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Old 05-09-2012, 09:01 AM   #64036
TrophyHunter
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Quote:
Originally Posted by Meter Man View Post
I've fallen back in love with the DR. Maybe I will pull it off the market....

Seems odd that I can't sell it for 15% below book value in Montana, land of the fireroad......

You're probably being protected by a nonspecifichighersource until you came to your senses.

I don't ride as much I would like and sometimes think - "maybe I should sell it" (usually refering to the Strom) but then I ride it. One good day of riding your bike around (maybe that's what happened) and bingo....back in lust.
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Old 05-09-2012, 09:29 AM   #64037
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Originally Posted by BadDogMax View Post
... Or, maybe everyone is suffering with the oscillation problem, and some solve it by revving the engine to 8000RPM before shifting?

Just kidding, this vibration is not like the bucking bronco you get when lugging the engine. I think the "jackhammering on the swingarm" description is close.

In fact, if I intentionally lug the engine while accelerating, the bucking bronco will go away as the RPM increases, then suddenly the jackhammering will start at maybe 50-55MPH, then suddenly stop again at 60MPH.
I have not drilled mine, my carb is stock except for a washer under the needle and a ProCycle mixture screw.

I have the same vibes with the 15t sprocket btw.
I have never experienced vibes as you describe, from stock through sprocket changes and carb mods (including drilling the slide). It sounds like something has "always" been wrong the way you describe it. I would focus on sprocket runout (as mongle suggested) and chain alignment. You have possibly had a rear sprocket that was not machined properly from the start, as in the bolt hole center is slightly off (causing rotation to move ever so slightly in and out of a perfect circle). Also check overall alignment by running a straight edge alongside of the rear sprocket and parallel with the chain

I have experienced the common lugging vibrations and was able to improve that quite a bit (but not eliminate) with carb tuning. It will never go away with the CV carb.
Good luck!


Edit: there could also be an issue with the hub itself and the alignment of bolt holes and axle centers, but I would focus on the sprocket first.

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Old 05-09-2012, 09:48 AM   #64038
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Originally Posted by bouldertag View Post
I was starting to get worried that something was seriously wrong as I have the vibes also.I have a 2009 3k miles and had the vibes since day 1 at 800 miles. I first thought it was the engine at a certain RPM issue. Doesn't really feel like a jackhammer but rather deep rattle at speeds talked about already, mine around 40-45 and only last during that 5 MPR zone then once under or above 40-45 it is gone . Can feel it on my pegs. I have the 14t front and stock rear. Took out the top roller when purchased. I was thinking it could be the top roller also. But the video helps to show it is the chain which makes me happy that it isn't in the engine.
Very interested in eliminating this issue or if it is totally normal and will be fine.

Thanks for visiting this area of concern.
boulder
My first guess for vibes is always motor mount bolts, especially in the head...
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Old 05-09-2012, 10:29 AM   #64039
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I know about the vibes, and I would have to agree that lugging the motor is what brings them out. I also have a 14t and stock rear sprocket and 50MPH is way to low to be shifting into 5th...I would definitely consider that lugging. My DR definitely lets me know when I'm lugging her by way of increased vibes. Keeping the RPMs high makes it run much smoother, IMO.
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Old 05-09-2012, 10:40 AM   #64040
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Originally Posted by BadDogMax View Post
I'll add that the video was taken while accelerating from 50-60MPH in 5th gear, with a 14t front sprocket. Not lugging it IMO.

I appreciate all the help and theories... maybe we can solve this thing!

Do you still have the stock BST 40 CV carb on your bike? If so is the top of the air box cut/modified?

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Old 05-09-2012, 11:20 AM   #64041
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Vibrations

I hadn't rode my bike for a few days, so I just went out for a little test run. I have a 14/43 gearing and a pretty well dialed in BST. I did a couple of roll-ons at 50mph (stock speedo) in 5th gear (used 50 instead of 55 because of 43t rear). It was turning around 3500rpm at the time, which is about as low as I want to turn in 5th gear with a normal load (my fat ass).

50mph roll on was plenty fast to avoid the common lugging\lurching issue but I did pick up an "ever so slight" vibration in the footpegs untill about 55mph. But I had to be really concentrating to feel it and had never noticed it before. I consider this completly normal for a big single, with CV carb, on it's way up through the power band (once over 4000rpm it really comes to life).
But seriously if this is what some of you are noticing you are far more picky then me. I would have never noticed it if I wasn't really REALLY trying to pick something up.
If I was doing anything other then cruising --- had a passenger, going uphill, or just accelerating hard in general, I sure as heck would be downshifting.

I am not discounting other issues magnifying the vibration, but overall It is not a happy place for the motor, in 5th gear with a load.

I suggest picking up the RPMs (downshifting) if you are loading the motor between 50\55mph in 5th, or switch carbs.

Just my opinion

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Old 05-09-2012, 11:44 AM   #64042
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Originally Posted by BadDogMax View Post
... Or, maybe everyone is suffering with the oscillation problem, and some solve it by revving the engine to 8000RPM before shifting?

Just kidding, this vibration is not like the bucking bronco you get when lugging the engine. I think the "jackhammering on the swingarm" description is close.

In fact, if I intentionally lug the engine while accelerating, the bucking bronco will go away as the RPM increases, then suddenly the jackhammering will start at maybe 50-55MPH, then suddenly stop again at 60MPH.

There is no jackhammer at steady state or at medium to full acceleration. Only with gentle acceleration or slight uphill. Not the kind of acceleration you'd normally downshift for, like passing a car, or racing that dude on the DRZ400 who lives in the next housing tract.

Here's my latest theory: the BST carb has a vacuum operated slide that has some resonant frequency where it's most likely to oscillate up/down. The chain on this bike has a very long span, and when stretched with the right tension by acceleration, also has a resonant frequency like a guitar string. When those two resonant frequencies are the same (or perhaps a harmonic of one another) the following sequence happens: the engine fires a pulse, whipping the chain, which causes a jerk back to the engine, which creates vacuum, which causes the carb slide to undershoot, which causes the engine to stumble, which whips the chain, and then the process repeats.

Low RPM lugging would be be basically the same mechanism, except without the added resonance of the chain. So the jackhammering is like a second onset of lugging, once you're past the "normal" lugging you'd get on a BST-equipped DR.

So if my theory holds any water, the million dollar questions is this: Have any of us experiencing the jackhammering drilled the carb slide? This would change the resonant frequency of the slide and perhaps break up the resonance problem.

I have not drilled mine, my carb is stock except for a washer under the needle and a ProCycle mixture screw.

I have the same vibes with the 15t sprocket btw.
I quoted this whole message because it's so accurate to what's also going on with mine. I have not drilled the slide. I think your latest theory is quite possible, but I'm not enthusiastic about buying a $470 TM-40 to try out. I think you should do it.

Next time you have the rear wheel off, look for wear a mark about 3" in from the left (welded on) snail adjuster. I posted pics a few pages back.

My jackhammering is not a harsh, metal on metal, clanking (hammer and chisel). The impact and resonance is there, but there seems to be some sort of damping, perhaps the hub cushions.

I'm going to put my 16t on before I ride today. Although too tall for my altitude, it was smoother on my Kali trip in February and needs a second ride, paying closer attention. The hammering was almost nonexistant with the 16t at sea level. This contradicts the 'rpm too low' theory somewhat, the 16t would lower my rpm, not spin it up.
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Old 05-09-2012, 12:05 PM   #64043
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Quote:
Originally Posted by ER70S-2 View Post
I quoted this whole message because it's so accurate to what's also going on with mine. I have not drilled the slide. I think your latest theory is quite possible, but I'm not enthusiastic about buying a $470 TM-40 to try out. I think you should do it.

Next time your have the rear wheel off, look for wear a mark about 3" in from the left (welded on) snail adjuster. I posted pics a few pages back.

My jackhammering is not a harsh, metal on metal, clanking (hammer and chisel). The impact and resonance is there, but there seems to be some sort of damping, perhaps the hub cushions.

I'm going to put my 16t on before I ride today. Although too tall for my altitude, it was smoother on my Kali trip in February and needs a second ride, paying closer attention. The hammering was almost nonexistant with the 16t at sea level. This contradicts the 'rpm too low' theory somewhat, the 16t would lower my rpm, not spin it up.
Couple ideas:
Are you sure your non OEM rear wheel and hub bearings are fully seated, 100%? Do they fit properly? I only mention this because of the unusual wear on your axle. What would cause that?

I see you've gone creative on chain alignment ... maybe go back to just matching up the snail adjuster numbers. My front sprocket has always shown a bit of wear on the outside. No other problems or bad vibes as a result. I DO change my front sprocket every 7 to 10K miles ... no matter what. REally helps with smooth running and saves chain.
OEM sprockets please.

I believe you mentioned you had your clutch off to do NSU. I would double check your work there, and while in there look for dig marks in basket slots from clutch plates. Look at Lukas' pics to see a PERFECT basket. A worn one would have little dents where the clutch plate tangs sit in basket slots.

http://advrider.com/forums/showpost....ostcount=19799

Usually for me drive line vibes have always been from worn sprockets or chain. Something is worn or out of alignment. I doubt it's your clutch basket, but if it's installed incorrectly or not torqued? Then who knows? I hope you torqued down the BIG nut to full spec? Can't recall number, but it's a BIG ONE.
I hope it's not that BIG ball bearing under the clutch!

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Old 05-09-2012, 12:15 PM   #64044
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Jetting question.

Picked up a 99 last Sat. Previous owner had opened the top of the airbox, installed k&n with foam cover and a dynojet kit using a 160 main. Bike runs great and starts easy. It has the stock muffler on it. I have a fmf q4 laying around that I was thinking about trying out. Have a couple of questions for anybody who has went this route before. First, will I have to go up bigger on the main jet? Bike came with the rest of the dynojet kit so I have a couple bigger ones if needed. Second, other than saving eight or ten pounds, is it worth fooling with?
Thanks,
Fred
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Old 05-09-2012, 01:44 PM   #64045
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Well. I can feel vibes in the foot pegs when I ride at certain rpms similar to what is being described. Also, I can tell by the shadow on the road in the morning that my chain jumps around just as much as the video. I put on a new chain and sprockets this week, along with new cush drive rubbers.

I wish I could ride one of these vibration plagued bikes for comparison, but until I do, I'll just assume it in your head.
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Old 05-09-2012, 02:25 PM   #64046
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Quote:
Originally Posted by gone fishing View Post
Picked up a 99 last Sat. Previous owner had opened the top of the airbox, installed k&n with foam cover and a dynojet kit using a 160 main. Bike runs great and starts easy. It has the stock muffler on it. I have a fmf q4 laying around that I was thinking about trying out. Have a couple of questions for anybody who has went this route before. First, will I have to go up bigger on the main jet? Bike came with the rest of the dynojet kit so I have a couple bigger ones if needed. Second, other than saving eight or ten pounds, is it worth fooling with?
Thanks,
Fred
No, IMO not worth it unless you like loud pipes and like to repack the muffler. Moreover since you say the bike runs great, just keep riding it.

But if you want to still go over to the FMF you can just try swapping the pipe and then trying it out before going to a bigger jet. Since you have a cut airbox and K&N filter you may get by without a jetting change.

I had a DJ kit on my bike with cut airbox and a K&N filter, but I think my main was smaller than 160...The bike ran good with great mileage. Now I have a FCR
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Old 05-09-2012, 02:30 PM   #64047
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Originally Posted by Dravintoad View Post

I wish I could ride one of these vibration plagued bikes for comparison, but until I do, I'll just assume it in your head.
It's a big single. I think it's in their heads also. I remember the first time I rode a streetbike after years of offroad experience with moto-x bikes. I thought there was something wrong with the tranny. I could hear it shift. It was just that the motor was so quiet. I think it's more just the nature of the beast. Big single sending individual shock waves at low RPM and high load. I could be all wet also.
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Old 05-09-2012, 02:31 PM   #64048
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Quote:
Originally Posted by BadDogMax View Post
Here's my latest theory: the BST carb has a vacuum operated slide that has some resonant frequency where it's most likely to oscillate up/down. The chain on this bike has a very long span, and when stretched with the right tension by acceleration, also has a resonant frequency like a guitar string. When those two resonant frequencies are the same (or perhaps a harmonic of one another) the following sequence happens: the engine fires a pulse, whipping the chain, which causes a jerk back to the engine, which creates vacuum, which causes the carb slide to undershoot, which causes the engine to stumble, which whips the chain, and then the process repeats.

Low RPM lugging would be be basically the same mechanism, except without the added resonance of the chain. So the jackhammering is like a second onset of lugging, once you're past the "normal" lugging you'd get on a BST-equipped DR.

So if my theory holds any water, the million dollar questions is this: Have any of us experiencing the jackhammering drilled the carb slide? This would change the resonant frequency of the slide and perhaps break up the resonance problem.
Still does it with my FCR pumper carb...

I think it's a combination of power pulses and tight/loose links.
My new chain didn't do it for a few thousand km's.
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Old 05-09-2012, 02:35 PM   #64049
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Originally Posted by gone fishing View Post
Picked up a 99 last Sat. Previous owner had opened the top of the airbox, installed k&n with foam cover and a dynojet kit using a 160 main. Bike runs great and starts easy. It has the stock muffler on it. I have a fmf q4 laying around that I was thinking about trying out. Have a couple of questions for anybody who has went this route before. First, will I have to go up bigger on the main jet? Bike came with the rest of the dynojet kit so I have a couple bigger ones if needed. Second, other than saving eight or ten pounds, is it worth fooling with?
Thanks,
Fred
If its running the stock muffler, I'd try going down to the 155 main. The 160 is really only used with an open pipe.
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Old 05-09-2012, 03:19 PM   #64050
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If its running the stock muffler, I'd try going down to the 155 main. The 160 is really only used with an open pipe.

Thanks for the replys. The FMF came with a 97 I bought last year. I commute on it almost every day. Its stone stock and gets about 60 mpg on my drive to work, so I didnt want to mess with it. I might try the pipe on the 99 but if its really that loud, it won't stay on.
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