Polini 177 pinging problem

I have a PX125 99 year which has a Polini 177 fitted and all cases matched,ported etc.crank cut,inlet matched and a JL right hand exhaust.

The timing has been set at 16 degrees.

The engine is suffering from a pinging noise at high revs.As soon as the speedo reaches 55 mph upwards the pinging starts.Its really bad and i'm at a loss.I have ordered a 177 head gasket from SIP but was wondering if this will cure the problem.Also would the MMW Malossi head conversion for the Polini you sell help at all?

Thanks in advance.



i think the problem here is the fuel type that you use. You have to use the high octane fuel with 98 octan or 100 or 108 octanbooster will help




Than your pinging is gone ;-)




Clutch has already been upgeared with a 22 tooth cog.

What carb and jetting are you running ? Also what plug is in there ?

BE3 is correct, 55/160 and two hole on the filter ...

18-19 degree in flywheel

I really need a quick answer to this question please.

I need to order either of these parts for this weekend.[:'(]

I have tried the 0.8 mm and the 1.5 mm head gaskets from SIP.

The only thing i haven't tried is the MMW head.

1,5mm is truly exagerated (you have a standard crank - stroke 57mm - haven't you?), 0.8mm is very high too but it still functions (loosing a lot of torque)...if you had the problem also with the 0.8mm gasket than the cause must be something else (in other words the MMW cannot solve your problem). I am sorry for having misunderstood the situation.

24-24 Si carb matched inlet.

160 BE4 125 main

52-120 idle

B8 plug

"Would using  head gasket from SIP or the MMW head help cure the pinging at high revs?"


I think so. The 177 polini suffers from exactly this problem, because of its head; the MMW is made just to solv the problem without loosing torque, while with a gasket, which is of course a much cheaper solution, you have to renounce to a little torque.

Hi dude


At fist make shure that your ignition is ok and that there is no mounting fault.


Is your ignition at 19 degreees and do you use a W4AC plug ?


Is the carburetor a 24 SI or higher ?

What jets do you use ?


Basically its really hard to advise you with a forum post to resolve your pinging.

I can give you only an idea or recommendations.


cheers and good luck.

it could also be that you need to upgear your scooter. the px125 gearing will overcook the polini. pinging because theres too much heat. And use as high a octane fuel as available

Tried a BE3 and 18 degrees timing.

Pinging was a lot worse than it is now.

So back to the original question....

Would using  head gasket from SIP or the MMW head help cure the pinging at high revs?