KTy

Alloha , I just freshly rebuilt a GTR engine from 71 for a friend of mine, I should add that I'm more used to rebuild kitted vespa engines... Almost everything have been changed, rings included, but when I start the engine, I am surprised how low is the compression... There seems not to have any air, oil or mixture leaks... Engine is working ok, but there is very little power at low RPM, I guess it is related to the compression as I have also double checked the ignition timing (22°). Besides that, points, condenser and ) HT coil are new. Carb (SI20/17) has been cleaned, but same disapointing results were found with a SI20/20... Mid and High RPM seem to be ok, cruising at 85-90km/h top speed... Exhaust is from PX, but it is not new. Any hints why the engine would be soooooooo lazy at low-RPM ? The deck clearance is more than 1mm in the cylinder head, could it be interesting to reduce the overall squish to something like 1.5-2mm by turning the cylinder head ? Thanks ! KTy

:love: :love:

Yep

Linda is very promising... :wasntme: Sorry for the offtopic

Strange !! Probably a bad connection or a bad component! There is *no* reason why the engine should not start... Remember, the 1uF/400V is a rather large capacity, and it is not polarized !! Send me your address via PM, I'll try to send you a "tested" one ;)

I've been told it is "only" 265euros ship. included directly with Tino Sacchi... :plemplem: ?!

15 french scooterists running this thing for some months now with no trouble at all, easier cold starting and smoothier ride And still no dyno nor any emission measures...

You *should* use the .............. SparkkkkkkkkkkkkkMagniiiiiiiiiiiifier :sabber: :wasntme: Already 15 peoples convinced

If you want to compare to mine that is supposed to be a Silent Pro: http://ktylife.free.fr/vespa/KTy133/zirriDimension.jpg

28 Italians HP ? :wasntme:

Okay mates Of course, everything is connected (like we all are :love: ), My crank is the standard one, I removed something like 10-15mm to it, and I also openened the case admission, something like 4+4mm... As for my jetting, I put the clip at the top of the needle, engine was smoother at mid-rpm I tried a 140 main jet :plemplem: , everything fine except full throttle still giving a freaking metallic sound, so I switch to 120, and that was it ! Much better under full throttle ! I will try the 125 tomorrow and I will probably keep it for reliabiliy reason Idle jet is 55, I unscrew the mixture screw 3-4 turns... I could probably switch to 60 idle jet, again, for reliability reason For now, I'm keeping the CF262 atomiser, I will try to take a picture of it, just to compare to an AV26x... Running on 8" wheels with 22/68, it is very funny ! Thanks to all for your help

I'll take a picture of it, but as far as I can see, it is pretty much exactly the same as the AV 262... I have a 120 main jet, I'll see if it helps... But I am affraid to size as the Leo pipe really push me in the high-revs !!

Some more information, Without any change to the carb, the engine rattle more easily at full-throttle when the load is increased (me + a friend of mine :D)... Main jet too big or too small ? Not enough kilometers to read the spark plug colour !

I already had a look a this website, it's a little bit helpful for a starting point, not really for fine tuning the engine ;) I will first try to set the neddle upper and see if it's change the pb at mid-rpm. I will also compare the engine agrreement with a bigger main jet, as I suspect the 262 atomiser to be just a little bit too small !

It's more probably a trouble with the atomiser/needle... I'm running with 18° of timing advance... Btw, the cutaway of the round slide is 40. Thanks, EDIT: Engine was smoother on all rpm range when it was cold... Too lean ?

So, I only manage to find a CF262 (from a PHBH28BD) that looks very very similar to an AV262... I put a 55 idle (I tryed 60, too much) and 130 main. Needle is still X2 and clip in second position from top. What I can say now: * Low to High rpm is smooth, but there is still something a bit anoying: If I maintain the throttle in the same position (for instance 1/3) for some times (few seconds), the engine revs smoothly then it starts to "rattle" (too rich or too lean ??) a little to bit, i.e, I cannot ride smoothly-all-the-time with the throttle opened between 1/3 and 3/4. During "transition", the engine is smooth, but when it is "stabilized" it can momentary do "Rrraararraraa" (4 stroke like ?!) . Atomiser too small ? Should I put the jet needle upper ? * I have the Leovince pipe and I think 130 is still too lean, the engine is reving a lot ! At full throttle in 3rd and 4th gear, the engine "rattle" also, but it's not like when it's too rich "Boooooahhh" , it's more like when the spark is misfiring... Possible ??

Comparing this one to an AV266, it seems there are exactly the same, except of course, the larger hole... I found it in a PHBH 28 BD !

Auto-reply after verification:-D : No, they are totally different !

Maybe the diffusor is my problem since the begining ! Where can I read about the differents between diffusors ? Can I use a diffusor from a PHBL 24mm ?? Thanks !

I just realize something, could it be that the diffusor (AV266) is too large for the needle I use (X2) ??

Engine is rebuilt *as new*, that is, new bearings, new seals, and the rest checked and/or replaced Of course, I could have done something wrong... The trouble is really at Low/Mid-RPM, exactly like if the chocke was engaged *from time to time* !! I checked and setup correctly the floater as mentioned by the Dellorto tuning guide. More detail about my config is: AV266 diffusor no air filter (rubber connection to the frame), no fuel pompe and original rotative valve (cut crank own made). Thanks

Ok guys, So I have freshly rebuilt a PX engine, with Polini 177, matched cases, cut crank, Leo pipe and, ... a PHBH 28 carb ... Let start by saying that I'm a bit suspicious about this carb (I couldn't tune my Polini 133 with it either but I thought I might have been quite impatient), but anyway... Idle jet is 60 and main jet is 120, needle is an X2 and circlip position is first from the top ... and I can't sort out what is going on at low/mid-rpm!! The best I could get was screwing in a lot the micture-screw... Engine is ratling quite violently, from time to time, low rpm is smooth and the second after the engine is boging. The only think that seems to be ok is high-rpm, but I'm aware that 120 is too small. I check the spark plug (new), but it was clearly dry/lean. So, maybe I'm too rich at low-rpm and too lean at high-rpm, and/or maybe I have some issue with the idle/low-rpm circuit inside the carb... Any idea reading my story ? Oh, and btw, the scooter is a VNB5T in 8" wheels with 22/68 primary, so running the Leo pipe is, for the first time, quite nice ! KTy

Great news :) Indeed: http://www.angelozirri.it/ita/news-techno.htm

I read it was something like 300?... I'm not sure though... Anyway, great to see that !! It's not yet officialy on the market, shouldn't be too long... Maybe some well informed people know more about this cylinder ? As one can see on the lateral transfer (clutch side) there is a *huge* potential for very very large transfer if one remove something like 2-3mm. Unfortunatly it won't be symetrical because there is not much material on the flywheel side.

Maybe I'm late but here you go a new 125.5cc alu cylinder !! http://lnx.et3.it/phpBB-2.0.17/phpBB2/view...der=asc&start=0