Bike won't start

[cuong-nutz]

My bike started to not want to start towards the end of the the trackday sunday. I thought it was my battery, so I left it on the trickle charger. Tried starting it and it'll turn over not fire up and run.

I'm thinking I might need to readjust my valves again but I just recently did them about 3-4 months ago. The transmission has popped out of geara few times at the track so it's hit the rev limiter a bit.

Is there anything else I should look at before I tear down the bike again? Perhaps I need to get the battery tested.

[EsrTek]

Spark Plugs?

[DaBlue1]

Originally Posted by cuong-nutz

....Is there anything else I should look at before I tear down the bike again?

Try swapping out the IC Igniter.

[alex.s]

just doesn't want to start? has ok power when it runs though? or wont run at all?

need 4 things to go boom, fuel, air, compression and spark... check intake for something plugging it... make sure you are getting gas in there, and check spark... if you have a gauge, check compression too... this should give you a good idea of what is wrong before you try to tear anything open

if your battery is truly ****ed, it could be draining so much power even on the trickle charger that the igniter wont get proper power and will throw everything off... but if it will turn the motor over off the trickle i'd say its not completely ****ed.

[Lychee]

spark?, air?, fuel?, compression? I doubt its the valves unless you had idle problems prior to the no start issue.

edit: ha like alex said.

[cuong-nutz]

Power seemed normal before it decided not to fire up. The plugs are fouled but there is spark and from all the gas fumes coming out of the pipes. Airbox and filter are clean too. Going to run to the auto parts and pick up some new plugs and see if they sell the adapter I need.

My compression tester doesn't have the right size adapter for these small plugs.

[alex.s]

does changing throttle effect it?

post a video of what it sounds like when its cranking

[cuong-nutz]

Originally Posted by alex.s

does changing throttle effect it?

post a video of what it sounds like when its cranking

Got it to fire up for a little. It after numerous tries and jumping the battery. I have the choke on and was opening the throttle. When it fired up I opened the throttle some more.

Link to original page on YouTube.

[alex.s]

ok well i dont think it would rev like that if the head was messed up or it was seriously down on comp... sounds like it might be some kind of electrical draw keeping it from sparking well... i would do a couple quick fuel tests... turn off the fuel tank, disconnect the carbs from the fuel line then drain each carb and make sure they measure about right, connect it up again and put the tank on prime for a minute, then off and disconnect it again and measure the carbs again... if its getting good fuel to the carbs i would try starting it with spraying some extra flamible stuff in the intake and see if it fires up right away... if it does i would investigate fuel supply more (jets clogged? intake leak?). if it responds similarly i would test all the major electrical components. (check for short on the main line, check main coils, pickup coil and stator resistance, make sure the cdi is receiving a good voltage power when cranking)

have you dumped and examined the oil yet? any time i have engine problems that's usually my first step. you'll know right away if its a small problem or something catastrophic. you can even send a sample to be tested and the different contents of metal will give you good hints on what problems the engine is facing

[cuong-nutz]

I can't really tell much about the oil other than that it's really dark.

Seems like I'm getting adequate fuel through the bowls. One things is for sure though, I flooded the crap out of my cylinders. I had the spark plugs out and turned over the motor (didn't undo the gas lines) and fuel was spewing out of the spark plug holes and leaking out the exhaust header flange.

[bruce71198]

Originally Posted by cuong-nutz

I can't really tell much about the oil other than that it's really dark.

Seems like I'm getting adequate fuel through the bowls. One things is for sure though, I flooded the crap out of my cylinders. I had the spark plugs out and turned over the motor (didn't undo the gas lines) and fuel was spewing out of the spark plug holes and leaking out the exhaust header flange.

The way it sounds on start up leads me to believe its a fueling issue. The fact that you have fuel spewing everywere leads me to believe its an over fueling issue. Check the floats, needles and seats. First though pull the vacuum line off for the fuel petcock and see if raw fuel comes out, you may have a ruptured diaphram in the petcock. When you get it figured out make sure to change the engine oil as it is surely contaminated with gasoline as well as the spark plugs.

[bruce71198]

Originally Posted by cuong-nutz

I can't really tell much about the oil other than that it's really dark.

Seems like I'm getting adequate fuel through the bowls. One things is for sure though, I flooded the crap out of my cylinders. I had the spark plugs out and turned over the motor (didn't undo the gas lines) and fuel was spewing out of the spark plug holes and leaking out the exhaust header flange.

The way it sounds on start up leads me to believe its a fueling issue. The fact that you have fuel spewing everywere leads me to believe its an over fueling issue. Check the floats, needles and seats. First though pull the vacuum line off for the fuel petcock and see if raw fuel comes out, you may have a ruptured diaphram in the petcock. When you get it figured out make sure to change the engine oil as it is surely contaminated with gasoline as well as the spark plugs.

[cuong-nutz]

Originally Posted by bruce71198

The way it sounds on start up leads me to believe its a fueling issue. The fact that you have fuel spewing everywere leads me to believe its an over fueling issue. Check the floats, needles and seats. First though pull the vacuum line off for the fuel petcock and see if raw fuel comes out, you may have a ruptured diaphram in the petcock. When you get it figured out make sure to change the engine oil as it is surely contaminated with gasoline as well as the spark plugs.

I really am not looking forward to tearing out the carbs again. The airbox gave me hell last time.

[alex.s]

it's easier if you take out the engine first



i would fill up the carbs with gas then turn off the petcock and and try starting it... if its overfueling it should start then stop after cranking for a few seconds. if you have a multimeter it only takes like 5 minutes to test all the electrics

[Lychee]

Originally Posted by alex.s

it's easier if you take out the engine first

Cutting the battery box off the airbox saves me loads of time when removing the carbs on my pregen.

[bruce71198]

Originally Posted by cuong-nutz

I really am not looking forward to tearing out the carbs again. The airbox gave me hell last time.

Practice makes perfect, after a few times it become old hat ( whatever that means). I dont know what level your meachanical skills are but I work on a lot of stuff, at this point its all just nuts and bolts !! Try to look forward to instead it makes it more enjoyable.

[cuong-nutz]

Got the 10mm adapter.

Link to original page on YouTube.

Link to original page on YouTube.

[beninja]

Just for learning purposes, does this mean you have to replace the rings that go around the piston to regain compression?

[cuong-nutz]

Originally Posted by beninja

Just for learning purposes, does this mean you have to replace the rings that go around the piston to regain compression?

Not necessarily.

If your rings are shot, you can try putting some oil through the spark plug hole to see if compression increases. If it doesn't increase than your valves aren't seating or are bent. You'll have to check your valves and see if they're in spec. and you can do a leak down test. which pressurizes the cylinder and checks to see if your valves are seated properly. If your rings are bad, you'll probably have to get the cylinder bored over and go with the next up oversized rings.

[cuong-nutz]

Wet compression test confirmed rings are shot. I had forgot to do this before checking the valve lash At least I know the valve lash is still within-spec.

Also, too much oil in the combustion chamber will kill your valve stem in your compression tester.

Options are "new" motor or bore over and bigger pistons.

Link to original page on YouTube.

Link to original page on YouTube.

[cuz]

:/ get that 1 engine from mh its almost newish

[cuong-nutz]

Originally Posted by cuz

:/ get that 1 engine from mh its almost newish

Yeah, it looks like the most plausible thing to do as doing an overbore won't be beneficial to me without upgrading the cooling system.

[rojoracing53]

Yeah sorry man I know even less about this stuff your dealing with then the members who have already posted. I was told on my 2 stroke to test its compression when its at operating temperature so that way everything is warm and in spec. This means riding it around for a few minutes then pulling the plug and testing. Is the test method different for a 2 vs 4 stroke?

My NSR50 has 2 full race seasons a 4hr and a 24hr endurance race on its original piston and rings and its still the fastest bike on track. Although the motor sound a bit sloppy it still makes 113psi.

[LoD575]

According to my manual (08-12) usable compression range is 139-213 psi.

Possible causes for low compression is:
leakage from cylinder head
valve seating
valve clearance
piston/cylinder clearance
piston seizure
piston rings/ring groves

Valve clearance would be the first thing I would check. If that checks out might as well pull the engine and tear it down.