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13-07-2019, 09:25 PM | #1 |
Registered User
Join Date: Feb 2014
Location: Powys
Bike: M900
Posts: 334
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Hypothetically- M900 mods.
If I was to try and get the best from an early M900, what could the improvements be?
So far - reworked front and rear suspension (Maxton and Wilbur). Keihin FCRs. (An ongoing idea, currently awaiting new seals) Tyres - Sat on Diablo Rossos at present, Supercorsas (medium) waiting to be refitted post mot) The criteria are... actually, no. I’m not making any! I know it’ll never keep up or outhandle with a Triumph Speed Triple - but how could it get closest?? Just a ‘for fun’ thread, really, I’m not saying I’ll go out and do any. I know that the whole magic of the bike isn’t Bhp! |
13-07-2019, 09:25 PM | #2 |
Registered User
Join Date: Feb 2014
Location: Powys
Bike: M900
Posts: 334
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Oh, not a turbo as one on eBay is sporting either!
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13-07-2019, 10:48 PM | #3 |
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Join Date: Jul 2014
Location: Portsmouth
Bike: M900
Posts: 1,518
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Decent Battery.
Rebuilt fuel pump. Ignitech Ignition module
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14-07-2019, 07:46 AM | #4 |
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Join Date: Jul 2003
Location: East London
Bike: Multiple Monsters
Posts: 9,731
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monobloc front calipers/radial master cylinder
carbon or magnesium wheels depending on your base motor cylinder head work/cams/big valves bigger pistons lighter flywheel Last edited by slob; 14-07-2019 at 07:48 AM.. |
14-07-2019, 08:09 AM | #5 |
Registered User
Join Date: Mar 2010
Location: Beachtown
Bike: M900
Posts: 2,188
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As far as suspension goes I can only speak from my experiences for both the transformation of the bike afterwards and the customer service (initially and later for service work) I received from both companies I chose to use:
Maxton GP20 Fork conversion Nitron NTR R1 rear shock Then probably one of the best real world tuning exercises ever done to a 2v motor: http://www.sigmaperformance.com/torquemonster.html
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14-07-2019, 08:44 AM | #6 |
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Join Date: Jun 2018
Location: Clevedon
Bike: M1200s
Posts: 562
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Why a lighter flywheel, I thought it would make the engine more peaky?
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14-07-2019, 04:11 PM | #7 |
Registered User
Join Date: Feb 2014
Location: Powys
Bike: M900
Posts: 334
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Mmmmm, Interesting ideas...
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14-07-2019, 07:38 PM | #8 | |
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Join Date: Jul 2003
Location: East London
Bike: Multiple Monsters
Posts: 9,731
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Quote:
probably look a twin plugging the heads too, since this is a theoretical exercise |
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14-07-2019, 08:05 PM | #9 | |
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Join Date: May 2007
Location: Stockbridge
Bike: M900
Posts: 1,984
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Quote:
The weight of the back wheel and tyre are more likely to affect pickup whilst riding?
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14-07-2019, 08:12 PM | #10 |
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Join Date: Jul 2003
Location: East London
Bike: Multiple Monsters
Posts: 9,731
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every part counts
i was surprised, running in a big bore motor with lightened flywheel, how fast it revved as i aimed to take it to 6k rpm and had trouble stopping the tacho needle at the desired point. lighter wheels will almost certainly give you the most ‘bang for your buck’, but the suspension is equally important, since no amount of power or brakes is any good if the tyres aren’t in contact with the tarmac Last edited by slob; 14-07-2019 at 08:19 PM.. |
15-07-2019, 10:42 AM | #11 |
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Join Date: Sep 2010
Location: Leics
Bike: M900
Posts: 2,888
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My Monster started as a project with just a frame and an engine and I did most of the above, including, big-bore, hi-comp, gasflowed heads, split-single Keihin FCR41 carbs, Ignitech, Ohlins, Radial calipers, light flywheel/clutch, Spaghetti headers, termis etc. and whilst it did get a 'tad' out of control spend-wise, it turned out good.
The light flywheel, combined with the (chokeless) Keihins does make it a bit stall-prone when it's cold but once warmed up it picks up speed instantly on the throttle and pulls strongly throughout the rev range meaning that it makes more torque up to 6,000 rpm than my (also tuned) 916, despite having 30hp less at the top end. It is a bit 'lumpy' at anything under 2,500rpm but still manageable in traffic and certainly has lots of 'character'.
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15-07-2019, 01:33 PM | #12 |
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Join Date: May 2007
Location: Stockbridge
Bike: M900
Posts: 1,984
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Physics dictates that rotational inertia impedes acceleration, which is why a lighter flywheel is considered to be a performance mod.
Less rotating mass = more acceleration, if all else is equal. I was hoping someone had done the maths on costs and comparative effects of losing 1Kg from the flywheel, rear sprocket, and back wheel & tyre? Weight reduction of the sprocket, wheel and tyre also has the benefit of reducing unsprung weight making the suspension’s job easier too.
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Original and Best since 1993 Last edited by Darkness; 15-07-2019 at 01:48 PM.. |
15-07-2019, 02:25 PM | #13 | |
No turn left unstoned
Join Date: Jun 2010
Location: leicester
Bike: M750
Posts: 4,554
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Quote:
Yes, one of the effects which I wasn't really expecting from fitting my carbon wheels was the improvement in acceleration of the bike. It stands to reason I guess but I hadn't expected the effect to be large enough to notice. In fact, I've ended up dropping another tooth off the rear sprocket as a result of the improved straight line performance. |
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15-07-2019, 02:45 PM | #14 | |
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Join Date: Aug 2011
Location: Southampton
Bike: M1100evo
Posts: 2,465
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Quote:
Here's an extract: "When you remove weight from the flywheel (and to a lesser degree, from the clutch) the effect on the engine’s ability to more quickly spin-up is indistinguishable from increasing your engine’s torque (and consequently horsepower) output. But only in neutral. In any other gear, there’s little benefit at all. Obviously, your bike’s ability to accelerate faster through the gears is enhanced by reducing the overall weight of the bike as well as the inertia of rotating components. The crankshaft, pistons and connecting rods, transmission gears, drive chain and sprockets, wheels and tires, clutch and flywheel are all candidates. However, the overall weight of the bike and rider completely overwhelms any reduction of rotational inertia produced by a lighter flywheel. A kilogram lighter flywheel on a 300 kilogram bike-plus-rider will accelerate only 0.3% faster. F=ma. Of course every 0.3% helps a racebike. When you reduce weight you’ll get faster acceleration, and faster lap times - IF - you can modulate your wheel spin driving out of corners. Factory racebikes make so much power, for example, that transmitting the power to the road effectively becomes the limiting factor - so heavier flywheels actually become a benefit. Fear the high-side." |
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15-07-2019, 03:11 PM | #15 |
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Join Date: May 2007
Location: Stockbridge
Bike: M900
Posts: 1,984
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Thanks Luddite. Yes, I’ve read that post previously but it doesn’t really answer my question.
The 0.3% improvement mentioned is solely due to the reduction in mass, a three hundredth of the weight of bike and rider. It completely ignores rotational effects. https://en.m.wikipedia.org/wiki/Newton's_laws_of_motion It should be possible for me to get my remaining brain cells to quantify the change, I was just hoping someone had already done it!
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