October 2014: planning for the winter in the workshop.

So, the last British Historic Racing club meeting of 2014 at Cadwell Park has been and gone. In our calendar that is the sign that winter is on it’s way. What normally happens is that you think you’ve got plenty of time to get on with your bike project(s) but all of a sudden, it’s Christmas. Then, no sooner than you’ve sung ‘auld lang syne’, January disappears too. You are then halfway through March before you know it and suddenly you realise that the season starts in April and you’ve a week before the first practice day and you are no-where near ready.
Even though I know this, it will still happen…

I had thought that the Super Squirrel wasn’t quite working as well as it should after the frenetic ‘development’ work I did just before the meeting, but was very happy that it was working at all. It certainly went well enough to be competitive enough to have some fun but I know it could be a lot better and it was with that thought that I took it to the dyno at the beginning of October.

October dyno run


Super squirrel torque curve - October 2014
Super squirrel torque curve – October 2014


Super Squirrel BHP curve - October 2014
Super Squirrel BHP curve – October 2014

Steve, who runs the dyno said pretty much immediately that he could see it was massively rich… so much so that it’s just not able to run anything properly. He’s up for a longer set-up session, and with that in mind I am now trying to get everything together that I’ll need.

I’d talked to Rex Caunt at Cadwell Park. Rex is a friend of Roger’s and it was with his help that we fitted a PVL system to his Scott many years ago. He went on to fit a BTH magneto and I inherited the PVL system.
Rex is not just an expert on racing ignition systems, but he’s also very much involved with two stroke tuning and we had a long chat about my plans for development. He suggested analysing the exhaust gas temperature with some thermocouples to give me some idea of what was happening. Pressure waves behave differently in different gas densities, so temperature has an effect on the speed of the wave. I picked some up really cheaply on ebay.
I also bought some new needles and needle jets as the one I did are not suitable.

Once I’ve got everything ready, I’ll be booking a dyno slot.

3 thoughts on “October 2014: planning for the winter in the workshop.”

  1. Hi Richard.

    Instead of T/C’s, wouldn’t auto OX sensors be more accurate?

    225 Mv = 14.7 mixture, more voltage = richer mixture.


    1. Hi Herb,

      Actually, I just made a decision to switch back from dope to petrol. The bike runs well on dope and with some attention to set-up could be really good but I can’t get away from the fact that I’m more nervous about the toxicity of methanol. I’m careful with it, but nowadays my two year old daughter likes to come into the workshop sometimes and I just don’t feel happy about having it around.
      Since I’m back at the beginning of a whole new carburation set-up, I thought that this was the time to do it.
      Also, the Moss Silk Scott engine will run on petrol anyway so it makes some sense to keep the same fuel.
      It was an interesting experience, and I hope that with work I can get it to run cool enough as that’s one of the reasons I switched in the first place.
      I’m sure we can make it work!

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