The 50

**cotswold** · 11th December 2013, 18:11

Originally Posted by Farmaken

If no one closer to home can help you , I am happy to do the job.

I may take you up on that, thanks Ken

**cotswold** · 17th December 2013, 04:22

Had the 50 at the track on the weekend and the first run was all good, heaps more go than before, I gave it to a lad to ride and it made 50 meters before popping and banging to a halt, I stuck in a new plug and off he went. When it came to race the same happened again. I stripped out the carb and it all looks clean and I checked the reed, so any idea's. I am thinking electrical but why would it run on a fresh plug?

**Henk** · 17th December 2013, 05:26

Check the earth for your coil.
Mate had an RM250 years ago that would run when cold, then start banging and poping so much it would shred the Kevlar reeds with backfires. Turns out the earthing lug that was bolted up behind the iron bit of the coil that mounts to the frame was corroded, replaced that and it was all good. Took him moths to find and was only a problem when it got hot.

**koba** · 17th December 2013, 05:28

Could be something else too, coincidence.

Try another Plug cap, could be that when replacing the plug you put it on just right for it to work but if slightly disturbed, such as by a running engine it stops working.

**TZ350** · 17th December 2013, 05:51

Originally Posted by cotswold

Had the 50 at the track on the weekend and the first run was all good, heaps more go than before, I gave it to a lad to ride and it made 50 meters before popping and banging to a halt, I stuck in a new plug and off he went. When it came to race the same happened again. I stripped out the carb and it all looks clean and I checked the reed, so any idea's. I am thinking electrical but why would it run on a fresh plug?

Weak Spark. The voltage rise time my be compromised by any of the problems listed above and/or damaged capacitors by trying to spark with the plug cap off.

The back emf from the coil punches holes through the capacitors internal insulation and that reduces the energy that can be stored in them by reducing the voltage they can be charged up to before it bridges the little gaps in the insulation.

With a fresh plug there is not so much to bleed the electrical charge away and the gap ionizes but a used plug is sufficiently compromised for it to drag down a weak ignition.

Possibly??

%$*&T*&(^%*(^ electrics.

**cotswold** · 21st December 2013, 07:57

Here's a clip of how my shed should look

http://www.youtube.com/watch?v=upQ2YAaSzJM

**cotswold** · 24th December 2013, 16:57

The shock on the 50 was all spring and no damping and being the cheapskate that I am looked under my bench and found this TZR250 one attatched to a swinging arm I had been given, it is the correct length but the top eye was too wide, under advise I attacked it with a disc cutter, trimmed the spacer back in the lathe and presto............it still wont fit due to the oil res fitting, so I will attack the frame and make it fit, even if it kills the frame, it will give me the nudge I need to start making one. PS merry Crimble one and all

**cotswold** · 27th December 2013, 19:54

Took to the frame with the trusty dremmel and made that sucker fit. I wont know what to do with myself now I have adjustment on the spring and the damping, having the rear tyre on the tarseal will be a feeling I am keen to get used to.

**cotswold** · 29th December 2013, 12:50

I think these photo's will show why my spark was a bit weak, the other question would be how did it ever run?

I think the moral of this tale is if you make a "race" bike out of a beach toy you should 1st remove all the sand.

**koba** · 30th December 2013, 15:56

Originally Posted by cotswold

I think these photo's will show why my spark was a bit weak, the other question would be how did it ever run?

I think the moral of this tale is if you make a "race" bike out of a beach toy you should 1st remove all the sand.

Al least there are worse places to have sand lodged.

**F5 Dave** · 30th December 2013, 17:13

What's the matter Stan. . .

**cotswold** · 5th January 2014, 06:28

A big thanks to Ken for not only cutting my taper for the Pvl but also making up a base plate and setting the timing, when I got to the track all I had to do was re jet and she now picks up like a mad thing. Very pleased.
Once again thanks.

**cotswold** · 5th January 2014, 16:46

Ken at work.............

**F5 Dave** · 5th January 2014, 20:19

Great to see the 50 in action. Sounded great and went well from what I could see. Anyway let's talk numbers later on and we'll get it really spinning.