Twin engine bikes

[Calkins]

Is there a 'big' advantage to running twin twins in an 'open' bike?

[slopoke]

.

[Dean Los Angeles]

From an aerodynamics perspective, having one engine behind the other, versus a single engine of the same size gives you a narrower package.

The complexity of the installation goes up by a bunch. Trying to figure out how to get the front drive past the rear engine, routing the exhausts and a bunch of other details. Tuning a twin so both engines run in sync is another chore. If one engine is off by a minor amount it pulls both engines down.

I saw a guy running a twin engine Triumph streamliner in the 70's that did an extremely poor job.

The engines were so close that there wasn't enough room for carbs on the front engine. So he ran intake tubing over the rear engine past the rear carbs to mount the front carbs. Must have been two feet of tubing.

Over all it was a pretty poor effort. It wouldn't pass tech today. The canopy didn't fit very well. You had to know exactly what went in first and kind of pull and push to get it to fit. The guy had his two kids trying to fit the canopy on all the while yelling from inside giving instructions. The engines had already been fired up and were starting to overheat before the canopy was finally latched.

They then pushed him off and he ran all of ten feet before falling over. We ran over to pick the streamliner up only to discover that the six or seven of us weren't enough to pick up that heavy beast. Fortunately he had a fire a little later that put an end to the effort before he could hurt himself. I know, it's hard to look at a fire as a good thing, but it was in this case.

[Calkins]

Ok slopoke.  Not really the long answer I was looking for.

Ok, dream along with me...
Twin 1953-5 Triumph Tiger 650s, running in A/VG.  Bored, stroked, carbed, ported, cammed, blah, blah, blah...

Is it worth it now?  With such a small engine size, would the extra weight make the idea not worth it?  I haven't looked yet, but I would think that you should be able to get 750cc-900cc out of each.

What about flatheads?

[Calkins]

DLA, I've seen a setup like that, but it had a blower on the front motor and piped to both.  Some guys would switch the exhaust/intakes.  The front motor would be standard and the rear would have the intake running into the exhaust side and headers out the back intake side.  Then they would have a blower piped to the middle of the two engines, kindof like a v-twin setup, but for four cylinders instead of just two.

[panic]

Tuning a twin so both engines run in sync is another chore. If one engine is off by a minor amount it pulls both engines down.

I don't think that's true.
The moment that the stronger engine develops any slack in the drive, the weak engine speeds up, and this is self-correcting (except for beating up the primary drive). It would obviously be better if both contributions matched, but the effect isn't any more important than trying to get all 8 cylinders to match.
Dual engines have been built with engines of different sizes and even completely different designs.
What I thought was surprising was that attempts to oppose the engines at 180° intervals (front TDC, rear BDC) all failed - the chain prefers very strong but wider shock intervals caused by everything going to TDC at once.

[Freud]

Calkins I have no idea what your goals are or if you are truly dreaming;

Ok, dream along with me...
Twin 1953-5 Triumph Tiger 650s, running in A/VG.  Bored, stroked, carbed, ported, cammed, blah, blah, blah...

Is it worth it now?  With such a small engine size, would the extra weight make the idea not worth it?  I haven't looked yet, but I would think that you should be able to get 750cc-900cc out of each.

Is vintage gas your challenge?

Do you just want  answers that will never be used?

Do you really want some speed for your financial investment?

Do you want to use up a bunch of the existing Triumph parts?

Denis Manning gave up on English twins about 30 years ago.

Contemplate what Bob Leppan did in the '60's.

If you want a good ride with less complications, go to the wrecked bike shop, buy several 600 cc Honda, Kawasaki or Suzuki engines and leave them alone.  Make your build around them and concentrate on your chassis. You will get more bang for your buck. If u ever decide to turbo them there is more equipment available than the Triumphs could ever tolerate.

Before the Manning, Akatiff and Wheeler skirmish developed, Don Vesco told me, "there are production engines available that have a warranty on them" that would raise the 318 record. Keep it simple and have fun.

Bored, stroked, carbed, ported, cammed, blah, blah, blah...

Todays stockers from a salvage yard will outrun all that expense and probably one of those engines will out perform vintage twins. Besides, with a single engine you don't have to contemplate syncro between two engines.

But on the other hand, you can attract many pipe smoking, grey beard stroking men that will talk all day about their Limey bikes they had in 1955

Where the h e l l did you get the LSD?.

FREUD

[Dr Goggles]

But on the other hand, you can attract many pipe smoking, grey beard stroking men that will talk all day about their Limey bikes they had in 1955
Where the h e l l did you get the LSD?.
FREUD

Pure Gold!!!!!!!

do the aero, buy cheap reliability and race while others fix or watch.

[Calkins]

Freud, I'm never surprised be anything you say!  I love it!

I have so many ideas, I could fill a school bus with my drawings.  I'd like to stick with Triumphs, I like them, and I'm drawn to them for some reason.  I'd also like to run in the Vintage classes to be on a more level playing ground; ie, no efi and the such.  I know that I'd be pi$$ing money away.

I saw The Thing thatWillie posted, and I've always wondered about twins.  They seem to be tricky, and trick.

Back in the day, there was a front engine dragster called The Odd Couple.  It had a hemi and a small block chevy.  There thought was the small block would rev fast and help speed up the car and the hemi had the power for the top end.  Weird.

[Peter Jack]

Calkins:

Your thought processes are strange enough that you should fit right in!

[Calkins]

Calkins:

Your thought processes are strange enough that you should fit right in!

Thank you.

[Freud]

I slept on my statement.

I'M WRONG. Practicality can not replace passion.

FREUD

[Calkins]

I slept on my statement.

I'M WRONG. Practicality can not replace passion.

FREUD

So, you don't nessesarily agree with the idea, but you understand the thought, right?

[panic]

The nice part about dreams (as opposed to practical projects) is that they're fun all the way up to the point where you die, even after you give up or sell it.

[1194]

The best ever Twin-Engine Tri. was the one build and raced by Boris Murray, he knew what he was doing............We build a chassis for a twin-Tri.....thought better of it....put one 750c.c Tri.
(Chatland Kit) engine in it...... running thru a BSA close-ratio gearbox.....bolted a "wheel on a stick"
on it (I know, sorry, but we were racing SCTA/BNI)
and set a record............................................................