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Top speed
Mar 30, 2021 8:51:00 GMT 1
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Post by joshready on Mar 30, 2021 8:51:00 GMT 1
Hypothetical one, what would one think an ok tuned( projected 60ish hp) Rd350lc could run on a race track with a 1km downhill straight with a medium bend on and fast corner off? Eastern Creek btw. 17/41 17inch wheels. Cheers
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Post by steve63 on Mar 30, 2021 17:44:11 GMT 1
Hypothetical one, what would one think an ok tuned( projected 60ish hp) Rd350lc could run on a race track with a 1km downhill straight with a medium bend on and fast corner off? Eastern Creek btw. 17/41 17inch wheels. Cheers Cadwell has two straights. One pretty flat with a 50mph corner onto it and 85 ish at the end one (Park) with 60mph on that dips down and then back up with 40/50 corner off. The first is maybe 0.5 k and the second maybe 0.6/0.7k long. My RGV250 VJ21 is standard and has 50.7hp. On standard gearing I was just using top at the end of the second straight and seeing maybe just 110mph on the speedo. When I say seeing I mean watching the video afterwards. There's no way I can watch the speedo and hit my braking marker . I could actually get away with leaving it in 5th but it was hitting about 11,000rpm. True speed is about 104/5 mph measured with my TomTom watch or Garmin GPS Virb. Last time I was there I changed from 15 to 14 front sprocket and even though I got into 6th earlier the top speed didn't really improve. Unless I can get onto them a lot quicker or take the corners at the end quicker or brake later (which is not going to happen) I think I've reached my particular limit. My last time there ended at A&E, that's how I know I seem to remember my proddy YPVS doing 110/120 on Park back in the 80's but that was speedo speed and from my fading memory I think we pretty much used 17/39 standard gearing most places. I don't know how the wheel size effects things but it would be more about tyres than wheel diameter. So say 160/60/17 would be 60% of 160 =96mm. 2 x 96 = 192 + 17" (432mm) = 624mm diameter. 110/80/18 (std. LC) would be 80% of 110 =88mm. 2 x 96 = 176 + 18" (457mm) = 633mm. diameter. So a decrease of 9mm dia or 28mm decrease in circumference. Not as much as some people think Please no one check my maths
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Post by midlifecrisisrd on Mar 30, 2021 17:56:26 GMT 1
On 17/41 gearing it will be about 110 flat out if it will pull to the red line
Steve
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Post by abar121 on Mar 30, 2021 18:05:45 GMT 1
My TZR250 race bike with 56bhp pulled 11k on the tach on the Revett straight at Snetterton, pretty much the longest straight on a UK track here.
That worked out to 126mph based on the gearing, but the tach is a bit optimistic, so I would guess 115 or so.
I remember following the quickest BEMSEE LC rider around there and we were dead even on the straight. He must have had more power to compensate for being naked.
I ran shorter gearing at Cadwell for sure.
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Post by steve63 on Mar 31, 2021 12:36:35 GMT 1
My TZR250 race bike with 56bhp pulled 11k on the tach on the Revett straight at Snetterton, pretty much the longest straight on a UK track here. That worked out to 126mph based on the gearing, but the tach is a bit optimistic, so I would guess 115 or so. I remember following the quickest BEMSEE LC rider around there and we were dead even on the straight. He must have had more power to compensate for being naked. I ran shorter gearing at Cadwell for sure. Sounds like standards have dropped dramatically. back in my day full leathers were compulsory. Even zip together weren't allowed....................
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Post by headcoats on Mar 31, 2021 12:49:38 GMT 1
My LC looks 100 mph while standing at the traffic lights LOL
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Post by steve63 on Mar 31, 2021 13:02:27 GMT 1
My TZR250 race bike with 56bhp pulled 11k on the tach on the Revett straight at Snetterton, pretty much the longest straight on a UK track here. That worked out to 126mph based on the gearing, but the tach is a bit optimistic, so I would guess 115 or so. I remember following the quickest BEMSEE LC rider around there and we were dead even on the straight. He must have had more power to compensate for being naked. I ran shorter gearing at Cadwell for sure. The 31K I raced had won a few races at Snetterton. Not with me on it unfortunately. The guy I bought it off said you don't win there unless you have a fast bike. I only went to Snett once and that was as a helper/hanger on for a guy riding a 500 Velocette in a classic series in about 1984. I had made him an open megaphone exhaust for it. I guess they never had noise limits then We never left the pits and I had no idea were the circuit went at all. I do remember it taking an age to get there in a 20 year old Transit with a top speed of 45. The opinion in 1985 was that a good valve will have about 60hp. I went head to head with a TZ250 E or F and we were pretty equal side by side on Park Straight so sounds about right. I remember going round Mallory on the YPVS and a guy called Martin Kilby on an LC being 6" off my back end all the way around. It tends to put you off a bit The Mark III Gamma came out and that was it for me really. The end of a very mediocre career.
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Top speed
Apr 1, 2021 10:26:25 GMT 1
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Post by joshready on Apr 1, 2021 10:26:25 GMT 1
On 17/41 gearing it will be about 110 flat out if it will pull to the red line Steve Does the lack of aero really affect them by 100mph?
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Top speed
Apr 1, 2021 11:10:15 GMT 1
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Post by midlifecrisisrd on Apr 1, 2021 11:10:15 GMT 1
It will have an effect but it should still pull past 100
If it didn't effect it then moto3 bikes would be naked lol
Steve
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Post by joshready on Apr 1, 2021 12:11:10 GMT 1
Ha, More power and revs then!
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Post by steve63 on Apr 2, 2021 10:37:00 GMT 1
On 17/41 gearing it will be about 110 flat out if it will pull to the red line Steve Does the lack of aero really affect them by 100mph? You kidding??? 😁 I used to get on the tank on my FSIE to get from 41 to 48mph. 100mph was just a distant dream. We used to all be flat on the tank side by side on our RD200's trying to pass each other at 85 😁
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Post by JonW on Apr 3, 2021 5:03:28 GMT 1
Josh, have you asked the PCRA boys on their Fb forum? plenty of them have run an LC over the years at EC and will know.
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