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Old 10-12-2013, 09:54 PM   #1
offtrackplanet OP
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Engine revvs up but no power to the wheel, ?? (78' R100)

I was riding my 78' R100 last week, gave it full throttle on a straightway and the engine revved up and then went back down before the power went to the wheel, what the heck? It's been happening ever since but only when I gun it.

I've had this bike for a few months, all the geneal maintenance has been done...I'm just starting to learn some of the basic mechanics but could it be the spline slipping? Problem with that theory is that my mechanic took a look at it recently and said it was in fine shape.

Somewhat seperate question...my friend took the packing out of the exhaust pipe last month (it's a two into one pipe) I don't remember there being a decrease in power right after, but it sure feels like there's been an overall decrease lately (especially in the low end). I'm wondering if that has to do with the packing or maybe it's linked to the above issue?

Any insight would be great! Thanks -
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Old 10-12-2013, 09:58 PM   #2
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Why would you unpack a muffler? I dunno if its got anything to do with the issue, but feel free to go ahead and repack that

a spline probably wouldnt slip like that, and still work afterwards sounds more like your clutch, kind of.. it could simply be out of adjustment, though, rather than toasted. Have you messed with the clutch levers at either the handlebar or the transmission in your latest maintenance?

If I suspected the clutch, I'd find a stragihtaway, get going about 20mph and put it in fourth or fifth gear and add throtle as fast as it would take it. If the revs went up faster than the bike did I'd think it was the clutch, and then I'd confirm adjustment and do it again to see what happened before I called it as a smoked clutch. If engine speed and speed were the same, I'd be more confused but look elsewhere for the time being. Splines? I would bet that they get thinner and thinner till they just let go. Not much middle ground on those.
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Stagehand screwed with this post 10-12-2013 at 10:05 PM
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Old 10-12-2013, 10:03 PM   #3
offtrackplanet OP
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We put on an easy clutch (one of these http://www.benchmarkworks.com/articl...to/clutch.html) back when I got the maintenance done and it was adjusted then, this just started recently. I can tell you that that's basically the issue though, giving it full throttle at a lower speed from any gear, the revvs go up and then come down before it gets to the wheel.
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Old 10-12-2013, 10:07 PM   #4
ME 109
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Sure sounds like the clutch is slipping.
You need to be able to easily move the clutch arm forward from the 'ball' on the end of the clutch cable with just your fingers.
If it takes a lot of effort, your free-play is non-existent and clutch slippage is highly likely.
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ME 109 screwed with this post 10-12-2013 at 10:13 PM
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Old 10-12-2013, 10:11 PM   #5
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how many miles ago was that? maybe the cable was new and stretched? has the play at the handlebar lever changed feel at all?

I'm guessing with the anti-simplicity of that thing, something has gone out of whack. I'd still do the clutch loading test, becuase how it shifts doesnt really tell you how the clutch plates are holding together under a high load, like when you whack the throttle open

Edit: never mind scrwe all that, didnt see the edit:

What he said. ^^
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Old 10-12-2013, 10:17 PM   #6
Plaka
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Quote:
Originally Posted by offtrackplanet View Post
I was riding my 78' R100 last week, gave it full throttle on a straightway and the engine revved up and then went back down before the power went to the wheel, what the heck? It's been happening ever since but only when I gun it.

I've had this bike for a few months, all the geneal maintenance has been done...I'm just starting to learn some of the basic mechanics but could it be the spline slipping? Problem with that theory is that my mechanic took a look at it recently and said it was in fine shape.

Somewhat seperate question...my friend took the packing out of the exhaust pipe last month (it's a two into one pipe) I don't remember there being a decrease in power right after, but it sure feels like there's been an overall decrease lately (especially in the low end). I'm wondering if that has to do with the packing or maybe it's linked to the above issue?

Any insight would be great! Thanks -
Splines have been known to rip off the rear drive. but once it happens you start pushing. it don't go again without a hefty cash injection. Fortunately I was only a couple blocks from home.

But slipping clutches are another matter. With luck simply adjusting it will be enough. Both ends of the cable get adjusted for correct free play and the instructions are in the manual you don't have. So get a Clymers at least. If you are not lucky the rear crankshaft seal has let go dumping oil all over the clutch. Seal is not expensive or difficult to install. Lot of places can get you into a third mortgage on the 8 wide to afford the clutch disk. If you don't live in a 'park, quit acting like it and put the packing back in the muffler. if the clutch is slipping badly the bike just sits there no matter how much you rev it up. You can pretend you're tuning it to save face.

if you have one of the cheap ass MAC 2-->1 pipes it can be identified by the single sheet metal screw holding the baffle in. It's also rusting badly even though you only bought it next week. Get a whole bunch of stainless scrubby pads from the Qwik-Way. Pay for them, right? Pull the staple in the middle and you have a nice doughnut. Stack these up on the baffle tube. Weld the baffle in before starting the bike. Lasts forever. Nice deep throaty sound of power. Trust me.


Yes, running the exhaust wide open will hose the power. It also marks you as a redneck loser unless you're me then it's cool. (but my pipes are made to look totally stock so everybody is looking around for the cool guy---thus the sunglasses). An open exhaust has to be tuned to work correctly that way. Gutting the muffler won't do that.


BTW, I used to live in Cinti, down in Northside. Damn that town looked good in the rear view mirrors. People that say "please?" when they mean "WTF!" and eat overcooked spaghetti thinking it's chile somehow. Brrr...
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Old 10-12-2013, 10:59 PM   #7
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How on earth do you have two lots of freeplay?
And a leaking rms generally doesn't oil the friction plate. A leaking input shaft seal on the tranny will tho'
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Old 10-12-2013, 11:07 PM   #8
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The flange on the rear of the gearbox may have come loose, and if it has keeping running the bike probably wont do the output shaft much good.

If it isn't , err, shafted already.
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Old 10-14-2013, 11:55 AM   #9
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Hmmm....I wonder why my clutch was slipping?



The opposite side was also missing a similar chunk.
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Old 10-14-2013, 01:53 PM   #10
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Quote:
Originally Posted by Beemerboff View Post
The flange on the rear of the gearbox may have come loose, and if it has keeping running the bike probably wont do the output shaft much good.
+1 On the two transmissions I've replaced output shaft seals, the nut holding the output flange on was WAY under torqued. It was either an error in assembly, or they all get that way after awhile...
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Old 10-15-2013, 01:59 AM   #11
Plaka
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Hmmm....I wonder why my clutch was slipping?



The opposite side was also missing a similar chunk.

Gap type racing clutch. Trick stuff...
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Old 10-15-2013, 12:07 PM   #12
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I recently took an output flange off a transmission that the nut was loose on. It was not loose enough for the flange to spin but it was not as tight as it should have been. I also think there was oil between the flange and the output shaft.

These are supposed to be clean and dry.
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Old 10-15-2013, 03:57 PM   #13
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There is an inmate here that has worked on more airhead trannies than anyone I know of. I wonder what his opinion on loose flange nuts is? Personally, I think it is because whoever tightened it down did not tighten it down to spec. I have worked next to a number of people that stopped way short of spec for thinking that they could feel the threads stripping. No. That was the flange spreading. I have found many a loose flange nut and the flange itself hadn't spun at all.
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