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I have a 1990 Honda NS125R that has been playing up since I got the ignition system replaced. It kept dying on me and it would only restart with full choke even when hot. I have adjusted the carb and it ticks over when hot and still starts ok when cold but won’t restart hot with or without the choke if I leave it for more than a few seconds (eg. getting petrol). Any ideas?
PS. I also have a 1992 Yamaha TZR125 that keeps melting the left main bearing.It seems a little obvious but i assume that you have had the timing checked since you replaced the ignition. Do they run points? – if so check gap and check plug gap.
You also want to check for any leaks between the carb and the cylinder head and the carb and the airbox – purchase new seals if necessary and fit new jubilee clips, they have a habit of stretching and you’ll find that eventually you’ll run out of thread but they’re still not airtight. Dont know if they have rubber inlet manifolds between the carb and the head, but again check these for splits and leaks. Splits can be repaired with silicone rubber and then wrapped in duck tape.
If this dont work, check exhaust for leaks and if all that fails maybe try a new set of reed valves…
As for the bearing, you may find that there are some metal or rubber seals fitted to the side or sides of the inner and outer races, depending on where you get them from. If so, you need to prise out at least the inner seal with a small screwdriver to allow some lubrication.
Check oil pump is set correctly – dont know for sure how it is set on that model, but there is usually a notch on the carb slide that you line up with a notch on the oil pump – if you cant do it just bung some oil in with your petrol and see if it lasts any longer – if so you need the pump setting to feed more oil.
If not and you cant solve the problem, get the size and go to your local bearing supplier – they’ll be in the phone book. they will supply you with the exact same bearings for probably a quarter or less of dealer prices – wont solve the problem but it will be a little more bearable.
GSX750 Ratfighter / SR125 Rat / GSX600F / Beamish250 / Honda70 Rat / Honda250 Rat Racer
Blackboard paint – Covers a multitude of sins!
Thanks. I checked the plug when i put it in but I’m afraid I foolishly assumed that the mechanic who changed the ignition checked the timing but I will find out for sure and then try all the other things you suggested. Didn’t know that about the seals on the bearings. Why would they do that?
Seals are there as when the bearings are supplied the manufacturers pack them with grease and then seal them. They also produce them without, but it may be that you’ve bought or been suppplied sealed ones – worth checking. Fine for some applications, rollers etc. but if they are fitted to a bike, the grease melts and runs out the bottom and then bearing gets no oil lube coz of seal – result one knacked bearing and another rebuild.
GSX750 Ratfighter / SR125 Rat / GSX600F / Beamish250 / Honda70 Rat / Honda250 Rat Racer
Blackboard paint – Covers a multitude of sins!
The bearings I have were supplied by Yamaha. I would hope they would have the sense not to seal them or at least put some kind of warning on them but I’ll check that before I rebuild just in case.
Were the bearings from yamaha direct or from a dealer? – they may have just purchased a load from a local supplier. either way, its worth checking. Another thing whilst i think of it, your local bearing supplier will be able supply common sizes in stainless steel, normally used on food machinery – may be worth checking if you can get them as they should last a bit longer as they have higher heat tolerance and greater strength – although they do need constant lubrication.
GSX750 Ratfighter / SR125 Rat / GSX600F / Beamish250 / Honda70 Rat / Honda250 Rat Racer
Blackboard paint – Covers a multitude of sins!
The bearings were from a dealer. I’m staring to think I’m far too trusting and naive. I should know better at my age.
The ignition system was replaced because the bike wouldn’t start and there was no spark. The ignition barrel, CDI unit, HT lead and the whole generator were replaced. The mechanic said the wiring was all burnt out. I had only had the bike a few weeks. I tested all that stuff before and the only fault I found was in the CDI unit. It wasn’t expensive though so I won’t complain too much.
I’m afraid I have no idea what a plug chop is.
God, I sound so green.One of our members gave a good explanation of what a plug chop is here
The post also highlights what problems poorly set up carbs can give, worth a read.Thanks. I feel a little bit less green now. I’ll give that a go along with everything else at the weekend. I’ll let you know how it goes.
Plug chop is the definitive way to know what is going on with the fuel mixture. It’s worth a few minutes to whip those plugs out. Most Haynes manuals (car too) have a page showing what plug colours to expect for what fuel mixture problem.
Good thoughts on the bearings GSXHooligan. Didn’t think of the outer seal ever being a problem until you mentioned the grease coming out. Makes sense that you can’t get any more in!
I’ve donated to the forum, have you?I didn’t get time to do everything I intended at the weekend but I did some work on the NSR. I borrowed a strobe and checked the timing which turned out to be spot on. The plug chop showed a nice clean light brown insulator. Looked good to me.
The boot seal between the carb and the head is beyond repair though so you were spot on there hoolie.
I also did a full service (a la Haynes manual) which solved a few minor problems and showed up a completely shagged battery. I’m sure that wasn’t helping matters.
I’m getting a new battery today and looking for a new seal. Hopefully that will be problem solved.
Thanks guys.With a stroker, you want to try to make sure that the engine is under load before you do a chop. run it up a moderately steep hill if at all possible making sure that it’s pulling, dont slow down when you get to the top just yank in the clutch and kill the engine immediately otherwise the result will not be as accurate. The seal will be making it run weak so when you replace it you will have to set mixture up again (but i assume you know this!)
GSX750 Ratfighter / SR125 Rat / GSX600F / Beamish250 / Honda70 Rat / Honda250 Rat Racer
Blackboard paint – Covers a multitude of sins!
Hi guys, I still need help (and so does my bike).
I changed the dodgy seal and the bike ran a bit better but still not right. Then the cylinder head gasket went. I changed that last weekend. I’ve been off the road since because the bike spat petrol in my eye while I was disconnecting the petrol tank (it’s evil) and I’ve been off work with a patch on it all week. The bike seemed even better with the new gasket (changed the exhaust and reed valve gaskets as well seeing as I had them anyway) but there was a problem with the kickstart which was getting worse. Discovered badly worn gear and ratchet which I replaced. Once I got it back on the road it was very sluggish but the carb was adjusted to compensate for all the leaks before so I adjusted it back and it is running better now than ever. I’m still having a couple of minor problems that I thought would have improved after all that but they haven’t.
The bike keeps dying for a split second. It only happens over 55mph though and it’s only been happening since I put the bike in to have the ignition system changed.
Also, it’s still not ticking over properly although it is very close and I’m still having a little trouble starting it. (It used to tick over perfectly and start first kick every time)
Can anyone help?PS.
I discovered when I went to get the new cylinder head gasket that the engine in the bike is actually an NS125F not an NS125R as I thought.
I think the guy I bought it from saw me coming a mile off.
I’m going to do another plug chop this evening now that it’s back on the road and see if anything comes up.
I also have noticed that there is sometimes a loud hissing noise from the end of the exhaust when I try to start the bike. Don’t know if this might be related to the other problems.
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