From: couyant@convex.com (George Couyant)
Subject: Re: Project XR600
Organization: CONVEX Computer Corporation, Richardson, Tx., USA
Date: Fri, 28 Aug 1992 01:25:28 GMT
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

> From: mcclend@hpnmdla.sr.hp.com (Mike McClendon)
> Subject: Re: Project XR600
> 
> Did you do anything to the ignition, like Roost Boost?

	Nup. I'm not convinced that a Roost Boost gives value for money.
	All we did on the ignition side of things was to advance the
	ignition timing 2 deg and run a one grade colder plug. There's no
	sign of pinging, so we can probably advance it a bit more...but
	it'll do for now.
> 
> This must have cost a fortune; what were the most cost-effective mods that
> would be well worth our hard-earned $'s?

	All of 'em!!!  ;-)

	Well, it didn't cost heaps (except for the clutch). Most of the
	The suspension was a few hundred and the 630cc kit was a few
	hundred as well. The rest was late nights. We even welded
	additional cooling fins on the head (rather than paying XR's Only
	to do it). The carby will cost a few hundred as well but it's
	worth it. Since the motor was new, we could reuse gaskets (seen
	the price of an XR's gasket kit lately?....gag...matter of fact,
	seen the price of any gasket kit lately?...gag...gag...How about
	$40 for a TT600's head gasket...gag..gag...gag...).

	The cheapest mod is to remove the choke butterfly...It made a heap
	of difference..pity it makes it hard to start in the morning.

	Best value for money mod was suspension. Progressive springs,
	revalve, good quality fluid. I reckon XR forks can be made to work
	as well as any of the exotic mega buck forks. The good thing with
	XR forks is that they will still flex when they take a big hit. It
	cushions your hands and arms. Stiff USD forks don't. The rear end
	got a better quality spring and revalve to stiffen compression
	damping near full travel. 10wt fluid up front and 5wt in the
	shock.

	The 630cc kit? Hell, why not. If I was stuck for cash, I wouldn't
	bother. I'd rather spend it on the cam and valve springs/retainers
	and porting. There are enough cc's there to begin with. It's just
	that XR's stock breathing is a bit asthmatic. The exhaust was
	remarkably easy to make. If you've got a welding outfit (not an
	arc welder....) and a big vice, you can make it no sweat. If you
	have access to a pipe bending machine, it's even easier. We
	didn't, so we crafted a few pipe mandrels to keep the pipe round
	as we bent it. For the severe bends, we filled the pipe chock full
	of sand (from the kids sand pit) and plugged the ends before 
	bending (keeps it from flattening). It's a matter of constantly 
	trying it on the bike, comparing it with the stock pipe and
	bending. A bit like fitting Bark Busters....Shaping and welding
	the join where the two headers meet into one was tricky.

	This could have cost him thousands of dollars if he had a shop do
	it all for him with off the shelf parts. I'd say that he did it
	all for under $1,500 AUS plus a few weeks of late nights. When you
	compare the total cost to say a Husky 610TE, he's laughing. 

	I'm kind of interested in doing something similar for me now. The
	TT's getting on a bit and I can't afford a 610.

	Cheers
	George C.
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