79cc powered bmx bike(mongoose)

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ironman

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Well since today is wacky wensday
I've decide to share one of my builds with you all.which I'm sure you will find entertaining
This was something I built for myself .
1.yes I know it's scary
2. No my kids don't ride it.
3.i know those are the ugliest welds but they do hold..
4.yes I have great health and life insurance .
5.yes that fire ex. Is the gas tank
I have yet rode this beauty still got a few things to do brakes,,throttle and (air bag)
So built this about year ago and decide time to finish it up.
As I'm getting a promotion and no longer will be in the field working be at a nice office desk.so any bones I break I still be able to work.
Please feel free to leave your thoughts
Enjoy....







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ironman

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Ill have to look can't remember off top my head
Clutch is a 11 I think goes to 10 than 12 on other side j.s. and some where in the 60 in the rear.
Have to look when I get home been a while.
Will give correct numbers later


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ironman

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Yea still needed to be drill out and vent cap for it.just thought be neat tank I get ask about the tank all the time.wife was like is that on there cause it catches fire.


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Poboy kartman

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ironman said:
Yea still needed to be drill out and vent cap for it.just thought be neat tank I get ask about the tank all the time.wife was like is that on there cause it catches fire.


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Click to expand...

Yeah...you only need a vent for fuel delivery....and a cordless drill will safely drill holes on low speed even with gas or gas fumes present.
 
ML-TOYS

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You need to have a way for expansion to release, ever have fuel in a sealed container and open it & feel and hear the pressure come out. Expansion ventilation.
How about the people who put the wrong type of cap on a plastic gas tank and then after running for times wonder why eventually it looks like its going to implode. Lack of air intake.
Cars have systems for this. Dirtbikes have the hose coming off the fuel cap.
The small engines we use have breathable caps. Etc etc etc
 
ironbutt

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Awesome!

I have a 79cc engine that I am swapping out from a Motovox MBX10. I was just talking to a buddy at work about possibly putting it into a bike.
 
itsid

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motorcycle tanks are generally not airtight (not even fuel tight tbh) ..
just as mckutzy said they "need ventilation"
And frankly I doubt a car's tank is (even more : I'm almost certain it's NOT)

The reason is fairly simple actually:
In worst case the tank is exposed to direct sunlight, but even in a car it cen heat up pretty fast.
And fuel evaporates much rasier than water does, so a non ventilated tank can build up pressure.

So far not exactly an immediate issue:
but such pressure can cause numerous problems:
it can pop seals (O-Rings for the petcock on a motorbike)
if the petcock isn't shut down, the pressure can push the float down and cause the carb to leak..

adn it can even prevent you from undoing the gascap (remember that glas coke bottles ;) half empty, one good shake and you weren't able to unscrew the cap)

So no vehicle gastank I've seen was actually airtight by design.

'sid

PS I don't know if build up pressure in a tank is even able to rupture the tank from the inside at least not under 'normal' conditions.. I doubt it... but it's still something I think manufacturers have in mind.
(say the vehicle catches fire and the gases cannot escape... makes the tank basically a multi gallon molotov as soon as it bursts :eek:)
 
Poboy kartman

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Poboy kartman said:
Yeah...you only need a vent for fuel delivery....and a cordless drill will safely drill holes on low speed even with gas or gas fumes present.
Click to expand...

ML-TOYS said:
Not exactly, a fuel tank needs proper ventilation.

http://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm
Click to expand...

itsid said:
motorcycle tanks are generally not airtight (not even fuel tight tbh) ..
just as mckutzy said they "need ventilation"
And frankly I doubt a car's tank is (even more : I'm almost certain it's NOT)

The reason is fairly simple actually:
In worst case the tank is exposed to direct sunlight, but even in a car it cen heat up pretty fast.
And fuel evaporates much rasier than water does, so a non ventilated tank can build up pressure.

So far not exactly an immediate issue:
but such pressure can cause numerous problems:
it can pop seals (O-Rings for the petcock on a motorbike)
if the petcock isn't shut down, the pressure can push the float down and cause the carb to leak..

adn it can even prevent you from undoing the gascap (remember that glas coke bottles ;) half empty, one good shake and you weren't able to unscrew the cap)

So no vehicle gastank I've seen was actually airtight by design.

'sid

PS I don't know if build up pressure in a tank is even able to rupture the tank from the inside at least not under 'normal' conditions.. I doubt it... but it's still something I think manufacturers have in mind.
(say the vehicle catches fire and the gases cannot escape... makes the tank basically a multi gallon molotov as soon as it bursts :eek:)
Click to expand...

Soooo....you basically made my point in several ways. Maybe I should have said MAINLY for fuel delivery. But for storage...no. Now...to access such stored gasoline...you may indeed need a pressure relief valve to vent excess pressure.

Anyways, it's a silly argument...but I'll tell you one thing...given a cap and seal equal to the "tank" (Fire extinguisher) ...I could build a campfire...throw it in...(with any ratio of gasoline in it)...and pull it out of the cold ashes in the morning.

BTW: I did something when I was a kid...filled a quart can with gasoline and threw it in a fire....when the can was almost ready to burst...I threw a rock on it...the result very closely mimicked an atomic "mushroom cloud" except it was completely comprised of flaming liquid!
 
itsid

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Poboy kartman said:
Soooo....you basically made my point in several ways. Maybe I should have said MAINLY for fuel delivery. But for storage...no. Now...to access such stored gasoline...you may indeed need a pressure relief valve to vent excess pressure.

Anyways, it's a silly argument...but I'll tell you one thing...given a cap and seal equal to the "tank" (Fire extinguisher) ...I could build a campfire...throw it in...(with any ratio of gasoline in it)...and pull it out of the cold ashes in the morning.

BTW: I did something when I was a kid...filled a quart can with gasoline and threw it in a fire....when the can was almost ready to burst...I threw a rock on it...the result very closely mimicked an atomic "mushroom cloud" except it was completely comprised of flaming liquid!
Click to expand...

Well Doug I haven't said ANY tank MUST be ventilated, did I?
I said.. vehicle tanks I know of ARE!
And explained why I think they are

No more no less...

And when I was a kid I did several things I wouldn't advice any kid (my age back then) to do as well..
the word is pubertarian bullsh-what was the letter?-t

And just because I'm alive and well.. I wouldn't say all of it can be considered "safe fun"

Like putting the german equivalent of a cherry bomb in an ants hill;
split seconds of fun, hours of pain.

Anyways.. sure fire extinguisher.. very unlikely to pop even in a camp fire.. and if; it'll likely degas in a controlled fashion (still not want to get hit by the flame though) (through the outlet in this case)

But ML-TOYS has a valid point!
tanks are usually ventilated;
and if only to be able to undo the cap or deliver fuel reliably.. it's STILL VENTILATED ;)

So in order to rule out a potential issue (say with fuel delivery) a ventilated gascap is still a good idea :D

'sid
 
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