Bad Sound When Starting

MYSCTR · Post by **MYSCTR** » Wed Nov 16, 2011 2:06 am

Listen to the sound when starting - sometimes much worse or a really hard solid kick - and then about about 20 something seconds, it starts right up.

Once started it seems to run smooth.

Any ideas? Starter going bad? Have not tried to kick start when this happens - have never had to kick start this one in 13,000 miles.

This has been happening off and on for about 2,400 miles - or ever since the mods were done.

Thanks for any input. Oh - be sure to tuen up the sound.

http://www.youtube.com/watch?v=U0eqFI3CwnM

Ethan Allison · Post by **Ethan Allison** » Wed Nov 16, 2011 2:32 am

It sounds like the motor is slipping when it tries to spin the engine. I'm not totally sure how it's all laid out but it sounds like whatever shaft or gear setup connects the starter to the engine is worn out.

Lostmycage · Post by **Lostmycage** » Wed Nov 16, 2011 4:18 am

What "mods" were done and by who?

It sounds like the starter isn't catching. The high pitched whine sounds like the starter motor spinning unresisted and the snap sound sounds like it's catching at too high of a speed. It could be the servo in the starter (if the buddy starter is anything like a car starter - I honestly have no idea).

With that said, I'd still want to look at these mods you mentioned since that was the starting point of the problem.

Also, can you kick start it?

agrogod · Post by **agrogod** » Wed Nov 16, 2011 10:09 am

Lostmycage wrote: It sounds like the starter isn't catching...

That's my first impression also. You can start simple by checking the hold down bolts for the starter, if they have worked loose, tightening may solve the noise problem. If its not the bolts then you may have a kaput starter.

smithrw · Post by **smithrw** » Wed Nov 16, 2011 11:26 am

We used to have a riding mower that developed a very similar sound . Turned out to be the starter bendix. I just thought there's a chance you are having the same problem. Hope you get it fixed.

babblefish · Post by **babblefish** » Wed Nov 16, 2011 3:34 pm

smithrw wrote:We used to have a riding mower that developed a very similar sound . Turned out to be the starter bendix. I just thought there's a chance you are having the same problem. Hope you get it fixed.

Like your train of thought, but the starters in most (all?) small scooter engines don't use a bendix. They use a one-way clutch (also known as a "sprag clutch", wiki: http://en.wikipedia.org/wiki/Sprag_clutch) mounted to a gear located inside the crankcase which is attached directly to the crankshaft.
Listening to the video, it sounds like this clutch is slipping because I can hear the starter motor spinning, but the one-way clutch is only catching some of the time. This is a known problem with some "GY6" type engines. This clutch is located on the right-hand side of the engine, behind the alternator. AFAIK, the engine has to be dropped in order to get to it.
This is my Blur's engine, but the Buddy will be the same. The clutch/gear assy. is the large gear in the middle. The set of smaller gears to it's left is what the starter motor drives. That small hump in the crankcase immediately to the left of the small gear set is the actual mount for the starter motor. How it works is the one-way clutch that is built into the middle of that large gear (can't really see the clutch - it's under the gear) only allows the drive from the starter motor to go one way. Once the engine starts and the crankshaft is spinning, the large gear stays stationary due to the one-way clutch action of the, well, one-way clutch. And in case anyone is interested, that metal plate with the two black screws to the right of the big gear covers the oil pump which is driven by a chain underneath the gear. Hope I didn't bore anyone...

This drawing is for a Buddy. The one-way clutch is item #20. Item #22 is the large gear I was talking about although they did not draw-out the gear teeth. Item #19 is the small gear set mentioned, and item #15 is the starter motor. BTW: the one-way clutch/gear (item 20) is sold as a complete unit already assembled. P/N C12430000001 and is about $97 from www.scooterloungeonline.com.

This is just my guess as to what the problem is. Suggest you consult with your local scooter mechanic to confirm.

MYSCTR · Post by **MYSCTR** » Wed Nov 16, 2011 6:56 pm

Thanks for all the inupt.

Kick started very easily last night after the video was done.

Switch started perfect this morning coming to work.

Had a meeting at lunch to go to and would not start or kick start. Not sure how I am getting home just yet.

Starter spins - does not catch and kick start just seemed to jump past the teeth straight to the bottom. Will try again later.

MODS - see post: topic19773.html

Mechanical adds:
171.3 Cylinder Kit (61mm)
Sliders (Dr Pulley 11g 18 x 14)
Iridium Plug
Variator
Clutch Arm Springs (1500 yellow)
Clutch Compression Spring (1500 yellow)
BANDO CDI & Coil
Stator

Looks like she is going to the dealer!

Scooterboi · Post by **Scooterboi** » Wed Nov 16, 2011 7:11 pm

"Sprag Clutch"
Amazing the things you learn on this sight! I was noticing that if I apply throttle while coasting to a stop there was this little "hitch" or "bump" before it would start accelerating. I was alittle concerned that something was loose but now I bet it was just the clutch engageing. No problem (Yea!) and Cool (and also good to know.) Thanks.

babblefish · Post by **babblefish** » Wed Nov 16, 2011 7:28 pm

Scooterboi wrote:"Sprag Clutch"
Amazing the things you learn on this sight! I was noticing that if I apply throttle while coasting to a stop there was this little "hitch" or "bump" before it would start accelerating. I was alittle concerned that something was loose but now I bet it was just the clutch engageing. No problem (Yea!) and Cool (and also good to know.) Thanks.

Ok, schools' back in session.

It isn't the "sprag clutch" that you're feeling. It's the "centrifugal clutch" (wiki: http://en.wikipedia.org/wiki/Centrifugal_clutch) located next to the rear wheel. Once running, no power from the engine goes through the sprag clutch. Or more correctly, the engine never turns the sprag clutch, the starter motor turns the sprag clutch which turns the crankshaft to start the engine.

Scooterboi · Post by **Scooterboi** » Wed Nov 16, 2011 7:29 pm

Again, thanks.

Syd · Post by **Syd** » Wed Nov 16, 2011 8:32 pm

My first thought was that it was firing (engine turning faster than the starter), but not starting. Then you said the kick starter just dropped to the bottom. Now I'm just confused.

babblefish · Post by **babblefish** » Wed Nov 16, 2011 9:34 pm

Syd wrote:My first thought was that it was firing (engine turning faster than the starter), but not starting. Then you said the kick starter just dropped to the bottom. Now I'm just confused.

He may have multiple problems. There is no direct mechanical connection between the electric starter and the kick starter other than the crankshaft itself. Basically, the kick starter spins the crankshaft from the left side while the electric start spins it from the right.

MYSCTR · Post by **MYSCTR** » Thu Nov 17, 2011 12:20 am

Well - no starting for me to come home - got a ride and loaded the scoot into the truck to be taken to the dealer Thursday AM to figure out what exactly is going on.

babblefish wrote:...There is no direct mechanical connection between the electric starter and the kick starter other than the crankshaft itself. Basically, the kick starter spins the crankshaft from the left side while the electric start spins it from the right.

So what are the odds I have a broken crankshaft? It sure sounds bad when it hits and now nothing.

babblefish wrote:...He may have multiple problems.

Of course I ride a Buddy so I don't have any problems - I am sure this is just a minor distraction and something else to learn about and of course add to the maintenance costs.

MYSCTR · Post by **MYSCTR** » Fri Nov 18, 2011 2:46 am

Ok, Ok, Gotta give big props to our fav Genuine dealer - VESPA DALLAS!

Took about 5 minutes & they had this one figured out – and Babblefish hit it on the head (THANKS!).

Sprag clutch – well actually it was the three little itty bitty springs that were the culprit. Got really lucky as one of the bearings fell out (of the sprag?) & could have done significant damage to the engine & so that is what all the noise was. Thankfully, no damage & if the part is in stock at Genuine looks like we might be riding before Thanksgiving!

So maybe the unofficial word is the 170 kit may be too strong for the springs either that or my starting/riding habits and 13,300 miles killed the springs. Anyway it feels great to know what the solution is and no real damage was done!

babblefish · Post by **babblefish** » Fri Nov 18, 2011 3:57 am

Glad you got it sorted out. As you found out, the stock clutch uses 3 rollers/springs - items 2,3 & 4 in the drawing. There are high performance sprag clutches available that use 20 rollers/springs that can handle higher compression engines. The only place I've seen it available is on eBay sold by autotech355.
While he doesn't say specifically that it will fit a PGO engine, most of these are pretty universal, though you may want to contact him to make sure. Would be worth checking out because even with shipping from Taiwan, it's cheaper than buying a new stock unit.

And just in case it's not clear for some people, it doesn't matter how much HP an engine makes, none of it goes through the sprag clutch. The only the load it sees is from the starter motor when the engine is started. Then, the amount of load it sees is determined by the compression ratio of the engine. The higher the CR, the greater the load. Hope that made sense.

eBay ad for HD sprag clutch: (or as he calls it; reinforce-starter-clutch.)
http://www.ebay.com/itm/Reinforce-Start ... 35b6dec679

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