Mid 70’s day

After starting out getting some old tyres off the rims for the 360 Bolt Up project, I decided to look at the 1975 CR250 as it might be need for Teifiside in a couple of weeks. 

Despite having not been cleaned or run for 3 months it fired up 5th kick. Went through it and tightened some bolts and sorted out the cables and levers. Clutch is pretty light anyway. The front brake is on the end of the adjustment but all in all not bad. The 1976 seat and base I put on it doesnt look perfect but it works. The 75 bike is taller than the 76 models for some reason so it is slight higher than some of the period. I’d fitted some YSS shocks a while ago and they work well. 

All tidy and ready for racing, I moved on to the 1976 360 Automatic. This had stopped working in the pit box and the Devon meeting back at the end of May and an evenings investigation with Paul afterwards failed to get it running beyond a lumpy slow run with no response from the throttle. 

Previous endeavours had looked at the crankseal, fuel tap, changed the carburettor, checked the flywheel and stator, checked the rotor side crankseal and removed the air filter. The somewhat toytown kill switch had also been connected. This latter expedient is slightly risky on a bike you cannot stall to stop and is only recommended if you have the air filter housing off and you can put your hand across the carb inlet. 

First up I changed the petrol (well you never know) but still the same low speed lurching. Some more research and could be that the ring is sticking. Unlikely given its relatively new but had a look anyway. Removed the head and barrel, but piston and ring looked fine. Next step was to change the crankseal behind the flywheel.  The seals and housing is the same as on the older 4 speed bikes (back to 1964) so had some in stock so swapped them over. 

Still no joy and the same lumpy running. Next moved onto the ignition as I’d earlier eliminated the fuel side of things. The stator looked worn with some plastic having come away. However, as it was easier I changed the ignition coil first. The one in stock had a short HT lead and the Motoplats are sealed units but managed to rig it for a test anyway. And voila, running okay. So the Motoplat unit was faulty. 

I rigged in the replacement using one mount bolt rather than two and this seemed to do the trick with just enough lead to reach the plug cap. 

Further tidy up and a cup of tea and a successful day in the garage. 

Leave a Reply

Your email address will not be published. Required fields are marked *