MairisLV Posted February 14, 2017 Share Posted February 14, 2017 Hello. Ive just registered here because I have just spent my knowledge. 3years ago I bought Sachs Roadster 125 bike, with Yamaha XV125 engine. I imported it from Germany. Bike worked smooth and without problems. After first few months of use, which were last moths of summer, I started basic maintenance. Air filter, oil filter, oil, ignition plugs. Then I discovered, that rubber tube from carb to air filter box was completely broken, like in half. But, I thought - nothing to worry, theres winter ahead, i have time. Throughout winter Ive changed oil, filter, repainted bike, ultrasonic cleaned carb... but couldnt find that rubber tube. Then I bought universal "sports" air filter and started to experiment. And voila - I put over the filter foam sock and the bike started to run smoothly again. But then I didnt pass technical inspection because of my shock absorbers, and the bike remained untouched for about 1,5 years. Last summer I found a shop in Germany, where i could find many of much needed parts. I bought a new air filter box with the rubber tube included, new original air filters, new carb intake manifold, shock absorbers and more... When I returned home, I immediately fitted bike with all new parts. And YES! It runned perfect. I even passed technical inspection without problems and got pass for 2 years. Bike started, runned like a charm. I even got up to 65mph(110kph) speed. And then the nightmare started... At first it was nothing serious. Engine just started to start with bit difficulties. But with time it just got worse and worse. Now I can barely start it. RPMs are climbing very slowly, like if only one cyl worked. And then, very often, i hear pops coming from carb. When I try to ride, there is no power. I struggle to get 25-30mph(50kph). And very often the pops continues. Sometimes the power sudden comes back, but just for a short moment. Could someone please help me? Any info would be much appreciated. Thank you Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 14, 2017 Moderator Share Posted February 14, 2017 perhaps there is water in the carb bowl...is there a drain screw you can run some fuel out ...put petrol tap ono prime (PRI) if it has that position Link to comment Share on other sites More sharing options...
robbo 167 Posted February 15, 2017 Share Posted February 15, 2017 Sounds like it is dropping a cylinder,if it is intermittant I would start with spark check to see which cyl is the problem (pull a lead whilst running or use see through spark checker)then work backwards..check coil and lead for affected cylinder..maybe a compression check just to make sure..is there any noises? Link to comment Share on other sites More sharing options...
MairisLV Posted February 15, 2017 Author Share Posted February 15, 2017 Thank you, but Airhead I've checked and cleaned the carb again and again... Robbo176 I've checked both spark plugs with spark checker and they are fine. Coil and lead I didnt check, because I checked if there is spark by removing spark plug from cyl and put it to cyl side and cranked engine a bit. The spark popped every second time the piston was up. I tried to change leads places, and that didnt help either. About compression - how many bars should i get? Link to comment Share on other sites More sharing options...
robbo 167 Posted February 15, 2017 Share Posted February 15, 2017 Compression will vary from bike to bike with use ,age etc but the important thing is the two cylinders should be the same....that way they should run together happily. Checking the spark like that does not simulate ignition load...with engine running pull each lead in turn..at idle the engine should run on one cylinder and change noticably when you put cap back on...if you have twin exhaust you can also tell which cyl is working/not working by the pulse at the end of the pipe,put your hand over the end ..should feel the same. Have you checked the rubber inlet manifold between carb and engine for splits?...it will suck air and run badly if so.... Link to comment Share on other sites More sharing options...
MairisLV Posted February 16, 2017 Author Share Posted February 16, 2017 Thanks Robbo. Ok, I will measure the compression this weekend. I have twin exhausts, but the mufflers are joined together. Ok, I will try to check cylinders like that. The rubber inlet manifold is brand new. My old one was cracked and splitted. Link to comment Share on other sites More sharing options...
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