hey guys haven't been on in a long time but my 1977 Yamaha dt 175 has suddenly given no spark. I was riding it to the shop when it stoped on the way, I pushed it in to the shop and put my new to me shocks I got off a Yamaha street bike. I screwed around with the plug and coil trying to get spark but no luck, so I decided to take off the cover where the points are and I undid the nut and pulled that tried to pull that brake drum lookin thing off. no luck so I put the nut back on and tried to spin it and it made this awful grindin noise and it would get really hard to spin. im not familiar with this thing so im wondering if I got it out of time or some crap. any help would be appreciated thanks!

Hi

The 'Drum thing' under the L/H case is the magneto rotor, when you take the centre nut off you should be able to see a L/H thread cut into the inner wall of the hub boss in the magneto, to get the magneto off with out damage and with the minimum of fuss you will need to buy a 'magneto hub puller'

something like this {Puller}. If you are gonna keep the bike it will not be a waste of money, it will be a useful tool to have and will fit other magnetos on other bikes,

the magneto should spin by hand and with the spark plug fitted to the engine as the rotor is turned it will get harder to turn as the compression builds up in the cylinder, however there should not be a grinding noise, only the quiet hiss type noise of the compression building up.

If the plug and the HT wire and coil are ok I reckon you will have to take the magneto off and do some further investigation .

MOVED.

It sounds like the woodruff key has snapped take the flywheel off 'that brake drum looking thing' using a flywheel extractor and you will see a groove cut out where the crank shaft slots through this is a locator for the woodruff key then look on the crank shaft that you've pulled the flywheel off and you should find whats left of the woodruff key.

should be able to find a new one on ebay only like £5 for new one

original plea for help 9th july, original poster not been on since 9th july...bad manners in the least .....pahhhh!!!!!

Double pahhhh!!!!!