Sundial Moto Sports

I purchased a load of t500 stuff recently including what appears to be a race tuned engine, heavy porting, squish heads, straight cut peimary gears, but the crank has been aligned to 0 degrees. It also looks like it had some chunks machined out of it beside the big end pins, possibly to help balance it.
Anyone ever hear of such a thing? I am tempted to try to run it like this, at least for a few minutes to see what happens.

How are the crank halfs aligned on these? Is there a keyway in there or something?
Thanks guys

What exactly do you mean by "0 degrees" JG.

If you mean that now both pistons rise and fall together i.e. they are both at TDC together this is more conventionally known as a "360 degree crank". Although zero degrees is just as good I suppose . If this is the case the engine has been converted to fire the pistons together in "big bang" fashion. How the engine performs in this configuration I have no real idea but it should still work. Vibration, never a good point on a conventional T500, might be somewhat interesting.

The conversion is relatively simple as the crank is not "pinned" and is simply pressed together (using a 10 ton press etc.). Post some photos, I would be intrigued to have a look at it.

Cheers Geoff

PS: If you find youself selling those centre plug squish heads I would be interested

Yes, but I would drive up, and pick them up.

Interesting to hear how this might perform....will it rev as freely as a conventional twin? Will it generate more torque? Could you run a 2-1 exhaust. Sounds like the crank has been lightened.

Intrigued. Please keep us posted. Pictures would be good too, and some port dimensions please.

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Keeping old 2 strokes alive !

This topic pops up every couple months. 30 years ago I pressed a 360 degree crank together for a flat tracker. I never rode it, but the guy said it hooked up well. I did build my “Titan Twingle” still with the 180 degree crank, but with a single pipe and single carb. That worked very well up to 6250 rpm. (There is a write up in the Customs section) No doubt it will shake like a 500cc single with a 360 crank, but still it would be neat and different. You could use a single or twin pipes on that combo.

I will have my man fly over in the Lear Jet to pick them up

You could even press the crank together with the crankpins 90 degrees apart, to give the bike a firing pattern similar to a V-twin ... in theory, it's good for torque and rideability because unlike a 180- or 360-degree crank, you never get a point when both pistons come to a dead stop at the extremes of their strokes, at the same time.

Of course, setting up the ignition timing is a bit trickier if you went the 90-degree route

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1976 GT380 - wounded by me, and sold on
2006 SV650S. It's got cams, and valves, and stuff

A GT500 crankcase + PEI ignition fires both plugs at the same time, so no ignition mods would be necessary when you switch to a 360 degree crank.

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BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
Yamaha 75 XS650
09 Triumph Bonneville SE

Thanks for all the replies folks.
I would post up some photos, but the file size is a bit to large at the moment.
A few points i guess
First being that, yes Geoff, it is 360 degrees, zero seemed more appropriate as it fires both at the same time 360 is for four strokes

https://uploads.tapatalk-cdn.com/201802 ... 3de15b.jpg
The crank can been seen here, it might not be very visible, but there are chunks machined out of the crank wheels on both sides of the big end rods.

Don’t know if that was meant to balance it a bit, but the PO said he would not run it with the crank in that configuration.
Luckily i got a spare crank, and an extra complete engine so i can swap thw crank out for now.

It was interesting to open this motor up, straight cut primary gears, (sadly no close rario gears)
Running a yamaha tr2 ignition. Every single port was worked on it looked like.
This thing will either be a beast or have a paperthin powerband.

Forgot to ask, would anyone consider running the crank this way? Or would i be better to swap in a 180 degree crank or have this one re aligned?
I am half tempted to give it a whirl as is, its only about an hour to have the thing torn down again if it shakes to much.

Hi jg,

Yep. I get what you mean about 0 and 360 degree cranks and the 2-st/4-st firing order. Never thought of it like that. I have chatted to someone who modified the camshafts on a 500cc Triumph so that both cylinders fired together so I guess you could call that a 0 degree crank too. it was done to provide better grip on a Moto-X bike but that old bug-bear vibration was too much, although it worked well in other ways apparently.

I hope you get the chance to at least give it a short run as I would be fascinated as to how it performs.

Cheers Geoff

Hmm, in that case i think i’ll run it as is, in the name of science of course

If you can, video it too please . A short road test just has to done as well .

Cheers Geoff

So i decided not to run the twingle in the end.
It just made no sense,
Especially with th chunks taken out of the crank wheels, even without the pistons and conrods shaking it to pieces.
Sorry Geoff

I might try the twingle on a stock set of cylinders another time.

Don't blame you jg .