andyh Posted October 28, 2008 Share Posted October 28, 2008 i have recently bought a yzf750r started no prob rode it back 75 miles following morning non starter have had the carbs checked cleaned and balanced bike then started three hours later restarted bike no probs left running for two mins turned of then started again following morning no prob later that afeternoon wouldnt start turned over no prob with a putting sound through exhaust petrol getting through no probs there can you help please want my bike back on road Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 28, 2008 Moderator Share Posted October 28, 2008 Can you take the fuel pipe off the carbs to check the fuel pump is working? Link to comment Share on other sites More sharing options...
andyh Posted October 28, 2008 Author Share Posted October 28, 2008 Can you take the fuel pipe off the carbs to check the fuel pump is working? fuel pump working fine no prob with that you can even hear it slight noise pumping fuel when first switched on Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 28, 2008 Moderator Share Posted October 28, 2008 Are the plugs getting wet with fuel on these starting attempts, have you checked for spark, is the choke mechanism working? Link to comment Share on other sites More sharing options...
andyh Posted October 28, 2008 Author Share Posted October 28, 2008 Are the plugs getting wet with fuel on these starting attempts, have you checked for spark, is the choke mechanism working? yeah these all seem to appear ok? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 29, 2008 Moderator Share Posted October 29, 2008 Well if youve got sparks, and got fuel then all you need is compression, you will have to do a compression test. It might be worth squirting a drop of oil into the spark plug holes, just to give it that initial seal to start though. Could the rings / bores be worn, done a lot of miles? Link to comment Share on other sites More sharing options...
andyh Posted October 29, 2008 Author Share Posted October 29, 2008 Well if youve got sparks, and got fuel then all you need is compression, you will have to do a compression test. It might be worth squirting a drop of oil into the spark plug holes, just to give it that initial seal to start though. Could the rings / bores be worn, done a lot of miles? is it possible that either the exup valve is sticking or the air flow sensors are dodgy the man thats working on it says it ay be the valves needs reseating Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 29, 2008 Moderator Share Posted October 29, 2008 Dunno, out of my depth with these things, (exup valves and flow sensors) hopefully someone will jump in and help out here! Link to comment Share on other sites More sharing options...
rf9rider Posted October 30, 2008 Share Posted October 30, 2008 Exup valve sticking shouldn`t cause the problems your describing. Whats the mileage on the bike? If its high mileage, could be the valve clearances need doing, but these normally cause problems when bike is hot, as the valves expand and close up. Sounds more likely to be carb/jetting problems. Just re-read through, if your`e sure the carbs are ok, it could be your coils breaking down under pressure. I`d get them checked first. Link to comment Share on other sites More sharing options...
pilninggas Posted October 30, 2008 Share Posted October 30, 2008 be very aware, the jets on these wear-out. this results in the bike being so rich it wont even start. So you can have spark and wet plugs (which would indicate it should start) but no action. Take the airbox off and try starting it (be wary of backfires!). Removing the airbox may shift the mixture leaner. At this age assume the jets and needles need replacing anyway! these guys are about as cheap as it gets: http://www.allensperformance.co.uk/index.html ....and in my opinion (others may disagree) do not be tempted by a dynojet kit. Link to comment Share on other sites More sharing options...
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