July 16th, 2017, 10:57 AM | #1 |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Top Speed
2007 250 Ninja. Yoshimura slip-ons, stock air box, 110 mainjets, 15/42 gearing. 90 M.P.H. in 6th, 95 M.P.H. in 5th. Does this sound like my bike's running OK?
Bill |
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July 16th, 2017, 11:20 AM | #2 |
Guy Who Enjoys Riding
Name: Jim
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To save me the calculation, what RPM was it doing at 95 in 5th?
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July 16th, 2017, 11:46 AM | #3 |
Rev Limiter
Name: Jay
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Sounds like overall gearing may be too tall.
110 Mains are pretty big for the stock airbox. Are you shifting at redline in all gears? |
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July 16th, 2017, 11:46 AM | #4 |
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Name: Chris (aka Reactor)
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Rider weight will also be a factor.
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July 16th, 2017, 11:55 AM | #5 |
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Weight makes a difference in accelerating time to top-speed. But top-speed itself isn't affected by weight. That's purely a function of cross-sectional area blocking and power required to bore a certain sized tunnel through that air. Cx*Cd, etc...
You'll find removing mirrors, hunched over with chin on tank, arms and hands pulled in with just pinkie-finger exposed to pin throttle will give you a couple more MPH. I see 98mph at end of front-straight of Thunderhill on my calibrated Vapor dash. Sometimes I can break 100 if I catch a tow, but then I'm over redline for those last couple seconds. |
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July 16th, 2017, 11:56 AM | #6 |
in your machine
Name: Scott
Location: Summer Shade, Ky.
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I'm about 220 lbs with gear, and in sixth gear I top out at about same 90~95, just short of doing the ton.
My gearing is +1/-2
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July 16th, 2017, 12:26 PM | #7 |
Guy Who Enjoys Riding
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July 16th, 2017, 01:29 PM | #8 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
My bike came with 105 mains and was too lean with the O.E.M. mufflers. I was going to increase the main jet size even before I installed the Yoshimura glass packs. Bill |
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July 16th, 2017, 02:07 PM | #9 |
Rev Limiter
Name: Jay
Location: WI
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July 16th, 2017, 02:41 PM | #10 |
Guy Who Enjoys Riding
Name: Jim
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I have my H2 geared like that too. I love the low RPM and low vibration at highway speed, but I'm sure top speed is in 4th now.
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July 16th, 2017, 03:35 PM | #11 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
Bill |
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July 16th, 2017, 03:56 PM | #12 |
ninjette.org certified postwhore
Name: Roger
Location: Mitchell, South Dakota
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Ours (6 in the family) all seem to be a touch rich on the mains and a bit lean on the needle with stock air boxes and exhaust, one has stock air box and full Muzzy and is the same. We're at 1300', so maybe that has something to do with it. I've played with valve clearance to adjust the top end power, in the middle of the lash specs mine have more midrange but have a hard time pulling past 12 or 12.5k, but when snugged down to the tight end of specs will pull happily to the rev limiter.
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July 16th, 2017, 04:08 PM | #13 |
Guy Who Enjoys Riding
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July 16th, 2017, 04:23 PM | #14 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
Thank you. See, I'm not too old to learn. Bill |
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July 16th, 2017, 06:11 PM | #15 | |
ninjette.org certified postwhore
Name: Roger
Location: Mitchell, South Dakota
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Quote:
And it gets a teeny, tiny bit more lift.
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July 16th, 2017, 08:24 PM | #16 |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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July 16th, 2017, 11:40 PM | #17 |
ninjette.org certified postwhore
Name: AKA JacRyann
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Same effect as more duration. Timing remains the same as lobe-center doesn't change.
Or if you're taking about increasing overlap with the same cams, you'd retard the exhaust and advance the intake cam. |
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July 17th, 2017, 12:05 AM | #18 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
Bill |
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July 17th, 2017, 06:24 AM | #19 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
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Bill, I had an automotive machine shop grind my boat's reverse rotation engine's cam for more lift and duration. It was cheaper than buying a new reverse rotation cam. The small block Chevys have different rocker arm ratios, so they have more lift at the cam than the Ford 289 in my boat. So the shop ground my 289's cam to Chevy specs. I plotted the profile before and after, and it was like the lobes grew taller and wider. The funny part is how you grind a cam so the lobes get taller.
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July 17th, 2017, 06:37 AM | #20 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
Bill |
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July 17th, 2017, 06:45 AM | #21 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
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Exactly, lower the base circle and the lobe gets taller. It just sounds funny when you talk about grinding more lift into a cam.
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July 17th, 2017, 06:52 AM | #22 | |
Rev Limiter
Name: Jay
Location: WI
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Quote:
You would gear it differently if it were a race bike and you needed top speed. By saying the overall gearing was too tall I was just pointing out the reason for the higher speed in 5th than 6th. |
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July 17th, 2017, 07:03 AM | #23 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
Boy, I'm grateful for this blog. I learned about valve clearance and duration and know about making a silk purse out of a sow's ear. Bill |
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July 17th, 2017, 07:13 AM | #24 |
Guy Who Enjoys Riding
Name: Jim
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I could have had them start with a cam blank, but the non-standard marine cam for reverse engine rotation runs the price way up. Since I already had a running cam, modifying it was cheap. It was the mid '80s and it was $60 to do the cam and $50 to grind the crank 0.010" under. Even if you account for inflation, that's still pretty economical.
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July 17th, 2017, 09:29 AM | #25 |
ninjette.org certified postwhore
Name: AKA JacRyann
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Wow... wish I could get cams ground for that price!
Depending upon the drivetrain layout, you'd insert a shim of same thickness as reduction in base-circle. This would prevent your hydraulic lifters or rocker adjusters from running out of range. Extra lift comes from thickness of this shim + original cam-lobe height. |
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July 17th, 2017, 09:44 AM | #26 | |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot.
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Quote:
$60 in 1985 when I had the V8 cam ground is about $140 in 2017 dollars. Still a good deal, and I suspect I could get one done for about that around here. |
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