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Can't rotate engine backwards

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ChrisB
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Can't rotate engine backwards

#1 PostAuthor: ChrisB » Sat Oct 21, 2017 12:15 pm

Just rebuilding my engine, all seems to have gone well. Engine rotates nicely going forward but won"t turn backwards. It"s in neutral. Is there something obvious i'm missing here?

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z1bman
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Re: Can't rotate engine backwards

#2 PostAuthor: z1bman » Sat Oct 21, 2017 12:18 pm

check the kick start mechanism especially the spring that locates between the crank cases

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Re: Can't rotate engine backwards

#3 PostAuthor: ChrisB » Sat Oct 21, 2017 12:19 pm

It doesn't have the kickstart mech fitted.

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Re: Can't rotate engine backwards

#4 PostAuthor: z1bman » Sat Oct 21, 2017 12:30 pm

remove the clutch basket to determine if its the crank or the gearbox that is causing the problem

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Re: Can't rotate engine backwards

#5 PostAuthor: ChrisB » Tue Oct 24, 2017 5:46 pm

ok, have some free time, going back into the garage!
Just before i start taking out large parts of the engine without the special tools, are there any other suggestions for checking various things which may cause this problem without removing too much?
Thanks for your suggestion Z1bman. I did notice that it would only engage first gear on the bench before it went back in the frame and was educated as to the Kawasaki gearbox designer's practical joke! When i split this engine, i kept the clutch complete on the gear shaft as i was only needing to have the crank straightened and the cases vapour blasted. Figured I could just pop everything back as was. Would this give any further clues to my predicament?

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Re: Can't rotate engine backwards

#6 PostAuthor: garyd » Tue Oct 24, 2017 6:25 pm

". I did notice that it would only engage first gear"

They are designed to do that...it will only engage 2nd etc once the gearbox is moving.

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Re: Can't rotate engine backwards

#7 PostAuthor: z1bman » Tue Oct 24, 2017 7:08 pm

when you turn the engine backwards is the output shaft turning?

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Re: Can't rotate engine backwards

#8 PostAuthor: Taffus » Tue Oct 24, 2017 7:22 pm

had this on my GPz1100
It was a dislodged shim, it would go forward on the spanner but not backward, it was a hard lock backwards. re seated the shim and it was OK

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Re: Can't rotate engine backwards

#9 PostAuthor: ChrisB » Tue Oct 24, 2017 7:39 pm

Thanks for the replies guys, here’s the latest.
Whipped off the generator cover. And it spins backwards and forwards. The reason I stripped the motor was a slightly bent LH end of the crank which was causing the rotor and stator to foul. SEP straightened it and I’m just now sorting the electrics etc to get it spinning. Now the genny cover is back on its quite a lot tighter to rotate backwards but it does turn. Obviously has a little more to turn now connected to the starter motor and the starter gear isn’t exactly free spinning but is turning. Haven’t checked the rubber behind the spray clutch for clearance assuming it hadn’t changed but might be a little tight. How critical is this? Certainly feel happier now it’s turning both ways.

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Re: Can't rotate engine backwards

#10 PostAuthor: z1bman » Tue Oct 24, 2017 8:25 pm

you should be able to turn the gear with your finger? the engine will be more difficult to turn backwards because it will be turning the starter motor this is normal

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Re: Can't rotate engine backwards

#11 PostAuthor: ChrisB » Tue Oct 24, 2017 9:25 pm

Thanks garyd. Picked that up in a previous post! Quick update. First took the generator cover off to check the starter clutch and the engine now turns backwards although much harder to turn it does still turn with the genny back on. Noticed that the clutched starter gear doesn’t exactly spin freely but seems to have been the problem. Didn’t remeasure the gap under the rubber spacer as i didn’t think it would have changed. How important is the gap?

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Re: Can't rotate engine backwards

#12 PostAuthor: ChrisB » Tue Oct 24, 2017 9:31 pm

Thanks z1bman, the gear does turn with my hand but has some resistance. Turns forward ok but again it’s not a uniform resistance ( I’ve taken the plugs out to stop the compression resistance) and I suspect that the generator still isn’t exactly centered between stator and rotor. This was the original problem when I first tried to spin the motor on the starter motor. It must have been fouling due to a crank which had a slight bend after a left side crash.( this is an unfinished project so feeling my way through it slowly)
Although better I’m not convinced SEP have got it exactly straight.

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Re: Can't rotate engine backwards

#13 PostAuthor: z1bman » Tue Oct 24, 2017 9:54 pm

have you tried it with the stator removed from the cover ?

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Re: Can't rotate engine backwards

#14 PostAuthor: ChrisB » Tue Oct 24, 2017 10:04 pm

Yes, with the stator off it turns backwards but when I have the stator and cover bolted up tight it doesn’t want to turn backwards but goes forward ok!

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Re: Can't rotate engine backwards

#15 PostAuthor: z1bman » Tue Oct 24, 2017 10:26 pm

what i mean is have you removed the stator from the engine cover & then fitted the bare engine cover ?


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