paulh
3rd Gear
Adrenaline is brown
Posts: 528
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Post by paulh on Sept 9, 2016 13:04:31 GMT -5
Dang it, now you got me thinking about getting back to my build. I really wanted to build a (obviously) reeded 250 with 60 RWHP just to be different.  But maybe a 350 would be more in order, a bit less hard tuning. The 400 looks too much like a Yammi motor, and we can't have that!  60 RWHP would be sweet! I'm very curious about the weight of the 250. Do you know? Cheers |
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paulh
3rd Gear
Adrenaline is brown
Posts: 528
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Post by paulh on Sept 9, 2016 13:07:12 GMT -5
Jeez, I hate you guys...  You're gonna get me in a pile of trouble here... I bet you want to build one too! .. |
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Post by autofobe on Sept 9, 2016 15:17:52 GMT -5
It's always good to shake things up & get people motivated. Moo,get going on that project,it's been under the bench to long! Drewski,dust off that 71 frame,Tracy,& the H2 drag motor....I know you want to.  I know the rest of you guys are thinging,I have a few neat things stashed away I could use. Get er done  Brad |
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Post by autofobe on Sept 9, 2016 15:39:22 GMT -5
Paul,I have an empty set of cases that I set in the frame & it fits like it was born there.As for the wheels,I have an aluminum flanged for the front which is in keeping with the vintage look.Or a flanged conical drum which would be very cool looking. But if weight is critical,I also have a Gp Honda RS 125 spoked wheel. which came in at an incredible 9 lbs with the tire still on it.  Brad |
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Post by JA-Moo on Sept 9, 2016 16:21:26 GMT -5
60 RWHP would be sweet! I'm very curious about the weight of the 250. Do you know? Cheers They are heavy for a 250, all the S series are about the same bike. 368lbs. with 3.7 gallons of gas, 369 for the 350. |
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Post by triplepoweredgpz on Sept 9, 2016 16:39:47 GMT -5
60 RWHP would be sweet! I'm very curious about the weight of the 250. Do you know? Cheers They are heavy for a 250, all the S series are about the same bike. 368lbs. with 3.7 gallons of gas, 369 for the 350. Brads right, I'd like to see this 60 HP s1... Get on it bud |
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Post by Walms on Sept 9, 2016 18:54:14 GMT -5
I might have some pipes to try on that project... 31mm diameter header.  |
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Post by JA-Moo on Sept 9, 2016 21:08:40 GMT -5
Well, as I wrote, I think I would like less of a radical tune, and a 350 top end would be better for that.
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Post by miller on Sept 11, 2016 2:32:02 GMT -5
Interesting goal, this HP/lbs figure, allowing many oportunities to achieve it. My stck engined S2-500 (early S-frame) weighs 167 kgs (367 lbs). No works has been done to reduce weight. With minor effort 20-25 Lbs can be removed leavng 345 Lbs, requiring 75 RWHP from the H1. This can be achieved with VM34's, cylinderraise, ex-port +1 mm, headreshape and expansionchambers. My S3-750 weighs 174 kgs (382 Lbs). The lightly tuned H2 has 100 RWHP, meaning 3.82Lbs/hp:  The bike handles great with stiff swingarm, 17" wheels and modern forks. It is a not so nice bike to ride around on at sort of legal speeds and around town. But good for trackdays and very long trips with a lot of Motorway-cruising. The best ticket I think is taking an old S1/2-frame (lowest weight) and S3-engine. The S-engine weighs 22 Lbs less than the H1 and with less wide crank which is also 5 Lbs lighter, changing direction is much easier. A stock (early) S3 weighs 155 kgs (341 Lbs). After an easy shave there will be 320 Lbs left, requiring 70 RWHP. A S3 reacts very will to tuninginput! Just a head-recut will give it 45 RWPH! Add 1mm ex-port, fit H2 carbs and expansionchambers and there is 60 RWHP@8000. And that with impressive midrange, with 54 RWHP at 7000 RPM and 47@6000. With some effort 65-70 RWHP is reached. The excellent gearbox of the S-Models is another advantage that cannot be overlooked. That said, Brad, have covered a lot of roadmiles with the good old S2-500 and enjoyed so many trackdays with it. That Hybrid realy is a good allrounder and a good citybike also. And 75 RWHP from a H1 is a breeze. So I'd suggest to go the S-500 route. Consider using the frontend of a modern Moped, like the Aprillia RS50. Very lightweight, good discbrake and with 35 mm downtubes much stronger than stock S-type forks. |
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Post by autofobe on Sept 11, 2016 18:26:29 GMT -5
Thanks for all the info.I have raced a 500 & a 400 & although the 400 was lightning fast I preferred.
the 500.So I will stick to my original plan.I think the 500 softly tuned in a lighter frame is the best option.I will be using the lightest wheels & parts I can find In keeping with the vintage racer look.
Brad
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Post by nevillelush on Sept 11, 2016 20:12:30 GMT -5
I was able to get the old race H1 down to 152kgs , with a full tank of fuel, but no lights. We still had a 530 chain and H1 rear hub, so still room to be lighter. Getting the power should be relatively easy. Modern carbs/pipes help, as Leo said.
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Post by autofobe on Sept 11, 2016 20:56:27 GMT -5
Wow that's pretty good. Works out to about 335 lbs wet.Was that a 70-71 500 frame?
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Post by nevillelush on Sept 12, 2016 0:20:28 GMT -5
!973 frame. 16 litres of fuel. We had 89hp at the tyre, but that will be tricky to get on a street bike easily. 75-80 should be easy.
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Post by daffey1 on Sept 12, 2016 4:53:22 GMT -5
Very interesting read. Can't wait to see the results👍
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Post by autofobe on Sept 12, 2016 15:13:38 GMT -5
Thanks for all the great info.Some of you guys are legends when it comes to getting triples to handle
& make huge power.I will try to put some of those ideas to good use.
Brad
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But maybe a 350 would be more in order, a bit less hard tuning. The 400 looks too much like a Yammi motor, and we can't have that! 
You're gonna get me in a pile of trouble here... 
