E50 polini tm24 jetting and plug

Luke Stroehlein /

Hi all, I have a polini project going and am trying to prevent seizing before I run it for the first time. I have the intake ports opened up a little, 4 petal dio knockoff, 24mm intake, hpi mini internal rotor, case matched, mlm Cali side bleed. What jetting would you recommend? Also wondering if you have a recommendation on the best plug heat to use. Thanks!

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Re: E50 polini tm24 jetting and plug

Dirty30 Dillon /

Why is your crank case tapped for vacuum?

Re: E50 polini tm24 jetting and plug

Luke Stroehlein /

Running a fuel pump, also mikuni, 14lph

Re: E50 polini tm24 jetting and plug

Dirty30 Dillon /

> Luke Stroehlein Wrote:

> -------------------------------------------------------

> Running a fuel pump, also mikuni, 14lph

Interesting. Seems like overkill unless you for some reason can't run gravity feed due to tank location.

Re: E50 polini tm24 jetting and plug

Luke Stroehlein /

I'm building a kinda overkill bike, trying to push the envelope

Re: E50 polini tm24 jetting and plug

Overpriced Parts /

Fuel pump is great for a tm24 cause because unless you have the float so high that it almost leaks out of the overflow you’ll be for fuel starved at hi p.m.

For a polini that the intake on the cylinder boost ports opened up a bit start at around 190 jet and work down should be good, stock without the intake opened up on boost ports the tm 24 carb may too big, 8# ngk plug

Re: E50 polini tm24 jetting and plug

Luke Stroehlein /

Awesome thank you! I need to check what jet I have in there, I know I changed it out but it's been a few years that I've left this project sitting. The ports are definitely opened up. I've seen some people here running 200 or even as much as 220 on a polini. 190 isnt gonna be too lean in your opinion? And 8 spark plug, got it!

Re: E50 polini tm24 jetting and plug

190 should more than likely be too rich. What pipe? Probaly more around the range of 155-160.

Re: E50 polini tm24 jetting and plug

Luke Stroehlein /

Mlm Cali pipe, she's a fatty that's it hanging on the frame during a mock up

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Re: E50 polini tm24 jetting and plug

B8HS is a good plug. Jetting around 170 BUT you have to be certain that you don't have any air leaks. Best way to check is a leakdown test.

What did you gap your ring to?

Have you tried doing a piston drop test (with the intake bolted on but no piston ring) to see if it's rubbing on the cylinder anywhere? Check out this thread:

https://www.mopedarmy.com/forums/read.php?7,2681917

Here's a good writeup for the polini:

https://magnumdash.wordpress.com/2010/03/18/guide-pro-tips-to-building-a-puch-polini/

Re: E50 polini tm24 jetting and plug

Overpriced Parts /

The drop test is totally different if you have the cylinder bolted to the case first, That’s the way I’ve always done it and it’s way different,

I bolt The head, cylinder, piston and everything on then I attach the intake to the cylinder it’slike night and day, the drop test that pulls up on the cylinder on intake side making the piston drag a bit is almost nil.

Re: E50 polini tm24 jetting and plug

Dirty30 Dillon /

How do you drop a Piston through the motor to test if the cylinder and head are bolted to the case?

Re: E50 polini tm24 jetting and plug

Brandon Weiss (Detective brandon to you) /

> Dirty30 Dillon Wrote:

> -------------------------------------------------------

> How do you drop a Piston through the motor to test if the cylinder and

> head are bolted to the case?

I think he means that he assembles the motor and then drops it on the floor, a durability test of sorts

Re: E50 polini tm24 jetting and plug

Luke Stroehlein /

Well I dropped the entire engine on the ground as suggested and now it's cracked, thanks guys... But in all seriousness thanks for some of the suggestions, I'm gonna do a little more tweaking and testing before I run it. Bought 2 BR8HS plugs today, one for the engine and one spare.

Re: E50 polini tm24 jetting and plug

Insert facepalm pictures

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