NS125F Not Starting

[JonnyFoxtrot]

Right so long story short, i decided to get into biking a few months back. Had next to no money to spend and only a trickle coming in so decided to bite the bullet and bought a non-running Honda NS125F. Previous owner had heat seized the old barrell and piston so bike needed a new top end. As well as that the bike had an array of bolts, pipes and male and female adapters missing or that needed replacing and a lot of rust and wear/tear (though im less concerned about asthetics and more about getting it running)

Couple of weeks ago i got a new top end so new barrell, piston and rings, gaskets etc (they were off a bike that had only just had them new so not technically new but run in for around 500 miles which can only be good) and the top end got rebuilt with the new parts.

Finished up putting everything back together tonight to do a first start up after taking most of the bike apart to re-oil/grease and check things like thermostat, carb, exhaust etc and give it a general clean up.

Annnnddddd....no start at all (not that i really expected a first time start up).

Just keeps turning over when kickstarting. Checked spark plug with a spark plug light thing that goes inbetween and lights up (no idea what its called sorry) and theres definitely a spark. Spark plug was wet with petrol/oil when we pulled it out to check so theres definitely petrol getting in there. Any ideas? I really dont want to have to end up taking it to a shop to check as it was all meant to be done on the cheap just so i could past my test, hence the getting a non starter and doing it up (which i have quite enjoyed actually!). Was thinking maybe something wrong with the carb or mixture? The con rod was always quite wet with oil in the crank when i had the top end off and was turning the flywheel to check bearings etc so could it possibly be too flooded with oil at the bottom? Should we maybe try pure petrol to do the start up rather than pretrol/oil combined? (the oil tank is not connected at the moment so just putting oil straight into the petrol) Just doesnt seem to want to catch the spark (although its strong) or ignite? :/

Thanks in advance and any help and advice welcome!!!

[simk2]

I am currently working on re-building my 1990 NS125R unfortunately there are a number of things that could be wrong, i take it you have tried a new spark plug, checked your fuel mixture, have you checked the carb jets are clear?

also do you know the reason the new (run in) barrell and piston were removed from the other bike?
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I Really Need Parts For My Bike

[Kickstart]

Hi

It is easy enough to flood a 2 stroke. Take the plug out and give it a good clean (blow torch). Also check that the carb is not overflowing (ie, worn needle valve, think the PHBH carb in the NS has a viton rubber tip which might have been damaged).

While there are numerous things that could stop it running (eg, sheared woodruff key allowing the ignition timing to slip, worn / non sealing reed valves, etc) I would be tempted to try bump starting it, or better get a couple of willing volunteers to push you on it to try and start it.

All the best

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

[JonnyFoxtrot]

[JonnyFoxtrot]

[JonnyFoxtrot]

Update as of 1:06 13th April 09:

Bump start did not work, tried a couple of times. Once full throttle, once without. Sounded like it was so close but just could not catch the spark.

Took spark plug off and it was very wet with fuel and when i turned the flywheel with plug out i thought i could hear a lot of "sloshing" so i'm guessing the engine is being flooded. Dried off spark plug with a lighter and tried again but still nothing. Any ideas? What is usually the cause of and a solution to the engine/carb being flooded?

Thanks in advance guys

[G]

I'd try more than a couple of times. Took about ten to fifteen to start my CRM125 when it hadn't bee used for a while. After running for a bit it started first kick fine a week later.
Marjay's Gas Gas we actually had to tow-start and tried that quite a few times before it got going. However, again, once we'd had it going for a bit it was fine and started nicely off the kickstarter for the rest of the time he owned it.

If it's flooded, bumpstart it a load of times with no throttle and no choke.
Then move back to trying choke/a bit of throttle. Some bikes need throttle when starting, others don't. All the 2 strokes I've used recently need a bit to a lot of throttle (mostly off road bikes though) while 4 strokes tend to better without.

[stirlinggaz]

hi,
this is kick start only, right?
i'd agree with the above keep trying!
but i'd remove the spark plug again.
& if the bike is kept indoors, i'd leave the spark plug out overnight, with a teaspoon of 2t down there.
then following day, give it a few kicks before puting a new spark plug in.
this always worked for me on my ns125r( tc01)
make sure the battery is fully charged.
check the floats are working ok, while your there might as well give the carb a clean & blow through with air-line.
test for a spark.
put it all back together,& open the drain screw at the bottom of the carb.
when petrol starts pissing out, close it.
the carbs full of petrol, so if you've got compression & a spark so it should start.
leave the air filter off for the time being.
then give it a few kicks,with choke on & throttle closed.
it WILL start, lol
cheers,
GAZ

[c-m]

This has only just been put back together - I know the barrel and pistons are new but have you tired a compression test? can't remember off the top of my head the correct figures but something like 105-130psi