2 stroke or 4 stroke

[ts1]

First (in Germany) Sento 50i / Many 50i.
Where shown at EICMA 2010 (Milano/Italy mc fair).
Still not on Kymcos website, it's an info from the German Kymco Forum (Admin is authorized Kymco dealer and usually well informed).

[axy]

Kymco will introduce a 50cc 4 stroke fuel injected soon.

I've been waiting for that for 2 years!

Would be really nice to just start and go on these really cold mornings.

You will notice quite a number of problems with cold starts on the 500i part of the forum, so I would not say that injection is a guarantee of good cold starts.

Personally, I think that injection is complete overkill for small scoots, especially for 50 cc scoots. To be honest, I have never heard of 50 cc injection scoots. It is still rare occurrence on everything <300 cc.

All people driving 50 cc scoots and tweaking them will have a lot of problems. It will not be possible anymore just to change air filter, rollers, exhaust etc... also, I doubt that it will be possible to change parameters easily.

I also expect rise in prices, not really desirable trait...

[ts1]

It is still rare occurrence on everything <300 cc.

Nearly every new 125cc uses fuel injection: Honda, Piaggio, Kymco, ...

[oswaldters]

It's not the starting that I'm worried about.  My scoot starts fine in cold weather.

Problem is until the engine warms up enough it is undrivable.  I know people with Yamaha C3s (fuel injected) who fire up and go without any waiting around for the scoot to warm up in the same weather conditions that I ride in.  Aprilia also does have fuel injection for some 50cc models.

Sure any major performance modifications would require the fuel injection controller to be remapped, but that's easier than diassembling a carb and changing jets if you have software program.  I've seen people remap their SR 50s with a Game Boy in a matter of a couple of minutes.

Besides, I'm looking for reliable transportation, not a racing scoot so I'm not too worried about making huge performance mods.  Since there are laws restricting the speeds I can operate my 50cc scoot anyway, I won't need any major speed improvements.
 

[axy]

Nearly every new 125cc uses fuel injection: Honda, Piaggio, Kymco, ...

Yes, nearly every manufacturer now has 125 cc fuel injected scoots. Not all models, but usually one or a few.

You will notice many people from USA switched in the past years to low consumption vehicles like 50 cc scooters because their MSRP is 1500 US$. Now, this price will go up 40 % just because they introduced fuel injection technology (with no other added benefits).

Furthermore, it will defeat the purpose because there are no easily serviceable parts inside injections, translating into many more trips to the service shop and increased cost of ownership when something goes wrong. That is the price of "progress", I guess.

In the beginning of 2000s, all the rave on 50 cc scoots was direct injection systems, used by Piaggio (Ditech), Peugeot (Jet Force) etc. The end result were machines with poor performance, totally unreliable machines that would die every 1000 kms and need costly repairs, constantly fouled plugs that were expensive to replace, problems with injectors and ECU errors.

They were even fitting mechanical compressors on 125 cc Peugeots... and managed to squeeze out 19 hp (the same would be accomplished by big bore-ing to 200 cc and keeping natural aspiration), with maintenance costs going through the roof.

I think this is just another technology fad that will die soon.

[axy]

It's not the starting that I'm worried about.  My scoot starts fine in cold weather.

Problem is until the engine warms up enough it is undrivable. 

This is a problem of carburetor fine-tuning and not type of fuel alimentation.

I have 50 cc 2 stroke, 125 cc and 200 cc 4 stroke scoots and two 200 cc quads.
All five machines are driven all year, in all conditions, up to lowest temp of -11 C in my area and there are no such problems.

I have owned close to ten different scoots and motorcycles over the past 11 years and even though every had its own quirks and "pace" of warming up, none have showed such symptoms. All had carbs, not fuel injection.

[Whisper]

  The 2 stroke makes power on each cycle, so you will generally see an extra 50% on power.  Using a synthetic, ashless 2 stroke oil actually makes them burn as clean as they can.

  That being said, you can do a few things to bump up your 4 stroke if you are mechanically inclined - An easy-flowing air filter, new carb, and exhaust will run you ~200USD and make a big difference.  You *may* have to adjust the drivetrain a bit.  Prolly take a nice Sunday's worth of work.

  However, a 50 2-stroke is SOOOOOOOOOOO easy to work on, and generally much lighter.  Throwing a whole new cylinder on is literally, a 2 hour job at a leisurely pace.  With some modifications, it is EASY to make a 50cc scoot WAY too fast for it's frame.

  Another benefit is reliability.  A 2 stroke is easy to kickstart, and most will go if the battery is lifeless.  I cannot tell you how many times this comes in handy.  There are no oil changes, you just have to make sure the spark plug stays nice and clean (I always carried a spare, just in case). 

  There are some great 50cc 2 strokes available in the US.  The Vespa and Stellas are dead sexy.  The Chinese scoots seem to be great too - Some with really great features.

Hope this helps,

W

[axy]

  That being said, you can do a few things to bump up your 4 stroke if you are mechanically inclined - An easy-flowing air filter, new carb, and exhaust will run you ~200USD and make a big difference.  You *may* have to adjust the drivetrain a bit.  Prolly take a nice Sunday's worth of work.

In most cases, there will be difference - in consumption and sound... and that`s pretty much it, if you do not mess with the engine itself and displacement.

A few years ago I did just that - bought a new Kawasaki and replaced carb, air filter and exhaust. Gained 17 hp on dyno and DOUBLED the consumption. Also got rough idling.

I would never repeat that experience again.

[ts1]

Why different exhaust on a 4stroke!?
The 4 strokes gas exchange is not influenced by the original exhaust.
There might be some psychological gain though.

And I doubt $200 would be enough.
The exhaust for the Kymco Agility 50 Basic (the smallest Kymco!) is 250.54 euros in Germany.
http://www.kymco-ersatzteile.de/shop/catalog/default.php?cPath=101_1579_1689_1712
Carburetor 216.10€
Air filter 81.44€
Together 550€ = $730.
Where do you get quality performance parts, better than original, for 1/4 of the original price?

[axy]

Why different exhaust on a 4stroke!?
The 4 strokes gas exchange is not influenced by the original exhaust.
There might be some psychological gain though.

And I doubt $200 would be enough.
The exhaust for the Kymco Agility 50 Basic (the smallest Kymco!) is 250.54 euros in Germany.
http://www.kymco-ersatzteile.de/shop/catalog/default.php?cPath=101_1579_1689_1712
Carburetor 216.10€
Air filter 81.44€
Together 550€ = $730.
Where do you get quality performance parts, better than original, for 1/4 of the original price?

You can get many performance parts for GY6 engines on scooterpartmania.com for 30 % of Kymco's list price.
Kymco has a very sweet margin on spare parts.