Well… It has been some considerable effort, but the new incarnation of my racer was wheeled out yesterday evening.
Always a little apprehensive before starting a new engine, It failed to even slightly worry me as it started instantly the moment my backside hit the saddle.
Its the most radical iron engine i’ve ever done and there is a bit of suck it and see with the flywheel weight especially being reduced considerably by the need to reduce diameter for inlet modifications. This will increase the vibes with the benefits of acceleration, but i guess i don’t know to what extent until i try it.
I will definitely be at Mallory on this Sunday (8th/Easter Sunday) for those who are interested, but as this is such a completely new and untested engine/induction system i have to at least pretend i am thinking of it as a practice session.
I think it could be fast. I think it should be fast, but if it cleaned up straight out the box (when i also haven’t ridden at mallory for over ten years) then we will be the first people in a while to witness a miracle at Easter!
Well good luck and try to keep it in one piece!
I will keep my fingers crossed! See you Tuesday evening!
And.. how did it go?????
I wont do the whole Story here because i should do a proper write up…
Sunday at Mallory park proved that i could really get this bike to go… The twin carbs, new head and barrel made the thing pull like a train… I felt like i’d really got something good going on!
so much in fact
that I was just about to peel into Edwinas (a chicane) on only the second lap of the first race and the Engine literally exploded.
The results of the ‘Race Engine to concrete mixer’ moment were so impressive that people were crowding around taking photos for the rest of the day!
The bit they especially liked was when you turned the rear wheel in gear and the barrel moved up and down.
I knew the crankcase had a couple of minor cracks in one of the mouths after the considerable amount of welding it had received in repairing it (originally one of Rogers 1970’s racing cases) but i figured it would be ok!
It also transpired that the sections were uneven in thinkness and that the Aluminium casting itself was not so good..
have a look at some ‘before and afters’ i quickly posted
Although its a lot of wasted work.. I know the engine worked well and i think it just needs a good strong case and a bit of sorting to be competitive (whether i am is another matter!)
so in fact i wasn’t as depressed as you might expect…
definitely one for our ‘failed racing component hall of fame’
I am taking on Rogers own racing case as he is making a new one for his racer. Of course it needs work! .. but its a great case and should hang together.
by hook or by crook we will make it to Oulton next month!
thanks to all those who have leant their support
I took the liberty of posting a picture of this on the RD forum, just to let them know that the Scott still rocks 😀
The crank looks good for more DT.
Wow, that sure is one for the hall of fame! But I am glad the engine explode and you did not…
Well, another project to keep you out of the pub ;o)
Gawd! That is really awful! My commiserations . . .
Certainly puts my Scott basket-case problems in perspective!
Still, (rapidly ducking for cover), on the bright side, it must make fitting the primary and magneto chains easier . . .
I am not immune to irritation or dissapointment but i have to say i found the absolute finality of the situation really quite cathartic.
I know when there is a chance of making a repair, but, there was nothing i could do.
I will be fitting Rogers race engine for Oulton, which is on the 12th May (i think) and this gives me the chance to do a new case for a bit later in the summer.
It certainly offered a rare example to see the differences in cross section over the casting… yikes… from about 1/8″ to just under 3/8″.
The thing is. if this had been a regular road engine it probably would have been ok, but i spent almost a week getting the head profiles matched to a point where i have only 21 cc head volume at T.D.C.
That is a hell of a compression. I think over 10:1 after the exhaust closes. I guess if you have weaknesses in the casting, they are going to show up …
I hope the RD boys enjoy the pics… my first ‘real’ bike was a 350 ypvs. We’ve still got it, and it will be going for its MOT on tuesday. A lot of smiles per mile!
As for the Scott
I’ve been offered a bit of sponsorship to put it on a dyno to test it properly once the engine has been rebuilt, so cross fingers…
It might just hang together : )