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JonnyWobbles

Help! 198A poor starting and runs backwards!

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I read that for more than 30 years and it never worked for me. Easiest thing here is to use the buzzer from your multimeter. Doesn’t require your attention and doesn’t stick to anything. The moment it stops buzzing, the contact has opened. As easy as that

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So the saga continues!

Armed with a new set of points from InMotion, I set about sorting the timing to the Bultaco procedure other than using a multimeter (on beeb) connected to disconnected black wire and earth, dial gauge through plug hole to set TDC etc.

First problem was setting points gap to 16 thou. as the hole in which the screw cam adjuster works on the points is too big and significantly bigger than original points. Eventually managed it by levering with screwdriver. Second problem, impossible to set timing to less than 5mm BTDC as there was insufficient adjustment on backplate slots! 

Comparing points seems to explain why!

655E49C1-A536-4D94-922E-3FCC5CFC73B9.thumb.jpeg.8d49068af46f99eff196f4a8dbd65551.jpeg

The angle and length of the insulated cam follower on the InMotion points is totally different compared to the ‘original’ points (fitted to bike when I got it) and a set of points I bought from F’ecked which themselves are faulty as the welded contacts are intermittent! I think a couple of mm and approximately 30 deg angular offset is not really acceptable if these are the supposed to be compatible!

So for now I’ve put original points back in (contacts are good, but cam follower looks worn) and set them up to 2.5mm BTDC with none of the problems above. But I’m really not impressed! No wonder it’s difficult to get these bikes running correctly if the quality and specification of the current points available is so poor!

I ran out of time (and patience!) so not put it all back together. I don’t think that the wear of the cam follower should affect the timing once set correctly, but I’d really like to replace with a ‘proper’ quality set if anyone knows where I can get some! 

Anyone want to buy a Sherpa? 

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8 minutes ago, JonnyWobbles said:

So the saga continues!

Armed with a new set of points from InMotion, I set about sorting the timing to the Bultaco procedure other than using a multimeter (on beeb) connected to disconnected black wire and earth, dial gauge through plug hole to set TDC etc.

First problem was setting points gap to 16 thou. as the hole in which the screw cam adjuster works on the points is too big and significantly bigger than original points. Eventually managed it by levering with screwdriver. Second problem, impossible to set timing to less than 5mm BTDC as there was insufficient adjustment on backplate slots! 

Comparing points seems to explain why!

655E49C1-A536-4D94-922E-3FCC5CFC73B9.thumb.jpeg.8d49068af46f99eff196f4a8dbd65551.jpeg

The angle and length of the insulated cam follower on the InMotion points is totally different compared to the ‘original’ points (fitted to bike when I got it) and a set of points I bought from F’ecked which themselves are faulty as the welded contacts are intermittent! I think a couple of mm and approximately 30 deg angular offset is not really acceptable if these are the supposed to be compatible!

So for now I’ve put original points back in (contacts are good, but cam follower looks worn) and set them up to 2.5mm BTDC with none of the problems above. But I’m really not impressed! No wonder it’s difficult to get these bikes running correctly if the quality and specification of the current points available is so poor!

I ran out of time (and patience!) so not put it all back together. I don’t think that the wear of the cam follower should affect the timing once set correctly, but I’d really like to replace with a ‘proper’ quality set if anyone knows where I can get some! 

Anyone want to buy a Sher

 I don’t think that the wear of the cam follower should affect the timing once set correctly, but I’d really like to replace with a ‘proper’ quality set if anyone knows where I can get some!

Ware will affect timing, and the points were always poor quality.

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I think wherever you buy the points from they are going to be the same pattern points you have already got. Ideally you need to try and find a set of original Femsa if they are still available but no idea where you would get some from. All of the parts stockists I know of, Spain included, sell the pattern points. The issue I had with them is the position of the terminal screw for the wiring which sits directly in front of the coil and makes it extremely difficult to connect the wires - enough so that I bought electronic for my bikes. Add to that I absolutely hate the fiddle of trying to work through a stupidly tiny hole in a flywheel...

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Now All Sorted! 😀

Thanks to all who helped with advice etc. InMotion replaced the rogue set of points they had sent me. Spent an afternoon resetting the timing and checking everything (multiple times). All back together and started 3rd kick In the right direction) and then easily thereafter!

So its probably time to move her on and let someone use her as I've another project (I'm cafe racer'ing my Triumph T140V) that I really need to move into the garage and I don't think I'm going to get chance this year to do any trialling!

I added up what I'd spent on the refurb which was rather frightening (don't tell my wife!) and listed it on eBay and our classifieds. Hopefully I'll breakeven!

Cheers

Jon 

 

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I am now on my 4th year with Electrex ignition (199A). No problem at all. It has been fit and forget.

With a new set of points it was permanet struggling. The new points came from Spain but timing was very difficult and the abscissa distance were not correct. Abscissa distance is the distance between the poles at the coil and the angular distance to the magnetic poles in the flywheel.

The Electrex ignition has been well worth the money

I assume other brands would do the same but it will be Electrex on my 199B.

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Just reading the "mail" - Maybe this will help - maybe it won't, but I had some similar problems with my Yamaha TY 250 A.

On the Yam- the flywheel is on the left side and spins Counterclockwise.  Yamaha put in a diode between the low side of the coil and the points and the arrow on the diode points to the points if you get my meaning- (cathode end to points)  it was added there to prevent the engine running backwards.   I put a diode into my 74 and although my timing might be slightly off, it does not kick back quite as much when you try to start it.  The setup parameters are slighly more advanced = 3.5 degrees BTDC in my case, but everything else is probably about the same.  You might also check the octane rating on your fuel as the higher octane premium fuel will have no ethanol in it to eat up rubber parts or fuel line that is exposed to it, and the flame front lasts a tiny fraction of a milisecond longer than with regular grade fuel.

One thing I found that was semi- critical was that you have to be very certain where the Top dead center is.   For this you can either put a tool down the spark plug hole or remove the head and measure with a dial test indicator.  Since the piston is not moving vertically at all when at TDC, the flywheel can spin thru several degrees before TDC without the piston moving much at all.   I finally resorted to marking the cases and the flywheel with a peen mark on each one that only lines up when at TDC. Having these marks makes it easier to find TDC next time around and saves a lot of hassle.  From there you can do the math and divide your flywheel's circumference by 360 and come up with a measurement  that puts the flywheel mark back before TDC by the equivalent of so many degrees- whatever your spec says.

That point before TDC is where the points should open.  If the low side of the high voltage coil is disconnected from the points circuit and a good quality ohm meter is attached across the points you should be able to detect an increase in the resistance to ground.  

That position of the flywheel is critical to the operation,but the points "gap" is also a setting to shoot for.  

There is also a very good anti- corrosion and contact preservative I use on every kind of switch contact, points, relays- battery contacts in a flashlight It might be hard to find but it's called  "ACF 50" .

 

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Thanks Tillerman6, all good advice! I use a DTI to find TDC and good multimeter to check points opening. Bultaco quote piston mm back from this to set the timing so its fairly simple but time consuming as I found you have to repeat the process a number of times as the measurement is affected by points gap, flywheel torque setting, magneto backplate screw tightness etc. But once set up it works and I've not suffered any kickback or reverse running since..... Can also vouch for ACF50 - I've been using it on my cars and bikes for many years!

Cheers

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No one used a stroboscopique light ?

Engine has to run but it is an easy test to do...😏

 

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On 4/7/2021 at 11:43 PM, JonnyWobbles said:

Thanks Tillerman6, all good advice! I use a DTI to find TDC and good multimeter to check points opening. Bultaco quote piston mm back from this to set the timing so its fairly simple but time consuming as I found you have to repeat the process a number of times as the measurement is affected by points gap, flywheel torque setting, magneto backplate screw tightness etc. But once set up it works and I've not suffered any kickback or reverse running since..... Can also vouch for ACF50 - I've been using it on my cars and bikes for many years!

Cheers

Johnnywobbles-

  As I have prognosticated for years while struggling with the points in my TY 250 A and because of my lack of extra funds and the high prices on new electronic ignition units, Up until last week I have had to make as much progress on setting my timing up as humanly possible.  So re-reading your struggle with the points on your machine- it sounds very much like my own frustrating time with my own bike.  However, I have found and eliminated one source of aggravation which should have been obvious, however not so easy to fabricate.  This has to do with the looseness and play between the points adjustment screw diameter and the width of the adjustment slot in the points breaker plate.  In my case, there was almost .025" of free play between these two parts, and when the screw was tightened, the breaker plate would shift and "squirm" under the screw head before it finally settled into it's own favorite position which would invariably be wrong for the timing that was so dependent on the exact position of the points wiper in the X, Y, and Z axis.  This was finally minimized by making a shouldered bushing that takes up the slack between these parts.  

One other source of play that is un-desirable and is easy to overlook is the diameter of the prong on the back side of the points breaker plate.  If your replacement breaker plate is not identical to the original factory item, then it is possible that there is another source of unwanted free play in the position of the breaker plate. In my case, the prong on the replacement plate was smaller than the factory original, and when tightening the clamp screw, the whole plate will move in the Z axis- totally messing up the timing again!

I confess that it might be possible to carry on in this fashion for several years assuming that you can still get factory breakers to replace what wears out, but  I finally opted out and ordered a CDI unit from Rex's Speed Shop.  Hopefully that will stop all these problems before they start. If you are still using points, however, another trick is to use  a 6 volt light bulb and a 3 volt battery source across the points- the HV coil should be dis-connected at this time.  The light will be brighter when the points are closed while approaching  TDC and then dim slightly when the points open.  This is a fairly precise indication of the exact position you are trying to find, and seems more reliable than an ohm meter.  It's also always good to check the final result with a timing light.  I do this by removing the spark plug- ground it to the frame- and turn the motor over with an electric drill- The light should flash when the points open and the relative position before TDC should be observable.  With all this done I still had the engine back fire several times, but the timing settings are as close to perfect as I can measure. Hope this helps in some way!

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Tillerman6 -

Appreciate everything you've said, although probably now of little or no interest to jonnywobbles as I believe he disposed of his bike some while ago, unfortunately

The ease or otherwise of setting contact gap and timing is greatly affected by preparation, and practice. With almost any pointed system the fixed contact is liable to moving when the adjustment screw is tightened and can be eased by lubrication and placing a suitable washer under the screw head if one isn't there already. Furthermore, a bit of practice will allow you to anticipate the direction and magnitude of this movement.

The biggest help of all is to use a buzzer, or multimeter with buzzer to determine points opening. Trying to look at a bulb, d.t.i. and flywheel at the same time  is just too many things to look at ! Especially when you've been temporarily blinded by staring at the bulb.......

Setting points through a small hole in the flywheel ? OK, it's a bit of a faff, but with practice doesn't represent that much of a challenge, really...

Stay safe,

Lorenzo.

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Gents, good to hear from you! You're right I did move the Sherpa on to a new home really due to the left hand kickstart which due to my dodgy knee I was struggling with. But I agree with Lorenzo that with the right tools (DTI with good solid mount, DVM with buzzer etc.) and practice which gives you an appreciation of the small variances when tightening things down etc. its not really a problem (and arguably part of the attraction of older technology bikes!). My issues were with poor quality aftermarket points described above once I sorted those out I set it up and it started no problems at all. I must admit I did fit an electronic ignition to my Triumph Bonneville T140V (Tri-Spark) which was originally a bugger to kick and sometimes tried to break your ankle for fun! It is very good as it automatically retards the ignition at less than 200 rpm to ease kicking and does remain set. I just need something to automatically balance the carbs as like the Bultaco is a matter of developing a technique - in this case two drill bits inserted under the carb slides that nod when twisting the throttle!

I am after another trials bike if you know anyone selling a righthand kicker!

Cheers

Jon

 

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Jon, 

Just FYI and you probably know this already, but a Yamaha TY is right handed for the kick starter I'm sure there are many others too. good luck searching!

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