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Re: Looking for 70cc polini big bore advice

Posted: Thu Jun 21, 2012 7:37 pm
by maddog
Hey Kona, been running the stock pump for 17 yrs. i can tell you that the stock pump gives out at 50,000 mi. so i replaced it with a sym pump at 1/3 the cost, just have to swap out the shaft, at 76,000 mi. i still beat the crap out this engine with a 44.7mm crank = 76cc polini :smile:

Re: Looking for 70cc polini big bore advice

Posted: Sat Jun 23, 2012 12:53 am
by kingkamehameha
Nice to hear from you maddog. I still wouldnt reccomend using the stock pump

Re: Looking for 70cc polini big bore advice

Posted: Sat Jun 23, 2012 4:17 am
by paulpauly7
on yahoo auctions japan you can buy a new modified oil pump for the af18 that pumps 1.5 times more oil than stock ideal for bbks without the hassel of premixing

Re: Looking for 70cc polini big bore advice

Posted: Sat Jun 23, 2012 7:20 pm
by veedubh20
oil pump plug are better , no hassle! :2thumbs:

Re: Looking for 70cc polini big bore advice

Posted: Sat Jun 23, 2012 10:54 pm
by scottinscotty
oil plugs equal.. to much hassle at the gas pump! i think pre-mixing hide's poor carb jetting skills! :geekdance:

Re: Looking for 70cc polini big bore advice

Posted: Sun Jun 24, 2012 6:58 am
by kingkamehameha
scottinscotty wrote:oil plugs equal.. to much hassle at the gas pump! i think pre-mixing hide's poor carb jetting skills! :geekdance:
You must be mentally challenged if you cant add 4oz of oil to a tank. In my case i can only put half a gallon at a time so 2 ozs is pretty quick

Re: Looking for 70cc polini big bore advice

Posted: Sun Jun 24, 2012 5:44 pm
by mmeadows
scottinscotty wrote:Taped a second hole.... I've put almost 2000 miles on my kit with the stock oil pump...

can we see a picture of this mod? think it would work on a af05 with bbk?

Re: Looking for 70cc polini big bore advice

Posted: Sun Jun 24, 2012 6:32 pm
by Trafficjamz
some oko carbs have the oil injection port built in.

I have a 28 mm carb that has it.
scottinscotty wrote: i think pre-mixing hide's poor carb jetting skills! :geekdance:


That make zero sense :crazy:

Premixed two stokes are not any easier to jet :*:

How do you deal with the split throttle cable to the oil pump? Do you just tie it open?

Re: Looking for 70cc polini big bore advice

Posted: Sun Jun 24, 2012 9:16 pm
by mmeadows
Trafficjamz wrote:some oko carbs have the oil injection port built in.

I have a 28 mm carb that has it.
scottinscotty wrote: i think pre-mixing hide's poor carb jetting skills! :geekdance:


some oko carbs already have two oil injection ports? so do you then just connect the the two ports to the one oil pump barb, and this somehow gives you a better ratio? why its still the same oil pump?

stock oil pump = extra trunk space and less hassle so i really want this to work but don't fully understand it.

Re: Looking for 70cc polini big bore advice

Posted: Mon Jun 25, 2012 2:21 am
by Trafficjamz
mmeadows wrote:
some oko carbs already have two oil injection ports? so do you then just connect the the two ports to the one oil pump barb, and this somehow gives you a better ratio? why its still the same oil pump?

stock oil pump = extra trunk space and less hassle so i really want this to work but don't fully understand it.

Some OKO carbs have a (single) oil injection port.

Most OKO carbs DO NOT.

Re: Looking for 70cc polini big bore advice

Posted: Mon Jun 25, 2012 4:20 pm
by mmeadows
Trafficjamz wrote:ome OKO carbs have a (single) oil injection port.

Most OKO carbs DO NOT.
well what about this "tapped second port" you ask scottinscotty about. can you explain it to me more. ive pmed scottinscotty but i dont think i'm worth his time :( which is understandable as i would be busy riding too if i had his set up :coolcruise:

Re: Looking for 70cc polini big bore advice

Posted: Mon Jun 25, 2012 6:27 pm
by Trafficjamz
the CT manifold had one hole tapped into it.

It is used to connect a vacuum line to the fuel petcock.

The stock manifold has two holes, one for vacuum and one for oil injection.

Re: Looking for 70cc polini big bore advice

Posted: Thu Jun 28, 2012 1:04 pm
by scottinscotty
well i have been on vacation.. when i get back home i'll take some photo's of the intake mod.. it's very simple.. if your running an oil injection pump "if you don't have a port in your carb" you'll need to tap a second hole and screw in a second fitting.. like i said when i get back i'll take a couple pics and post them... :geekdance:

Re: Looking for 70cc polini big bore advice

Posted: Thu Jun 28, 2012 1:10 pm
by scottinscotty
If you richen the pre-mix ratio (20:1 as opposed to 30:1) there is more oil and less fuel in the same volume of liquid, which effectively leans the air-fuel ratio. And this fact gives the clever tuner one more tool to use when the correct jet is not available or when none of the standard jets are exactly right. You can richen the jetting by slightly reducing the pre-mix ratio (less oil). You can lean the jetting by increasing the pre-mix ratio (more oil). The best part is that changes in the pre-mix ratio affect the jetting over the entire throttle-opening range, but the changes in ratio must be small to prevent excess wear from lack of lubricating oil or fouled plugs from too much oil.

Re: Looking for 70cc polini big bore advice

Posted: Thu Jun 28, 2012 1:13 pm
by scottinscotty
so when your mixing 32:1 your gonna go up on jet size... or if your running 50:1 your going down on jet size to compensate for the lack of or excess of fuel..