Oh the shame of it all. Jan’s relentless progress, and Performance Bike magazine getting their CR500 engined Mito running this month has given me a real kick in the ass. Plus constant jibes from my biking buddies at work – I really must make some progress. But I finally finished all the booze left over from Christmas so have started to slink back into a freezing shed after lights out armed only with a fan heater and a woolly hat.
The whole project was being held up by the expansion chamber, which I managed to put off for another couple of months by doing a lot “thinking about it” and by making more cardboard models. Just to give an idea of the problem I face look at the size of this. And that’s without the stinger and can!
I finally decided to get a standard one and chop it up, so ordered this an some other bits off a very helpful motocross breaker up north.
What I received was a box of mud, but on further inspection each sod contained a component.
Imagine my surprise when I chipped away at the biggest one to find this gold series FMF fatty!
Sadly it’s chromed and the first bend again gets too close to the front wheel on full bump. The chrome could come off, but even cutting a re-welding (in a similar configuration to what Jan has done) would mean that I couldn’t fit the fairing back on without chopping a big hole it in – which is not the look I’m after.
I found a further stash of beer and some far more important things to do instead, like coil and CDI bracket, front sprocket cover etc, pretending the expansion chamber would sort itself.
Unfortunately it didn’t sort itself, so after another few iterations of wire frame and cardboard models I was left with the final design - which is this.
Because the engine was offset slightly to get the chain run correct, and because there’s only a tiny water pump not a huge generator on the right side, it means there’s more space over this side. I think I might even be able to fit a fairing!
The level of procrastination was getting embarrassing so finally metal started to be cut.
Bar turned into this,
Which has turned into this – the first bend.
130mm done – only 1250 to go!
Jan – I’m glad to see that you’ve gone for 2 silencers. I hope it works. The reason for this is that I want to keep mine looking standard, so I intend to have two stingers running off the end of the convergent cone, The internal bore of the KX stinger is 30mm. This would look wrong as the o/d would be about 33mm. Two standard KR1-s stingers would do the job, and as they are slightly longer than required their slightly larger than the ideal 21.2mm bore would be fine.
I don’t want to chop my KRI-1 expansion chambers as they’re in fairly good nick. I don’t mind unbolting the cans of course. Has anyone got some really manky expansion chambers that are beyond repair? If so cut the stingers off and I’ll buy them off you.