Jamesyz250 Posted August 22, 2017 Share Posted August 22, 2017 Hows it going guys? Im new to yamaha club and i would appreciate any help i can get from you guys. I have a 1980 yamaha sr250 and the bike is driving me insane. The bike originaly belonged to my grandfather and he abandoned it. Once he abandoned it, my father took the bike off his hands. This was probably in the early 90's. I was just born haha. My father rode the bike here and there untill he ran into a problem with it. He would start the bike, and the bike would idle perfectly. But as soon as he touched the throttle, the bike would die. No biggie. My father told me he spent a year on an off trying to fix the bike until he finally gave up on it. Here i am now, 23 years old, and i love motorcycles more than anything in this world. My grandfather passed away and i figured it would be neat if i got his motorcycle running. The bike has not been running since 2001. The first thing i did was buy a new battery, drain the gas tank, and clean the carburetor with compressed air and some carb cleaner. To my suprise, the bike fired right up. I went to give it some throttle, and the bike died. Immediately, i knew what i was. The pilot jet was the culprit. So i pulled the carb off again and made sure that i did a thorough carb cleaning and diddnt miss anything. I fired the bike up, and the same thing happend. Long story short, i have literally cleaned this carburetor about 15-20 times. Every single jet, orfice, circut, diaphragm has been cleaned. Im really stumped on this. I thought maybe the diaphragm was bad, but its actually in great shape. So right away, i orderd a new pilot jet, a new float, a new needle valve, a petcock rebuild kit, and i also orderd a new (used) carburetor. Once the parts came, i rebuilt the petcock and i rebuilt the carburetor with the new parts that i bought. I did not buy a full rebuild kit. Only what i mentioned up above. I put the carb back on, fired the bike up, and had the same results. Now im thinking a little more like a mechanic. I want to take a look at the spark plug. I pulled the plug out and the plug was dry, white, and brand new. The bike also runs better with the choke on. This tells me the bike is running lean. I decided to take a look at that air filter to make sure that nothing made a home of it. I opened the air box up, and there was a mouse nest in my air box. There was no air filter to be found. I was absolutely certain that this was the problem. So i ordered a new air filter and waited. Long be hold, the new air filter diddnt fix the problem. Now im starting to get frustrated. I decided i would check my exaust pipe and make sure nothing made a home of that either. All is well. The next thing i decided to do was check my valve clearence. My valves seemed a little bit tight so i adjusted them to spec. I diddnt have a metric feeler guage, so i was skeptical if i was making the right measurments. After i adjusted the valves, i figured i would take my carburetor off, and try putting the new (used) carburetor on the bike with the new float, needle valve, and pilot jet. I started the bike up, and BAM. I could give the bike some gas. The throttle was responsive and everything seemed normal. I let go of the gas, and the bike stalled. So now the issue im having is the COMPLETE opposite of what it was. The bike WAS running lean and now its running rich. The bike used to idle but i could not give it gas. Now i can give it gas but the bike wont idle. The spark plug WAS dry and white. Now the spark plug is carbon fouled. I can even take the bike for a spin around the yard now but then it starts to back fire a little bit once it gets warmed up. The bike is also very hard to start all of a sudden. Could i have made my valves to tight? To loose? I am really at a loss with this bike. I know this short story is alot to read but i sincerly thank anyone who takes the time to help me! Link to comment Share on other sites More sharing options...
fras1 Posted August 22, 2017 Share Posted August 22, 2017 Check the ignition coil. The problem sounds electrical rather than fuel related. A duff coil will give you enough spark to start the engine,but not enough to keep up with higher revs.People often think the problems caused by duff coils are being caused by the carbs,and go off on the wrong footing. You have clearly sorted the carb,so don't waste any more time on it. only takes a few mins to check the resistances of the coil. Plenty of U- tube stuff out there to show you how. 1 Link to comment Share on other sites More sharing options...
Jamesyz250 Posted August 22, 2017 Author Share Posted August 22, 2017 Fras1, i appreciate the response. I will keep you updated! Link to comment Share on other sites More sharing options...
fras1 Posted August 22, 2017 Share Posted August 22, 2017 No problem, also I have noticed that your bike uses a contact breaker in the ignition circuit,- (us old guys used to call them points) -these are mechanically operated and wear out. You should check this too,I am willing to bet it's either a worn out contact breaker or a burnt out secondary winding in the coil, and the more I think about it,the more I think it's the contact breaker. If it's been the same contact breaker since the days of your grandpaw I'll be surprised if it's still functioning properly. But check the coil as well as the contact breaker.(Which I think you will find will be horribly pitted). Plenty on U tube about contact breakers too. best of luck 1 Link to comment Share on other sites More sharing options...
Jamesyz250 Posted August 23, 2017 Author Share Posted August 23, 2017 Thank you for all of this information! I never would have thought of any of this. I diddnt have any time today after work but i will definitely be checking this as soon as i get the chance. I will keep you posted! Link to comment Share on other sites More sharing options...
fras1 Posted August 23, 2017 Share Posted August 23, 2017 The points (or contact breakers) on bikes and cars of this age were designed to be removed easily and quickly as part of routine maintenance. So the contact breaker for your bike will be routine to remove. (They were the fore-runners of CDI units) They were also designed to be easy to set to the correct gap, there will be something on the net I'm sure which will give you the correct gap and how to adjust it for your bike. The contact breaker might only need its faces sanding down and the gap re-set in order for the engine to run. --- You might be able to fix this whole thing with just some sand paper. Lots for you to learn on U-tube.......... let us know how you get on with this, I'm sure other guys on here will also be able to give further advice ... Link to comment Share on other sites More sharing options...
Moderator Cynic Posted August 23, 2017 Moderator Share Posted August 23, 2017 3 hours ago, fras1 said: The points (or contact breakers) on bikes and cars of this age were designed to be removed easily and quickly as part of routine maintenance. So the contact breaker for your bike will be routine to remove. Quick and easy to remove and adjust. Hmmm. Agree to differ there. Link to comment Share on other sites More sharing options...
slice Posted August 23, 2017 Share Posted August 23, 2017 Have to agree with Cynic here points were never easy to remove and setup they are and always will be right bastards..! That's why the Japanese went for CDI units as soon as they could cos then the bike starts first time every time. Get your self a new set of points and don't even bother fiddling with the old ones, get the manual for you bike as well, all the info for point setup are in there and easy to follow. Good on you for persevering in getting your Grandad's bike up and running, he will have a grin on his face watching you shout at his old bike then riding it. Link to comment Share on other sites More sharing options...
fras1 Posted August 23, 2017 Share Posted August 23, 2017 Fair enough,guys,I have to confess I'm not familiar with this particular bike,I was equating removing the points from most older style cars, which was quite easy - I once had a knackerd old Ford Escort van which had 'em and they came out no bother, -could sand them down to get rid of the pitting and put them back in,all in quite a short time. This not the start of a thread on knackered old vans...... 1 Link to comment Share on other sites More sharing options...
Moderator Cynic Posted August 24, 2017 Moderator Share Posted August 24, 2017 Had a mk2 and a mk 3 myself as well as metro's fiesta's. All the points were easy. The A series even more so with a keyed dissy drive. You could do it on the bench. My dt's on the other hand. Setting and adjusting through a gap you can only fit 2 fingers into and stripping off the sidecase, gear lever and then pulling the flywheel off. (Easy now with hub centre pullers) to change them, not to mention the condenser. The bigger villan if you ask me. I used to move them so they were fitted in pairs outside of the generator so if (ha ha) when it failed it was easy to change. 1 Link to comment Share on other sites More sharing options...
fras1 Posted September 17, 2017 Share Posted September 17, 2017 H i Cynic & Slice et al, (and James of course) I am back after a short absence including a rain- sodden bike rally in my native Scotland. I hope my (beer-influenced) entry on removing points hasn't influenced young James 's attempts to fix his bike. There really was quite a difference between the engineering of Brit cars & Jap bikes in the 70's - I should have taken account of that. (J.I.S screwdrivers ,anyone?) But---- --James _ was it the contact breaker ? Have you got the bike running? Do keep everyone up to date, I'd like to know if/how you have fixed it ,I'm sure everyone else here would like to know too. Link to comment Share on other sites More sharing options...
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