Pete Bags wrote: ↑Fri Mar 27, 2026 7:41 pm
My 1098 has been mildly warmed - Kent cam, Hif 44 carb and LCB exhaust - it is probably now similar in performance to a 1275 engine.
Would it benefit from having a harmonic damper pulley fitted?
Phill recommended that I fit a harmonic damper pulley on my completely standard 1098 and I am convinced the engine is smoother compared to the standard pulley. I believe it also helps the engine to last longer between rebuilds. Unfortunately, there is no new off the shelf pulley of the metalastic type that can be fitted without some modification. There is a suitable pulley you can buy new but it has a timing disc on it that must be removed by drilling out the rivets. This is because the pulley is for A+ engines. The holes can be tapped to 5/8" UNF enabling the use of a puller to remove the pulley in future. Part number AHU1878. You may be able to find second hand damper pulleys but the rubber deteriorates and cracks and they are all rather old now so potentially they could fly apart.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
To remove the timing disc from the rear pf the damper pulley the rivets can be drilled out and the holes tapped 5/16" x 24 TPI (not 5/8" UNF ) for the bolts of a puller.
Damper pulley 1.JPG (914.82 KiB) Viewed 2540 times
Again a harmonic damper is the best modification you can do to a 1098cc 'A' Series
There are normally only three rivets holding the timing disc to the rear of the damped pulley. You appear to have six!
Those three drilled out rivet holes are then tapped for the puller.
) for the bolts of a puller.