jimbotipler Posted December 27, 2014 Share Posted December 27, 2014 Hi. My first post here so please be gentle with me ;-) Bought a tw125 a few weeks back and I'm really pleased with it. However it's just started mucking about. If anyone could give me a couple of pointers I'd appreciate it. I'm suspecting a carburettor issue. Once started it runs great. Starter motor turns over fine. Good compression, there's a good spark and I can bump start quite easily. It doesn't idle correctly - either running too fast or too slow and thens stalls. Once it stalls, it turns over but will only fire after a long struggle! I have had the carburettor apart and the starter plunger was a bit stiff to get back in to the housing so I'm wondering if it's not seating correctly? I'm also wondering if the throttle is sticking open slightly? I've cleaned it out with carburettor cleaner but I don't have an airline to really blow it out properly. Is it worth persevering with the carb or possibly look at something else? Link to comment Share on other sites More sharing options...
blackhat250 Posted December 27, 2014 Share Posted December 27, 2014 Hi jim,,,a mate has the trailway 125" and I noticed its a pig to start when hot, Now going on moto x [4 strokes] they were the same. and they cured this by adding a Hot start" lever, this injects more fuel, As I believe when engine is hot the fuel evaporates as it entres the head, Now am not saying this is your problem, but if your idle is hunting- you may have a pilot jet or air leak, Now pop up to new members and say hello... ">http://http://s1110.photobucket.com/user/Blackhat750/media/20140910_172858.jpg.html'> Link to comment Share on other sites More sharing options...
jimbotipler Posted December 28, 2014 Author Share Posted December 28, 2014 Thanks mate. Sorry for breach of etiquette :-) should have introduced myself first of course. Have done so now and will enjoy participating. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted December 28, 2014 Moderator Share Posted December 28, 2014 Sounds fuel related. How fresh is the fuel? Have you cleaned out the petcock? Have you tried starting it with the fuel cap open (if the tank vent is blocked bikes can be hard to start)? How old is the air filter? Has the spark plug been changed? Have you tested how tight the HT lead cap is on the coil wire (they tend to be twist in's? Any cracks in the rubber parts between the carb and cylinder or carb and airbox? Link to comment Share on other sites More sharing options...
jimbotipler Posted December 28, 2014 Author Share Posted December 28, 2014 Thanks for the tips dirtydt. What's the petcock? Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted December 28, 2014 Moderator Share Posted December 28, 2014 Sorry, fuel tap. Bike tanks tend to run on gravity so all the bits of grime and stuff goes into the tap. Most have a mesh in them that acts like a filter. The basic rule of bike fault finding - unless you are sure what is wrong - is cheapest and easiest first. If nothing else it eliminates possibles and you know when you changed items. The tank vent being blocked is a classic hence trying to start it with the fuel cap off. Link to comment Share on other sites More sharing options...
jimbotipler Posted December 28, 2014 Author Share Posted December 28, 2014 Gotcha. Cheers 1 Link to comment Share on other sites More sharing options...
jimbotipler Posted December 29, 2014 Author Share Posted December 29, 2014 I'll try all those thanks. I'm going to give the carb another clean out and get it blown through. When I put it back together does anyone know if I should lube the choke plunger with anything? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted December 29, 2014 Moderator Share Posted December 29, 2014 I'll try all those thanks. I'm going to give the carb another clean out and get it blown through. When I put it back together does anyone know if I should lube the choke plunger with anything? a bit of thin oil wont do any harm but it's not really essential jimbo Link to comment Share on other sites More sharing options...
jimbotipler Posted December 29, 2014 Author Share Posted December 29, 2014 Thanks mate Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted December 29, 2014 Moderator Share Posted December 29, 2014 Whereabouts are you located Jim? Link to comment Share on other sites More sharing options...
jimbotipler Posted December 29, 2014 Author Share Posted December 29, 2014 Near Hailsham, East sussex Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted December 29, 2014 Moderator Share Posted December 29, 2014 Near Hailsham, East sussex Ahh. A little too far to pop 'round and use my ultrasonic cleaner on your carb. Link to comment Share on other sites More sharing options...
jimbotipler Posted December 29, 2014 Author Share Posted December 29, 2014 That's a really kind offer anyway. Cheers mate. Actually, just blown it out, lubed the choke plunger and its starting like a dream. I'm suspecting that was the problem. Thanks everyone for the help and advice to 50 year old novice! Haha. 1 Link to comment Share on other sites More sharing options...
jimbotipler Posted January 4, 2015 Author Share Posted January 4, 2015 Bugger. Looks like I'm back at square one. Went out for a long ride yesterday. Stopped a couple of times and had trouble restarting. This is beyond my meagre skills now. I've had the carb apart so many times. Blown it through, rechecked spark and compression (as much as I can without a compression tester). Cleaned the petcock through and filters, I'm gonna have to surrender it to a local bike man to see if he can get to the bottom of it. Really frustrating cos once started it runs like a dream. You can only do so much as a novice:-( Link to comment Share on other sites More sharing options...
blackhat250 Posted January 4, 2015 Share Posted January 4, 2015 Aye jim, if it intermittent fault, its hard to find, ,,its inlimination process , coil could be breaking up when hot,, av see brillo pads in fuel tanks, that swish about , causing intermittent faults , Link to comment Share on other sites More sharing options...
jimbotipler Posted January 11, 2015 Author Share Posted January 11, 2015 I'm wondering now if it's possibly something more fundamental. In fact I'm wondering if it's a couple of issues. Poss inlet valve prob and battery. When I get it running (quite easy to bump it), it's backfiring every once in a while Here's what I've checked: Carb (cleaned thoroughly by me and a local mechanic), reset carb to spec, carb join to the cylinder, air filter, spark, cut end off ht lead, plug gap, valve clearance, timing and a load of other bits and pieces. I've got a new battery on charge which I suspect may aid starting but not tick over. Can anyone suggest what I try next? I'm quite up for dropping the engine if necessary. Link to comment Share on other sites More sharing options...
jimbotipler Posted January 11, 2015 Author Share Posted January 11, 2015 I've only tested by compression by sticking my finger over the plug hole but I'm guessing a proper compression year would be the thing? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 11, 2015 Moderator Share Posted January 11, 2015 is the exhaust to cylinder head joint and exhaust to silencer joint nice and tight and not leaking? Link to comment Share on other sites More sharing options...
jimbotipler Posted January 11, 2015 Author Share Posted January 11, 2015 Yep, with new seals not so long ago. Link to comment Share on other sites More sharing options...
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