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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Starter motor spinning, but not engaging to engine
Post Info TOPIC: Starter motor spinning, but not engaging to engine
NeilB


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Starter motor spinning, but not engaging to engine
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My 2004 Blue TTR250 has sat for a while not being used. Wouldn't start at all, but turned over fine, so I stripped & cleaned the carb. Turned out the float valve was sticking closed, not letting any fuel in.

All cleaned up with carb cleaner, then I put it all back together & it started reluctantly, but was much happier after a few trips round the block.

I was happy. I spent an hour chasing a few minor electrical problems - loose lightbulb connections, etc, then tried to start it up to run it back into the garage. The starter motor was making a wizzing sound - sounding like it was disconnected from the engine, not under load. The headlamp dimmed slightly when this was happening, but not as much as it does usually.

Tried a kick start -  nothing, not that the kick start on this bike has ever worked reliably!

Tried rolling back & forth a bit in 1st gear to see if that helped, but still the same problem.

 

Any ideas would be appreciated.

 

Thanks,

 

Neil



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TTRfan


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First thing to do is to pop the starter cover off - just the three bolts and check that the starter pinion is still in good nick and is properly engaging with the starter gear.

If it is then I can only think the sprag clutch has failed cry

Brian



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NeilB


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Thanks Brian,

I followed your advice - starter pinion and the idle gears look in really good condition - no signs of wear. so I started following your sprag clutch disassembly process - really detailed - thank-you!

I got as far as taking the flywheel off, but don't have a flywheel puller - is there an approved second choice method for getting the flywheel off? I would order the puller from you,but I am in Zimbabwe, so getting it here is an issue! Is it a special part for Yamaha bikes, or something that a local mechanic is likely to have?

Everything seems fine in terms of gear teeth & needle bearings so far. The large gear behind the flywheel rotates freely - is that what you would expect?

Cheers,

Neil

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TTRfan


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Good news on the starter pinion and gears Neil!

The rear axle has the same thread as the puller

You should only be able to spin the starter gears freely in one direction. The sprag clutch should engage in the opposite direction and prevent the gears spinning. Does that happen?

Just a thought - if the starter motor was running in reverse it wouldn't engage the sprag clutch. Have you done any work on the starter motor or moved the connections between the solenoid and starter for any reason?

Best regards

Brian



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NeilB


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Thanks Brian,

The starter gears spin in both directions freely, so I guess that confirms that the clutch has died! I haven't done anything that would affect the electrics on the starter motor.

Does the sprag have to be spinning fast to engage?

I am trying to visualise how the flywheel comes off... as you screw that puller into the centre, does it push on something that releases the flywheel, or does the flywheel unscrew?

Do I need that big wrench to stop the flywheel from turning as it comes off - I found an old basin wrench that fitted nicely - thanks to a long past plumbing job!

If so, I can just find a bolt with the right thread, before I sacrifice my rear axle.

I guess that you'll be expecting a sprag clutch order from me soon!!



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TTRfan


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Doesn't sound good on the sprag clutch Neil - sorry. It shouldn't need speed to lock it.

Puller screws into centre of flywheel - as hard as you can - and then give it a sharp tap and the flywheel should pop free.

Hold the flywheel with whatever you can. I use an old tap wrench ground to fit. 

Trish tells me only one sprag left in stock so move quickly if you want it wink

Brian

PS When you have the flywheel off check the boss on Gear 3 is in good condition as that's where the sprag does its work...



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