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 70cc kit piston seizing 
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Newb
Newb

Joined: Mon Oct 22, 2018 5:33 pm
Posts: 7
Post 70cc kit piston seizing
So a few weeks ago I installed a 70cc polini kit on my 2008 zuma 2T. I currently have a17.5 carb with 88 main jet and Uni air filter and Leo Vince exhaust. Today while riding wot the engine just shut off on me. I was able to kick start it but it didn’t run normal at all. I took it home and realized the piston was seized and the bottom ring was prtially seized not allowing it to move. Br8ES is the plug I was using.

Anyone know what could have caused this? I suspect overheating and maybe due to lack of oil? I read some guys add a little oil into the gas like a premix to supplement. Does this sound about right?

I’m debating going back to my 50cc or not. The replacement piston and rings are not cheap.


Sun Dec 16, 2018 7:06 pm
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Scooterologist

Joined: Fri Aug 31, 2018 5:18 pm
Posts: 90
Location: Fox Valley Wisconsin
scooters and mods: 2 2004 Vinos derestricted variator and exhaust upjetted carb 2004 Zuma Dual Headlight Mod Malossi Wild Lion Exhaust
Post Re: 70cc kit piston seizing
That Sucks
2 Thing that probably contributed
Did you rejet with with multiple jets and do plug chops to make sure that you were running at a safe tempature after you put on the bbk .
With the uni filter You were running very lean they require constant monitoring with weather changes.
The Uni filters work best for racers Because they tweak there bikes by the day for the weather and altitude.

You changed carbs
Did you bleed the oil pump .
If you didnt then a air bubble could have got in the way of the oil .

With the Cast iron sport KIts plenty of people on here have got over 6000 miles with the stock oil injection without going to premix.

If you premix you are actually making your scoot Leaner So you could still seize .

_________________
2004 Vinos Derestricted exhaust and variator stock carb with mikuni 75 main jet needle down 1 clip 38 mph
2004 Zuma 43 mph Dual Headlight Malossi Wild lion exhaust 84 main jet 46 pilot jet needle 1 clip rich
2005 eton beamer still stock bbk on the way 35 mph


Mon Dec 17, 2018 7:14 am
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Newb
Newb

Joined: Mon Oct 22, 2018 5:33 pm
Posts: 7
Post Re: 70cc kit piston seizing
I didn’t bleed the oil lines. Sounds like that could be my problem right there. Can I stil use the cylinder with a few light scuffs inside? Ok


Mon Dec 17, 2018 8:01 am
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Scooterologist

Joined: Fri Aug 31, 2018 5:18 pm
Posts: 90
Location: Fox Valley Wisconsin
scooters and mods: 2 2004 Vinos derestricted variator and exhaust upjetted carb 2004 Zuma Dual Headlight Mod Malossi Wild Lion Exhaust
Post Re: 70cc kit piston seizing
That is one of the best things about cast iron .
You can rehone put in new rings and back in business.
Light Scuffs maybe OK a compression test would be your best clue after install. 150 ish psi Good ,100 psi not so much
Do you have bigger jets for carb those Uni filters are very tricky and need very large jets .

_________________
2004 Vinos Derestricted exhaust and variator stock carb with mikuni 75 main jet needle down 1 clip 38 mph
2004 Zuma 43 mph Dual Headlight Malossi Wild lion exhaust 84 main jet 46 pilot jet needle 1 clip rich
2005 eton beamer still stock bbk on the way 35 mph


Mon Dec 17, 2018 6:17 pm
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Scooterologist

Joined: Fri Aug 31, 2018 5:18 pm
Posts: 90
Location: Fox Valley Wisconsin
scooters and mods: 2 2004 Vinos derestricted variator and exhaust upjetted carb 2004 Zuma Dual Headlight Mod Malossi Wild Lion Exhaust
Post Re: 70cc kit piston seizing
One of other area that could have caused problem .
Plug chops would have picked this up.
You changed cylinder so you put exhaust back on did you check for exhaust leak by plugging tightly with your gloved hand and a rag the end of the pipe .
If it died within seconds you are good .
If it keeps running you will be sucking in air and will be lean.
The crush gasket for the leo vince should not be reused if you have to slather it with permatex.

_________________
2004 Vinos Derestricted exhaust and variator stock carb with mikuni 75 main jet needle down 1 clip 38 mph
2004 Zuma 43 mph Dual Headlight Malossi Wild lion exhaust 84 main jet 46 pilot jet needle 1 clip rich
2005 eton beamer still stock bbk on the way 35 mph


Mon Dec 17, 2018 6:39 pm
Profile
Scooterologist

Joined: Fri Aug 31, 2018 5:18 pm
Posts: 90
Location: Fox Valley Wisconsin
scooters and mods: 2 2004 Vinos derestricted variator and exhaust upjetted carb 2004 Zuma Dual Headlight Mod Malossi Wild Lion Exhaust
Post Re: 70cc kit piston seizing
How did you like the polini bbk ?

Was it the contessa or corsa ?

What was your top speed ?

_________________
2004 Vinos Derestricted exhaust and variator stock carb with mikuni 75 main jet needle down 1 clip 38 mph
2004 Zuma 43 mph Dual Headlight Malossi Wild lion exhaust 84 main jet 46 pilot jet needle 1 clip rich
2005 eton beamer still stock bbk on the way 35 mph


Sat Dec 22, 2018 7:49 am
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Newb
Newb

Joined: Mon Oct 22, 2018 5:33 pm
Posts: 7
Post Re: 70cc kit piston seizing
My problem seemed to be a pinched oil line. I think the pinch was not allowing the oil to go through. My top speed was 46 mph with 88 main jet. I'm going to order another kit and new variator and rollers.


Mon Jan 07, 2019 7:22 am
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Scooterologist

Joined: Fri Aug 31, 2018 5:18 pm
Posts: 90
Location: Fox Valley Wisconsin
scooters and mods: 2 2004 Vinos derestricted variator and exhaust upjetted carb 2004 Zuma Dual Headlight Mod Malossi Wild Lion Exhaust
Post Re: 70cc kit piston seizing
A buddy of mine did the same thing with a new carb he kinked the oil line .
He says he should have used slick 50 like the commercials and it would run forever.
Are you going polini again ?

I just bought polini clutch and variator myself boxing day special from scootertuning.

_________________
2004 Vinos Derestricted exhaust and variator stock carb with mikuni 75 main jet needle down 1 clip 38 mph
2004 Zuma 43 mph Dual Headlight Malossi Wild lion exhaust 84 main jet 46 pilot jet needle 1 clip rich
2005 eton beamer still stock bbk on the way 35 mph


Mon Jan 07, 2019 4:29 pm
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