Skipper 172, Malossi 25mm carb problem..

Some time ago I started similar thread about original vm20 carb... http://www.scootershack.co.uk/threads/skipper-172-vm20-carb-problem.26169/
Well it was not ok after all, it was running rich from off-idle to 1/8...1/4 throttle, so I was thinking that malossi 172 kit would work better with malossi 25mm carb. (Malossi 172cc kit (AC kit with malossi head), stock airbox, stock "runner" exhaust )
It did not,.. exact same off-idle to 1/4 throttle 4-stroking/pig rich! Up from 1/4 it is "ok" so main jet is fine. I have checked all external thing that could affect this richness but no results

Why is this, I have not heard that most people had need to "tune" (this carb/cylinderkit) with idle jet or slide, or different needle??

 

I had this exact setup pretty much i didnt need to change anything only the main jet.

 

i run a 25mm dell carb, i was told it was set up to run fine with stock airfilter but required most jests changing when i whent over to an open filter,

have you checked what jets are fitted in yours, and wether they are clear and not blocked

 

This is so weird, couple of days ago I changes original idle jet (45) to 38 and it did not help much. Idle is so rich that I can turn in idle mixture screw all the way (yes, idle mixture, not idle air screw) and then idle revs start to rise. If I open "start enrichment" when engine idles, engine dies. Engine also idles well just after start without enrichment.
I even lowered the needle to lowest position (original setting was 1 higher..) not much difference.

I just checked reed block, it is solid metal with rubber coating/sealing and it is tight.. just to be sure I changed original reeds but did not test run it yet (idling was about the same..)

 

what about your pin in there carb were is tht set ?

 

Sorry, language barrier, "pin in there carb"? (you mean carb slide needle->above post)

Here is little demonstration of the problem (just using very little throttle..) Running sound "heavy"..

 

Now this starts to clear up... as I figured it was not mainjet, and testing showed that it was not slide needle height, nor choke and I tried lot leaner and little leaner pilot jet and it did not fix it.. And even reeds were ok. And no air leaks.
What was left other that malossi 172 kit was "broke".. just carb slide. Malossi 25mm carb somehow uses richest slide available (30) so my last try was desperate and could have ruined the slide. I filed it leaner, original cut height was 3.0mm (somehow slide number 30 fits to that measurement ) So I cut it to about 4.5mm and it did a lot!! Now it starts to be close..just little roughness so I'll file it little more and then hopefully I can enjoy driving it

 

dounds like u have a knocking noise coming from the engine might just be then vid ?

any air leaks maybe its getting air from some where giving it more air to burn the fuel so its raising the revs i could be wrong just an idea

 

I have struggle with exactly the same problems on my Runner 172.
I have a slide 60 on mine, still not good enough.

 

Nice to hear that I'm not alone with this issue Well, I was too happy to soon.. I filed the slide even more (to about "60") and it did not improve any more.. so issue is not resolved yet and there is not much to do.
I wonder why malossi cylinder kit behaves like this.. it is not even high end in terms of power.

Italjohn, what kind of tricks you have tried with this problem?

 

There is only aq260-270 available?? 282 atomiser would make it even fatter in up to 1/4 throttle.. (stock is 266, if I remember right..)