The Big Bang Motor

Well, with the 2007 bike now effectively sold, I'd best get on with building the prototype motor. we'll have to mate it with the chassis around February, so time is becoming of the essence!

Here are a few piccies from the Team Thumper Solar Workshop (yes, it's totally self-sufficient, unlike our race Team!).

The Yamaha XTZ bottom end was originally water cooled, with a starter motor. Here you can see where the starter boss has been cut off and welded up.

On the other side, you can see the beautifully machined blanking plate where the water pump used to live. Going aircooled makes for a simpler build, and should mean that the engine doesn't "cook" as badly on the grid. It will also be lighter, and without the additional expense of a radiator. The latter is also an easily wrecked item, in event of the inevitable spills!

And here's the newly honed barrel, for the brand spankers 100mm (640cc) piston.

There's a bit of work with WD40 and a toothbrush there I think! Its an XT item I think, as is the head:

If you look closely you can see the spring clip retainers to hold the header pipes on, so we dont have to use the original Yamaha retainers, and makes it nice n easy to get the pipes on and off. However, I noticed today that the right hand one in the photo above has got one of the clips broken off. There's another job for Mr B! It came with stainless valves and springs, and a Yoshimura Stage 4 cam...

Looks happy, doesn't he? And so he should with such fetching headgear!

The motor came with a beautiful Carillo rod, and the crankcase mouth has been machined to accept a 690 104 piston. Thats on it just now, but I think its probably a bit much and may compromise reliability.

Size matters, apparently:

So the first job is to locate a new base gasket, get the 640 piston on and slot it into the bore. I'll let you know when its done and then get started on the head. I have to get a bit of advice on that, from some learned men, but in the meantime I can clean up mating surfaces etc, and think about what method I'm going to use to tie the barrel down. I'll be seeking advice on what barrel and head I actually have, and how best to go about things.

Cheers for now, Andy