need an expert to diagnosis this! By glutton4punishment (Read 1,015 times)

[glutton4punishment]

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.

[tvnacman]

take out the spark plug and put some motor oil in the hole . Then turn it over by hand do this several times , it may loosen it up some . Some people like to dump the engine oil and fill the crank case with diesel and put some diesel in the spark plug hole and work the crank by hand . If it loosens up dump the diesel put in fresh oil . put the spark plug in it and try to start it . Only run it for 3-5 min and dump the oil again . It will take a few oil changes to get out all the diesel . I have filled the entire crankcase and let it sit a few days with diesel . check the spark plug hole and make sure it is topped off . This way you know your soaking both sides of the pistion .

John

[Alleyoop]

Take the valve cover off and check it may have dropped a valve if it is that hard to get past one of the rotations.
Alleyoop

[glutton4punishment]

thanks for the replies!

I got it to revolve by spraying wd-40 in there. the motor oil is very clean.

The way my engine is laid out, the intake valve cover is on top, the exhaust on the bottom. for my sake, I hope the problem is from above.

I assume a dropped valve will look like it's not there or too low from the POV of the valve adjust nut?

thanks, anyway, I'll check it out ASAP.
BTW, I assume that

[Bashan]

If you're using this thread as a reference I had a :

The amended post below should be correct:[/I]

Yes, you're correct, there will be a relatively large gap from the rocker arm to the valve stem. The blue arrow points to the gap:

Rotate your cam lobe away from the rocker to measure the gap. Not to insult your intelligence but new people read these too, the valve stem terminates at this button that the rocker pushes on:

The space between them is called the valve gap. If this gap has suddenly jumped to say .01" from .006" your radar better go up, maybe even less than that amount. The stem can drop due to many factors such as a broken spring or even the seat can come loose. The bike may still run if it hasn't discombobulated. The bike will start to run like crap and the valves may make a hellatious noise. You can also run into situations like this one where the valve hits the piston and won't let it rotate. or if you're riding it may seize.[/b]

[mike6736]

Hey Rich... Could you please show a little dirt or oil when you are working on a scoot. Darn, ya make us all feel bad

Magoo

[Bashan]

Nitrile gloves Magoo......nitrile gloves. I hate 'em but I use my hands all touching people and they probably wouldn't appreciate greasy looking hands on them.

[tvnacman]

I bet its high detergent motor oil .

John

[mike6736]

Heck I mean the motor looks clean and allthe parts, don't you ever ride them... so clean

Magoo

[Alleyoop]

It is all show and no go, look at the oil CLEAR AND CLEAN.
Alleyoop

[tvnacman]

looks like it was in the washing machine .

John

[justbuggin]

nah he just has a spare motor for taking pics of like nascar host when showing how def parts of the cars work

[glutton4punishment]

well, I wish my mind was as clean as that engine!

So what's it mean, do I have to take off the head and take it to a shop or what???

[Alleyoop]

Not yet, take the VALVE COVER off 4 bolts then you will see the VALVE studs and springs and rockers.
And FOLLOW what RICH said with the pictures he put up to see if a valve dropped. If it did then yes you have to take the head off to either check if it damaged the piston or you can just a new head or you can replace the Valves and springs.
Alleyoop

[glutton4punishment]

thanks for everything, very clear..now I need to find some time. Will report back with good news (I hope).