Polini 210 and long crank

Hi

Installed Polini 210, Dellorto 24/24, SipRoad last summer and it worked fine. Now need to replace the crank due to flywheel came loose. What is needed to run with a long crank with this cylinder, spacings? What stroke do you recommend?

Thinking on CDI ignition, any suggestions?

 

Thanks

 

 

Hello Dave, I am running a DRT 24/24 Si carb. 160/ Be3- 128, idle jet 50/140, throttle slide 4.1 with a standard air filter with holes above the idle 5mm/ main jet 8mm

MMW touring head, no gasket

SIP road 1.0

lighter flywheel 1.8kg 

Tameni  57 crank stock timing 55degrees ATDC

Cheers R.

Richard what carb set up are you running? I've just fitted polini 210 with sip Road. I want to get it right so really interested what works for you.  

Cheers Dave

in general any crank that closes after about 65degrees after top dead center you have some blowback from fresh mixture when you drive with a Si carb. the original Piaggio crank closes the inlet after +/- 55degrees after TDC, this is on the save side. The blowback results in less performance in the lower revs. and difficult carb. tuning. 

A Mazzucchelli original crank 55 Degr. ATDC

A MazzUcchelli racing crank about 70degrees ATDC

A Pinasco Racing crank 62 degrees ATDC

A Polini Racing crank 70 degrees ATDC

Tameni racing the same as the original crank 55 degrees ATDC

I tried some different cranks on the Polini 210 and the Piansco 57 racing crank gives beter results in the higher revs, the Tameni 57 gives more Torque in the lower revs but can not rev as much as the Pianasco crank. For me more Torque in the lower revs is the way to go. Some like a more reving engine.  

When driven with a PHBH carb with a longer inlet track the situation changes.

Hello Hans. If you instal a 60mm crank on a Polini 210 you have to use a thicker basegasket because there is no internal squisband to compesate the higher piston position, with the thicker basegasket the timing is way of and the cylinder does not run great.

Its beter to use the 57 crank with the moderate timing of the 210 cilinder, it give's beter performance.

If you use a 24/24Si it is better to use a crankshaft with stock timing of 55degree after TDC, this gives a good solid engine with great torque down under

I have tried different crankshafts and the Tameni 57 crank with the stock timing runs great with a standaard like exhaust like Sip-road, lots of torque down under! Best setup!

 

 

Hi

It's now all fitted and re-fitted many times. I have 2 questions I hope to get some very needed guidance on. 

1) The parmakit ignition seems to work well, but seems to be different ideas on what timing to set it on, the polini 210 needs 18 degrees with a fix timing, will that mean that I shuld set it a 18 on ideling and then it goes down to 11 at max. Or should I set it at 25 so it ends up a 18 at full speed?

2) I have the same card best up as you mention above, it runs well from half throttel but very bad below and only without air filter fitted, when fitting air filer (with holes) it won't run well on any rpms.

Greateful for some insights into these problemas as I'm soon out of options.

Thanks

Thanks richard

Seems as a bad idé to go for a longer crank. I'm not that familiar with stock timing, are the cranks tuned differently and what effect will different stock timing have on performance and for example ignition setting?

Thanks

/Hans 

Thanks Richard

Today the Tameni crank arrived together with new ignition. A week of joy to fit it and then hopefully a good ride in the weekend.

Thanks for your explanation.

/Hans