CB Points

[lewisweaver]

So guys as you all know i've aquired a Tomos a3. Upon arrival i found the bike didnt have any spark! . After hours and hours of tinkering and web browsing it has all let to the points and condensor. Now i managed to get the flywheel cover off and was turning the flywheel to check the points. Now there is absolutely NO movement in the points whatsoever, so I think this may be the cause of lacking spark. Anyways, the points should open at top dead center, right? There is no movement, so i've ordered new points and condensor, because they were cheap and seemed a good idea to replace. Now can anyone tell me if i've done the right thing? I mean, could the points just be set wrong so they're not opening at all? or are they f*cked?!. Help would be vmuch appreciated. Thanks, Lewis

[garryl]

Apr 26, 2011 21:45:21 GMT lewisweaver said:

So guys as you all know i've aquired a Tomos a3. Upon arrival i found the bike didnt have any spark! . After hours and hours of tinkering and web browsing it has all let to the points and condensor. Now i managed to get the flywheel cover off and was turning the flywheel to check the points. Now there is absolutely NO movement in the points whatsoever, so I think this may be the cause of lacking spark. Anyways, the points should open at top dead center, right? There is no movement, so i've ordered new points and condensor, because they were cheap and seemed a good idea to replace. Now can anyone tell me if i've done the right thing? I mean, could the points just be set wrong so they're not opening at all? or are they f*cked?!. Help would be vmuch appreciated. Thanks, Lewis

Not familier with that type of bike but most points are operated by a 'lobe' on the cam or crankshaft which the points are fixed to, ie as the lobe rotates it hits the heel of the points and they open then close as the cam/crank rotates

Check that the crank/cam is actually turning and as such operating the points, the pic below shows the heel touching the crankshaft which has the lobe on - which hits this heel thus opening/closing the points.....



Another simple check is with the ignition on, if you open/close the points with a screwdriver you should see a spark between the contacts........ providing you've a good battery, of course.

You should always set your points gap when they are at their max opening, not always TDC as this is more for the actual ignition timing.

[93fxdl]

some small engines have the cam lobe on the back of the flywheel, so it has to be in place and you set the points gap/timing through a window in it. often they specify a range of gaps in the points so you set the timing by varying the gap
ttfn glenn
ps timing should be a few degrees before tdc

[lewisweaver]

Okay guys had a proper look. Ive had some new points in the post. The current ones look very worn, almost as if about 1mm off each side of the contacts has gone. The only way they open is if they are on very tight on the camshaft. Now this is obviously because they're worn. New ones look pleasing, i've also got a condensor coming so I feel why not replace the lot. got a friend coming round with flywheel puller shortly. Will keep you all up to date!