17 replies to this topic

[timmy850]

A lean spike on acceleration means the piston is rising too quickly. You’ll need to:
Make sure the damper oil is filled up
Change to a thicker oil

[Cheeser]

https://sucarb.co.uk...pe-carburetters

I ran a 1098 with 997 cam for many years. It had an HS4 which was more than enough to produce good power and torque. The HS4 will be much easier to set up than an HIF 4 or twin HS2s both of which will be more complicated. I would suggest you look at the link to Burlen which will give you good advice on how to rebuild/adjust your existing HS4, don’t add more complication and room for errors! Good luck

[mad4classics]

As others have said, either stick with the HS4 or go for the twin HS2.
I've got a set of twin HS2 similarly from a Spitfire; still got the Spitfire ID tag of AUD517 off them. I changed the dashpot spring; dashpot damper and needles aswellas a full tefurb to run on the Mini. I'm running The Keith Calver 997 on a 998 with an 12G202 head, skimmed to suit - so pretty similar spec to you.
The carbs work equally well with springs pulling from below as above.

Edited by mad4classics, 21 November 2023 - 12:53 PM.