UPDATE: NSR Gearbox problem - Not the gearbox, Losing Power

[SilvaRizla]

Hi,

I bought an NSR about 5 weeks ago, and sometimes when you pull away in 1st after being stopped it jumps in to fifth (I think) and pulls away really slowly and you have to work down the gears really quickly to get going.

My dad has had a look but it didn't happen to him so my brother had a go and he said that it sets off as if in first and sort of looses power and you pull the clutch in but it just dies, he didn't try to go down the gears though.

My dad reckons its possible it wasn't really going down a gear but the constant jiggling and clutch movement kept the engine going and as it slowly speeded up it sounded like I was going down the gears, so it could be the plug or an electrical problem. I'm not so sure though.

Any ideas?
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I'm Ivan Dobski the Meatsafe Murderer only I never done it, I only said that I done it so they'd take the truncheon out of my bottom

[finpos]

Think your dad+brother are probably right, it's not unheard of for a bike with a worn 'box to jump out of gear, but I've never heard of one jumping INTO another gear:)

finpos.

[Pete.]

I had a Honda in the past where you could keep going round and round on the shift drum changing from first into top gear so it could be possible, but it depends on the slots in the shift-drum not having a stop-end, like most do. Not being familiar with the NSR gearbox I couldn't say but it sounds like you have a worn component allowing the drum to turn further once you have got into 1st gear.

Your dads explaination could be true if you were in the habit of "banging down the box" with the clutch in when approaching a junction or after coming to a stop. You might THINK you're dropping down gears when actually you're not. If, however, you change down gears as you slow down and actually engage each gear and let out the clutch in order to use a bit of engine braking to slow you down, then you would definately know you were changing down properly and therefore have a gear selection problem.

[SilvaRizla]

Righty - Update

I changed the plug in September and the problem went away, I was idling it in neutral a couple of days a go to let it warm up a bit while I was getting my gear on and I gave it a little rev and rather than do what you expect, the revs didn't really move (dropped a bit as if to cut out) and there was a low rumbley rev, the same rev I get when I think I'm pulling away in fifth.

So I backed of the throttle for maybe half a second, as soon as I did the idle rev returns to normal and try again and it was fine.

Coming home from work today (this is dead embarrasing), I was on a dual carrigeway in the right hand lane and pulled up to be first at the lights (definatley went down the gears) and there is a ped boi next to me so I let on to be friendly and he starts revving his engine with brakes on. I had a little chuckle and thought, "Right ok, I won't rev, I'll just blitz past you and start laughing" - so lights go green and I try to fly away, the revs die as the bike moves at about 2mph and he shoots off, so I pull on to the side (where pedestrians cross), back of the revs and wait for the traffic behind me to clear before continuing.

I know a new plug will fix this but considering the time away I've had I shouldn't be buying new plugs every 3 months (should I?), and from memory the old plug didn't actually look that bad anyway.

Any idea whats causing this then?

Thanks

Silva

PS- If you read this matey I'm up for a rematch as soon as I'm sorted
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I'm Ivan Dobski the Meatsafe Murderer only I never done it, I only said that I done it so they'd take the truncheon out of my bottom

[alains]

give your engine a good cleaning , i meam
- tank (and petrol tap)
- air foam filter
- carb including the round strainer , change jets as main=138,slow=42,power=65 , set needle second notch from the top , adjust pilot screw 2 1/2 turn out (or 2 3/4), idle screw at 1400 rpm (this after 5 mn warming)
- control your oil pump adjustment
- fit a BR9EIX
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the worst day fishing is better than the best day working

[fuzz]

If it's a UK spec bike with no airbox/filter/exhaust mods, I suggest you use the standard jets of 135 main, 40 slow. I used the bigger jets that Alain decribed only to make the engine handle worse. Only fit those jets if you have a freer flowing air intake/exhaust. Plug needs changing every 2500 miles if your using the standard BR9ECS.
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https://www.bikepics.com/members/fuzzbcf/
Bikes: '99 NSR125R, '00 SV650S, K1 GSX-R600, '97 CB500, K3 SV1000S, '16 VFR800

[SilvaRizla]

I'm using the BR9 but its a french import - problem didn't happen today though
____________________
I'm Ivan Dobski the Meatsafe Murderer only I never done it, I only said that I done it so they'd take the truncheon out of my bottom

[alains]

BR9ECS are bull shit !!! i know BR9EIX or Denso IW27 are expensives but you spare at least 3/4 L petrol by tank , your engine is much smoother and the plug can run well over 4000 miles
do a simple operation 115 miles a tank which is about 21 tanks for 2500 miles , you spare 15L petrol so about £12 (the plug cost £8.5 and can run 2500 more miles)
try it once , you will see
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the worst day fishing is better than the best day working