Double Trouble

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Double Trouble

Postby John H » Fri Feb 21, 2020 10:21 pm

Back in the day (60s & 70s) drag racers were into twin engine drag bikes. Some went pretty fast including
Boris Murray who won more than one championship on his Triumph. Anyone who followed racing back then
remembers the famous photo.
I was lucky to find one of his bikes back in the 80s and finally have time to start a restoration on it.
Boris Wheelie.jpg
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This machine hasn't run since 1970 when it blew the top off the rear engine. With a lot of cleaning we'll see what it takes to bring it back to life.

Tri Double.jpg
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John
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Re: Double Trouble

Postby ATinkerer » Fri Feb 21, 2020 11:03 pm

Another interesting machine you will make look better than it did when new.
If it isn't smoking, it's broken.
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Re: Double Trouble

Postby ATinkerer » Fri Feb 21, 2020 11:03 pm

and be better also.
If it isn't smoking, it's broken.
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Re: Double Trouble

Postby John H » Sat Feb 22, 2020 10:02 am

Thanks, only downside is I probably will never get to ride it. At least shouldn't. It was running low 170s back then, slow compared to speeds today.
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Re: Double Trouble

Postby ATinkerer » Sat Feb 22, 2020 10:14 am

Unfortunately, the Hailwood observation that "the throttle works both ways" doesn't apply well to drag machines.
But, bet you can find some young, immortal that would like to try it out for you.
If it isn't smoking, it's broken.
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Re: Double Trouble

Postby ClineDesign » Sat Feb 22, 2020 4:44 pm

I hope there's a photo op somewhere along the rebuild process!
Always wear protective gear. Usually SPF 30 will do.
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Re: Double Trouble

Postby John H » Sat Feb 22, 2020 5:14 pm

This time around, it's going to be a disassemble, inspect, do an inventory of parts needed then loosely assemble it for the bike show in late April. Then tear it down and build it to run. Lots of homemade parts to make and remake.

1969
TriDbl1.jpg
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Re: Double Trouble

Postby John H » Sat Feb 22, 2020 10:22 pm

The bike had sat outside in the weather for a few years when I got it. The original rear wheel and fuel tanks were missing as well as the crank, rods and pistons for the rear motor. I've located a wheel, crank and rods but will need to fab the tanks.
Here I thought I'd be starting in on my Black Shadow about now. Maybe next??
Those MTC Eng tanks go with the Tedder/Muldoon Honda dragbike that will get it's resto some day.

TriDub.JPG
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IMG_2085.JPG
IMG_2085.JPG (226.92 KiB) Viewed 4903 times
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Re: Double Trouble

Postby John H » Wed Feb 26, 2020 11:21 pm

More surprises as I get into the teardown. Lots of weld repair on the rear crankcases and reinforcing plates welded in both engines. This was added after popping the top of the crankcases off from nitro backfires.
TriDbl5.jpg
TriDbl5.jpg (70.57 KiB) Viewed 4882 times


Notice the gear on the magneto. It's arc welded to a tapered hub, probably from a HD. Guess this means I have to make one for the rear engine. I located another Hunt mag from another HD so the shaft will need to be replaced for the vertical twin firing. I still haven't figured how the oil lines run. It looks like the oil was pumped from one engine to the other then back to the tank. I'll have to think on that one.

IMG_0824.JPG
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Re: Double Trouble

Postby John H » Sun Mar 01, 2020 9:34 pm

With the rear engine out I can now see a choriographed reassembly will be required. With engine out and separated it's obvious they broke a rod and punched some holes in the cases. The Main bearing bores are hammered out as well. Luckily the broken rod didn't wipe out the special cams but came close.
IMG_1581.JPG
IMG_1581.JPG (247.55 KiB) Viewed 4814 times


The Norris cams are a special grind with .363 lift and a ton of overlap. I will put gauges on the rockers on the front engine to get all the dope on total lift and timing. I do have two sets of Harmon cams that I got with the bike but no specs on them so will stick with the Norris for now.
IMG_8165.JPG
IMG_8165.JPG (210.67 KiB) Viewed 4814 times


Still lots of exploring and inspecting going on.
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