calculated top speed

**Sun Sep 16, 2007 7:25 pm » Post: #1 » Download Post**

Just wondering how fast I'm going at the end of the straight??? 12000 RPM sometimes 12500 RPM if I get a good drive. MC 28 primary gears, MC 21 6th gear, 16/40 final gearing, and a 160/60 17 rear tire. I'm thinking 135MPH????????????????????????????????????????????????????????
_________________
1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike

**Sun Sep 16, 2007 7:44 pm » Post: #2 » Download Post**

HRC gear box chart says 109mph @ 10,000.
_________________
If I have to take the carbs off once more...

**Mon Sep 17, 2007 3:12 am » Post: #3 » Download Post**

Work it out:

Need to know rear tyre circumference. Let's guess at 1.954m

MC28 Primary - 2.500
MC21 6th - 1.083
16/40 - 2.5

12,500rpm/2.5/1.08/2.5 = 1846.722rpm rear wheel

1 rev = 1.954m so that gives us 3608.5m per minute or 3.6kpm or 216.5kmh or 134mph.

So you're pretty close.

Interestingly I just worked it out for my 300 yesterday and it was hitting 130mph at the end of the chute. Pretty pleased with this as I'm running ancient Dunlop GPR's that are worn out and I was tippytoeing round the final corner so as not to highside. The Supersport 600's I used to spanner for were hitting 133mph at the same point back in 2000. Gotta be happy with that.

**Mon Sep 17, 2007 1:01 pm » Post: #4 » Download Post**

We must get Matt out of that little dark room sometime! Laughing

_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

**Mon Sep 17, 2007 1:13 pm » Post: #5 » Download Post**

For those of you who race this link is ideal for working out your gearing and speed in each gear.
faq.f650.com/FAQs/gearing_v12.xls

Hours of fun!!!!!!
_________________
MC21 300
Aprilia RS250 track bike

**Mon Sep 17, 2007 1:18 pm » Post: #6 » Download Post**

3.6kpm

Damn that makes it sound fast! Shocked

_________________
Hesitation is Fatal!!

**Tue Sep 18, 2007 12:19 am » Post: #7 » Download Post**

So if I put on my 36 rear she'll pull 150 mph. Twisted Evil

Not bad for 300cc Do you think she's got the mojo Matt??? Wink

_________________
1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike

**Tue Sep 18, 2007 12:25 am » Post: #8 » Download Post**

jkolewski wrote:
So if I put on my 36 rear she'll pull 150 mph

Theoretically!

I reckon you'll be needing well over 70hp, and well under 70kg on board to do it though.

What was your '28 making when you were trapped at 150+ Matt? I seem to recall you saying you were only about 65kg then too. I bet the bike was bloody light too!

Good on you if can do it, but I think that 16mph is going to be hard to find.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

**Tue Sep 18, 2007 12:39 am » Post: #9 » Download Post**

I think I've got the over 70 Hp covered. I'd like to dyno this winter. I'm a porky 85 kg without leathers.My 28's between 117-119kg The 135 is on a 3200' straight too. Road America is an even bigger track but hey if i wanted to go 200MPH I would have kept my 1000. Just nice to know the one place the diesels have the advantage is getting smaller Laughing

_________________
1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike

**Tue Sep 18, 2007 2:21 am » Post: #10 » Download Post**

Jeremy, it sounds like she's got the mojo required.

3200' is what? Just under a km on my calculator. 135mph for an 85kg rider is pretty good.

I went over 150mph on the MC28 with 76hp. I weighed in at about 65kg in my Y-fronts, and the 28 was on the scales bang on the 118kg limit.

Paul's old 28 250 measured at 135mph flat out with him on board. Buried in the red up the motorway. Impressive 'cos Paul's not exactly a lightweight jockey! A gearing change wouldv'e probably seen another 2~3mph. Or it might have gone POP!!

**Tue Sep 18, 2007 2:44 am » Post: #11 » Download Post**

Matt@TYGA wrote:
I weighed in at about 65kg in my Y-fronts...

Hmmm... not a pretty thought! Glad I wasn't tucking in a bowl of Coco Pops when I read that! Very Happy

_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

**Tue Sep 18, 2007 2:52 am » Post: #12 » Download Post**

Those Y-fronts were probably worth a kilo mate. Shocked

Maybe I should've slipped into my speedos Wink

**Tue Sep 18, 2007 3:18 am » Post: #13 » Download Post**

Aaaaargh... stop it!!!

_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

**Tue Sep 25, 2007 7:51 pm » Post: #14 » Download Post**

Andy, she pulled the 16/38 this weekend Very Happy

. Should be about 142MPH. The 36 isn't happening at that track though. I will try at a different track next season.
_________________
1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike