Italian NSR 125

joebucks · Derestricted Danger Joined: 04 May 2011 Karma :

Hi fellas,

I've just got an NSR125, and guess what ... there's something wrong with it ... it's an italian import, definitely an 8

Tops out at 75mph downhill, doesn't feel like it should high up the rev range.

I've read much conflicting information about Italian bikes, they are supposed to be full power, which I have tried to verify, the exhaust doesn't look restricted, it does have a collar inside but it looks nothing like the ones on https://www.nsr125.com/derestrict.htm ... can take a picture if anyone thinks it's worth seeing, but it's a collar a few mil thick, and I see no welds so assume it's part of the pipes structure ...

There's no inlet restrictor, the CDI doesn't contain any serial/model, just KB3 on the epoxy'd side ... the RC controller is tv-78 ...

I changed the spark plug because it was fouled, not soaking or covered in bits, just black and electrode didn't look too good ...

Sitting still, it'll hit the red line no problem, when in motion not so much after 1st ...

I know a compression test is next, the bike is a 20k mile machine and I know it's coming up for a top end rebuild anyway, I just don't want to spend the time and money on it if there's something more sinister going on ...

I just have a gut feeling, it feels electronic not mechanical ...

So, I'm asking, is there anything else, anything at all that could be restricting the bike, and also, does anyone have a good way of counting teeth on sprockets my eyes get confused ...

Also, when ticking over, it's pretty high, 1800 maybe ... there's a bit of a rattle coming from what sounds like the barrel, this is the little end bearing isn't it ?? The noise goes when revved at all and the engine revs smoothly and sounds all 2 strokey like it should ...

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Depends on the age, but for most models there would be no reason for an Italian market bike to be restricted.

Alains is the one who can give you the details though.

I have seen a power valve fail on an NSR, dropping down and flopping around in the exhaust port. This would rattle and destroy performance.

All the best

Keith
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joebucks · Derestricted Danger Joined: 04 May 2011 Karma :

It's a 95 model ... it's before the year was included in the frame number so no way to verify that is there ??

Might be worth taking the exhaust off and having another look at this valve thing ... I didn't look before, you can't see it operate without the engine running ( right ? ) ...

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

I wouldn't want to look up the exhaust port with the engine running Laughing

.

However I think the valve should cycle when the ignition is switched on, so with the exhaust off looking up the port you should see it move as the ignition is turned on.

Being a 1995 Italian bike there is no way it should be restricted.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

joebucks · Derestricted Danger Joined: 04 May 2011 Karma :

The valve is fine, there's a bit of play in it, but I see it ... didn't think of working the ignition ... doh ...

I'll have to leave a compression test for another day, I'll test the valve on that day ...

I think right now, for peace of mind for the rest of summer I'll just rebuild the top end anyway, on a 20k bike it's not even gambling my money seeing as the guy I bought it off doesn't know when it was last rebuilt and never done it himself ...

I had a look at the throttle needle, and moved it to 2nd from top ... the end of the needle has a kink in it, is that normal ???

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

No a kink in it isn't normal. And I suspect it might have worn the atomiser tube as well if it is kinked.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

joebucks · Derestricted Danger Joined: 04 May 2011 Karma :

I'll put up a picture when the bike is next in bits ...

It is odd that it's kinked, but I would have thought it would run really rough, be difficult to start maybe and stutter and the throttle would stick ... which is why I asked ...

What a puzzle ...

joebucks · Derestricted Danger Joined: 04 May 2011 Karma :

https://www.dellorto.co.uk/merchandise/products.asp?CategoryID=2&PartsectionID=24

Can someone point out which atomizer I need from that page please ??

I'll check jets when I have it in bits, and there's only one needle ...

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

It is 3 or 4 (not sure without a digging a carb out)

They are fairly helpful so ring up with the bike model and explain what the issue is and they should be able to sort the bits out.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

lozza · Nova Slayer Joined: 23 Sep 2010 Karma :

1. get it compression tested - with 20k this is most likely your problem.

2. the sprockets should have their size imprinted on the face of the sprocket.

3. the powervalve doesnt cycle like other bikes when you turn the ignition on. however you can manipulate the servo pulley to the wrong position when the ignition is off so that when you turn the ignition on, it returns it to the right position. download the manual for the bike, take the cover off of the powervalve pulley on the side of the engine and follow the guide to check that its lined up properly.
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rrrring ding ding ding