mojothejester Posted October 14, 2011 Share Posted October 14, 2011 was riding home at the maximum my bike can usually mangae, 50mph, on A roads from preston, the bike suddenly lost power, stayed at 40mph for about 5 minutes then just lost power and died. coasted to a stop. the cylinder head was smoking a bit... spent about 5-10 minutes trying to start it, check fuel, bump start it, etc... it started on a bump start, then managed another few miles then died again when i got on the B roads (slowed to 30mph this time, no matter what gear)... i had to push it until a guy (called Paul on an '09 R1) came to my assistance and took me pillion home. picked the bike up today, checked the spark (against cylinder head, it sparked), checked fuel, topped up oil (throught the glass, couldn't see any, even though i put a litre in 4 days ago), and took the carb apart (never done so before, but there was no deposits in it or slimy fuel) and reassembled, but still won't start. the piston is turning, the valves are moving, fuel is going in, don't understand what it could be... could the head gasket have anything to do with it? there is a slow oil leak from the sump (rounded off nut on it, so a bit difficult for me to replace at the minute) and someone in work told me the head gasket may have a slight leak. i need this bike to get to work and have no other means of transport or much money to fix any problems until pay day on the 28th (which may not be much if i can't get to work) David, Skelmersdale, Lancashire Link to comment Share on other sites More sharing options...
mojothejester Posted October 16, 2011 Author Share Posted October 16, 2011 does anyone know if it could be a blown gasket that won't make my bike start? everything else seems ok, but a mate said that's what it could be... Link to comment Share on other sites More sharing options...
2 Wheels Posted October 16, 2011 Share Posted October 16, 2011 does anyone know if it could be a blown gasket that won't make my bike start? everything else seems ok, but a mate said that's what it could be... Get a compression tester,,,,,put it in the plug hole,,,,,hold the throttle on full,,,,,,push the start button for a rew seconds. Wat does the reading say in PSI. Yes if the head gasket is leaking it can make the bike hard to start. Link to comment Share on other sites More sharing options...
mojothejester Posted October 17, 2011 Author Share Posted October 17, 2011 Cheers :-) I'll get a compression tester over next couple of days, what psi am I looking for with normal working engine? Any help is much appreciated, going to borrow Haynes manual too... Dave Link to comment Share on other sites More sharing options...
mojothejester Posted November 7, 2011 Author Share Posted November 7, 2011 Quick update... I replaced gaskets, fitted new piston and new rings (even though I snapped my first set so had to order another piston kit) and bought a battery charger, now the bike runs :-) I did fit a bigger front sprocket (16 teeth) but at the moment it still tops out at 50ish with an occasional surge of power on a steady throttle. Mysterious. I did fiddle with the screws on the Carb when the engine was in pieces, so hopefully a bit more fiddling will get it running good again :-) Link to comment Share on other sites More sharing options...
Moderator Airhead Posted November 7, 2011 Moderator Share Posted November 7, 2011 Quick update... I replaced gaskets, fitted new piston and new rings (even though I snapped my first set so had to order another piston kit) and bought a battery charger, now the bike runs :-) I did fit a bigger front sprocket (16 teeth) but at the moment it still tops out at 50ish with an occasional surge of power on a steady throttle. Mysterious. I did fiddle with the screws on the Carb when the engine was in pieces, so hopefully a bit more fiddling will get it running good again :-) interesting so there more to be had somewhere when does it do this?...any clues, like running on to reserve Link to comment Share on other sites More sharing options...
Ratty-matty Posted November 7, 2011 Share Posted November 7, 2011 I had a little sr125 trick for speed is simple ! Loose some weight , rear foot pegs , change the exhaust etc etc , also try changing the rear can & rejet the carb that's what I done and was getting 65 70 at a real push also make sure you don't short shift Link to comment Share on other sites More sharing options...
mojothejester Posted November 8, 2011 Author Share Posted November 8, 2011 It does it at random times, but I have noticed if I hold onto the revs in 1st, 2nd and 3rd, it does run quicker... I do short shift a lot though, since putting the new rings in i don't want to rev too much for a while. I've gone about 90 miles since fitting them, not sure how long they need to be ran in for... Its already got no rear footpegs, original exhaust, and I weigh 10.5 stone. Don't know how to rejet carbs, was looking at alternative ones on eBay last night though. Will any Carb work since there's no connection to Electrics the bike wouldn't know the difference... Was also thinking of part exxing for a ybr instead, now that it's running... Link to comment Share on other sites More sharing options...
mojothejester Posted November 8, 2011 Author Share Posted November 8, 2011 Oh yeah, with the bigger sprocket on, it'll go to 20 in 1st, but with the surge of power it sometimes gets it'll go to 30 before I changed gear as the bike screams it's lungs out. I may try new exhaust, but websites don't generally list the sr125 as a compatible model. I'll keep looking and tinkering with the screws on the Carb :-) I did just see a picture of someone's sr125 with a pit bike exhaust on it, on the pit bike forum. how would i go about fitting an end can to the downpipes that are on a stock sr125, with the stock silencer welded to the pipes? Link to comment Share on other sites More sharing options...
KirriePete Posted November 9, 2011 Share Posted November 9, 2011 I did just see a picture of someone's sr125 with a pit bike exhaust on it, on the pit bike forum. how would i go about fitting an end can to the downpipes that are on a stock sr125, with the stock silencer welded to the pipes? *Cough!* Hacksaw *Cough!*, then get a 'silencer' with an internal diameter that matches the outside diameter of your stub. I've had some .... errrr .... 'interesting' results with tailpipes from Feked - Clicky Link - the old GN400 Suzuki was "quite fruity" (words of Mr MOT man) with one of their Universal Cone jobbies on it. As for rejetting - any old carb won't do, there are different bore sizes as well as a multitude of jet options, and randomly fiddling with the screws is always going to end in frustration, reset everything to factory standard and then move on from there. If you can afford it, a session on a decent dyno will reap rewards, as they can see exactly how it's being fuelled throughout the rev range and advise on any changes, maybe even rejet for you while you wait, with another run on the dyno to show improvements. Definitely a black art if you ask me.... Link to comment Share on other sites More sharing options...
tiko Posted November 9, 2011 Share Posted November 9, 2011 i had the same issue on my old sr125, would struggle starting when it would start there would be hardly any power i had a spark and everything although this was the problem, it was creating a spark but it wasnt good enough turned out the spark plug was buggered so i changed it and solved the problem, it may be a long shot reading what you have done also with the carb there is a guy in victoria station in manchester who repairs them http://www.nrp-carbs.co.uk/index.htm Link to comment Share on other sites More sharing options...
mojothejester Posted November 9, 2011 Author Share Posted November 9, 2011 :-) i've added fedek to my favourites, once kids have christmas presents i'll try get an exhaust. I like the slash cut one, but no baffle :-( and NRP carbs is also saved, i'll try make a visit there soon... i knew forums must have some uses, thank you everyone Link to comment Share on other sites More sharing options...
tiko Posted November 9, 2011 Share Posted November 9, 2011 :-) i've added fedek to my favourites, once kids have christmas presents i'll try get an exhaust. I like the slash cut one, but no baffle :-( and NRP carbs is also saved, i'll try make a visit there soon... i knew forums must have some uses, thank you everyone i have used nrp for my old suzuki marauder and he did a fantastic job is very helpful and i will be using him again to service the ones for my xs Link to comment Share on other sites More sharing options...
mojothejester Posted November 11, 2011 Author Share Posted November 11, 2011 one last quick thing (for a while), the previous owner has drilled the airbox cover so it has two 2" holes in it, one on the side and one facing the front. will that affect the power surges i keep having? was thinking of putting k&n cone air filter on and taking the airbox out... and i've got a blue electrical connector hanging loose which, according to the manual, should be connected to the thermostatic switch, but the themostatic switch is missing. can't find one on ebay either. all problems aside, i love riding my bike and can't wait to pass my test and upgrade to a better bike and take the missus out :-) Link to comment Share on other sites More sharing options...
Recommended Posts