KimB Posted January 15, 2014 Share Posted January 15, 2014 Hi everyone, I bought a YBR as a non runner, I had to do a top end rebuild on it, everything seemed fine and went well. It does start but only with easy start ? When it does start the revs seem to sit quite high ? Any ideas what it may be ? I have adjusted the valves as well so it isnt that. Any thoughts would be great to hear. Thanks Kim Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted January 15, 2014 Moderator Share Posted January 15, 2014 You really need to say a hello in the New Members Section as most people don't reply to first post question. Did you set the timing chain correctly? Link to comment Share on other sites More sharing options...
KimB Posted January 15, 2014 Author Share Posted January 15, 2014 You really need to say a hello in the New Members Section as most people don't reply to first post question. Did you set the timing chain correctly? Oh really, I didn't know Sorry. Yes I did. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted January 15, 2014 Moderator Share Posted January 15, 2014 I bought a YBR as a non runner - this means that there could be multiple issues with it not running and makes diagnosing things a little more difficult. I had to do a top end rebuild on it, everything seemed fine and went well. - Did it run after the rebuild? Why was the rebuild necessary? Did whoever did the bebuild do a proper job and got all of the settings correct? It does start but only with easy start - This is really a positive, It may rule out major electrical issues however, minor ones may still lurking When it does start the revs seem to sit quite high - Carb or injection? Did the re-builder check the bore and piston rings? The starting may be helped by taking out the plug, while the plug is out, check what kind of spark you are getting, Pour a spoonful of engine oil down the bore and get the piston moved up and down a couple of times - in gear and rock the bike does it. Leave the plug out overnight. tomorrow fit a NEW plug and try again. The bore could be washed out with fuel and there is not enough compression for the bike to start. It takes a faulty plug out of the equation. Don't forget to say hi. Link to comment Share on other sites More sharing options...
KimB Posted January 15, 2014 Author Share Posted January 15, 2014 I bought a YBR as a non runner - this means that there could be multiple issues with it not running and makes diagnosing things a little more difficult. I had to do a top end rebuild on it, everything seemed fine and went well. - Did it run after the rebuild? Why was the rebuild necessary? Did whoever did the bebuild do a proper job and got all of the settings correct? It does start but only with easy start - This is really a positive, It may rule out major electrical issues however, minor ones may still lurking When it does start the revs seem to sit quite high - Carb or injection? Did the re-builder check the bore and piston rings? The starting may be helped by taking out the plug, while the plug is out, check what kind of spark you are getting, Pour a spoonful of engine oil down the bore and get the piston moved up and down a couple of times - in gear and rock the bike does it. Leave the plug out overnight. tomorrow fit a NEW plug and try again. The bore could be washed out with fuel and there is not enough compression for the bike to start. It takes a faulty plug out of the equation. Don't forget to say hi. Thanks for the detailed reply. Hi yes I put everythig back how it was, The previous owner tried to do a rebuild but bodged it and used silicone instead of replacing the gaskets . So put all new top end gaskets on. I forgot to add its a 2005 so carbed model with 8000 miles I didnt check the piston or ring gap, wish i did do it now ! The spark wasn't too bad. But i will remind myself late/tomoro. Sorry if im being silly but i didn't understand these two bits of what you said : in gear and rock the bike does it. The bore could be washed out with fuel and there is not enough compression for the bike to start. It takes a faulty plug out of the equation. Thanks again Kim Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 15, 2014 Moderator Share Posted January 15, 2014 what dirtydt means here is compression is aided by a film of oil in the bore and around the piston / rings. Repeated attempts to start can mean that the petrol washes this oil away and to some degree the 'seal' needed to aid compression is lost so compression is reduced. Try squirting a little engine oil down the spark plug hole to improve the seal and maximise compression. Attemp to start with choke and little or no throttle Link to comment Share on other sites More sharing options...
KimB Posted January 15, 2014 Author Share Posted January 15, 2014 what dirtydt means here is compression is aided by a film of oil in the bore and around the piston / rings. Repeated attempts to start can mean that the petrol washes this oil away and to some degree the 'seal' needed to aid compression is lost so compression is reduced. Try squirting a little engine oil down the spark plug hole to improve the seal and maximise compression. Attemp to start with choke and little or no throttle Uhh, Thanks for explaining that. Will give it a go tomorow thanks for your help Link to comment Share on other sites More sharing options...
dt502001 Posted January 15, 2014 Share Posted January 15, 2014 Not sure if this help or not but I have seen many people put the slide for the carb in backwards= bike wont start or if it does it revs realy high. If the bike starts and runs then it kinda narrows it down to a carb issue. O hi and welcome Link to comment Share on other sites More sharing options...
KimB Posted January 16, 2014 Author Share Posted January 16, 2014 Not sure if this help or not but I have seen many people put the slide for the carb in backwards= bike wont start or if it does it revs realy high. If the bike starts and runs then it kinda narrows it down to a carb issue. O hi and welcome Hi thanks for the input, The bike does tick over low but idles high and goes low, I know i wouldnt have put it in backwards as that was something i was always taught Thanks Kim Link to comment Share on other sites More sharing options...
dt502001 Posted January 16, 2014 Share Posted January 16, 2014 Hi thanks for the input, The bike does tick over low but idles high and goes low, I know i wouldnt have put it in backwards as that was something i was always taught Thanks Kim So it "hunts for idle" high then low? .I say spray some wd 40 at the intake and check for air leaks Link to comment Share on other sites More sharing options...
KimB Posted January 16, 2014 Author Share Posted January 16, 2014 So it "hunts for idle" high then low? .I say spray some wd 40 at the intake and check for air leaks Good idea ! I will have a look Thanks Link to comment Share on other sites More sharing options...
ybrric Posted January 16, 2014 Share Posted January 16, 2014 non runner = standing for long time = blocked pilot jet (more often than not) Link to comment Share on other sites More sharing options...
KimB Posted January 16, 2014 Author Share Posted January 16, 2014 non runner = standing for long time = blocked pilot jet (more often than not) Unfortunatly not, Checked twice. Thanks Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted January 16, 2014 Moderator Share Posted January 16, 2014 So you have some advice, let us know what you have tried, and what happened and we can add more. Link to comment Share on other sites More sharing options...
KimB Posted January 21, 2014 Author Share Posted January 21, 2014 Hi Everyone, Okay so I think I had a look at it yesterday, I did the oil in the bore thing it wouldnt start but did have much more compression, I then managed to fire it with a spray of easy start once up and running it was same as before, revs fluctuating quite allot, it seemed to get worse the warmer it got. If I then put the choke on the revs would drop down around tickover. I also checked for air leaks and totaly stripped the carb again to make sure all of the seals and everything else was fine, which it was. Once it was warm I could start it fine but as soon as it was cold it wouldnt start. ? Thanks Kim Link to comment Share on other sites More sharing options...
blackhat250 Posted January 21, 2014 Share Posted January 21, 2014 Its deffinatly that carb kim" the choke should kill it when warm,[ excess fuel] and having to spray to start cold, points to the choke system not working, in the carb bowl, there may be a deep well, the choke pipe feeds off this well Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 21, 2014 Moderator Share Posted January 21, 2014 Not sure if this help or not but I have seen many people put the slide for the carb in backwards= bike wont start or if it does it revs realy high. If the bike starts and runs then it kinda narrows it down to a carb issue. O hi and welcome C'mon own up, you found that one out the same way I did. Bluuugh Bluuuuugh waaaaahhhhhhhhhhhh. Bollocks.lol Link to comment Share on other sites More sharing options...
dt502001 Posted January 21, 2014 Share Posted January 21, 2014 Kim this might sound absoutly nuts but are you shure you not turning the choke the wrong way.Realy sounds like you just having trouble with the choke circut cold once it warms up you turn it off ( but in your mind you turned it on) and the bike idles properly. I am have trouble gettting this the symptoms of hard starting from cold and increasing revs as it warms is exactly what the bike would do if the choke was on,and once warm if you turn it off it would settle into tick over. You just did the T/E of the motor R U shure the valves are adjusted properly .002 intake clearence and .004 inch exhaust. Link to comment Share on other sites More sharing options...
KimB Posted January 23, 2014 Author Share Posted January 23, 2014 Hi guys, so I had another look at it today, re checked the valve clearances and they were fine, now that you said the carb seems the issue the only problem i noticed was that as you can see in the photos bellow the two holes that lead to the bottom of the float bowl its blocked ? should that be blocked ? I put a drill bit down the long bit of the hole and it didnt go all the way to the bottom ? but the hole at the bottom of the float bowl seemed to go all the way to the other. Also this is choke off ? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 23, 2014 Moderator Share Posted January 23, 2014 use a dropper and dpip petrol down the hole, it should come out inside the bowl through that little black hole, Link to comment Share on other sites More sharing options...
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