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honda cbf125 starting problem


redlineluke
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hey folks, basically i brought a Honda cbf125 2012 plate back in august 2019 and had no issues what so ever until now, basically the bike is taking ages to start up in the morning from cold, once the bike was up to running temp i could switch it off and then back on and press the starter and it would instantly spring into life and run perfectly with in half a second. Well from further investigations with a fag in one hand and a multi meter in the other the coil is reading 14.79ohm across one terminal and the inside of the spark plug cap, across the two coil terminals its around 9.95ohms so now im not so sure the coils to blame but here is the dodgy bit i took the spark plug out and rested it on the cylinder barrel and pressed the starter no spark so i thought ahaa bad coil but i noticed when i released the starter switch it began sparking this continued until i put the plug back in started it up after 4 or 5 blasts on the old starter switch and ran it for a few mins then took the plug back out and retested, it was sparking fine upon pressing the start switch so now i dont no what to think bad coil, dodgy cdi, faulty crank sensor i dont want to be unnecessarily replacing bits if there fine i did test the out put from the magneto and it was showing a nice clean voltage so i dont think thats the issue, the bikes been serviced every 6 months new oil, new plug and i never noticed this before when the bike came with an old battered looking Bosch plug, im now using an ngk iridium plug and the battery is only 6 months old and has been load tested and passes with flying colors so im after a bit of advice really if any one has any experience with this particular problem with this bike or any other bikes all and any advice is greatly appreciated thank you in advance :cheers:

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I had a very similar issue with my YS125 a few months ago. Starter solenoid was u/s (sticking).

i had overlooked that and will be checking it, it was clicking on and off fine but i will certainly heed your advice and give it a good going over cheers buddy

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I'm not sure if this is true on fuel injected bikes but on a carb bike if there's water in the petrol and you leave the bike parked for a while the water settles out of the petrol and collects in the bottom of the carb bowl and at the bottom of the tank so the first time you try to start the bike after leaving it parked for a while it'll have a hard time starting because it's trying to start on a high percentage of water. After you get it started the first time it starts more normally because the water is now mixed around with the petrol, then if you leave it parked for a while and it'll have trouble starting again. As I said though I'm not sure if that would happen on a fuel injected bike but it might be worth checking if there's water in your tank. It usually gets in because the drain pipe in the tank under the filler cap is blocked so rain water goes into the tank instead of draining away.

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  • 2 weeks later...

I'm not sure if this is true on fuel injected bikes but on a carb bike if there's water in the petrol and you leave the bike parked for a while the water settles out of the petrol and collects in the bottom of the carb bowl and at the bottom of the tank so the first time you try to start the bike after leaving it parked for a while it'll have a hard time starting because it's trying to start on a high percentage of water. After you get it started the first time it starts more normally because the water is now mixed around with the petrol, then if you leave it parked for a while and it'll have trouble starting again. As I said though I'm not sure if that would happen on a fuel injected bike but it might be worth checking if there's water in your tank. It usually gets in because the drain pipe in the tank under the filler cap is blocked so rain water goes into the tank instead of draining away.

excellent idea in theory, yes me bike is pgmfi basically fuel injected its got a little baby injector stuffed in there in the front of the throttle body, and the drain pipe seems to be working pretty well but i do blast a load of wd-40 down it from time to time as a general maintenance as well as cleaning out the crank breather, the issue seems to have resolved its self recently since i fiddled about with the starter relay was a bit of that usual white powdery crap all over both contacts so cleaned all that off and haven't noticed the issue since also cut the end off the coil lead and re screwed the spark plug cap on so i can only deduce it was either a bad contact on the relay or a poor connection on the spark plug cap.

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