engine power problems

[Valentino Mossy]

Been out on the ns125r again today (still running it in after the top end replacement) and i'm having some problems.
Going up to brecon and in 2nd/3rd it wont go over 40mph and rev higher then 5k. so i stoped and decided to turn back.
Same thing happpened again on the way back, 2nd/3rd/4th and wont go over 40mph and 5k revs. Then all of a sudden "Blam" ! Instant power,straight up to 70mph .
Its done it quite a bit today, hardly any power and hesitating over 30mph and 30 seconds later powers back to normal.
Towards the end of the day it seemed to only do it 5th, throttle right back and hovering about 5k ,then 15-30 seconds later straight up to 7k revs. (I know i should stay under 5k running it in, but i was bored )
Anybody got any idea's ? - something sticking ?

Btw Anybody else think the weather today has been pucker ! Summer is on its way !

Cheers all !
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[mr jamez]

I'm going to have a stab in the dark and say the powervalve

Apparently it's a biatch to set up properley after messing with it?

[Valentino Mossy]

power valve ? I dont think there is one on mine, but on the later models, Mines a 1991 ns125r, not a nsr125.
I might be wrong !
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Ducati 916,white framed corse replica https://www.bikechatforums.com/viewtopic.php?t=239309
Ducati 160 monza jnr soon to be cafe racer
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[mr jamez]

Sorry, read it as NSR125R, stupid Honda

[Ian (GPX)]

Nah, It's not the power valve, it's not fitted to the NS125R, the chamber is blocked off with a fixed valve.

Could be the pipe (zaust). Richard, do you know if the zaust has a restrictor in it ?

[Valentino Mossy]

The bike and exhaust is fully derestricted. (Dodgy parts ian ? ).
Has been a bit of smoke coming from the where the exhaust meets the engine, but i really tighten it back up,but still seems to be some smoke and oil coming through . (Is there supposed to be a gasket on there ?)

Btw how is it that the bit i mentioned up above is leaking a bit of oil ?

Cheers
Richard
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Ducati 916,white framed corse replica https://www.bikechatforums.com/viewtopic.php?t=239309
Ducati 160 monza jnr soon to be cafe racer
https://blauschatfroums.freeforums.net/

[mr jamez]

There should be a gasket between the port and exhaust

And the smoke might just be oil burning off from where you were working on it.

[Valentino Mossy]

[ZaphodBeeble]

Hey Rich,

It sounds like the crank pressure isn't building up enough to get it into the powerband. Maybe your air filter is blocked or something. Try taking the filter out and take it for a quick blast to see if it makes a difference.

Is there enough or too much oil getting in? Check you exhaust fumes for the trademark blue smoke colour.

It could also be your crank seal as your problem is a symptom of a dodgy crank seal. If you don't sort it out soon I'll pop over again if you want, I'll come over on the DT.
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Current bike: VTR1000F Firestorm. Previous: Firestorm (written off) - XJ600 Divvy - NSR125 - DT125 and a load of offroaders.

[Valentino Mossy]

Cheers mate
I'm going to have a look at the ht lead and plug as well, a mate from work took it for a quick spin and thinks it's not sparking right,maybe even that sensor thingy again ? What do you think ?

Any way back to revising, theory test on wednesday

Btw Its a great feeling when it hits that 7K revs ! Sluggish on minute then ..........Barph...barph.. Weee !

Richard
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Ducati 160 monza jnr soon to be cafe racer
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[ZaphodBeeble]

Hmm, I can't see it being the sensor (CDI pickup). It's the kind of thing that either works or doesn't. Make sure you have the correct spark plug in there too because I remember you having two lying around and you might have put the wrong one back in.

I'm still having a bit of trouble with my bike but I think I'll have it finished in the next day or two. The back brake has brand new pads but still doesn't work very well, I found out yesterday that it's a crack in the metal pivot on the lever. I can get it welded today (my friend has a mig welder) so that shouldn't really be a problem.

The last thing to do then is the bottom spring bush. I'm still waiting for Bob Wilding to get it for me (been 3 weeks now).

Should be out and about legally soon hehe.
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Current bike: VTR1000F Firestorm. Previous: Firestorm (written off) - XJ600 Divvy - NSR125 - DT125 and a load of offroaders.

[Valentino Mossy]