Boosting the Minibike

[thepowderblue]

so I have this mini bike I put a 6hp Honda motor on, Its fast. It will pull the front wheel off the ground if you punch it. I mean my friend broke his clavicle bone on it a month ago.that being said, It needs boost.
I have this turbo.
I am going to use a dirt bike radiator as a innercooler.
will I have to rejet or can I just re adjust the carb?I was thinking about putting the carb before the turbo, what do you guys think?
That motor is a honda gx200. It has a oil pump and pressure switch to kill the motor if it runs out of oil. I was just going to T off of it to get oil for the turbo. do you guys think it will put out to much or not enough pressure for the turbo or deprive the motor of oil or should it be fine? will i need a valve or something to slow the flow to the turbo?
check this out http://honda-tech.com/showthread.php?t=522974
The turbo is going to higher the the valve cover so thats where my return line is going to go.
the turbo is a IhI rhb31
check it out on ebay
This is everything about the motor http://engines.honda.com/models/model-detail/gx200

The bike, soon to have a wheelie bar

The Turbo




this is a diagram showing the oil set up.


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[Leung]

you sure that's a smart idea?

[dj_ender]

[drew12000]

PLEASE make a vid of your first rid e after the turbo install haha

[toycar]

Its difficult to turbo anything carb'd. I dont really think you'll be setting yourself up for anything other then an explosion.

Why not swap a different motor?


Under positive pressure, the carb needs to be designed differently. If you put the carb infront of the turbo, the turbo would be getting unburnt fuel? im not sure why you said you could do that, but thats a bad idea and not going to work like your thinking.

The only thing that should pressurize the exhaust housing is exhaust.


That being said, returning hot oil from the turbo through the VC is going to put above average temp oil ontop of your valve assembly. You need to return the oil somewhere else.



Asides from those couple bad ideas, I think the motor itself is going to explode from normal wear and tear. Nobody owns a mini bike that doesn't beat on it. Its gonna blow with a turbo in no time.

[RagingAsian]

I think its time that either I disband myself from Arizona...Or you stop coming up with these ludacris ideas.

[PR CB7]

Carbs before the turbo works, maybe not in paper but many bike owners get away with it, ill need a bigger carb, the return line will also work, you'll be beating on it but it won't be a race bike, there's no doubt you'll blow the motor, and it'll be once you start raising the boost but so what those motors are very easy to find and theyre cheap, don't forget to change the plug and gap it, carb from a 10hp briggs will work great, good luck

[toycar]

Seems to me like you could swap in a bigger motor w/out much headache. Theres a ton of room in your bike, thats a freakin tiny motor. My self propelled lawn mower makes more power

[NightmareCB7]

You do know that the stock rod will only hold so many RPMs before it breaks. With it in stock form it will throw the rod a WOT. Unless you plan on getting a billet rod then you really cant hit boost before breaking. BTW the OHV engines are not the best for performance without some high end parts.

[toycar]

Explain to me how you get away with putting a carb in front of a turbo?

Like a draw through style?

Maybe Im not understanding you correctly.... Are you talking about routing the inlet on the turbo to a carb and then routing the compressor outlet to the previous intake?

How is that possible without running unburnt fuel through the compressor? Or is that exactly what you are aiming to do?


If you set it up like that, draw through style, you'll create a BOMB in the radiator turned intercooler. You cannot do that.


Thats one of the downsides to draw through carb on a turbo setup. Once the fuel/air is compressed, if you try to cool it the gas will seperate from the air and pool in the cooler then eventually explode. Been there, done that.


Thats why Im confused. Your talking about using a radiator to cool the charge, and placing the carb in front of the turbo.

My suggestion;


Get a blow through style carb and use something to cool the charge temp. As nightmare mentioned, upgrade the internals.


Use good fuel to reduce detonation, and hope for the best. I would pick the carb out using the compressor flow map associated with the compressor. Since the carb wont really be all that adjustable in a draw through setup, you really would have to pick the right carb from square one. Get a blow through, or be very careful picking out the right draw through style carb.


I think it'd be better money invested in a larger motor and max out your "engine bay" I guess before adding something like forced induction.



Side note;

I love mini bikes. SOooo much fun.

[NightmareCB7]

If it was me then I would swap that OHV Honda for a L head Briggs. There much stronger stock. Ive got a L head 5HP Briggs on my mini bike and thats all it needs. BTW its not 100% stock so dont let the rust foul you.



PS I use to own a lawnmower shop and race mowers so I know mower. I still run in mower derbys, tractor pulls and I have a drag mower that about 80% ready for this year.

[MortsAccord]

I wanna know WTF toycar is even thinking.
Tony do you have any idea how a carb works?


You guys are silly. Carbed turbos are just fine. buy some cheap spark plugs 1 heat range cooler and adjust jetting by reading the spark plugs. I guess you could have an AFR meter used on it until its tuned out.

Compression check it, whats the motor get?
Use 93 gas.
I doubt you'll need a bigger carb, just adjust jetting.

I wouldn't use a radiator, those passages are pretty small compared to an intercooler. maybe a intercooler off a DSM, but thats probably still too large.


He needs to know how much oil pressure the bike makes, and how much pressure the turbo needs. If needed he can run a restrictor on the turbo, but if the supply line is smaller than the drain line there shouldn't be a problem really. A turbo that small always is a journal bearing, and its hard to fuck those up.

Its a midget engine who cares if it blows up? its like 20 bucks used lol

[toycar]

I wanna know WTF toycar is even thinking.
Tony do you have any idea how a carb works?


You guys are silly. Carbed turbos are just fine. buy some cheap spark plugs 1 heat range cooler and adjust jetting by reading the spark plugs. I guess you could have an AFR meter used on it until its tuned out.

Compression check it, whats the motor get?
Use 93 gas.
I doubt you'll need a bigger carb, just adjust jetting.

I wouldn't use a radiator, those passages are pretty small compared to an intercooler. maybe a intercooler off a DSM, but thats probably still too large.


He needs to know how much oil pressure the bike makes, and how much pressure the turbo needs. If needed he can run a restrictor on the turbo, but if the supply line is smaller than the drain line there shouldn't be a problem really. A turbo that small always is a journal bearing, and its hard to fuck those up.

Its a midget engine who cares if it blows up? its like 20 bucks used lol

I'm assuming your taking about my comments on the cooler exploding? Yeah, run compressed air/fuel mixture through an intercooler long enough and gas will start to pool in the tank(intercooler tank)

The tank sees pressure, enough gas build up plus pressure and BOOM. Maybe not in a lawnmower, but definetly in a car.

Read up on it if you don't believe me.

Honestly I've never turbocharged a lawnmower engine. But I've blown several intercoolers like this throughout my life.

[F20A CB7]

Wtf is a drag mower.

How much weight do u drag?

[toycar]

Just out of curiosity I'm wondering if carbs on mowers have interchangeable jets? How are the jets setup on a mower vs a car.

Very familiar with cars and carbs, lawnmowers not so much. I didn't really think you could change the jets on a lawnmower carb.


Anyways, someone educate me.