anyone know anything about scooters?

[andym]

Before I got my 125 I had a 50cc scooter which according to the speedo would do up to 58mph.

It had a couple of holes in the exhaust (OK more than a couple), I patched them up and it ran like a pile of crap (dropped 15-20mph and had no power), so someone said something about the back of the exhaust being knackered inside and it was causing a problem with back pressure. The easy way to find out if that was the problem by knocking a couple of holes into the down pipe. I put 2 holes in it and it went back up to normal speed isntantly. So figuring the old exhaust was dead I bought a new one..... £85 and a bitch to fit, but I got there and the speed dropped again, now it struggles to get up to 30 and manages 40 downhill.

I spent a fair few quid on the scooter (moto roma wasp which is impossible to get parts for), and now I want to sell it on, but I want to get the speed back up to what it was. so does anyone have any ideas.

I was told that when you fit a new exhaust you have to fiddle with the mixture settings.

Before the exhaust incident I bought a new sports clutch for it thinking that was the problem, the only difference that made was I had to rev the bollocks out of it before it moved, and it was adjusted to its loosest setting.

[truslack]

Does the new exhaust have a restricting washer welded in?
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[andym]

nope.... I was told that some times they are a bit to over enthusiastic with the wadding and that it would have burnt off after 60-70 miles.... that was about 500 miles ago, and because there isn't a problem with the exhaust... technically... they won't take it back

[Rogerborg]

Why would they? Most 50cc bikes are sold restricted to 50kph (for licensing reasons). Why would you expect yours to go faster with stock parts? If you want it to exceed 50kph, you'll have to modify it.

As truslack said, get the exhaust off and have a look in the throat - see if there's a washer or similar in there restricting it.

[woodyfjr]

I'm not familiar with your scooter but it sounds like a 2 stroke if so the exhaust is a very important part as they do need back pressure to work correctly.

If there is to much wadding it can reduce power drastically just remove some.
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If you don't pay your exorcist you can get repossessed.

If you have to rev it! Don't Buy it!

[Damon]

Chris is right. Do not remove any of the wadding. It is not in your expansion chamber but packed around the inside wall of the end can. Doesn't do anything to airflow.

Is it possible that the previous owner had holes in the exhaust and rather than fix the problem just jetted it to suit? If so then now you have put a proper system back on it is running too rich.

Just an idea

[andym]

OK I'll try to answer as much of them replies as possible....

The exhaust that was on there looked like a bit of a sieve around part of the down pipe where it had rotted away, it was the standard/original exhaust. New one is totally different in shape and style but was told by the supplier that they have sold quite a few for my scooter and never had any problems with them restricting the speed.

How would I adjust the mixture to the best setting? I know how to adjust it, but how do you know when the mixture is right?

Should I just lose the £85 and try to repair the old one (which I have cut a large hole in to see if anything was blocking any of the holes in the silencer.... incidentally all of the wadding had gone from that exhaust.

Since I have the old exhaust, the new one and the twin pipes from the 125 I think I might try throwing something together and experimenting a bit

[Damon]

[Ichy]

The easiest way to check the mixture is to take a look at the spark plug. If its covered in carbon then the bike is running rich. If it looks white or the electrodes are damaged then its likely to be a weak mixture.

[andym]

When I beat the camera into submission I'll post some pictures... but I took the sparkplug out and it looked like it was covered with oil (black and sticky, although the scooter hasn't been started for about 3 weeks and even at that it took about an hour to start, (and probably a chipped bone in my thumb when I got fed up trying to kickstart it).

I'm just going to go and rip the exhaust off now...

[Ichy]

Might not be oil, it could easily be a heavily carbon coated plug that has been soaked in petrol from trying to start it.

[andym]

OK I got some photos...

[andym]

separate tanks, and yes it was brand spankin' new when I got it.... although fitting it left it with the odd scratch here and there, and it has done about 500 miles since it was fitted.

[skatefreak]

to be honest the old one looks like a 2 stroke tuned pipe with a correctly shaped expansion chamber to send a return shockwave back where as the new one looks straight through.

This should explain it a little better...

https://www.southernskies.net/page_pics/miss/two-stroke_c.gif

Shows how the expansion chamber is tuned to push back fuel into the chamber improving the engines performance which would other wise just escape with the exhaust...

-Jvr

[c_dug]

Agree with the above, although you can't /really/ say just by looks it does look as though the "original" one (which I doubt was standard) was a sportier pipe.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[woodyfjr]

If the end pipe section (Stinger) has to much wadding it will poke through the small holes and reduce the gas flow, it will be nice and quite though.
If there was no wadding at all the stinger pipe should have no holes at all for best performance apart from the exhaust end.

Ahh the sound of TZ250's.

Looking at the photos you should get the correct pipe as the new one looks like a cooker/commuter item.
____________________
If you don't pay your exorcist you can get repossessed.

If you have to rev it! Don't Buy it!