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Bultaco 250 astro

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Hi does any one have an idea of the top speed standard of these 70s  250cc machines. originally a flat tracker and I think used in go karts  Thanks stu

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Hi, one of the locals ran a Pursang in out sprints some years ago, max speed was about 75. The limiting factor always is the size of gearbox sprocket.  13 T with a 520 chain. However, you can go bigger if the kickstart shaft is removed. Likewise the rear hub, not much you can do to fit a smaller rear sprocket, the best thing to do there is to find a hub from something else. What exactly is your intended plan ? A few more details would help, then I am sure a fellow reader of these posts may have done what what you are setting out to do. Hope this helps.......

 

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Thanks for that very good info I'm toying with idea for a cafe road racer project I've been thinking of doing for some time now .A metralla engine would be first choice but rarity and price of engines is a no go. so looking for an alternative bultco engine that could be geared for good road use .

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I have been looking at this for a while as i have been considering building a track bike with a 370 motor i have in pieces. Still trying to decide whether to commit though. I had come to the same conclusion regarding the rear hub and losing the kickstart but the sprocket would still be very close to the ignition rotor cover. I notice AJR in Spain have larger front sprockets for the TSS. Would you know if these have the same 25mm splines?

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 Is an Astro easier to find than a Metralla?

 As I recall, when Pursangs first switched to wrong side shift, the rear brake was moved to the right (or wrong) side of the wheel with a two piece rear hub. I would think you might be able to fit a smaller sprocket to that hub.

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13 hours ago, petorius said:

I have been looking at this for a while as i have been considering building a track bike with a 370 motor i have in pieces. Still trying to decide whether to commit though. I had come to the same conclusion regarding the rear hub and losing the kickstart but the sprocket would still be very close to the ignition rotor cover. I notice AJR in Spain have larger front sprockets for the TSS. Would you know if these have the same 25mm splines?

I own an original TSS and unfortunately can confirm it has a 30mm spline. Although I'm sure a company like Talon could manufacture one to your dimensions.

The other thing to maybe consider would be clutch, The TSS has a gear driven primary with a vastly heavier duty clutch over the chain driven Pursangs or Metrallas and even this struggles and slips with tall gearing  

IMG_5241.jpeg

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35 minutes ago, petorius said:

Thanks for the info WT, is that a Model 6?

No its a Mod29 1969 350 although the cases in the picture are actually from a El Bandido Mod18 built into spare engine with TSS internals way back when.

The El Bandido & TSS both shared the same cases and gear driven primary although that's where the similarities end.

For the sake of originality I tend to race it with the 'Frankenstein' engine and keep the original on the shelf.

   

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Can you share more photos of your TSS plse? Do you take it to circuits these days? I race a Metralla MkII Kit América in Belgium and - some day - owning a genuine TSS would be eh...fantastic. Do all TSS's have a 30mm spline? Best to all.

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