PK50XL2 Automatic

Wheels by PK · March 6, 2008 at 20:01

Hello,

Apologies for the English - I have no German skills.

I'm a Canadian living in The Netherlands and am currently rebuilding a German 1992 PK50XL2 Automatic. This model was never sold here in Holland and there is very little information available. I need help with a running problem.

I have completely rebuilt the engine using new bearings, oil seals and piston. The engine originally had an oil injection system, I have removed this (too complex), and have switched to using premix fuel (easily available at service stations here in NL). I believe I have two problems. The engine has not been modifed.

Carburetor - the engine is difficult to start when cold (it has electric start only), requiring full choke and at least 15 - 30 seconds of starter. Once it is running, it is easy to start. I also find that twisting the throttle results in a slow response. It builds revs slowly compared to the 1986 PK50XL, that one is much more responsive to the throttle.

Variator / Clutch - when I rebuilt the engine it contained 7 weights 16mm x 13mm at 6 grams each. I have reduced this to 5.5 grams to improve acceleration. This has helped somewhat. I also wanted to modify the clutch but the springs appear to be unique to this model. The three friction shoes weigh 135 grams each so I have reduced these to 124 grams. This has improved the acceleration somewhat but it is not where I feel it should be. I don't want to do more modifications to the drive system as I feel the carburetoration needs attention.

When accelerating, it is very slow to take off from a stop. You almost need to put your foot down once or twice before it is stable. The belt drive doesn't move into 'high gear' until about 30kph. It will pull strongly from about 15 to 40kph and will reach between 50 and 55kph max. I don't push it too hard as the new piston/rings only have about 70 km on them. I have no idea if this is normal but compared to my XL (4 speed), or my 50S (4 speed), the XL2 is very sluggish.

Any assistance would be appreciated including any documentation on how to modify these engines. I don't want to increase the displacement due to the strick regulations here in NL but would like to improve the performance a reasonable amount.

I will thank you in advance for your words of wisdom.

Thank you and take care,

Peter Keun +31.61.583.1123

sylle · March 6, 2008 at 20:21

At first sorry for my bad english.

The problem with the clutch and the fathers i doesnt understand because it fits from the new scooter.
but you must use a very weigh fether

The automatik is very slow your problem will be away when you make a 75 ccm kit from pinasco on the scoot it will be help at the start and when you flow that cylinder you will have much more power.

attention it is the only which will fit on you scoot

i hope i can help

Wheels by PK · March 10, 2008 at 18:45

Hello Sylle,

Thank you for your answer, your English is quite good. Two questions - what do you mean with the words 'father' and 'fether'? I assume you mean weights.

Are there any documents about the XL2 Automatic in the forum archives that would help me? I would try to translate these using Babelfish (Altavista).

Many thanks and take care,

PK

gandisgarage · March 10, 2008 at 18:49

father
[Blockierte Grafik: http://www.tv-nostalgie.de/Sound/EddiesVater2.jpg]

fether
[Blockierte Grafik: http://www.rojo24.de/bilder/feder/feder_950.jpg]

sylle · March 10, 2008 at 21:55

hehe thank you my english teacher is still not amnused

I meant the fether.

Yes it gives a reparature Guide for this model. But only of german. You can ask Kasonova then he can send that so you can try to translate that with Babelfish.

chup4 · March 11, 2008 at 10:10

fether=vogelfeder

was du meinst ist "spring"

in addition to the problems:

i do not exactly know HOW sluggish you baby is, but an automatic is always way sluggier than the handshifted models.

to the starting problem:

have you tried the standards:

-brakecleaner spray into the air-intake (faster start then?)

-what colour does the spark plug have?

the wheighs, you reduced, make the transmission way shorter. the reduction you made is not very much, but i must admit, i do not have an automatic

one thing i didn't get is:

when you start your vespa, it accelerates, stops accelerating, and then goes on? when reducing wheighs you need more engine-RPM to accelerate.

Wheels by PK · March 11, 2008 at 19:35

Hello Chup4,

Thanks for your reply. Let me try to better explain my situation.

Cold Starting - When the scooter is cold it does not start as easily and quickly as my PK50S. I need to use the starter for many revolutions (with full choke), before it will start. Then it may stall once our twice within the first one or two minutes. After the engine is a little warm it is no problem.

Acceleration - it will accelerate reasonably well and smoothly but not as quick as my PK50S. I understand that this seems to be the nature of this model. This is why I started to modify the Variator and clutch.

Variator - the engine was in parts when I bought the scooter. The weights were 16 x 13mm 6.0 grams each. I assume these are the standard (original?), weights. I felt the Variator was a maximum diameter too early (~ 30 Kph), which is why I reduced the weight to 5.5 grams. I feel it now engages around 35 Kph allowing the engine to use more of the rpm range.

Clutch - similar situation as with the Variator. I felt that clutch was fully engaged too soon, well before the V belt was at it's maximum ratio (~ 30 Kph). To me it should slip more to allow the engine to rev longer, this would improve acceleration especially out of corners. Normally you would just replace the springs with lighter ones but these are no longer available. That is why I reduced the weight of the 3 shoes from 135 grams to 124.

The change to the Variator and the clutch have greatly improved the performance without any change in top speed. At the moment, the top speed is between 50 and 55 Kph. The piston is still new with only 75 Km on the engine plus I weight 90 Kg so I can't push it too hard.

I hope that helps to explain my situation. Hopefully your English will allow you to understand better.

Thanks and take care, PK

sylle · March 11, 2008 at 20:23

The weights for the variotar normaly 15*15
But i drive 15*13,5 7,3g and it works like the orginal

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