Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Vintage Royal Enfield => Topic started by: skipsoldbikes on November 22, 2013, 05:52:37 am
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Hi all!
I rebuild Lucas & BTH magnetos with modern ceramic capacitors & just finished an SR2 for a customers '59 Enfield Indain. He has no service manuals for the bike, can anyone fill me in on the timing procedure? I assume lock the auto advance to full advance & bring the piston up to (1/2"????) before top dead center on compression stroke, then tighten the advance onto the mag? Not even sure how far BTC this motor should be. Any Help would be greatly appreciated & thanks in advance.
Skip Brolund
P.S. Lucas & BTH magneto questions answered for free :)
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Timing should be set to 3/8" BTDC with the auto advance in the natural full retard position.
Scottie
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I don't want to start an argument here, Scottie, but I would say 3/8" BTDC would be a full advance figure for the ignition timing, otherwise it will be firing at about 3/4" BTDC on full advance if you set it retarded to 3/8" BTDC.
B.W.
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How do you figure the auto advance will retard the timing an additional 3/8" by advancing the spark? That's how my bike is timed and it runs great.
Scottie
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How do you figure the auto advance will retard the timing an additional 3/8" by advancing the spark? That's how my bike is timed and it runs great.
Scottie
3/8" BTDC is the position for firing with the ATU fully advanced. If you time your ignition 3/8" BTDC retarded, then when the weights open out, that will advance the timing more, to around 3/4" BTDC. If your engine is timed like that and runs great, it will run even greater timed properly, I guarantee it. I don't mean to sound arrogant, but I will stand by what I said above.
If you doubt me, I have timed all of these, below and they all run great, too. [links to some short videos below]
B.W.
http://s956.photobucket.com/user/rossemma/media/BobMacRESuperMeteor.mp4.html
http://s956.photobucket.com/user/rossemma/media/RE500TwinRacer.flv.html
http://s956.photobucket.com/user/rossemma/media/RE700twinPT039.mp4.html
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Ok, I miss understood what you were saying at first. And apparently I did the timing wrong as the manual I was originally going off of didn't say hardly anything about setting the timing with a K2F auto advance. Just looked in my recently acquired Interceptor manual and you're right. I did eventually get the timing set by feel, but it would have been nice to have this information in the spring. Lol
Scottie
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Thanks, Scottie 8), I wasn't 'having a pop' at you, by the way, but it's important to have [and give] the correct information, especially with things like timing.
B.W.
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Yup, 3/8" with the timing advanced.
Bare
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Thanks, Scottie 8), I wasn't 'having a pop' at you, by the way, but it's important to have [and give] the correct information, especially with things like timing.
B.W.
No harm no foul. Actually thank you for correcting me because I hadn't realized I had the wrong information. :)
Scottie
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You guys are all so civil it chases the trolls away. :)
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Thank you all! Seems most brit iron comes in from 3/8-1/2 BTDC w/full advance, but this info eliminates the trial & error (hopefully!). I normally prefer to use a degree wheel, but on this RE Indian I am trying not to make a big project of putting the mag back on.
Thanks again !!!
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Starting trouble :-[. At first I turned the points cam the wrong way due to me being used to most other English bikes that the mag turns anticlockwise from the drive end (Royal Enfield & Vincent go clockwise from the drive end-anticlockwise from the points end).
I got that correct now (I think), now it will fire up after 3 kicks & run for 1 to 1 1/2 seconds & die. Plugs seem a little dry, so I will go through the carb this morning.
I also noticed when checking the rocker arms in determining TDC, that there is maybe .001 valve clearance (lash). Shouldnt that be more like .006-.008 ?
I am embarrased not having a manual for this bike (like I normally would), but its not my bike & I am just trying to help a guy out. I should also mention the bike has sat for 3 years, so I expect goo in the carb :(
Nowdays its almost not worth rebuilding Amals when the complete kit costs $50 with a new needle & main jet (plus labor), when you can buy a New one for $20, or a Wassell one for $130.
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The Indian trailblazer manual says .002" both. The British manual says nill for intake spin more for exhaust. 6 to 8 would be very noisy. This is for the 700cc twins. ERC
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Ok, thanks. I am more accustom to working on Nortons & they spec more clearance. Seems the lash on this bike may be correct then.
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Does anyone know how many degrees before TDC 3/8"would be? I would rather use a degree wheel than a measuring stick in the plug hole.
Cheers,
Roger
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About 34 degrees. ERC
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Perhaps this page can be of help to you. The exhaust valve closes at 35* after TDC and the intake closes at 73* after BDC. My guess is timing would be 35-38* before TDC. But I honestly don't have a clue. Ace should be able to figure out the degree with this info. Hopefully he will chime in here.
(http://i6.photobucket.com/albums/y217/lethalinj/ConstellationEngineTechSheet_zpsf2cfe931.jpg) (http://s6.photobucket.com/user/lethalinj/media/ConstellationEngineTechSheet_zpsf2cfe931.jpg.html)
Scottie J
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I thought he was talking about ignition timing not valve? ERC
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I thought he was talking about ignition timing not valve? ERC
He is, but if you know what you're doing you can figure out the ignition timing based off of valve timing. I personally don't know how, but I'm sure someone does.
Scottie J
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I'll let my son figure that one out he's a Mechanical Engineer and teaches Physics for a living. ERC
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Alright, I think I got it, I found a calculator online for figuring this out. I went out to the garage and measured a rod and it is exactly 6 1/8" which converts to 155.575 center to center, and I know the stroke is 90mm. 3/8" converted is 9.525mm, that subtracted from 90mm is 80.475mm. For our crank and rod set up 80.475mm translates to 135.75*.
TaDah!!!
I think..... ???
http://www.dansmc.com/mc_software2.htm
(http://i6.photobucket.com/albums/y217/lethalinj/CrankDegreeChart_zps31de3716.jpg) (http://s6.photobucket.com/user/lethalinj/media/CrankDegreeChart_zps31de3716.jpg.html)
Scottie J
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That would give you piston travel but not the ignition advance degrees. ERC
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That would give you piston travel but not the ignition advance degrees. ERC
I realize this shows piston travel. But I thought piston travel/position WAS relevant to ignition timing? The manual clearly states that the timing is to be set 3/8" BTDC at full advance. I'm no rocket scientist, but that sure sounds like a measurement based off of piston travel to me. As far as advancement, I think the Auto-Advance is good for 32*, not sure about the manual advance control, but I'm sure it's similar.
But if I am wrong, then riddle me this. How exactly is one to set timing with a degree wheel on the crankshaft if the degree and location of the piston are irrelevant to the timing degree angle? ???
Scottie J
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Have no idea how they figure it. Something to do with radian and pi formula to convert inches to degrees. ERC
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Right. I thought that calculator I used did just that. I found it when googling something like "how to convert inches to degrees for timing a bike" or "how to set timing with a degree wheel on a bike" or some damn thing, I don't remember exactly what I typed in. Anyways, I came across a BSA forum where guys had been discussing this same topic and the one guy (that appeared to know what he was talking about) had posted the link for that calculator and claimed that this was how you could convert a vertical measurement into a degree measurement off of the crankshaft. Granted I've never used a degree wheel to set timing, I believe what I posted is correct. According to the hour or so of research I did yesterday anyways.
Scottie J
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Yea their is a formula, I just know when you put the wheel on my bike bring the piston down 3/8" it basically shows 34 degrees. ERC
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Fair enough.
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Here's a Vincent chart that shows what I found on my bike. If I can add the thing not good at this crap. ERC
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OK I see on that Vincent chart they go from 0* at TDC. So going off of that and my numbers with TDC at 0* that would put my numbers at 44* at full advance. Which sounds closer than 135*, and being we don't know what the stroke and rod length for the Vincent, this could be correct. I wish I was better with algebra.
Scottie J
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Good Afternoon Gents,
Thank you very much for your insights regarding the timing wheel measurement. I think I can figure it out with all of this information. On most other British twins it is 32 -36 degrees before TDC so I suspect that the Meteor will be somewhere in this range. The idea of it firing around the 100 degree mark would cause it to fire near the bottom of the stroke which would afford no power when the piston reaches the top of the stroke. I will have a chance to put all on your inmformation tothe test onTuesday. I will let you know how thingsgo. By the way here is a picture of the bike that you helped with in August of last year. We have decided that it is a 1956 Super MeteorSome of the tinware is not correct but we think it works.
Cheers,
Roger
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Nice bike! :D
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That came out real nice. ERC