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FZ750 - Cranking / Starting Issues


andrewed1
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My issue is getting it to run. As when i hit the starter it sound like the starter just spins, and every now and then it will crank..

Ok.. YES 100% the carbs are clean, once it starts it run yes rough but runs.

Coils tested and in spec

New Plugs, Leads and Caps

Tested Spark = yes all cylinders do spark when it cranks..

Solenoid works, and connections are tight..

here is a video for more understanding of the Cranking issue..

please help needed....

https://youtu.be/InAcMSib08E

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Pretty sure your starter clutch is the problem, you need to take the starter off and check the teeth on the starter ring to make sure that there aren't any teeth missing or worn down. Then oil the shit out of it to free anything that's stuck, you might also need a starter clutch kit to re-furb the starter, don't know what spares are like to get where you live but Wemoto or Yambits and Fowlers have them in stock for about £30 a set. Get yourself a mirror and a torch then check the starter ring inside the engine for missing or worn teeth, turn the engine over by hand and see if there's anything amiss inside.

http://yambits.co.uk/fz750-starter-clutch-repair-kit-p-11049.html

http://www.wemoto.com/bikes/yamaha/fz_750_n_s/85-86/picture/starter_clutch_repair_kit/

https://www.fowlersparts.co.uk/?gclid=CMuW1baytdMCFbgK0wodZs0M5w

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Pretty sure your starter clutch is the problem, you need to take the starter off and check the teeth on the starter ring to make sure that there aren't any teeth missing or worn down. Then oil the shit out of it to free anything that's stuck,

 

Yes already did this and could not see any missing.. might have to do it again..

 

Get yourself a mirror and a torch then check the starter ring inside the engine for missing or worn teeth, turn the engine over by hand and see if there's anything amiss inside.

 

Where would you place the mirror and torch for this inspection?

 

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You hold the mirror inside the engine space facing you then shine the torch at the mirror and shine it in the hole, with your third hand turn the engine over slowly while dancing in clogs and wearing a ballerinas outfit.:lol:

Oh and don't forget to check the end of the starter motor gear as well it might look ok but they do wear.

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You hold the mirror inside the engine space facing you then shine the torch at the mirror and shine it in the hole,

 

Sorry were would i find this? What cover do i need to remove.

 

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Ok, when you take the starter motor off you have a gert big hole where it slides into the engine, that's the hole you need to look inside of, you should see the ring gear sticking just out from the bottom of the hole and as you turn the engine it should turn anti-clockwise to you, if you have a mate that can help, get him to stick his finger in the hole and turn just the ring gear one section at a time, it's a right bastard to get to and can take ages but if you see any missing or worn teeth there's your problem half solved.

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Just to be clear here this >Related image goes to this >Image result for FZ750 starter assemblyOK?

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Thanks Slice..

 

 

Well i removed the starter motor to check the idler gear teeth and no teeth are missing. The starter motor teeth look ok to me and works.

 

 

The idler gear spins freely 1 way but the otherway feels like it catches the starter gear, is this correct?

 

 

So is the next step to try and inspect the starter clutch gear teeth? Using your mirror method as i will need to purchase a inpection mirror..

 

 

 

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Yes mate, you really need to make sure there are no teeth missing first, the starter clutch on these bikes is a type of "sprag clutch" ie it spins free in one direction and locks tight in the other direction, they can wear and just slip causing the engine to refuse to turn over usually cos they are badly worn. It looks like this when it's apart and the little rollers are the ones that do all the work, that's what needs replacing if yours is fubard Related image the thing is you can't know for sure if it's fucked till you get it out. In your Video the motor sounds ok and seems to be spinning the clutch ok but the only other thing I can think of that might cause this is deeper in the engine and not sure you want to go there yet! These clutches are pretty robust but when they go you have no choice other than to repair or replace them I'm afraid. Can you get the side panel off of the engine and look directly at the clutch? this would make it much easier to diagnose any fault you have and then you would be halfway to a solution.

P.S. You don't need to purchase a mirror any mirror will do as long as you can get it in the space where the starter motor came out of, find a bit of broken mirror or even one of your wife/girlfriends compacts, if they still use that sort of thing?

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Didn't you missus tell you to use your own compact when you tried that slice......

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22 hours ago, slice said:

 

 

Can you get the side panel off of the engine and look directly at the clutch? this would make it much easier to diagnose any fault you have and then you would be halfway to a solution.

 

 

 

From looking at the service manual if i remove the clutch i would still not be able to see the starter clutch as it appears to be sectioned off. Once removed what would i be looking for.

Also:

Quote

 

the only other thing I can think of that might cause this is deeper in the engine and not sure you want to go there yet!

I do not think this is an issue as i have been able to get the engine to start just took a long long time, as cranking was very intermittent

Thanks i appreciate your time and help.

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Well done on getting it running mate, you never know that might be all it needs. keep trying it and see if the cranking gets any better. If not then your going to have delve deeper into the engine, for now tho just enjoy annoying the shit out of your neighbours! :lol:

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sounds good too, well done.

 

As Slice says, it may get easier to start as the engine has loosened up a bit

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make sure that there aren't any teeth missing or worn down. Then oil the shit out of it to free anything that's stuck, you might also need a starter clutch kit to re-furb

 

 

Whats the process to the oiling the shit out of it?? Would i use a pump through the starter motor mounting hole???

I try anything too free it rather the splitting the cases [emoji4] 

 

 

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Ok, If it was me I would use my air line and the oil can attachment that it came with, what your trying to do is get fresh oil into the internals of the starter clutch, so turn your compressor up to max then shove the end of the oil can into the part of the gear that you can see in the hole in the engine, SPRAY, pull it out and turn the gear a quarter turn and do it again till you have gone right round the gear, let it soak for a few minutes then do it again, then try to start it, do this half a dozen times and see if it makes any difference, Oh and DON'T use car oil use motorcycle oil, keep an eye on how much oil you put into the engine as well as it all adds up and you can easily over fill the engine if your not careful.

something like this is ideal Related image   it's called a paraffin gun?

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Just been thinking about your problem, if when you re-attach the starter motor you leave the fixing bolts slightly loose then grab the end (starter motor) furthest away from the engine and pull it upwards slightly, about 3/16ths of an inch is about all you should need, now if what I'm thinking is right try to turn the engine over at this point, if it cranks the engine over then it's the end of the starter motor that's worn and not the internal part of the starter clutch. Remember this is just to see if it works not a proper fix, if it does work then your going to have to replace the starter motor rather than the starter clutch. It means that the end of the starter motor has worn to the point that it no longer reaches the gear inside the engine, if this does not work then it almost certainly is the starter clutch that's the problem.

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12 hours ago, slice said:

Ok, If it was me I would use my air line and the oil can attachment that it came with, what your trying to do is get fresh oil into the internals of the starter clutch, so turn your compressor up to max then shove the end of the oil can into the part of the gear that you can see in the hole in the engine, SPRAY, pull it out and turn the gear a quarter turn and do it again till you have gone right round the gear, let it soak for a few minutes then do it again, then try to start it, do this half a dozen times and see if it makes any difference, Oh and DON'T use car oil use motorcycle oil, keep an eye on how much oil you put into the engine as well as it all adds up and you can easily over fill the engine if your not careful.

something like this is ideal Related image   it's called a paraffin gun?

Oh I got one of those somewhere.

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