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Old 04-14-2013, 12:14 AM   #46
ontic
 
Joined: Jul 2008
Location: Melbourne
Oddometer: 1,045
Quote:
Originally Posted by R-dubb View Post
I did a hot rod boxer engine years ago for McPeeDee, and it was truly a joy. Fantastic power aside, it was smooth as silk. That came from balancing the crank, rods and pistons. This time I did the balance, clutch and flywheel included, but did not go for high end rods or the 1050 kit. I decided that this would be a garden variety R80 with the balancing alone. I had to pull the crank anyhow, so a couple hundred bucks to spin and give her a haircut was an easy decision.

Yeah, I'd like to know more about the balancing too. I was planning to do my own piston and conrod balancing, and then after reading a bit about it have considered I should be digging deeper and doing it right with the crank and clutch as well...
this was a good read
http://www.advrider.com/forums/showthread.php?t=420346

When the time comes and with the parts on hand I'll probably call around my local specialists and see what it would cost to pay a pro to do this.
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Old 04-14-2013, 01:41 PM   #47
Beemerguru
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Any chance you used Armando in Sunnyvale?

I had the entire engine (crank, rods, pistons, wrist pins) done to a tenth of a gram..both K bikes and airheads.

You just have to wait while he finished the 246GT Ferrari, 904 and 906 Porsches, etc,
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Old 04-14-2013, 07:14 PM   #48
R-dubb OP
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Quote:
Originally Posted by Beemerguru View Post
Any chance you used Armando in Sunnyvale?

I had the entire engine (crank, rods, pistons, wrist pins) done to a tenth of a gram..both K bikes and airheads.

You just have to wait while he finished the 246GT Ferrari, 904 and 906 Porsches, etc,
I have used Gromm Racing in San Jose (near air port). Bob runs a very old school, cash only shop. He is meticulous, and I've been very pleased with both jobs. He starts with weighing and shaving from the con rods up. Then he spins and balances the crank, and flywheel bits, lightening as he goes. Don't know the lightening formula. I've been totally please with the smoothness of both builds. Very reasonable price and quick turnover.
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Old 04-14-2013, 07:37 PM   #49
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I think many good, racing oriented machine shops are equipped to do the balancing and lightening along the way. They produce a report of what was done in terms of the weight values for each part including material removed from the crank. The machine work is certainly money well spent. Very low risk, high reward.

The catch, if there is one, is that you've got to get the crank out of the block in the first place. That's the tricky business as it requires a few simple tools, some heating, and technique. That's where the risk lies, cause you can F'up the whole motor if not prepared for the task.
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Old 11-10-2013, 11:41 AM   #50
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I got a PM asking about geometry, ground clearance, forks, tire clearance and such. I thought I would post my comments here for others:

Quote:
Originally Posted by R-dubb
Years ago, I did a similar frame reinforcement and set up a swing arm with a 100mm extension. I abandoned that project (sold it) because I didn't like the idea of a long wheelbase with a super tall seat height. It just makes no sense, since my KTM690R is so much better than that setup would ever be for Baja style desert riding on open sand or technical trails.

What I really wanted was the compact feel of the G/S for weekend dual sporting over long distances including 4x4 jeep roads and such. The bike is so nice, I really don't want to bash it to pieces but it is very capable and handles beautifully in rough stuff.

In terms of setting up the suspension, I started with the drive shaft. I had Guy Hendersen do a U-joint rebuild. Then I carefully ground the lobe corners to maximize the flexibility and prevent contact with the housing at maximum extension. By doing this, I was able to get about an inch of ground clearance, before the bell made contact at the frame. I used this measurement to order an adjustable length YSS shock 25mm longer than OEM (370 vs 345). I assume there is some risk of shaft failure, but so far it's doing just fine.

The fork is a WP 4357 mounted in the R-dubb designed triple clamps made years ago by HPM. The fork came from an LC4, and was shortened to balance the ride with the new ride height after the bike was fully assembled. I also used stiffer springs which I cut and peened to match the shortened length with minimal preload.

I like the TKC80's. It is a 120/90-18 rear and clears the swing arm easily. My clearance issue is around the shock spring which is way bigger than stock, but just works with this size tire. Like I said this bike is for long weekends with pavement miles getting to the dirt. Don't need anything more aggressive as it wouldn't be any good on the road.

R-dubb screwed with this post 11-10-2013 at 12:01 PM
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Old 11-10-2013, 11:46 AM   #51
Airhead Wrangler
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Just curious, what spring rate did you go with for your forks?
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Old 11-10-2013, 12:10 PM   #52
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Originally Posted by Airhead Wrangler View Post
Just curious, what spring rate did you go with for your forks?
.54kg/mm - They are stiff. Maybe a tad too much, but they feel good as long as the damping isn't set too heavy, especially on the compression side. I have them fit with zero preload, just long enough that they don't rattle. In the 43's, I don't think it is feasible to go much stiffer since the wire diameter is snug to the damper and might bind to the slider at full compression if it were any bigger. The one complaint I have is sticktion. No better or worse than on the KTM, so that's just the way it is.
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Old 11-10-2013, 01:09 PM   #53
Stagehand
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54's are big!
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