Chinese Scooter Club

J€Di · Posted: Thu Jul 24, 2008 12:23 am Post subject:

YES!!!!

Okay so another alternative is that your engine has sucked up so much grit and crap that your rings are worn and the black wet fouling is due to oil leakage past the rings.

Nice one dad. Rolling Eyes

Get a compression test done ASAP, if it's less than 140psi do the test again but this time with fresh oil in the bores. if it goes up, it's time for a rehoned cylinder and new rings. Tell your dad to get his checkbook out.
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chaz e z · Posted: Thu Jul 24, 2008 12:27 am Post subject:

thanks, thats great then... I will have to wait for another 2 weeks after holiday because he said he can't afford it at the moment.. Could I just check the rings instead of the compression test?
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Lambretta=150cc
Vespa pk=125cc
Yamati rx-50=50cc

J€Di · Posted: Thu Jul 24, 2008 12:29 am Post subject:

No, you need to check how well the rings are seating against the bore walls while the piston is in the engine.

How many km have you done without the air filter in place?
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chaz e z · Posted: Thu Jul 24, 2008 12:31 am Post subject:

a lot... 1000
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Lambretta=150cc
Vespa pk=125cc
Yamati rx-50=50cc

J€Di · Posted: Thu Jul 24, 2008 12:33 am Post subject:

Dude... that's not good. Really really not good.

I'm crossing my fingers that the engine is salvageable, in the meantime if you do any riding at all put the air filter back in first. It won't repair any of the damage already done but it'll stop it getting any worse.

Let us know the results of the compression test, then we can tell you the best place to source new parts.
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Fox · Posted: Thu Jul 24, 2008 12:35 am Post subject:

You need more air. Open up your air box. If there is small tube inside it, remove it! I drilled holes in my air box to get my plug color right....See the pics:

Take this tube out!

chaz e z · Posted: Thu Jul 24, 2008 12:36 am Post subject:

ok, thats great. Thanks for your help I'll take a look tomorow, I remeber saying to my dad to put it back in a couple of weeks ago (did the 1000 km in the past week) hopefully he put it back in but I doubt he has.
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Lambretta=150cc
Vespa pk=125cc
Yamati rx-50=50cc

J€Di · Posted: Thu Jul 24, 2008 12:37 am Post subject:

Fox... he's done 1000km without an air filter element fitted! I don't think a lack of air is his problem, I think it may be oil fouling from worn rings which is why I'm suggesting a compression test.
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Fox · Posted: Thu Jul 24, 2008 12:46 am Post subject:

chaz e z · Posted: Thu Jul 24, 2008 12:05 pm Post subject:

I couldn't find my pressure guage so I took out the smaller pipe like you said fox and put back in the air filter element. It gave me a bit more accceleration. I also edjusted the washer on the needle to the middle which gave me more noticable acceleration but not a higher top speed. I'm guessing its because I have 4.5 gram rollers. If I wanted decent acceleration and a good top speed how much heavier rollers should I get?

ps: I will get a pressure test done at garage in 2 weeks time
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Lambretta=150cc
Vespa pk=125cc
Yamati rx-50=50cc

Fox · Posted: Thu Jul 24, 2008 3:17 pm Post subject:

J€Di · Posted: Thu Jul 24, 2008 3:42 pm Post subject:

Here's the thing... heavy rollers reduce acceleration, lighter rollers increase it. But... there are limits.

The way the rollers work is you match your engine speed on acceleration to your torque peak. So if your engine produces peak torque at 7,000rpm then you fit rollers that means your engine does 7,000rpm when accelerating. 4.5g are widely renouned at being the best rollers for a 50cc bike as they let the engine rev to peak torque.

So there are no other rollers you can fit, if you want to go faster or accelerate quicker then you've got to increase engine power. This means a capacity increase - there are no easy bolt-on goodies you can fit to increase the power of a 50cc because.... well, it's 50cc.

If you want good acceleration and a high top speed, sell your 50 and buy a 125. 50s are only designed to be reliable cheap economical transport, they are not desogned as performance bikes.
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Captain Jack · Posted: Thu Jul 24, 2008 5:05 pm Post subject:

chaz e z · Posted: Thu Jul 24, 2008 5:39 pm Post subject:

erm sorry to intrude again but, iv been trying to derestrict it but its just not working, I moved the needle and there is no pink wire in the cdi, no washer in the crankcase, no cover on the variator, no brass screw under the cap either. What could it be?

ps:I'm getting 35/38 on a flat
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Lambretta=150cc
Vespa pk=125cc
Yamati rx-50=50cc

Yellow Scooter · Posted: Thu Jul 24, 2008 6:34 pm Post subject:

Sorry, but theres nothing left from the stock setup. If you were promised more by the seller, then I'm afraid you been had.
You might get a mph or 2 with an upjet, but if your getting 35-38 on the flat, then that is all she's got. It's not going to get any faster without a bore kit and an upgear.
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