Texas Two Step Taco

[Texasstar]

Left is the bultaco model 51 clutch bar and on the right is the model 70 two clutch bars with a ball bearing. You can see the wear on the model 70 wear the ball bearing is. This stuff fascinates me. I am going to install the model 70 to see if it makes any difference on the need for Popeye forearms to operate the clutch. Still planning on doing John’s clutch conversion if I have to feather the clutch on launch and not just drop it.

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[John Murray]

You'll definitely need to slip the clutch off the line to get a good 60'. Rpms will need to be in the powerband. It'll take quite a few practice launches in your driveway, your neighbors will love it. Cultivate a deep hatred for the clutch - you need to be ruthless.

 

[teazer]

Interesting you mention dumping the clutch. I don't know anyone successfully does that. It's too hard on the transmission and motor, plus the bike bogs and is hard to get decent, repeatable times. Many riders get the clutch out fairly fast, by street standards, but few dump it.

You could use an MPS clutch lever which uses air pressure to release "fast" but smoothy. It can be adjusted to get the right balance and consistency.

Clutches are definitely a consumable item which is a PIA in some of our bikes. It always fascinates me to see H2 riders swapping clutch packs between runs. But to them consistency is king. They have to know what time the bike will run so they can choose a dial in that gives them the best chance of winning. I, on the other hand, am so inconsistent that I could pick a dial in time out of a hat and not be any further away.

Drag racing depends on consistency..

BTW, this is our battery.. https://www.ebay.com/itm/RC-Turnigy-Graphene-1300mAh-3S-45C-LiPo-Pack-w-XT60-/262611749332

 

[John Murray]

I think you'll get the hang of it pretty quickly with a bit of practice, you just have to be aggressive off the line and keep slipping the clutch long enough to prevent the engine falling off the pipe. Once the rpms dip below the powerband your race is over. Be confident and aggressive, and remember the clutch is evil and must be punished.

 

[Texasstar]

I think I dumped it twice last time and John was right race over.


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[Texasstar]

According the the manual the clutch springs should be 28mm minimum. However I have two sets of new springs one is 26mm and the other is 25mm.

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[John Murray]

I wouldn't worry too much about the free length so long as the springs can provide enough force to prevent slippage - without requiring so much preload that you rupture your forearm.

 

[Texasstar]

I wouldn't worry too much about the free length so long as the springs can provide enough force to prevent slippage - without requiring so much preload that you rupture your forearm.

Did you take a look at that MPS air clutch?
Popeye was tired of eating his spinach and made an air clutch.

MPS Air Clutches

www.mpsracing.com

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[John Murray]

I really like the air clutch but I don't think it's something you should be thinking about at the moment. You already have enough - if not a bit too much - going on right now, the last thing you need is another sideshow to distract yourself from the bigger issues.

With a project like this I think it's important to focus on those things that have the most potential, or in other words address the big problems first before moving on to the next item. In your case number one would be achieving an adequate power level, so I'd be focused on that alone at this stage. Get it on the dyno and do whatever it takes to get the numbers. Next thing might be to practice some launches - and I strongly suspect with just a little practice you'll be able to get it off the line quickly and cleanly without the need for any gadgetry. With little bikes like this it isn't hard; right hand goes full throttle, left hand modulates the rpm until the bike gains some speed. It'll feel un-natural at first but after a little while something will just click and it'll become easy - your left hand will be driven by what your ears are hearing and you won't be making conscious movements.

To be honest I'm still not a fan of the Zeel or the two-step - I think they are just bleeding attention away from more important endeavours. But you've already put the bike on a diet (and quite successfully too), the next step should be to make the power numbers. If you can then learn to launch the bike successfully - and I'm sure you will - then you've done all that's important in your quest to defeat the Ducati.

 

[Texasstar]

Agreed that is why his moniker is Teazer...lol. We are going old school. The clutch is way better with the split shaft and ball bearing.

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[NoRiders]

When my Suzuki GT200 engine was being rebuilt, Andy the builder, explained the two piece clutch shaft....they contra-rotate against each other to reduce wear and friction and provide a lighter action. No ball bearing on the Suzuki possibly as it's only a 200 and fairly light clutch springs.

 

[Texasstar]

When my Suzuki GT200 engine was being rebuilt, Andy the builder, explained the two piece clutch shaft....they contra-rotate against each other to reduce wear and friction and provide a lighter action. No ball bearing on the Suzuki possibly as it's only a 200 and fairly light clutch springs.

The glories of DTT and the knowledge of a community. Thank you! That explains why the wear is on the center shafts at the ball bearing and there is a significant difference in clutch pull over the single shaft!


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[Texasstar]

First ride. Rev limiter set at 6300. Road it for 6 minutes varying revs.

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[teazer]

John is right. Focus on one thing at a time and power is next followed by getting off the line.

If I might be so bold as to suggest that you stop trying to ride it like a street bike and get that throttle open and then use the clutch to get it moving without losing revs. Maybe not around the neighbors though.

 

[Texasstar]

John is right. Focus on one thing at a time and power is next followed by getting off the line.

If I might be so bold as to suggest that you stop trying to ride it like a street bike and get that throttle open and then use the clutch to get it moving without losing revs. Maybe not around the neighbors though.

Will do lol...just following the break in directions.


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[John Murray]

Will do lol...just following the break in directions.


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I'm truly sorry to sound like a broken record but those break in directions aren't doing a thing. On the positive side I'm in awe of your self-control - I bet not many of us here would be able to ride it like that and resist getting it on the pipe even once.

 

[Texasstar]

I'm truly sorry to sound like a broken record but those break in directions aren't doing a thing. On the positive side I'm in awe of your self-control - I bet not many of us here would be able to ride it like that and resist getting it on the pipe even once.

The engine temp after a 5 minute ride in 90 degree Texas heat was 271.

I thought we were knocking this piston into shape? Short bursts. Not to long...Varying the throttle. I set the rev limiter for 3/4 throttle. We are running rich and have a healthy stutter but when it comes on the pipe it is a glory to behold...Out on the road away from my neighbors. I haven’t even got to your tuning guide yet.

Clutch needs to be adjusted.


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[John Murray]

Yep short bursts on the pipe. No more than a couple of seconds at a time at first, gradually increasing in length, backing off between bursts to let the piston cool a little. Disable the rev limiter or at least raise it enough to let it make some power. What we're trying to do is beat the piston into shape (and that requires being on the pipe to load it) but not let it get hot enough to grab or smear in the process. After an hour or two it'll safely run at full noise continuously.

 

[Texasstar]

Yep short bursts on the pipe. No more than a couple of seconds at a time at first, gradually increasing in length, backing off between bursts to let the piston cool a little. Disable the rev limiter or at least raise it enough to let it make some power. What we're trying to do is beat the piston into shape (and that requires being on the pipe to load it) but not let it get hot enough to grab or smear in the process. After an hour or two it'll safely run at full noise continuously.

Ok will do more of that tonight. Got on the pipe 4-5 times in short burst last night. Have the ignition timing set at 19 degrees and was getting a stutter right before getting on the pipe. Cleared as it was on the pipe. Will raise the rev limiter up to 8k.

The neighborhood dogs were not happy with me.

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[Texasstar]

What CHT should we be looking to avoid?


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