Weak advance and retard springs

[Sprinter]

so my 1979 RC01 ticks over very poorly, i think i might need to do a bit more carb cleaning over winter but the current issue is erratic tickover, in fact so erratic that it has been quite hard to set the timing, with the stobe i can actually see it advancing and then settling back, then repeating continuously allowing me to get the timing in the ball park only (and its riding better than it was).

After spending quite a bit of time looking for suitable springs i decided to see if i can get a replacement 425 Advance Unit, one turned up today, brand new and is suppose to be Honda original, not sure if it is but i dont care as long as it works better than the very weak on that is in there currently.

Will let you know how i get on

 

[brettp]

A bad idle could be carbs not synced, or even a vacuum leak. May not be timing. Have you ruled out the other two?

 

[Sprinter]

Yes, although I stripped and rebuilt the carbs with a raandaks kit I think a winter clean might help, bench synced and then bike synced

Vacume leak found and fixed, and coils, plugs, HT leads and CDIs replaced.

I can see it advancing and retarding at tickover with the strobe, I'm just glad to have found a new old stock replacement

 

[Sprinter]

A quick update,
Just fitted the new 425 Advance Unit, its a different bike now, well worth the effort and cost (£102), the old unit had seriously weak springs, I think someone might have swapped them out in desperation at some point in this bikes 45 year history, i cant time it fully, until my son comes home and holds the revs @ 3k rpm, whilst i confirm the advance with the strobe, but she now has a very stable tickover and timing looks good other than confirming the advance curve.

You wont find the unit online, but if you call Dave Silvers spares in the UK, he sources one, took 7>10 days for delivery so i am guessing it came in from Japan, either way i am extreamly happy

 

[brettp]

Great news!