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Royal Enfield Motorcycles => Vintage Royal Enfield => Topic started by: High On Octane on January 22, 2013, 12:56:02 am

Title: Cleaning A K2F Auto Advance Mechanism
Post by: High On Octane on January 22, 2013, 12:56:02 am
Alright.  So, I got the new carb installed on the Indian and it starts on the first kick and idles great!  However, when I take it around the block it accelerates super slow.  I can get up to speed, but it seems like the auto advance just isn't advancing the spark as the RPMs increase.  I'm thinking that this bike just sat for so long that the advance mechanism seized up and is no longer moving.  I heard from the guy who sold me my carb that I could remove the advance mechanism and soak it in parts cleaner for a couple days to clean it up and get it moving again.

What are your guys' thoughts and opinions on this?
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: ERC on January 22, 2013, 02:15:18 am
Sometimes the springs get to relaxed or break. Easy to fix. ERC
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: Arizoni on January 22, 2013, 03:56:13 am
It does sound like its running in the retarded starting position and not advancing.
At least that would explain the easy starting and no power.

The only thing I know about auto advancing mag's is the drawings I've seen show the flyweights on the gear end and the points on the other end.
That could mean that the flyweights are free to move but whatever advances the points cam might be stuck.

Kroil or Break Free CLP will penetrate into the smallest nooks and crannies and loosen things up if it has a day or more to soak in.
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: High On Octane on January 22, 2013, 10:08:32 pm
I just finished soaking the auto advance in penetrating oil and it moves freely now but it's not really going back to the retarded position after moving it into the advanced position.  I'm thinking the springs need to be replaced.

But here's the kicker.........
With the choke installed in the carb, the bike pretty much starts right up but runs slow.  I opened the carb to move the needle down a position and decided to remove the choke just to see what happened.  Now, the bike is nearly impossible to start and started back firing through the carb again.  It accelerated slightly better, but I can't hardly keep it running.

When I had the timing cover off, I inspected all the timing marks and tension, and made sure the points were just opening at 3/8" before TDC.  The only thing I can think it can be is 1 of 2 things.  A: The loose springs are causing the timing to fluctuate too much.  Or, B: The cam shafts are completely shot and not allowing the motor to run properly.

Obviously, I'll be replacing the springs.  Does anyone think this will solve the problem?
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: rotorwrench on January 24, 2013, 12:46:35 am
The Lucas 47613 auto advance unit is not really made to be serviced. They are available from Hitchcock's in the UK with an LU part number prefix and I've purchased them from flea-pay on several occasions. The springs are relatively weak on these units. I imagine the advance is all in with just a little bit of throttle on these. If the mag drive chain is too tight, it can cause the advance unit to be sluggish in operation and it can sometimes stick in advanced or retard positions. Make sure your timing is adjusted with the advance unit in full advance. The unit is primarilly designed to make the engine easier to start and that's about it.

If you get an Amal concentric to function well, I'd put a lever on it and leave'er alone. They are designed to work with all the parts installed. If you start with the recommended needle & jet combination for a 700cc motor, it should function normally as long as it's not too big a bore. I much prefer a good Amal monoblock carb to the concentrics but they are like an apple and an orange in performance differences and many of the old monoblocks are worn out and need to be resleeved and have a new slide put in. The 700 cc standard cam engine version seems to respond best to the Monoblock 389 1 1/8" bore types. They will run with a 1 3/16" but they can run pretty rich. If yours has the big cams of a Constellation or Interceptor type then it should run OK with a larger bore carb.

There may be other reasons the engine is low on power. Low compression, valve clearances too tight or too loose, inlet manifold air leaks, etc. The cams may have a lot of wear but I haven't seen too many that were all that badly worn. Something else usually wears out first. Make sure you have good exhaust flow. If its wide open header is should blow a pretty good breeze out the back. Definitely make certain you have oil flow back to the reservoir. Also make certain your oil feed plug in the timing cover that feeds the bottom end is clear and the bobin seal is in good condition for proper lubricant flow.

A year or so ago Hitchcock's had some 8:1 forged pistons made up to fit the twins. They hadn't been available for many many moons unless you just happened upon a set. Many of these old motors were rebuilt with low compression pistons so they would be more reliable. They used to blow head gaskets pretty easy with the high comp pistons.
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: High On Octane on January 26, 2013, 05:34:10 am
Booooooooo    :(

Got the new timing springs installed and set the valve lash.  Got it running a little better but was still backfiring.  Went around the block a few times, trying to enjoy myself but disappointed in the lack of performance, and went back to the garage.  And it was then that it hit me.  By sheer coincidence, I looked down and noticed that the left pipe had a some carbon around the muffler tip, and the right pipe had a wet oily/gassy collection at the tip.  I reached down, and sure shit, the right muffler is ice cold.  I pulled the plug and it was soaked with no carbon what so ever.  It doesn't take a rocket scientist to see that there is little, to absolutely no firing out of the right cylinder.  :'(  It's obvious the armature windings are shot and not providing enough electricity for a consistent spark.  This clearly explains the backfiring and complete lack of power.

Good news is that damn near everything except the motor, trans and the magneto itself are now brand new.   :)

Bad news is now I'm going to have to fork out another few hundred bucks to actually get this thing running like it should.

Oh the joys of trial and error when restoring a 55 year old bike that you previously knew NOTHING about.  Thanks again everyone for your knowledge and advice.
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: bullethead63 on February 01, 2013, 02:16:34 am
Keep those posts coming,Brother...I'm restoring a '59 Chief,with a K2F,and need all of the info I can get!
Title: Re: Cleaning A K2F Auto Advance Mechanism
Post by: High On Octane on February 01, 2013, 06:18:03 am
For what it's worth, I decided that rather spending money on rebuilding the armature, that will no doubt fail again, I'm going to convert to an electronic ignition.  There's a few of them out there, but I'm going with the Thorspark conversion.  It's only about $300 shipped out and has a 5 year unlimited mileage warranty.  It only takes about 10 minutes to install and another 1-2 hours to set the timing with a light.  Then you're good to rock-n-roll and never have to mess with it again!  Here's the link on Ebay.

http://www.ebay.com/itm/150976650798?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Just make sure if you order one to specify in your order that you're installing it on an Enfield, as the RE's are a counter-clockwise rotation and the K2F's on other Brithish bikes are a clockwise rotation.