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Discussion Starter · #1 ·
Hello guys, i’m starting to get a bit desperate and sad.

So the story is, i bought this bike about 100 km away from where i live and drove it perfectly home, with stops on the way. And got home, stopped the bike, everything was fine and i was happy with the purchase. Then next day i was gonna start it but it wouldnt crank properly, as if the battery was bad/dead. And i’ve swapped battery, starter and cables to the starter. Still the same problem.

Sometimes it can crank a few times, and also ignite, just one big boom, and then i cant crank again, i can hear the relay going off, and the starter trying to turn the engine, but seema like there is not enough power in the starter, both the old and the «new» one.

Sorry for the long post, i hope this makes u understand my problem, and i would greatly appreciate any tips or solution to this. And by the way, the engine turned fine without spark plug. (Just wanted to see if something had got stuck in the engine and stopping it from rotating.) also, sorry for my english.

Thanks for all replies in advance.


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I’ll take a stab at it. With all the new starter-related parts you have installed, it seems logical that if the starter COULD spin the engine, it WOULD. The difficulty the starter is having, plus the big “boom”you describe could indicate a slow leak of fuel past the float valve/float needle in the carburetor. As the fuel gravity feeds into the carburetor, the carburetor floats rise in the bowl closing a needle into the passageway from which the fuel flows from the tank. If the “float height” is off, or this float valve is worn or misadjusted, fuel will continue to flow into the carburetor up the main jet/emulsion tube passageway, into the throat of the carburetor and down into the engine. This may create a situation of “hydro lock” where there’s a cylinder full of fuel and the starter cannot overcome it. T
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If this happens the spark plug will be wet when you inspect it. After you pull and dry the plug, crank the starter over with the plug out. You may see fuel spraying out of the plug hole. Turn the fuel petcock off and keep pumping that fuel out with the starter. Replace the plug and see if it will turn the engine over. It may even try to start. Either way, if it turns over with improved speed, turn the fuel petcock back on and start the bike. If it starts you need to rebuild that float valve assembly and reset the float height. Until then, simply shut the fuel petcock off and let the bike die of fuel starvation every time you shut it down.
 

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Discussion Starter · #5 ·
Thanks for the replies so far. I will check out this as soon as I have time for the time.

And yes, it turns fine without sparkplug. It’s like the starter is too weak or doesnt get enough power, but i feel that i’ve almost done everything i can, without this latest tip though. Will definitely check it out asap! Thanks again!


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Discussion Starter · #6 ·
It rotates fine without spark plug again, but it spitted some fuel, dont know if that amount is normal. The plug was dry though, but it’s been standing for some while now. But I removed the plug, closed fuel valve and cranked the engine a few times, and left the plug out of the engine until tomorrow. Then I will try to mount the plug and crank the starter without turning on the fuel crane. Again, if this fix it, i’d do whatever you ask me to! I’ll keep updating as soon as i know more.

Adding a pic of the plug. Seems I cant add clips from my phone.


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Discussion Starter · #7 · (Edited)
So now. I’ve tested, left the plug out over the night, fuel was off over night, also cranked a few times. Today i put everything back together, fuel still off. Plug back in its place, holding decomp while pushing start.. same as before, god damn! I wanna ride.. Anyone have a clue? Next step?

Here’s a video about it. Is that air surkeling sound normal? Sound like that whats holding it back..

https://youtu.be/WrDDl3zk2gw

Dont mind the clutch house bolt missing, i’ve had my shares


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To me that sound your battery is just bad(when you think that engine turn so slow, even whit decomp), there is not power, you should check how low voltage is dropping when start. Not sure that air sound in it is normal, but you are using decomp.
What would happen if you spray some "start spray"...

But so you have check these
-Engine get fuel
-You have spark
-Battery is ok, when start
-Valve clearance are ok
 

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Discussion Starter · #9 ·
To me that sound your battery is just bad(when you think that engine turn so slow, even whit decomp), there is not power, you should check how low voltage is dropping when start. Not sure that air sound in it is normal, but you are using decomp.
What would happen if you spray some "start spray"...

But so you have check these
-Engine get fuel
-You have spark
-Battery is ok, when start
-Valve clearance are ok
The battery is brand new. Engine gets fuel, there is spark. Only thing on your list i havent checked is the valve clearance, i feel that i dont have enough knowledge to go that «deep».

I’m charging the battery as we speak, and i’m gonna measure it’s voltage while trying to crank. And yeah, next time I will try with start spray, i think that might help getting it to rotate those few times i need. And I think if the engine is hot the starter will work. If it does, it have to be the battery or the starter, right?


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but if you was chance new starter and cables. To me that sound like there should not be any faults in starter or cables, when they are new, if that starter work like normal. Only what i would see is that how that battery can hold those voltages when start. Those valve check is pretty easy, when it sound little odd, if the engine spin normal with out spark plug, but not will spin good when install spark plug.

Also it sound like in that video, it missing that force to start, it sound so heavy. If you check other start videos in you tube, you can hear what i mean, but check that voltage when start, it should tell something:hmmm:
 

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Discussion Starter · #11 ·
but if you was chance new starter and cables. To me that sound like there should not be any faults in starter or cables, when they are new, if that starter work like normal. Only what i would see is that how that battery can hold those voltages when start. Those valve check is pretty easy, when it sound little odd, if the engine spin normal with out spark plug, but not will spin good when install spark plug.

Also it sound like in that video, it missing that force to start, it sound so heavy. If you check other start videos in you tube, you can hear what i mean, but check that voltage when start, it should tell something:hmmm:
Yes. Running double cables from starter to battery, so should be very good current between. And i checked the battery while trying to crank, it was almost 13 volts with ignition on, and 5-6 volts when holding down the start button. I appreciate ur help btw, many thanks! And maybe i’ll try to open the valve cover and have a look around in there. Just bought my first house, so i’m a little bit busy nowadays.


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Yes. Running double cables from starter to battery, so should be very good current between. And i checked the battery while trying to crank, it was almost 13 volts with ignition on, and 5-6 volts when holding down the start button. I appreciate ur help btw, many thanks!
That battery volts sound ok, when don´t start, but it sound little odd when it goes that low when start, cannot remember how low is ok, under that volts it is bad..No problem clad to help, if these help is helping..
 

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I'm not terribly familiar with the 510, but are you sure your decomp lever is working properly? The fact that it turned over fine with the plug out makes me wonder if the decomp lever isn't working and the starter motor isn't able to turn the engine over with full compression.

I would take the crankshaft nut cover off, and try manually turning the engine over with a breaker bar, do it with both the decomp lever pulled in and not pulled in. You should be able to feel a difference. Before doing this the spark plug should obviously be in, also turn the ignition off to eliminate any possibility of the engine firing while you try to manually turn it. I doubt you've ever handcranked an old car/tractor but you don't want the engine backfiring or starting with the breaker bar on it.
 
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