Speedy2415 Posted November 13, 2011 Share Posted November 13, 2011 Hi all, names Adam I own a wee SR 125 thats giving me some major headaches right about now. Owned her since last november, she died February this year and only got the cash and time to rebuild about 2 months ago. Cylinder has been rebored, new piston installed, other sundries etc; My problem now is, the bike has died again. Was riding home from work about a month ago, just come off a 2 mile stretch of road where I had the bike cruising at around 50mph (should also add at this point she was only 250 miles into being run in again after rebore) when the bike lost power, wound down gracefully and died. Thought hmm, thats odd, maybe I had run into reserve, so duly switched into reserve, went to start the bike... Nothing happened. Anyhoo, after fruitless attempts at starting and bumpstarting, I pushed it home. The bike was running absolutely perfectly prior to this, in fact passed its MOT with flying colours the week previously. I've spent the last month or so attempting to get her started with no success whatsoever. Battery has been charged twice now (I ran it down starting), valve clearances checked, air filter checked, carb stripped down, cleaned and checked, starter relay checked (this was why the bike died in February), spark plug checked, CDI from a running bike installed and checked, anything else I can think of as well. I know fuel is getting to the cylinder as the exhaust will pop after a time, and there appears to be a good spark. I am completely baffled as to why my bike will not run! Even the the man in the shop I took it to was confused as to why it won't start, as he checked it as well. Any ideas or help would be massively appreciated, as i'm getting to the point where i'm gonna take a bloody big hammer to it... Regards, Adam Link to comment Share on other sites More sharing options...
Moderator Airhead Posted November 13, 2011 Moderator Share Posted November 13, 2011 is the plug getting wet, have you tested the compression? please see my signature line Link to comment Share on other sites More sharing options...
mojothejester Posted November 13, 2011 Share Posted November 13, 2011 Are the piston rings installed right? When mine died last month, the ring ends weren't in the position they're supposed to be, they were directly above the one underneath, so the seal wasn't effective, and the bike just wouldn't start or bump start. I put new piston and rings in and new gaskets and it works again now, even though it still doesn't run on full power... Link to comment Share on other sites More sharing options...
Speedy2415 Posted November 14, 2011 Author Share Posted November 14, 2011 Hey, Sorry for not posting in the new members forum, my bad. Will be duly updated as soon as. The plug is indeed getting wet, and compression wise, the ole' thumb over the spark plug opening and kick it over trick seems to show that there is. The piston rings were installed correctly, me and the old man triple checked we did this right before the piston was installed back into the bike. I have yet to take the head off of the bike, and im rather reluctant to to be honest, due to being chronically skint . Regards, Adam Link to comment Share on other sites More sharing options...
Moderator Airhead Posted November 14, 2011 Moderator Share Posted November 14, 2011 even though its sparking buy a few more new plugs and try them Link to comment Share on other sites More sharing options...
Speedy2415 Posted November 14, 2011 Author Share Posted November 14, 2011 I'll give that a try, gotta recharge the battery again now though. Thanks Link to comment Share on other sites More sharing options...
Speedy2415 Posted November 21, 2011 Author Share Posted November 21, 2011 Ok folks, update time. Charged the battery, put a new spark plug in, checked everything over again... nothing. Still refuses to start. This bike has now had a new battery, spark plug, HT lead, and every swear word ever invented thrown at it. I am at a total loss as to why it wont start! Its got everything it needs to, good spark, air and fuel. The plug is definetly getting wet. Any ideas? Regards, Adam Link to comment Share on other sites More sharing options...
Moderator Airhead Posted November 21, 2011 Moderator Share Posted November 21, 2011 you should do a compression test Adam Link to comment Share on other sites More sharing options...
Speedy2415 Posted November 21, 2011 Author Share Posted November 21, 2011 Ill see if i can get one done tommorow. Gonna take it to a place I know not far from me, hopefully they can shed some light on it. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted November 22, 2011 Moderator Share Posted November 22, 2011 have you rechecked the timing? don't forget its on compression when the spark fires. Not out by 360' ? do the same with valves too Link to comment Share on other sites More sharing options...
Speedy2415 Posted November 28, 2011 Author Share Posted November 28, 2011 Hi guys/gals Quick update, the bloke who's looking at it right now said the compression is a bit low and he suspects a blocked jet? He said he's only done a basic checkover of the bike so far, but lack of cash has forced me to curtail his efforts any further, and ive now had to get a SORN for the bike. Gettin rather annoyed at the lack of life in my bike! Me and my old man have checked the valves 3 times now, he said the ignition timing was fine, although I suspect I shall also get this checked when I have some cash again. Link to comment Share on other sites More sharing options...
Speedy2415 Posted December 5, 2011 Author Share Posted December 5, 2011 Ah, bad times. Just got my bike back, the guy showed me the compression tester after he used it.... 50 psi was 75 psi the other day according to him! Possibly the tappets are too tight? That and the small jet was in fact blocked (shows how much I looked then....). Needless to say, im now screwed for a bike over christmas, seriously considering buying a new engine.... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted December 5, 2011 Moderator Share Posted December 5, 2011 if its only the valve adjustment why cant you re-set them or have your mechanic do so? its no use looking at new engines just yet! Link to comment Share on other sites More sharing options...
Geoclinton Posted December 5, 2011 Share Posted December 5, 2011 All isnt lost try the valve settings first Even if you do have to take the head of it can be done I new very little about bikes only a couple of months ago now I can strip mine and put it back together with knowledge. My advice is find somewhere warm ish to work on her and chip away dont give up there isnt much too them so in theory there isnt much to fix comparative to cars and vans Geo Link to comment Share on other sites More sharing options...
Speedy2415 Posted December 11, 2011 Author Share Posted December 11, 2011 Update time! Me and the old man decided to take the head off the engine yesterday, see what could be wrong... Well, certainly found something! Turns out the exhaust valve is in poor condition, a small chunk is missing from it. Could be the cause of low compression? Everything else checks out on the bike, all the electrics etc. Havent looked at the piston itself yet, may do that as well when I can get a new gasket set. Just relieved that we've finally found something after all the head scratching! Regards, Adam Link to comment Share on other sites More sharing options...
Moderator Airhead Posted December 11, 2011 Moderator Share Posted December 11, 2011 yes Adam get a new valve bought Link to comment Share on other sites More sharing options...
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