NSR125 exhaust/engine/clutch problems

[jobzter]

Hi all, after a hunt for a project i ended up with a NSR125r 2001 model with 19k on the clock. Theres just a few things id like the 'pros to clear up for me.

Firstly when i start the engine the starter motor turns over but the initial start makes a loud bang, asif the teeth are clattering as they connect when it first starts, This may be related to the next question.

When starting the bike in a gear, with the clutch pulled all the way in the bike tries to move forward, asif its draggin? (From what iv been searching, that seems the most obvious) is this hard to adjust.

Also there is a whole or two in the exhaust and the tubes that lead to the final can on the exhaust are pretty rusty, the wholes are where the welds/joins are and im pretty sure the rusty tubes arnt rusted very deep at all. Is it worth trying to repair with holts firegum?. or just buy a new exhaust?. would it be possible to file the tubes clean and BBQ paint them? Oh and whats the best price for anexhaust too? i dont want it to look rusty n shite

Finally the fairings are ok but a couple of screw holes are broke, how hard is it to remake the fairing with fibreglass, sand and redrill the attatchment holes? Im planning on sanding scratches out and repainting anyway so, ideas? Heres a picture to explain:
https://a.imagehost.org/0456/howtofixpanel.png


Any help much appreciated


~Stevo

[Frost]

The clutch can be adjusted where the cable meets the lever. Yes this is very likely causeing your banging noise. The bike will probably go into gear with a real bang aswell.

The fairings can be repaired with fiberglass, i did an ideantical repair a few months ago and it held perfectly. Get to halfords and get some fiberglass resin & hardner.
Make sure you get some of the tissue style sheet:
https://washford.scene7.com/is/image/Washford/400-219162?$h20listthumb$

NOT the mat:

https://washford.scene7.com/is/image/Washford/219154?$h20listthumb$

The tissue stuff is far better for doing detailed stuff and doesnt come appart. Use about 4 ply thickness on the back of the mount, once thats dry use another 4 on the front so it's held both sides, then drill out the hold again. try to keep air from getting in and leaving bubbles.

The exhaust problem i don't really understand whats up, all i know is that exhause gum is shit. It starts off as chewing gum untill it gets hot and sets, then it turns to chalk and falls off with a slight vibration.

[jobzter]

Thanks for the reply Frosty, i did adjust the clutch on the lever side to its max and it had no effect, i think theres another adjusted on the other end of the cable ill have a look at that. Thanks for the advice on the fairings too!

and yeah changing gear is a little too clunky for my likeing, especially when im used to my CG125 running smooth as .... !

And can anyone confirm that an nsr125r 2001 should be able to get more than 60mph? yeah it is restricted but surely it has something to do with the knackered exhaust?

Any other suggestions on my 'over religious' exhaust folks?

~Stevo

[Frost]

There will probably be 2 bolts holding the cable in place at the other end, adjusting using this alone will be a pain to get right. Screw the adjuster on the lever all the way in, then adjust the bottom, then use the one on the top to get the tension correct

It should go above 60 even restricted. The top end of the engine will probably need rebuilding every 10k miles, so assuming it was done when it was supposed to, its probably due doing again now.

The exhaust problem shouldn't effect performance too much provided the holes are after the expansion chamber. You could probably get them welded up on the cheap.

[jobzter]

Aha ok, i understand, ill get that pesky clutch sorted.

Could you please alaborate when you say the top end needs rebuilding?. you meen the top housing of the engine (Where the spark plug goes in) needs removing, then what new bits do i need?. Also is this safe to do so?. will there be tonnes of oil when i take the top of? will i need a gasket kit for when i put the top back on?

and yeah i have a mate who will weld for me no problem. Looks like i may have got a bargain after all, i thought id got a banger lol.

Cheers!

~Stevo

[Frost]

A top end rebuild does require gaskets and removing the top of the engine, but no you won't get covered in oil. First thing that needs to be done is to compression test the engine. I'd recommend getting a garage to do it rather than buying a tester. If the compression is below what the manual says, then the seal between the rings and cylinder has gone giving you less power and speed, requiring a rebuild (i personally think it needs one from what you have described, and even if it doesnt, i'd probably do it anyway so you know it's been done.)

Rebuild will require you replace:

Piston (£20?)
Piston rings (£10?)
Gasket (£15?)
Rebore the cylinder (£30?)

Its not hard to do, i could probably do it in half an hour, you could probably do it in about an hour with the manual for assistance.

[baldy]

The nsr has a plated bore so it can't be rebored. David silver does new barrels for £90, along with all the other bits you will need.
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One day i will rule the world, just not today.

[alains]

piston £45
rings £20
cylinder+piston £125 (no rebore , they are coated)
pin,clips,bearing,gaskets £30
your bike has 2 possible colors re/white/blue (R127) or black (NH1) if it's a year 2001 . if you give me your serial number , i can tell
i suggest to look on ebay for the fairings but could be difficult to find your color . the lower fairings are expensive , the upper affordable in your color type . as your pict tell , i dont agree with using glass fiber tissue , it wont keep on for long , better to buy a seond hand part & eventually to respray
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the worst day fishing is better than the best day working

[jobzter]

Alrighty then, last question. How serious is a rebore?. i think i could probably replace a new piston and the rings etc, but how wouldi go about a rebore?. im guessing i have to take it to a shop for that? or is it easy to do yourself.

I never knew this had to be done every 10,000 miles?. My current bike, CG125 i've done 4000 miles in 5 months, surely i cannot be reboring that engine once a year?. there'd be no engine left after a few years of making the barrel wider?

Sorry to appear stupid but i would just like to clear things up so i know exactly what to expect.

[Edit]

Didnt see the other replies there. Im wanting to spray them to change the colour to white and red as the red/white/blue just looks commonly tacky, as for the rebore it sounds a little expensive for my liking so i think ill just leave it. allthough i might buy a gasket so i can take the top end of and see what the condition of things are like. That'll give me a chance to BBQ spray th e top end.
Thanks guys

~Stevo

[RudiRulez]

Well if your not going to rebore atleast get a new piston and rings(or even just rings), if your gonna have the top end off anyway you may aswell.

[Frost]

The reason your CG didn't need it doing every 10k is because it is a 4 stroke. The NSR is a 2 stroke, this is a common maintanence task. You wouldn't be able to do a rebore yourself, however mechanics charge a shit load for labour so if you can get the barrel off yourself you will save money.

Like i said, get it compression tested first to find out if it actually needs doing or not, though i suspect with that milage and performance, it does.

[boundy]

I thought my old NSR needed a new barrel ect. but when I stripped it down and took the piston and barrel to my local honda dealer the mech said there was almost no ware so he told me just to get the rings, gaskets, small end bearing, cir-clips and gudgeon pin. cost about £70 all in from honda, it was about £8 more than david silver could do it for but had it in 2 days and the rebuild took less than 5 hours all togeather and when finnished it went about 95 - 100 indicated on the flat, or 110 with a tail wind going down a very big hill

[Frost]

5 hours, bloody hell!

Carb off.
Exhaust off.
5 bolts to get the head off.
4 bolts to get the barrel off.
2 clips to change the piston.
Clip the rings on, put some oil on things and put it all back.

I did an rgv250 with 2 barrels in under an hour, and that was without a manual!

[boundy]