Minarelli Polini 80cc Kit Questions

Hey all, I picked up a Gadabout (Minarelli V1) moped for $250 a couple months back. It has the following: 80cc Polini Kit + a Brand new 80cc Kit, Polini Custom Head, MLM Intake, Dellorto PHBG Carb, MLM Peoples Pipe, 2 brand new tires. Also all the stock stuff and a spare engine. Plus a title!

He broke a ring and it looks like he never chamfered the ports and it got snagged. The inside of the cylinder has a slight scuff where you can see it snagged it. So I'm just going to move forward with the brand new 80cc kit.

The plus for me (I've only had stock bikes) is he already has the carb and timing set up for the new kit because he rode this for a year with this setup. I think it would just be smart to overlook what he did just to know exact things like jet size & if he timed it correctly for the new kit.

Does anyone have any tips for me installing this kit? It seems pretty self-explanatory but I don't want to screw anything up. The trickiest part seems like getting the rings on the piston & chamfering the ports. Any tips or tricks would help significantly. I have looked at some of the wiki articles on installing a kit. But this will be my first time. Thank you!

Re: Minarelli Polini 80cc Kit Questions

post some picts of the damaged cylinder/piston. some will chime in on whether its usuable, better to mess up one thats messed up b4 u mess up the new kit.

Re: Minarelli Polini 80cc Kit Questions

Here's the cylinder that he broke the rings on. The worst is the groove in the first picture.

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Re: Minarelli Polini 80cc Kit Questions

Here's the piston.

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Re: Minarelli Polini 80cc Kit Questions

you could totally run the used one if you want to but since you have a new one i would just build using that one and sell the used one.

those kits are pretty tough to kill, you gotta mess up bad to seize them.

i'd definitely check the crank seals and make sure that didn't have anything to to with seizing... that looks like a classic hot seize, either too lean of jetting or spark timing too advanced. or like i said a blown case seal causing an air leak.

Re: Minarelli Polini 80cc Kit Questions

Thanks for the help man! To check my case seals would it be just looking to see if oil is seeping out of the case past the seals? Or is there other things I should look out for that are red flags.

So I need to chamfer ports, double check the timing & jetting, check out the state of the crank seals. (One of these is the issue that caused him to seize and break a ring, correct?)

I'm hoping to remember every little important step now so in the future i'm not tearing it down because I missed a rookie step.

Re: Minarelli Polini 80cc Kit Questions

when you see that scratch where the ring land is, usually that is from not gapping the ring correctly, the ring expands and gets too big for the cylinder, i guess it can break from that but that piston doesn't show any of the signs of a broken ring. that looks like a classic hot piston scuff.

you can build it and see how it runs, chekc for an air leak after its running, i would probably pop in new seals at the very least while you have it on the bench. v1's are pretty easy to get the seals out with the engine all together.

Re: Minarelli Polini 80cc Kit Questions

Brandon Weiss (Detective brandon to you) /

One thing that can really help when pulling out old seals from an assembled case is to push the seal farther in a touch! Its way easier to unstick the seal from its position with a sharp tap from a hammer/dowel than it is to overcome it with a seal puller.

Re: Minarelli Polini 80cc Kit Questions

Okay good to know, he definitely was running too hot. Come to think of it he never said the rings broke in the cylinder they were just broke when I bought it. He may have broke them trying to get them off.

As for the seals, I will go ahead and buy them just out of caution. Are all of the seals able to be replaced without taking the engine apart? Thanks for the tip on pulling them out! I will definitely do that.

Another question I have (it may be stupid) is the exhaust hole and the cylinder exhaust port suppose to be a different size? The exhaust is significantly bigger than the polini cylinder. Will the gasket still seal this up alright?

Also a pic of me organizing things that need to go back on the bike.

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Re: Minarelli Polini 80cc Kit Questions

the exhaust thing is no big deal, you can probably google or youtube how to pull those seals with the engine still together, i usually use a #4 sized sheet metal screw to pull them out but you can also use a hook style seal puller or punch a hole in the seal and pry it out with a pick.

you have one of my heads, lucky you! that should help with the cool running, check your timing and tuning and as long as everything else is ok it should be running high 300's max. those polinis can run super hot and be ok, but with that head it shouldn't be breaking 420 with the right tuning. when we developed that head we used a very similar setup to yours, stock head was running 450 ish max temp under full power blast, with that head we came down to running 380-390 almost all the time with brief spikes up to 400 under heavy accel.

Re: Minarelli Polini 80cc Kit Questions

Hey thanks again man, you've been a really big help! I will have to youtube how to pull the seals out with the engine still together. Hoping it's not too big of a headache and it will go rather smoothly.

That's awesome about having the head you created! It sounds like as long as I get the timing to be correct and make sure there's a big enough jet in the carb I should be pretty set. I bought a temp gauge so I will definitely keep an eye on the temp to tune. Super good to know I shouldn't hardly ever be breaking 400 or something is wrong.

Should I go ahead and replace all the seals or just the crank shaft ones? The crank shaft seals I can get out without splitting the engine but the others I need to tear into the engine correct?

Re: Minarelli Polini 80cc Kit Questions

yeah the crank ones are the ones that cause air leaks so they are the most important to replace.

you don't gotta replace them if they look good, i'm just saying its one potential cause of air leak, its up to you if you want to do it for preventative maintenance. they just can be super frustrating if you cant find the air leak because they are tough to troubleshoot.

if it were me i'd do them because they cost $4 and i can get them swapped over in like 10 minutes, but for a first timer its kind of a tricky operation... i dunno what to tell ya. I always rebuild engines before i kit them period but V1's are one engine that tends to hold up to a kit without being rebuilt pretty well...

i dunno, more confused now? i guess look at what it takes to change the seal, then look at your seals, then make a decision if you wanna do it. its not hard, but it is tricky.

Re: Minarelli Polini 80cc Kit Questions

You're incredibly good at describing stuff. Sounds good, I will take a look at them this weekend and go from there. Excited to start on this! I just need to make a list and take each step at a time. The main thing is trying to figure out why it was running too lean/hot in the first place. But I think I got this.... for now lol

Re: Minarelli Polini 80cc Kit Questions

One other quick thing. Is it beneficial to get a needle bearing for the con rod instead of the brass one that's in it? I feel like i've seen that somewhere. Also if so does anyone know the size?

Re: Minarelli Polini 80cc Kit Questions

Dirty30 Dillon /

You can't swap a needle bearing in where the bushing exists. You can replace the conrod or entire crank with a needle bearing unit if you so desire.

That said, I have seen plenty of brass bushing v1's last a REALLY long time

Re: Minarelli Polini 80cc Kit Questions

Awesome I will roll with what I have. Thanks man!

Re: Minarelli Polini 80cc Kit Questions

Me again... I bought a little set of files and I'm going to get the cylinder ports chamfered this weekend. Would it be beneficial to do the piston skirt as well? Or will that not really do much for me?

Also my list i'm going by:

- Chamfer Ports - take the sharp edge off of the cylinder ports

- Chamfer Piston Bottom Skirt

- Gap rings 0.188mm-top ring | 0.002mm bigger-bottom ring (beveled edge towards top of piston)

- Install rings, pin, piston & circlips (align clips so the gaps are either up or down)

- Install Kit & Gaskets

- Install Pipe Bracket & Pipe (take off back tire and suspension to get to bracket)

- Install new tires & tubes

- Check Timing - 21mm BTDC

- Check carb settings & main jet

- Replace Crankshaft Seals (can be done without splitting engine / use screw method)

-Install pedal arms & pedals

Re: Minarelli Polini 80cc Kit Questions

Brandon Weiss (Detective brandon to you) /

Well, you can only install the rings one way due to the shape/location of the gap and pin, and theyre both the same type of ring, so no need to worry about that.

Ring gap seems to match what the wiki suggests.

Re: Minarelli Polini 80cc Kit Questions

sounds like a good plan.

what do you mean by 21 mm btdc on the timing?

it should be something like 1.6 mm of piston travel or 18 degrees. i don't know exactly what the piston travel should be on a V1. are you using a piston stop micrometer or measuring flywheel circumference or what?

if you are running stock points just set timing using the service manual specified gap and set the stator rotated fully retarded, if you are using a head temp gauge you can use that to tell you to advance or retard timing from there. With that big pipe on there, especially for break in, you'll be wanting to be at 16-18 degrees of timing until you understand how its running and can dial things in.

Re: Minarelli Polini 80cc Kit Questions

Thanks Brandon, only one way that should make it easy!

Graham, I have a piston stop micrometer that the guy included but i've never used one. I will have to watch some videos on it. Somewhere on Mopedarmy someone stated 21mm btdc so I just wrote it down for now haha.

So it sounds like I should set it to around 18 degrees. I can acheive this by setting the specified gap and then set the stator fully retarded. Is this correct?

Good to know on the 16-18 degrees, writing it down now.

Re: Minarelli Polini 80cc Kit Questions

if you have a piston stop micrometer you'll need to find a conversion chart for the V1 that converts degrees into mm BTDC.

it wont be 21.. unless that is some kind of magic number from the installed distance with it in the head or something? i dunno.

it should be something in the neighborhood of 1-2 mm. tbh i'm surprised nobody has chimed in on this thread to call me a dummy and say what the actual correct number should be. i don't fux with V1 much... call andy scouten.

Re: Minarelli Polini 80cc Kit Questions

Okay cool. Dude thanks so much for answering everything! You've been a HUGE help! I will search on here a little more and see if I can find someone else setting their timing with this kit. I'm assuming it's somewhere.. I won't be messing with the timing for another week or two so I will research some more. Thanks again Graham!

Re: Minarelli Polini 80cc Kit Questions

>>>taykoff [s2m] /

Let me start by saying that Graham is one of the most helpful members on this forum, thanks for being so rad.

From the manual,

V1 Manual

The points should just start to open at 23 degrees before top dead center (BTDC). There should be alignment marks on the flywheel and the casing.

Once you get everything set-up stock, you can get more out of your kit by matching the exhaust port to your pipe.

Have fun, V1's are a blast....(edited)

Re: Minarelli Polini 80cc Kit Questions

Thanks man! I will get it set up to the alignment marks on the flywheel so it will be 23 degrees BTDC and then retard it slightly to around 18 -21 degrees. I think this seems like what most people are running with.

And yes I can see that Graham is one of the coolest guys on here. Full of knowledge and willing to share and help out someone like me that most of the time have never attempted anything past just basic maintenance.

I will have to share pictures throughout the next few weeks as I tackle my list.

Re: Minarelli Polini 80cc Kit Questions

Thought on this brand new cylinder. I was getting ready to start chamfering and noticed this small crack between the two ports. The last picture is of the other side that does not have it. Would this have the ability to snag a ring or is it something I shouldn't worry about? As always thank you!

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Re: Minarelli Polini 80cc Kit Questions

I'd send it back .

Re: Minarelli Polini 80cc Kit Questions

It was included with the moped I bought and never used. So unfortunately I didn't get it directly from a company. Damn, what a start to the weekend... lol

Re: Minarelli Polini 80cc Kit Questions

Well, if you can't send it back, you can always send it to me and I'll try it out for ya, to make sure it's safe. wink wink

Re: Minarelli Polini 80cc Kit Questions

kevin Smellaflange /

yeah me too.....

Re: Minarelli Polini 80cc Kit Questions

Lol.

Anyone know if this will be a problem or not? I just don't want to go through the hassle if it will just end up breaking rings. I wonder if I can shave it down any?

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