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Discussion Starter · #1 ·
I am building an Ol skool double Shovel for a customer with a few twists thrown in so I thought a build thread was in order.

This will be a classic early 70's style double running high gear only with a slipper clutch.

The first order of business is to build a set of motor plates to hold the two engines.

It all starts will two pieces of 6061 aluminum plate.


We are using 21" of crankshaft separation as well as raising the front engine 1". This makes the exhaust a little easier to do without making the engine package too long.



This is the finished left side with jackshaft location.
 

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Wow, this is gona rock!
 

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Don, are the cutouts to clear the cam chest?
 

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Discussion Starter · #8 ·
Here's the right side showing the cam chest cutouts.


Then I have added the crossties that the cases mount to.


This is the completed motor plate assembly. Now we have something to build a frame around.


Next time I'll start laying up the frame.
 

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Douhhh, got my left and right backwards, lol. Thank you for taking the time to post these build pics, theres nothing quite like a twin, twin.
 

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Discussion Starter · #11 ·
One thing that has to be considered as I start the frame is ride height.

My single engine frames have 2 1/2" of ground clearance but that will not be enough due to the increase in wheelbase for the double.

It was also decided to go from a 26" tall tire like I normally build for to a 28". That is a more period correct size as it will be running a 10" wide tire.

It was decided to change the axle position one inch and then let the one inch difference in the radius of the tire bring it on up to a two inch increase in ride height.

Here I am tacking up the rear axle plates and checking the position of the engine module.



Next an engine cradle is tacked together and checked for fit.



The steering head ,backbone and top loop of the rear section are put together in a separate fixture and then that subassembly is trial fitted.

 

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Discussion Starter · #12 ·
The upper tubes of the rear section are tacked in place and the engine module goes back in to verify some height measurements.



This will be the business end.



Then the front downtubes are checked for fit.



Next some rear section braces are added and the rear uprights that will be the mounting points for the engine module.



That's the basic skeleton . You can see the classic double profile starting to take shape.
 

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Hell yes! Cant wait to see progress maid on this one, thanks for posting!

-Justin
 

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I've always loved these double engine bikes.It will be cool watching this go together.What is the purpose of the motor plates, rather than making engine mounts directly on the frame?
 

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Discussion Starter · #17 ·
I've always loved these double engine bikes.It will be cool watching this go together.What is the purpose of the motor plates, rather than making engine mounts directly on the frame?
Motor plates are just an easy to build, extremely rigid, lightweight way to mount engines in dragbikes. A lot of singles were built that way as well and in fact many still are.

With unit constuction engines that have to have the trans. compartment cut off they become almost manditory.

Obviously that doesn't apply here ,but this type of constuction will apply to just about any engine pair.

I think the only double I ever saw in person that didn't have motor plates used two RD350 Yamahas for power.
 

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Thanks for the explaination...its cool watching things like this that Ive never seen.Its lookin pretty wild already.
 
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