Texas Two Step Taco

Texasstar

Can't is a four letter dirty word
It should release unless the springs are fully coil-bound. Does it feel right? If you take out the inspection/adjustment plug can you see the pressure plate move as you operate the lever? It won't move much; about 1mm at most. If it isn't moving check for stripped or loose ignition side cover screws. A very slightly warped or bent plate is enough to make the clutch not release - they have to be dead flat.
Pressure plate is moving and it feels like it is not pushing as far as before with only three turns out.


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John Murray

Member
It should move the same amount regardless of the spring tension, though as the tension is increased there could be some motion lost as the cable and actuator etc. flexes. If you can't free it up with the kickstarter or by rocking it back and forth in gear you might need to check the plates for flatness. Make sure the left side cover is pulled up firmly too; any flex here will reduce the clutch movement.

Edit: Just noticed the Bandido/Monty engines don't have the release mechanism in the left side cover so ignore that last bit :oops:
 
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Texasstar

Can't is a four letter dirty word
Here is the 41.5 whp pull on our Bultaco Drag bike. Our first pull was 36.5 whp and the air fuel was at 12 with a 230 jet. 65% humidity and 85 degrees. We changed to a 220 jet. Bill had a timing curve in there as follows:
23@5k
22.5 @6k
21.5 @7k
21 @ 7500

Air fuel was mid 12’s



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Texasstar

Can't is a four letter dirty word
Here are some things I need to correct:

1. The chamber is bouncing all over the place.
2. The clutch. Bill is going to be really sore this morning from spinning that rear wheel and 500 lbs drum.
3. Move the electronics.
 

Texasstar

Can't is a four letter dirty word
That sounds sooooo much cleaner now.
It is really amazing what you can do with the Zeeltronic and how much it moves the curve and broadens the curve. The very next run we dropped the jet to a 210 and ran 21 static and it fell on its face and only made 35 whp. It was still fat and fouled a plug.


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Texasstar

Can't is a four letter dirty word
John did you change your exhaust flange design? My right leg was getting plastered with fuel from the flange.


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teazer

Well-Known Member
DTT BOTM WINNER
Add more sealing goop aka high temp RTV or change to an O ring design. TZs use a pair of nylon (?) O rings and they still allow oil to seep out, Make sure the retaining springs are strong enough and seal the slip joint. A double slip joint helps but goop is usually enough,

That last 21 degree run is interesting in that it's the same advance at 7500 as Bill's curve but presumably the pipe isn't as hot as revs rise causing the motor to not clean out properly. That way it would be fat all the way because it isn't burning all the fuel. Excess fuel will burn in the pipe but will restrict power. As the timing gets closer to ideal, combustion should be more complete which should raise power and engine temperatures.

If the steel plates start to slip you could try machining the ID to make them more like the other two plates you showed.

Great progress so far. Don't stop now. There's more HP hiding in there, waiting to be unleashed.
 

Texasstar

Can't is a four letter dirty word
Add more sealing goop aka high temp RTV or change to an O ring design. TZs use a pair of nylon (?) O rings and they still allow oil to seep out, Make sure the retaining springs are strong enough and seal the slip joint. A double slip joint helps but goop is usually enough,

That last 21 degree run is interesting in that it's the same advance at 7500 as Bill's curve but presumably the pipe isn't as hot as revs rise causing the motor to not clean out properly. That way it would be fat all the way because it isn't burning all the fuel. Excess fuel will burn in the pipe but will restrict power. As the timing gets closer to ideal, combustion should be more complete which should raise power and engine temperatures.

If the steel plates start to slip you could try machining the ID to make them more like the other two plates you showed.

Great progress so far. Don't stop now. There's more HP hiding in there, waiting to be unleashed.
Going to the chamber thingies, rubber dodads, exhaust boots


Well after we finished that 41.5 whp run and we looked at the timing curve I turned to Bill and said, “Bill, I don’t remember putting in that timing curve.” The thing I really like about BB is that he knows that I learn by doing and he is always messing with me. Like letting me blow it up all by myself. Lol!!!!


Oh and I was kicking myself for not listening to you about using the co2 air shifter. We lost two runs because the air shifter was low on air and it got a false neutral. Moving the gauge to my handle bars.

Going to 4 springs.

I will post more dyno sheets later. We were cut short to 8 dyno pulls. Bb lost an O2 sensor at the track a while back and we were having a hard time trying to figure out why we lost power and the EGT’s were so cool.
IMG_8712.jpg



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Texasstar

Can't is a four letter dirty word
That last 21 degree run is interesting in that it's the same advance at 7500 as Bill's curve but presumably the pipe isn't as hot as revs rise causing the motor to not clean out properly. That way it would be fat all the way because it isn't burning all the fuel. Excess fuel will burn in the pipe but will restrict power. As the timing gets closer to ideal, combustion should be more complete which should raise power and engine temperatures.
.
Bingo! Did you see the AF on that run? Look how lean it was with 23 degrees advance at 5k
IMG_8654.jpg



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teazer

Well-Known Member
DTT BOTM WINNER
So the bung managed to break free. That will do it.

We did some runs a few years ago on an eddy current dyno with 7 gas analysis. It showed unburned HC as well as A:F and CO2 and we could see good A:F with high HC levels which told us that what burned was fine but too much fuel was not burned. Some level of excess HC is acceptable, but too much is never good. Two strokes will tend to have more unburned HC than a 4 stroke so that's harder to interpret.
 

John Murray

Member
John did you change your exhaust flange design? My right leg was getting plastered with fuel from the flange.
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.
 

John Murray

Member
If the steel plates start to slip you could try machining the ID to make them more like the other two plates you showed.
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.
 

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