keuk

Hello, I have two SKF explorer 6204 bearings for my smallframe engine, a standard one and a C3 one. I'm going to use them on my racer engine. Which one should I use for the crankshaft and which one for the drive shaft ? Thanks.

Do I really read 50hp on the curve, and 35Nm !!!? WOWW

Yes I removed it.

Hello, I use a 9,6mm spacer under the barrel and the actual curve of the transferts in the casings looks really steep, I haven't modified the curve in the transfert ports of the Polini. Should I modify the Polini curve and mill the parts to have something more round ? Here are some pictures of the actual shape with original curve ( left view):

Ok ! Do you know where I can buy some ? It's hard to find webstores that can send it to France.

What is the red material that you use to make a copy of the transfert ports ? ( the one on the pictures of the first page ). I have started to make a 3D model of the Polini evo cylinder for fun, and I would like to have something more accurate for the transfert ports. Here are some previews:

Do I cut the lower part of the piston too on this side ?

Hello, Can I cut the base of the barrel to fit with the casing intake ? Is it ok if the lower part of the piston goes a little bit further than the blue line ? (Transfert ports are not yet ajusted)

Hello! I have a curious thing on my et3...I have the original electronic ignition, but the timing change ! The timing should remain the same but when I throttle it increases of 5/10 degrees to a new stable value...Is it normal ? ( I use a stroboscopic light connected to an external battery)

Hello, What is the good torque to tighten the nuts of the cylinder head on this aluminium cylinder ?

Hello, I hesitate between two kind of crankshaft for my Polini Evo racer with engine casing intake. I hesitate between a plug'n play crankshaft or a full circle one that I would have to modify. At the beginning I was interested by the DRT Sprinter model, but I realise that the shape is very different of the reworked models that I have seen on the Polini Evo thread. Here is a scheme of the DRT model, it lets the full access in the casing maybe a bit late. Here is the model from the Polini Evo thread: It allows to open the access sooner than the DRT one, but I would have to reworked and then to adjust the balance of a full circle one... I'm still undecided..

So for a daily use, is it better to have 185 or 180 with 30* blowout ( with pm40 / koso 28 / lighter flywheel...) ?

It's gonna be thick !!! Even without touching the transfert ports of the cylinder.

Original flywheel, and even reduced Sip flywheel don't pass !!! I should have known !! I wil have to machine a chamfer...... Timings without any gasket: 180/120 Timings with base 0,5mm gasket 182/123

I would like to adjust the timings to use it with a PM40, If I remember rightly I should have 185 to the exhaust.

Thanx for the advices guys !

Thanx !

The original is already 68/69% (56,7mm barrel with 43mm width)

Hello, For a daily use, and a good torque, is it better to keep the original Polini EVO exhaust shape and just add a few millimeters (to increase de blowdown to 185°) or to change the shape as the third one ? Maybe the third is better for a race use ?

Hello, What is the connecting flange diameter on a PM40 exhaust ?

No no these are all the dimensions I took on the cylinder, exhaust hight, laterals hight, and cylinder hight, I deduced the squich with these values and the theorical "64" "64,5"... Next week I'll know the truth. By the way, is it better/easier to machine the cylinder head or the cylinder to adapt the squich ?

Das ist sehr richtig.

I have checked the timings of my Polini EVO cylinder on solidworks. I'm not really close of the timings in the Polini assembly instructions notice... There are two versions, one with 64mm between the crankshaft axis and the base of the cylinder and one with 64,5... I don't know yet how much I have on my engine but in both case I haven't use the gasket (I have added 0,1mm for the Dirko / Loctite for the gaskets). I think in any case I will have to use the 0,5mm copper gasket because there is no clearance between the matting surface of the cylinder head and the top of the cylinder... So the squich will be 0,3/0,5mm higher.. Well, it just a simulation, it will be probably different once I will put it on the engine casing. But the squich is very very secure.

Thanks !

Sure, I'll take more or less this measure and adjust it to find the same timings annouced by the manufacturer, (here the 126/178° of the Polini EVO) then I will check how many millimeters I have to increase the exhaust port to have 30° blowout. (that's just a simulation I'll take the correct timings once I have access to my engine). I think it should be 1/1,5mm. Thank you ! So when the manufacturers annouce the timings of their cylinder it will differ on each engine casing right ?