Double Trouble

[John H]

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 (9.03 KiB) Viewed 80265 times

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 (164.74 KiB) Viewed 80265 times

[ATinkerer]

Another interesting machine you will make look better than it did when new.

[ATinkerer]

and be better also.

[John H]

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.

[ATinkerer]

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.

[ClineDesign]

I hope there's a photo op somewhere along the rebuild process!

[John H]

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 (237.83 KiB) Viewed 80257 times

[John H]

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 (214.44 KiB) Viewed 80255 times

IMG_2085.JPG (226.92 KiB) Viewed 80255 times

[John H]

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 (70.57 KiB) Viewed 80234 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 (242.34 KiB) Viewed 80234 times

[John H]

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 (247.55 KiB) Viewed 80166 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 (210.67 KiB) Viewed 80166 times

Still lots of exploring and inspecting going on.