nsr125 help



  • not to sure if any one on here knows too much about them but can only ask
    my son bought a foxeye nsr last year and it needed a few things doing to it so as a good dad I thought I would do them for him to save him money , any way got it all running for him but could never get it right so changed the carb and it improved it a little but not much it had no power under 7k and would splutter like it was running out of fuel , guy on another forum said it sounds like the choke so bought a new choke again little improvement , so I did a compression test was only showing 80psi at best so I have done a top end rebuild as I was told that they should be 150psi , well finished it yesterday and it started on the button thought great , today it had trouble starting, spluttering and not revving clean so played with the choke a little nothing adjusted the carb a little nothing now wont start at all , done another compression test 95 to 100 psi , before I did the rebuild I took the barrel to a mechanic and he said the barrel was fine so I rebuilt it with new piston and rings , plug is black and wet , carb is clean , air filter is clean , fuel is new , if any one can offer some advice on this or come round and beat it with a big stick or me before it goes to a mechanic , ii have pics of the barrel if needed and a vid of it running before the rebuild
    thanks



  • @mad73 I'm no expert but seeing as the top ends been rebuilt and all torq'd down to the manufacturers spec etc and going by the fact it did start once you rebuilt it id say it's definitely a carb related issue! It sound like the carb is possibly flooding. I'd probably start by taking the full carb apart again and double checking everything and make sure the floats aren't jamming and also check the throttle cable to make sure it's not kinked anywhere



  • will have a look tomorrow if I get time but def check the carb is ok
    thanks



  • Hi buddy.

    Never worked on the NSR myself. But assuming two stroke then there really is only a limiting factor on what can go wrong.

    I know people have problems with Carbs and I never understand why. The best thing you need to do with that carb, or any carb, is set it to factory settings. Get it all back to how it was out the factory. Then that's the carb eliminated.

    Yes the top end may be fantastic. But if the bottom ends gone it'll be down on power. If the crankshaft seals are gone it'll suck oil into the bottom end causing misfiring, down on power and excessive smoke. Problem is, if its anything like my bike, it'll smoke loads anyway.

    The scent will give it away.

    Other factors can cause poor power such as weak or intimittent spark. Faulty CDI or perhaps the signal pickup has moved.

    How does the engine sound? If it soundd sweet and is not burning gearbox oil then let us assume the bottom end is sound.

    If it sounds like a bag of nails then it's probably time for a rebuild.

    If the ignition timing pickup has been moved then it will be down on power throughout the rev range. If the bike has never run. Or has had a rebuild in the past. It could be a timing issue!

    Other points are gunked up exhausts. Both expansion chamber and silencer. The system needs to be absolutely free flowing.

    I presume they run a powervalve. That needs to be assembled and operating correctly. Best way to see if it's a powervalve issue is to remove it all together. This will cause lack of power in the bottom end. But will rev out flat to the red line. Of course provided the exhaust chamber is scavenging exhaust fumes effectively.

    If that side of things is okay, then you could look at the intake. To eliminate possible issues with the intake you can crudely remove the filter, if it's a box type. I presume the bike has some form of air duct to get oxygen to the engine bay. This must be completely free of any crap. This makes a maasive difference.

    If you're happy the inlet is clear then make sure you are using the correct spark plug heat range. It might not be igniting the fuel.

    Make sure the engines up to temperatuee before riding it.

    If thw engine revs out with no power then it will be a clutch issue.

    Another good point to check is brake binding. Just prop the bike up and make sure the wheels spin freely.

    Depending on the condition it may be a combination of all these things.

    I urge you not to take it to a garage as all these things you can check yourself. The beauty of two strokes is that they are incredibly simple. Anyone can work on them. If they weren't owned by teenagers then they would be reliable too!

    I was lucky that my two strokes were nearly new when I bought them. And now trivial things like poor performance doesn't bother me since I know I can fix it.

    Keep blogging and I am sure we will fix it.

    Peace.



  • I had a 'full power' NSR foxeye j22 j think it was. Although I never had any problems like yours, the powervalve would stop working all the time and would retard the engine. Sounds similar to what you're experiencing, I just ended up pinning the valve wide open and it never gave me an issue again.

    I'm not saying this is your solution, but it would be something I would take a look at regarding the running issues. With regards to PSI and compression, definitely check everything is bolted down to correct torque settings. Double check everything, make sure the carb is installed tight, no air leaks, proper float movement and clear jets. I know it's all simple stuff but sometimes stuff gets overlooked and it's the simplest thing that's stopping the bike from working.

    http://i1227.photobucket.com/albums/ee433/RV02-Sachs/NSR 125/ADA2BEBF-043A-46C8-9B71-7A61B3F637ED.jpg



  • cheers for all the tips ,,, its full power I think , to start with this is a swiss import and from what ive read these are near impossible to derestrict but I think this has had the engine and loom changed as this will rev right out and its got full power cdi and power valve servo controller ,i rode it before the strip down and was really gutless until 7k then took of quite fast was surprised by how quick it went seeing I'm used to superbikes and when I say gutless it was bad prob as quick as a 50cc when ii did ride it it was choking up and it was like it was running out of fuel then it would catch and sort of go ok , soon as I get time will pull apart again and check things over , this is a link to the video I took of it before the strip down
    https://www.youtube.com/watch?v=Y0tsIy5Ye1c



  • Definitely sounds fuel related, correct jets etc?



  • yeah got the correct full power jets , I think its a carb / fuel prob but will check every thing again



  • Could be a spark issue too, it sounds asif the spark is being retarded at that point. Could be the cap or the coil breaking down and then working again at high revs! Just a suggestion



  • ok had a little play today , carb clean everything looks right , checked to see if the plug is sparking ok and it looks a little strange to me when I hold the plug against the head nut no spark until I lift it off a little and it sparks between the plug and nut ( orange ) but looks to have a blue spark in the plug gap is this right as ive only ever seen a blue spark in the plug gap , is this a coil problem ? cap or lead ?



  • ok bought a new coil and iridium plug to see if this sorts the problem out will fit tomorrow if I get home in time from work , this might sound like a silly question but how do u fit the cap to the lead do u just push it on , never fitted a new cap and lead b4



  • @mad73 The cap screws onto the lead, quite odd to me at first as i had never done one. But when you see it you'll understand



  • changed the cap plug and lead and started straight away thank f'@=k just needs mot now , took for a quick spin up the road all seems fine cant really test properly as needs running in , QUESTION its running a kph to mph converter does this mean the trip meter will show miles or will it still run up in kilometers and what sort of mileage or kilometers should u run new piston and rings in I was thinking about 150 miles ?
    thanks for every ones advice hopefully soon have a dt and can pick every ones brains some more also once I dig my yzf out the garage il stick some pics up of that project as well



  • how do I stick a pic up copy and paste don't work





  • does the pic need to be on photobucket or something can I not get them out of my pics on the laptop ?



  • @mad73 Correct. You need to upload them to Photobucket.

    This forum can host its own photos. I could enable the forum so that we could upload photos to it.

    Draw back is that this forum is being hosted from my house, on one of these!

    http://cdn1.alphr.com/sites/alphr/files/6/14/raspberry_pi_b_2_0_0.jpg

    And I only have a 32Gb SD card for it.

    SD cards are notourious for failing. I back the forum up to my HDD every week. But when it fails, we are going to lose a weeks worth of posts 😞

    Sorry but the forum isn't busy enough to warrant paying hosting company.



  • no probs I understand , I have a photobucket account any way so I just put them on there then put on here
    thanks



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