Texas Two Step Taco

Texasstar

Can't is a four letter dirty word
Yes, but not because it leaked. On the air-cooled engine I found that if I used a slip joint the outer sleeve was so close to the flange bolts it was difficult to work with. So I just welded the flange directly to the pipe and bolted it on with a little silicone. To prevent the pipe and cylinder being stressed I allowed for some movement at the rear mount - the mounting lug on the pipe sits vertically and has an oversize hole. It's attached to the frame via a bolt, a fender washer on each side of the lug and a small spacer that fits in the hole of the lug. When the bolt is pulled up tight there's just enough clearance between the fender washers and the pipe lug to allow a couple of mm fore and aft movement. There's no leaks, no cracks and no wobbles; it worked so well I use this setup on all my pipes now.

But a little silicone will seal your leaks and you'll find as you continue to increase the power the engine will run cleaner. Your video shows next to no smoke; a big difference from the earlier vids.
That makes a lot of sense. BB did something similar but he has no bolts involved. His stinger slides into a collar that allow the pipe to float and then the 4 springs retain the chamber. He has to take off 3 chambers at a time.

He uses the rubber collars going into the exhaust flange but I was wondering if that would dampen the pulse and change the resonance of the chamber?


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Texasstar

Can't is a four letter dirty word
The trouble with the steel Bul plates is the T and L shaped holes punched in them - you can't bore them out very far without breaking into the holes and making the plates too flimsy. But you could probably achieve the same result by facing off about 0.010" from each side out to a diameter about 20 - 25mm less than the OD. You could make a centering plug to position the plate on the faceplate while it's clamped down with say 4 finger clamps (or a ring), then the plug would be removed while making the cut. And of course the first thing to do would be to investigate why the clutch isn't releasing.
IMG_8719.jpg

This is what I did...the outer collar slides into the the flange and the inner pipe matches the port but any separation would interrupt the resonance. You can watch it at 8 k and it will separate from the port.
IMG_8722.jpg



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Texasstar

Can't is a four letter dirty word
So my thoughts were to cut pieces of the collar pipe to insert to tune the chamber.


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John Murray

Member
So my thought were to cut pieces of the collar pipe to insert to tune the chamber.


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I guess that could be made to work. Though I usually make length adjustments in the belly section (if there is one) to avoid having to deal with changing the length of a tapered header pipe.

I suspect that a cylinder like this - with limited blowdown T/A and just two high-velocity transfers - might like a fairly strongly tapered header to help with blowdown followed by a relatively gently tapered diffuser. But I have zero test data to confirm this :(
 

Texasstar

Can't is a four letter dirty word
Even a smallish leak at the joint can have a surprising effect on power so do whatever you have to do to seal it.
As soon as the egt bung started cracking we lost major power. We couldn’t figure out why the EGT’s were dropping on each run until the bung fell off.


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John Murray

Member
As soon as the egt bung started cracking we lost major power. We couldn’t figure out why the EGT’s were dropping on each run until the bung fell off.


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I know I've said this a million times but this is the last time, I promise. Don't get distracted by EGTs and F/A numbers at this stage; all you need to be watching right now is the torque readings. It's the tuning equivalent of keeping your eye on the ball. The EGT is a reference number you'll use when tuning is completed, the F/As are little more than an opinion. Don't let them lead you on a wild goose chase.
 

Texasstar

Can't is a four letter dirty word
I know I've said this a million times but this is the last time, I promise. Don't get distracted by EGTs and F/A numbers at this stage; all you need to be watching right now is the torque readings. It's the tuning equivalent of keeping your eye on the ball. The EGT is a reference number you'll use when tuning is completed, the F/As are little more than an opinion. Don't let them lead you on a wild goose chase.
We saw 26 ft lbs of torque and I am excited about my new t-shirt! With every dyno session we have a new list of corrections.

Well it was a wild goose chase for over half of the 11 pulls. You are right a little leak will cause a dramatic drop in power and 6 pulls had a leak and you can see it in the EGT. I can see how the air fuel can be misleading but I can also see why we need fuel injection. ;)


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teazer

Well-Known Member
DTT BOTM WINNER
John,
Do you want to hold him while I try to slap some sense into him or would you like me to hold him so you can have the first slap? o_O:eek::D

That's a good point about those inner steels. You could potentially machine them thinner on the hub side.

And just as an FYI, fixed gear kart racers modify the short parallel part of the header to fine tune their pipes, so you are not wrong there. But that isn't simple to seal if you do that. They use replaceable pipes to change from track to track and to adjust for changes in weather etc.
 

John Murray

Member
Just imagine how much power we could make and how efficient a two stroke could be if you could also control the fuel curve like the ignition curve. Paris Hilton tuning would have to give way to Elon Musk tuning. https://www.cycleworld.com/story/motorcycle-news/kawasaki-to-design-supercharged-two-stroke-hybrid/


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You can, it's already being done and the performance advantage ranges in size from minimal to non-existant. The big advantage to FI with two-strokes is emission reductions. It's important too, and is why manufacturers like KTM and SkiDoo can continue to sell two strokes. But if it's performance you're after you're barking up the wrong tree.
 
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Texasstar

Can't is a four letter dirty word
You can, it's already being done and the performance advantage ranges in size from minimal to non-existant. The big advantage to FI with two-strokes is emission reductions. It's important too, and is why manufacturers like KTM can continue to sell two strokes. But if it's performance you're after you're barking up the wrong tree.
I know it is like herding a barrel of wild monkeys. This is why team old age and treachery is so strong. I hear y’all! Focus. We could spend 100 dyno pulls just exploring the 220 jet with the Zeeltronic let alone spraying at TDC and BDC with fuel injection.

Just a recap. We made 11 dyno pulls this session, clutch held, we fouled one plug, Broke a bung, and made some more torque! I made a collar for the stinger so that the chamber can float and not buck like a wild bronco.

The smoke is starting to clear in the dyno room and our eyes are no longer watering.
We have made 26 dyno runs. BB has done that in one day lol.


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John Murray

Member
That damn Zeeltronic is your worst enemy - not only has it wasted your time by making you look for power in rpm ranges you'll never use it was so damn feeble it couldn't even fire a fouled plug!!! Absolute garbage!

Edit: that was a bit harsh wasn't it. There's more power to be made, just try to make it easier on yourself. I can't wait to see this bike on the road!
 

Texasstar

Can't is a four letter dirty word
That damn Zeeltronic is your worst enemy - not only has it wasted your time by making you look for power in rpm ranges you'll never use it was so damn feeble it couldn't even fire a fouled plug!!! Absolute garbage!
I love a friend with convictions!


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