the back of my mind for a long time now, but the disprover is how well the damn thing runs out on the road. It gets to 50, 55 very easily and quickly and will cruise at 50 in 4th with no sweat at all and 5th is a whole 'nuther world from the stock engine.

             Second thing: You've got me all confuzalated now with this resistor thing. The HT wire, coil and plug cap are stock to this '08 AVL and I've never used anything but BPR9ES (except 8s for while) in it since new and no other plug has ever been recommended here that I know of (I've been on here since '09 or '10 I think). Now I'm second guessing something ELSE again...

           Is it a resistor cap or isn't it? It's shiny metal like a beer can. It appears to be steel  :)

           Kevin? Isn't that the plug in CM's catalog?  Ace? Adrian? Arizoni? Vince?

            Should I locate a coil tester? Or just go ahead and get a Pertronix (put a whole Pertronix setup in my '70 DS (and a '72), good stuff).   
« Last Edit: October 20, 2016, 06:31:06 pm by tooseevee »
'08 Black AVL Classic.ACEhead 9.8:1/manifold/canister. TM32/Open short bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades


portisheadric

  • Grand Gearhead
  • *****
  • Posts: 712
  • Karma: 0
Reply #14 on: October 20, 2016, 07:19:09 pm
If its the original AVL metal encased plastic plug cap it'll have an inbuilt resistor.
Currently riding either a quicker than stock '19 Speed Twin or fairly standard 500 Rebel