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Discussion Starter #1
Hi All.

Took my M900Sie out on Saturday for a shakedown test/drive.

A little history first though. I bought the Bike "blind" from the other end of the country in March and when it arrived it looked even better than in the Pictures, amazing in fact. However, it didn't run well at all. The battery was dead, Fuel Pump dead, Fuel Filter blocked, Injectors needed cleaning and the Valve clearances had been ignored so long that to get the Bike rideable I had to remove the heads and Lap the Valves (the leak down test showed 20% Lekagae before the Lapping and less than 5% after). TPS reset, Balanced the TBs too and deglazed the bores. Anyway all that, It fired right up and runs well. I added a K&N, SlipOns and the DP ECU in the process. CO Trim is at 30, which feels rich, and i have an appointment to get it set properly.

So, bike rides well but doesn't seem eager to rev really, though that might just be in my head. I had to rag the crap out of it to keep up with my riding buddy (He rides a 2009 Tuono) and when we stopped for fuel he complained that something was wrong with his bike because he wasn't pulling away from me as expected. :)
I haven't ridden a two-valve bike in a few years so my expectations might not be ... fair to the bike.

So, to the point, in 6th on the Autobahn at 170kmh - 200kmh there is a vibration through the bars which at lower speed i might attribute to an outta balance wheel - maybe it is that - but after everything i have had to do on this bike i am super Paranoid. I pulled the clutch to eliminate the motor as a source for this (it doesn't do it in lower gears) and the bike decelerates so quickly its hard to be sure what it is. The forks are crap/very bouncy and have little damping and the front wheel feels like it's floating away from me in long sweepers so i am overhauling those tomorrow (oil, seals and probably bushes too).

On my list:
Some weird aerodynamic anomaly
Out of balance Wheel(s) or a flat-spotted tyre from standing too long?
Transmission related issue
or... whatever you guys can come up with.

I am enjoying the bike so far but this bothers me, not because its an issue all the time, but because after so much time and effort i want it to be right.

Any Ideas?
 

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That's a clean bike. Nice.
All the work done on it I don't think I noticed any mention of new tires. That would be my first guess. Especially given the amount of neglect it seems to have endured. At least check the balance on them perhaps. More of an up and down vibration than side to side or steering wobble?
 

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Discussion Starter #3
No, no new tyres yet, but the DOT number has them at 2017, so not really old.

The vibrationvis a thrumming, bit like a washing machine on spin cycle. And only in top gear and only at speed. I guess i couls see if 5th is long enough to get there.
 

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Yeah you never know. I'm not sure what type of wheel weights they use over there, sometimes the little stick on ones go missing. I think I got my current bike in 2017, and it's long overdue for it's 3rd set of tires since I've had it. If we had an Autobahn, I can't imagine the tires I'd go through. I balance them myself. It's a little tedious, but nothing beats a hand balanced tire as opposed to putting it on a machine and just sticking a couple weights where the machine says to put them. The view from the mirrors is as clear at 100mph as it is sitting in the driveway.
 

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Discussion Starter #5
I am in the Garage tonight, I have a long list starting with the Forks, so I'll have a look and see if any of the stick on weights look absent. The clip on weights that wreck the Wheel surface haven't been used here for years on alloy wheels so, it is possible they got flung off
 

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I’d say either balance issue or out of true. Make yourself a pointer out of some wire and get it close to the edge of the rim, then spin the wheel to see if the rim is straight. Point at the center of the tire and spin to see if the tread runs true. If everything checks straight, rebalance the wheels. You don’t know if they were ever right to begin with.
 

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Can't add anything, except to say; I hate you! ;) ... just kidding, 200klms on a freeway? Here in Australia we have draconian speed laws, 100k MAX in most states, 110k in W.A. Strictly enforced, with cameras everywhere.
Get caught doing 200, we almost risk jail time. Double the speed limit and it's classed as reckless driving, endangering the public??? Ask me how I know? Got done many years ago, dragged off to lockup in handcuffs.
Well, we still do it, such is life.
 

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Discussion Starter #8
Morning all,

New Fork oil, and Brake pads last night, which has transformed the front end from a wet sink sponge to something like a front fork that stops too.
Wheel seems to be straight, as best as i could tell with my improvised pointer. New tyres next month probably so i'll "ignore it" till then.

Autobahn, yeah its a blessing and a curse TBH. Yeah you can go VERY VERY fast - i had an "indicated" 275khm on my Aprilia, but because it is allowed it gets boring quite quickly. And if you are just pottering or in the car and taking your kid somewhere and a Porsche or Mercedes blasts past you going 150kmh FASTER than you in the NEXT LANE it becomes less amusing and actually quite dangerous.
 

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While waiting for tyres, check your rear chain also. At that speed it's moving very fast, any stiffness or dry stretched links would appear as vibration at high speed.
 

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Thrumming... the more I think about it, take a real good look at the chain and sprockets for tight or loose spots. I’ve had chains stretch in spots before and a chain issue could cause vibration at speed for sure.
 

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Discussion Starter #12
Gave the chain a good clean and oil. Definite improvement!

While we are on the subject of Chain and Sprockets, I am currently running 14/39.
15/39 is too long in the first 3 gears around town but OK on country roads and 14/39 is great around town but a bit short on country roads and I feel like I am ragging the crap outta the bike all the time, constantly between 6 and 8K RPMs and spend most of the time in 5th and 6th.
I don't remember where I read it but have somewhere in the mess of my memory that the M900Sie came with a close ratio box from the 748 instead of the 900ssie ratios,

True? Or do i really need an S4R? :)
 

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Make sure you rotate the rear wheel all the way around while checking chain tension. A tight spot can cause pulsing vibration as it continually goes around the top. The tightest spot on your chain should still be within spec . If you have a tight spot, the real solution is a new chain and maybe sprockets .
 

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Discussion Starter #14
Absolutely, But when i do that i want to get the gearing closer to making me happy than it is now. Or choose to ride that bike either in the city or country roads. It also has the weird front sprocket with a shoulder on both sides.
 

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Gave the chain a good clean and oil. Definite improvement!

While we are on the subject of Chain and Sprockets, I am currently running 14/39.
15/39 is too long in the first 3 gears around town but OK on country roads and 14/39 is great around town but a bit short on country roads and I feel like I am ragging the crap outta the bike all the time, constantly between 6 and 8K RPMs and spend most of the time in 5th and 6th.
I don't remember where I read it but have somewhere in the mess of my memory that the M900Sie came with a close ratio box from the 748 instead of the 900ssie ratios,

True? Or do i really need an S4R? :)
I ran a 14/39 for a year or so. The bike did fine, but never quite perfectly happy. When the 39T was toast I replaced it with a 38T and it was like night and day. Dramatic improvement across the board.
 

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14/38 ??hmm, your getting smaller on both sprockets, smaller on front means 'tighter rotation' for chain, That damn vibration at speed.?? also can get to rub on swing arm, again, rubbing could cause another vibration when going fast.

Personally, I would stick to 15 on front and then go up to 40 or 41 on rear. 40 tooth rear sprockets seem hard to find though. I had 15/41 on my 900ie. hard to keep front wheel down around town, but as you said, revs a lot out on the fast roads. Finally, changed to stock 39 rear, better going fast but next change will be 15/40.

Did I say 'fast roads'? well, if we ignore the speed limits.
 

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I have 15/41 on my SS and it’s perfect on back roads. I don’t even use top gear. It sounds a little busy on the highway but it’s really not , actually right up there in the torque band. Good throttle response, no downshifting necessary.
 

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Discussion Starter #18
Yes, i used to run 15/43 on the supersports I've had, but am sure the ratios for 5th and 6th were longer.

I've got a 41 comingfor the rear so I'll see how that goes.
 

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Top gear is probably the same on both.
 

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Discussion Starter #20
So, decided to have a look and the ratios on the Monster are shorter. think this is what's irritating me. The difference between 5th and 6th is as good as negligible

Monster
15/39

Total gear ratios:
1st gear 15/37 (900),
2nd gear 17/30 (900),
3rd gear 20/28 (900),
4th gear 22/26 (900),
5th gear 23/24 (900),
6thgear 24/23 (900).



Supersport
15/40.
1st gear 15/37 (900).
2nd gear 17/30 (900).
3rd gear 20/27 (900).
4th gear 22/24 (900).
5th gear 24/23 (900).
6th gear 28/24 (900).
 
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