Author Topic: k2f magneto  (Read 631 times)

Offline agonda1

  • Moving Up
  • **
  • Join Date: Apr 2015
  • Posts: 20
  • Karma: 0
k2f magneto
« on: 15.08. 2016 16:25 »
Had the mag overalled by a club member.Hardly any improvement but since I was confident a professional job was done I did not question the work.This sent me on a never ending search in all sort of wrong directions - Bad fuel / carb problems etc.Eventually I returned to the mag.Observations -  weak and inconsistent sparks bike sometimes starts and sometimes not at all.The said person who carried out the restoration suggested that the magneto had suffered fuel contamination from a dripping carb.I find this all a bit odd since a carb drip tray is fitted

Any ideas

Offline RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5033
  • Karma: 48
Re: k2f magneto
« Reply #1 on: 15.08. 2016 16:45 »
Recapping, for clarification, this goes back to your June 8, 2016 post regarding easy starting cold and hard starting with warm engine. I have just started having this same issue, so I am telling a bit of my story hoping you get something from it and, also, tagging along for whatever advice is offered.

My immediate suspicion was magneto problems, either a bad cap or LT windings leaking with heat. My cap is a new EasyCap, so that is very doubtful. To test the issue I went out for a ride that was long enough to warm everything up. On getting home, I immediately pulled the plugs and tested for spark across about a 0.150" gap. No problem leaping that gap. I also tested with the plugs that I had just pulled from the bike and the result was a good hot spark. Tested compression on both sides. All good. This was all just yesterday, so I have yet to check timing and look for possible carb issues.

Richard L.   
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline a101960

  • Wise & Enlightened
  • *
  • Join Date: Sep 2007
  • Posts: 1040
  • Karma: 12
  • BSA RGS BSA C12
Re: k2f magneto
« Reply #2 on: 15.08. 2016 17:15 »
A blocked or partially blocked pilot jet can give the same symptoms as a failing magneto. How do I know this? Well I was having intermittent starting problems (both hot and cold). Even had the worry of an intermittent misfire. I cleaned out the pilot jet and everything has been fine since. On a couple of occasions I forgot to turn the petrol on after I had filled up, and I had a terrible job re-starting the engine. I had ridden some distance and the mag was nice and hot, so I thought the mag was failing. After much kicking it did eventually start. The engine would also misfire when cold and under load sometimes, but not always. Since cleaning out the pilot jet my bike has returned to being a reliable easy starter hot or cold. So it is definately worth removing the pilot jet and making sure that it is clear before doing anything else. Actually a new jet is cheap enough to buy.
John

Offline RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5033
  • Karma: 48
Re: k2f magneto
« Reply #3 on: 15.08. 2016 18:50 »
I thought about the pilot as a possible culprit. I'm running a concentric, so can't take out the jet and clean it, but I'll blow some air through it and, maybe, send a welding-tip cleaner in there. I'm usually setting pilot air (almost wrote "error") on a cold engine. I wonder if it's possible that I've just optimized pilot setting for a cold engine and I need to be somewhere in between.

(I've said before that I'm weak on carburetors.)

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline a101960

  • Wise & Enlightened
  • *
  • Join Date: Sep 2007
  • Posts: 1040
  • Karma: 12
  • BSA RGS BSA C12
Re: k2f magneto
« Reply #4 on: 15.08. 2016 19:27 »
Quote
I wonder if it's possible that I've just optimized pilot setting for a cold engine and I need to be somewhere in between.
Richard, for optimal carb tuning the engine needs to be at running temperature. Best results are obtained after riding for at least 20-30 minutes. I have a Colortune, and that makes setting up much easier. My bike is fitted with a 389 monobloc so pilot jet removal is easy. You are right the Concentric does have a fixed pilot, but from all I have read the way to clear the pilot is to use either a piece of guitar string, or probably more practical a #78 drill. Just a little bit more information about my experience. What completly misled me was the fact that despite all the problems I was having the plug colour looked absolutely fine ie a nice rich coffee colour. That more or less convinced me that the magnento was on the way out. I should add that once the pilot was clear the plugs were black and sooty. I had to retune the carb and then all was well. I am not sure about this, but those with more expertise than me may be able to verify, or even tell you how to do it, but I feel pretty certain that I have read on more than one occassion The the Concentric can be modified to accomodate pilot jet removal and replacement.
John

Offline muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8237
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: k2f magneto
« Reply #5 on: 18.08. 2016 01:12 »
Before we get too far into carburation in the electrical section. A #78 won't do it try a #80. Yes the fixed pilot in the concentric can be drilled out and the removable screwed into the hole at the carb/bowl face.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Triton Thrasher

  • Scotland
  • Wise & Enlightened
  • *
  • Join Date: Feb 2009
  • Posts: 1500
  • Karma: 20
Re: k2f magneto
« Reply #6 on: 18.08. 2016 11:48 »
A #78 won't do it 

Yes it will.

Online Triton Thrasher

  • Scotland
  • Wise & Enlightened
  • *
  • Join Date: Feb 2009
  • Posts: 1500
  • Karma: 20
Re: k2f magneto
« Reply #7 on: 18.08. 2016 11:50 »
I thought about the pilot as a possible culprit. I'm running a concentric, so can't take out the jet and clean it, but I'll blow some air through it and, maybe, send a welding-tip cleaner in there. I'm usually setting pilot air (almost wrote "error") on a cold engine. I wonder if it's possible that I've just optimized pilot setting for a cold engine and I need to be somewhere in between.

(I've said before that I'm weak on carburetors.)

Richard L.

Air will fail to clean the pilot bush.

You have to set the mixture to be correct on a fully warm engine.

Offline muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8237
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: k2f magneto
« Reply #8 on: 18.08. 2016 20:04 »
A #78 won't do it 

Yes it will.

The pressed in pilot in a concentric is equivalent to the #20 removable pilot jet. The smallest tip cleaner I have is 16 thou" and will not pass through it.  *dunno*. I admit I don't have any # drills and have not tried a #78 which is 16 thou". I will now order one and try it.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7