From: tomw@megatek.com (Tom Wright)
Subject: Re: lane-splitting etiquette (& **** Harley questions ****)
Reply-To: tomw@megatek.com
Organization: Megatek Corporation, San Diego, California
Date: Mon, 4 Jan 1993 18:46:45 GMT

In article <1992Dec30.204916.14840@rtsg.mot.com> svoboda@rtsg.mot.com (David Svoboda) writes:
>In article <1992Dec23.184102.9663@megatek.com> tomw@megatek.com writes:
>|In article <102961@netnews.upenn.edu> ggrevera@gradient.cis.upenn.edu (George Grevera) writes:
>|
>|	(other stuff deleted)
>|>
>|>1) Why did Harley deem it important to develop belt drive?  (I know chains
>|>are dirty.)  It seems that many clamor for performance (carbs, cams, exhausts)
>|>but few clamor for belt drive.  Let me put it this way.  From what I gather,
>|>to add belt drive to a Sporty costs about $400-$500.  And an S&S E costs about
>|>$300 and say you get a cam for $200.  Would you rather belt drive or a carb
>|>and a cam for your money?
>|>
>|IMHO belt drives are a major advance. You're right that chains are messy, but
>|that's only the start of it. Two Japanese bikes I owned in the 1970s put their
>|drive chains through their engine cases. 
>
>Chains are better now.  Even back then, I assume you neglected your chain to
>have such a catastrophic failure.

Not so. This was a well known problem for the first 2 years of the Honda 
CB-750. The chain setup was inadequately engineered. This is not surprising.
The bike had so many inovations (first of the new wave of multi's, first
mass produced motocycle disk break, etc.) that it had to have a weak point. 
The problem was so common that engine cases were unobtainable. Aftermarket
duplex chain kits were even produced.

>|Freequent oiling and adjusting are required. 
>
>A light lubing is required every few hundred miles on an O-ring chain (takes 
>about 30 seconds, if you have a centerstand, which is stock on nearly every 
>chain-driven bike), and pre-stretched chains almost never require adjustment.
>
>It is a good idea to clean off the grime every 1000 miles or so, if you ride
>in a particularly dirty environment.

It seems to me that you've made my point. Belts require *no* maintenance
and even when totally neglected last longer that even the best cared for 
chains. And even with light oiling, chains still make a mess of the rear wheel.

>|Chains and sprockets wear out fairly freequently and the sprockets
>|are expensive and should really be replaced in pairs. 
>
>A chain and sprocket set, cared for properly, and not abused, lasts about 
>50K miles.  Replacing the chain and both sprockets runs under $150.  I can
>do the entire job in under an hour, with only a few wrenches and pliers.  
>Big deal.

I've never heard of a chain lasting 50K miles. Have you personally achieved
this? And if you did, did you oil your chain 200 times and clean it 50 times?
Even using your very optomistic 30 second figure for oiling only, that 1.5+ 
hours of chain oiling. Myself, I'd rather be riding my bike.

>|Chains can be reliable
>|and efficient in the right environment, but flapping around in the breeze
>|with no continuous oil bath picking up road grime is not such an environment.
>
>Chains are required for situations of high stress and low clearance.  A belt
>just cannot take that sort of stress.  

I believe I've read that supercharger belts on top fuel dragsters transmit 
roughly 300 hp. Clearly if chains were better for this, these people would 
use chains. 

>And any environment that you subject
>a chain to, I expect you subject the belt to.  Belts die, too, and are MUCH
>more expensive (time and money) to replace.

While belts are in the same hostile environment, they are not oiled and so
road dirt does not stick to them. Once the dirt is stuck to the chain, it
works its way into the innards and adds to the wear. 

>Is it even possible to change the drive ratio, with a belt?

Same as a chain: get alternative sprockets.

>|I've also owned a BMW, which of course has shaft drive. I found the play
>|("lash") annoying, and the maintenance was a pain -- 2 more places to change
>|the oil and measure the oil to be added.
>
>At least on my shaft drive bike, the oil can be changed very easily, and no
>measuring is necessary.  The drain plug is right in plain sight, and you just
>fill it until you can't any more.

Still, you have to do it. Again, belts require *no* maintenance.

>|My Harley mechanic tells me their belts generally last 75,000 miles, and
>|often need only one adjustment (at 500 miles).
>
>Okay, 1-1/2 times as long as chains, under MUCH less typical stress.  Check
>out the cost/lifetime ratio.

There was a posting about a big twin with something like 150K miles that was
still on the original belt. Because the belt is so much softer than the 
sprockets, the sprockets almost never need to be replaced. I suspect that mile 
for mile, by the time you wear out two sets of chain sprockets and two or more 
chains, I would still be only on my second belt.

>|They're clean, tight, 
>
>Agree.  Those are the saving graces of belts.  I think a belt is just about
>perfect for the Harley intent.

Here we agree totally. I would say that yours is the best answer yet for the 
orginal question, (paraphrased) why did Harley decide to put a belt on the 
big twin?

>			Dave Svoboda, Chicago

Tom Wright
'89 Heritage Special Calssic
Newsgroups: rec.motorcycles.harley