need help with a diagnosis!

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need help with a diagnosis! by: glutton4punishment - Apr 29, 2013 13:34:26 GMT -5

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Post by glutton4punishment on Apr 29, 2013 13:34:26 GMT -5

hi, gang.

I've got a 150cc water cooled sym joyride scooter as a "gift", DOA, around 43,000km.

At first, the engine was seized, but with a wrench to the thing that drives the variator, I got it to rotate.

It wouldn't start with the battery b/c it kept getting "stuck" in one place, i.e. the starter would turn the engine over, but that's all. The battery driven starter would work for a few seconds, hit a spot of high resistance, the engine wouldn't turn any more, and I would shut it off b/c of fear of burning up the starter.

So this is what I would like diagnosed: when I revolve the engine with the wrench, it spins pretty freely till I hit a certain spot. At that point, I have to apply a fair amount of force (let's say 3X the normal amount) to get the engine through the rough spot, and then it spins easily again till I hit "the zone".

Before I take it apart (I'm not really sure it's worth it, and that's a big part of why I'm asking here) what do you think is the problem?

Thanks a zillion.

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need help with a diagnosis! by: urbanmadness - Apr 29, 2013 13:54:37 GMT -5

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Post by urbanmadness on Apr 29, 2013 13:54:37 GMT -5

Are you sure you are not comming up on compression for the rough spot?... try taking the spark plug out and see if it turns freely..... comming up on compression would be once every two revolutions of the crank shaft.

2007 Verona 150cc
115MM Hoca variator
12 gram weights
relocated battery
Mukuni fuel pump
300lbs rider
top speed (58mph on GPS)
Upgraded valve stems after a blow out

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need help with a diagnosis! by: jeepsteve92xj - Apr 29, 2013 14:33:51 GMT -5

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Post by jeepsteve92xj on Apr 29, 2013 14:33:51 GMT -5

Is it once around freely or twice?
If it had dropped a valve, it would be hard at the top of each rotation. If it is only the compression spot, then it should be once every other rotation.

2008 Xingyue ITA 150.
HID modified headlight.
13gr 20x15 Dr. Pulley Sliders.
139db horn,
7100+ miles,
jets: Ecotrons EFI.
Pod filter and 1" header and muffler.
11-pole stator upgrade.
Manual fuel valve.
2008 Znen XY150T-F
1" header and shorty 'muffler'.
stock 12-pole stator.
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need help with a diagnosis! by: alleyoop - Apr 29, 2013 14:44:09 GMT -5

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Post by alleyoop on Apr 29, 2013 14:44:09 GMT -5

Yes, if it is really hard to turn at a certain point that you ACTUALLY have to crank it then something is broke inside. Like Jeepsteve said it could be a dropped valve. Take the Valve cover off and you will be able to tell if a valve dropped on you.
Alleyoop

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glutton4punishment PM glutton4punishment glutton4punishment's Posts glutton4punishment's Threads New Rider Currently Offline Posts: 3 Likes: 0 Joined: Apr 27, 2013 16:34:15 GMT -5	need help with a diagnosis! by: glutton4punishment - May 4, 2013 16:42:29 GMT -5 Reply Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by glutton4punishment on May 4, 2013 16:42:29 GMT -5 Unfortunately, the spark plug was out when I described the problem. If I do find the valve dropped....what then do I have to do?

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need help with a diagnosis! by: glutton4punishment - May 13, 2013 6:35:34 GMT -5

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Post by glutton4punishment on May 13, 2013 6:35:34 GMT -5

Just to let you know, I've never taken apart an engine before. so for me, this is a big learning and exploring process!

so, I got off the head, the cylinder,and the piston head (HC&P). Remember, the problem was that as I rotated the engine, I would hit a spot of greater resistance, and then it would rotate easy once through the "friction zone".

With the HC&P off, I rotated the engine again. Hmmmmmm, same "friction zone". Looking at the the connecting rod as I rotate the engine (after I fished out the timing chain), the friction came as the connecting rod (CR) was coming out (kind of like when you stick out your tongue). So what I did was spray some WD40 right at the point where the CR is attached to the crankshaft.

Wow, BIG difference! No friction!

Now, before you ask, the engine oil level is full, according to the screw in plug. But there is ONE more interesting thing (for me).

When I rotate the engine, sometimes the cams on the crankshaft get a coating of oil on them, but sometimes not. When it does get oil on it, it only covers about half of the bottom of the cams.

BTW, the crankcase seems to have been apart b/c there's red silicone sealer there.

Well, what do you think???

Last Edit: May 13, 2013 6:37:24 GMT -5 by glutton4punishment

need help with a diagnosis! By glutton4punishment (Read 1,111 times)

Post by glutton4punishment on Apr 29, 2013 13:34:26 GMT -5

Post by urbanmadness on Apr 29, 2013 13:54:37 GMT -5

Post by jeepsteve92xj on Apr 29, 2013 14:33:51 GMT -5

Post by alleyoop on Apr 29, 2013 14:44:09 GMT -5

Post by glutton4punishment on May 4, 2013 16:42:29 GMT -5

Post by glutton4punishment on May 13, 2013 6:35:34 GMT -5

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