Jetting 14.12 Dell'orto, 75 Polini on Minarelli V1

So this will be my first big tune and I'm curious who has done what... with a similar setup as myself.

After reading the Polini book that came with the kit, it says for SHA 14-12 to #54 jet the carburetor.

I know people have probably tried quite a few of the jets and I'm itching to hear some results.

Would continuing to up jet allow for a greater top speed? (i know about the break in cycle) but afterwards it would be nice to push 40-45mph.

I'm willing to do the trial and error myself, but any input would great, even a starting point.

Thanks a lot!

Joel

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

My only constructive feedback for you is that the Polini manual is wayyyyy off. :D

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

If your carb is a stock (not bored out) 14-12, I would go with a larger jet until it is broken in and then work down to something that gives you some good plug readings.

Also, you might get a little more speed but to get a lot more speed you will have to up carb, get a pipe and also re-gear.

Be aware that if you re-gear, you will lose a little acceleration.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

I highly highly recommend getting a 15.15 dellorto at the very least, for engine safety as well as performance.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Perfekt Timing Angel /

I would go even bigger than that...19mm at the smallest. The SHA's really lean that kit out. I know others will say it's ok, but I have had absolutely no luck with either a 14:12 or a 15:15.

If anybody has the secret to tuning a 14:12 with that kit, please fill us in.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

A SHA carb will not tune withing the RPM range that is available for that kit.

If you take off nicely, you will be lean up top. Switch that around and it's also true.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

sha on a polini 75cc for over a year right here people.

the secret is....in the exhaust! thats what limits/restricts the V1 no matter what the cylinder. our shit is a bored 1412, 14 14 now and only with like a 54 or 56 jet in it! why? because anything bigger was too rich. sounds insanely small right? not if you're sporting a stock or nearly stock exhaust which keeps your revs down, which keeps your air intake down, which means you dont need as much fuel.

still got some decent torque and she pulls well to 35...but the stock exhaust flatlines here right there.

so to the OP, we need to know what exhaust you're running.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

HMMM search button works great.. its been talked about... good luck dont sieze that bad boy.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Yes the Exhaust is the key in the hole 2 stroke. Its huge part of it as is the carbie and porting. I don't understand why get a kit and freakin limit/restrict when it is ment to run rpm into the powerband hmm.. 7.5hp right? Just my 2 cent. Angel has driven some of my peds they rip 13-44 gears. 19mm no porting, exhaust is a stock sarfari turbo pipe 17mm I reflanged/mod/welded it bigger. When I switched from the mamba pipe to this pipe lost 10mph and had to play with the jetting for a bit. I have a air cleaner on it now as I was running it that paint cap.

1210080308_dsc02222.jpg

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

I did body work on the tank thats why its white.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Haven't chosen an exhaust yet... Sounds like this was more of the equation than I had anticipated... Thats good because my next performance question was going to be about exhausts with Polini kits.

Ya know Ed, go ahead and look for 14/12 14.12 14-12 in the search for yourself, I've taken a gander more than enough, and without the answer I was looking for I resorted to just starting a new thread... isn't that what they're available to do? :p

Anyway, sounds like I should possibly pick up a slightly larger carb and finalize an exhaust. This will still leave me wondering jet size, but live and learn.

Thanks for your help gang!

Joel

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Just buy a range of jets appropriate for your carburetor, you'll need a few jets to tune properly anyway. I think a good range to get started would be perhaps....

for 14/12mm: maybe 56-65, 16mm: 62-80, 19mm: 85-120

It also depends on how restrictive your airbox is and what pipe you're running and if you've ported or case-matched or done anything else to the engine, of course, so its hard to tell exactly. If you're going quick and you hear your rings start to chatter, lay off and upjet.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Perfekt Timing Angel /

See, I've used a Mamba on all my bikes, kit included. So yea, having the stock pipe would restrict the RPM's and keep it within tolerable levels. You won't get stupidfast from it, but it'll make the torque.

The first time I used an SHA on my kit, I would IMMMEDIATELY go into a wheelie from the amount of torque at 1/4 throttle. That's how lean I was. Aaaaaaand, I was jetted with a 58.

I switched to a 15:15 on the next set-up, jetted at 70 ish?. I opened it up a few times on some back roads, probably doing about 40-45ish without seizing. I try to climb a big will one day and just gave a little too much throttle. WHHhHAHHAAAAAA-Ziiiiiiiiiinnnnnnnngggg. Done.

I have an Estoril that I'm going to try with my new set-up.

Bitter must have some super awesome powers or something. Ha!

And yes, Ed is a mastermind when it comes to Minarelli performance. Trust him, his bikes are scary fast.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Read about plug chops now. Joel. :) That will help with your jetting.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

https://www.mopedarmy.com/forums/discuss/7/86328/86328/

I did find one that silverfox did a while back.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

Thats some good info I never expected! My search abilities suck... I don't know how I missed that thread, I've been on here a lot lately trying to pull info.

I'm thinking that moving up to a larger carburetor later this summer will be the way to go, until that day comes I will tune my current build to perfection.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

19mm PHBG on ebay for $70+shipping.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

havent settled on an exhaust yet, though tig class this fall broadens the possibilities. i have a biturbo from a tomos i got cheap and repacked myself, i'm going to frankenmuffler that onto the V1 and see where the power band goes.

also planning to make an intake the the 19mm PHBG...cant run that with the stock exhaust lol.

Re: Jetting 14.12 Dell'orto, 75 Polini on Minarell

hey dumb dumb, get a bigger carb, your kit will thank you!

Ps just kidding about the dumb dumb part.........

you should try using the search, it works really good!

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