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Discussion in 'Motorized Bicycle General Discussion' started by Springfieldscooter, Jun 10, 2015.
Anyone use it?
Like it or not?
Unless you plan to build some form of a drag bike, it just doesn't have a practical street use. With the air cooled engines both 2 and 4 strokes they have a set rpm that they're capable of. If you exceed it they will blow on you.
Not a good idea for daily use, those nitrous oxide kits are a ripoff anyway since they don't add the required additional fuel into the mix, they can overheat and blow a hole thru your piston if on the juice a second or 3 too long, but for the most part, don't it... none of these "kits" i've seen have any means of delivering the extra fuel it takes to make the power and save your engine from self destruction, and they add *maybe* 1/3 to 1/2 hp for about 3 to 5 seconds.
Here's the lowdown on these kits...
The "nitrous holder and trigger is a C02 cartridge type bicycle tire inflator, then they supply about 5 feet of aquarium tubing and a nipple barb for your intake manifold, and the nitrous cartridges are the same size as those C02 cartridges except filles with nitrous oxide and they are commonly used for those whipped creamers where you put in the cream and push the button and it dispenses a foamy whipped cream. You can look up these cartridges on ebay and places for the whipped creamer and see the real price...
The tire inflators usually sell on ebay as tire inflators for around $10, and we all know aquarium tubing is really dirt cheap... so somewhere back when pocketbikes became really popular somebody replaced a C02 cartridge with a nitrous cartridge and plumbed it onto a pocketbike manifold and they used to sell like crazy until there were a LOT of disapointed customers... Basically, you can build one of these kits for just under $20 and these people sell them for $50 to $75 or more not to mention charging an arm and a leg for those cartridges they bought in bulk for whipped creamers for maybe $1 each so there's the first rip off, the second rip off is that it makes no significant amount of boost, and the boost only lasts about 3 to 6 seconds per cartridge. The lack of additional fuel keps these from making any decent power, but is also very dangerous for your engine...
So my simple answer is Don't do it
Dave has written out the exact facts on those kits there. I am however wanting to install a tiny motorcycle NOS system on my 4 stroke build if I can reasonably figure out the extra fuel needed. It's an absolutely stupid ridiculous idea I have but I like ridiculous conversation pieces ha ha. And if I don't rip the spokes out of a bicycle wheel at some point I will feel like I have failed at engine building.
Somewhere at home I have the jet size charts for the horsepower levels for both the nitrous and additional fuel... it would be real easy to add 10 or more ponies to your engine as long as you have
A 12 volt power source... any small battery will do, as long as it can make it down the track a few times between charges
A set of nitrous and fuel solenoids... they do make some nice small ones now
A set of fogger nozzles, 1 for fuel, and 1 for the giggle gas
The RIGHT size jets for the horsepower level you're after, and Yes, you can drill your own
An electric fuel pump capable of 4 psi
a nice blue bottle in the smaller size... They make small 1 1.5 and 2lb bottles that are Easily hidden under a motorcycle tank or seat...
10lb bottle will last about 120 seconds at a 100hp boost level so if the math is correct, a 1lb bottle would give about the same for a 10hp boost... I could be a little off on those numbers since it's been forever since I messed with nitrous, but that's a close guess...
With the nitrous to horsepower level charts etc, it's real easy to manipulate the math for small engines where you wouldn't want to boost like 50hp from a Briggs... it would be fun as **** for about 3 seconds tho, but common sense...
You could try looking on some of the nitrous kit sites to see if they post the power level charts and jet size charts for the fuel and the nitrous, and from there it's not too hard to design a setup. Try NOS, Zex, Top Gun, Nitrous Works, and Edelbrock's sites to see if they got the conversion charts... Somebody's gotta have them online
I will actually set it up on the 4 stroke. I have the fuel pump and tank already at work, the tank is very small but will only be used for additional gas on spray. I need to set up a Lipo battery pack to run the pump and I have seen a NOS bottle that would work perfectly. I was putting the parts together to spray my Briggs Vtwin but that project is on serious hold so I will put the system on the Predator for fun.
for this amount of effort to get that little power wouldnt it be more worthwhile to try and do a turbo upgrade?
considering that either way it is a more of a "because we can" thing than a "because it's a good idea" thing I would wager it being more worth it to have the power increase be available all the time and not need an extra fuel type.
that said between the extra metal, the fuel pump, solenoinds, battery (and if you need it once you have the thing running an oil cooler) by the time all is said and done the extra power would just be enough to make up for the extra weight
having just typed this out I feel the need to add: that pointless bike would be really awesome regardless.
I've played with a wet system on a 50cc BZM and it's not worth it. I've melted or made pistons crumble. It's cool for the first 3 shots but after that...boom!
It's been tried before with small engines and so far I hadn't seen a single successful small engine turbo application.... part of the problem I will admit is just about every one of them I've seen had way too big of a turbo to be practical... there's no way a Briggs 5hp can push enough exhaust volume to spool up a t3 turbo... it maybe able to spool a gt15 or an ihi rb31 up to about 3 psi, but by the time ya spent the money on the turbo, the necessary plumbing and all, not to mention the space required to fit on a bike or go kart etc, it quickly becomes cheaper and easier to move up to a bigger engine or to soup up the existing engine beyond what that amount of boost would have improved... it takes about 15psi boost to double the output of an engine minus the efficiency percentage, and minus whatever else needs to be done to prevent the engine from self destruction like timing retarding, lowering the compression ratio, running higher octane fuels, and so on... so a turbo that can produce 15psi boost that has a 70 percent efficiency can basically increase power by 70 percent at 14.7 psi... this is good for automotive engines and motorcycles 500cc and up, but pretty much useless for smaller engines due mostly to the lack of availability of small enough turbos, but with all this being said, adding an ihi rb31 size turbo to a pred 212 would be a worthy experiment since it is enough engine to spool the turbo to around 8 psi if you can beef up the head studs, add in a billet rod, and drop the compression ratio down to around 7.5:1, of course, that'll get you from 6.5hp to about 9hp and most of us in here know there are other ways to get that kind of power a lot cheaper...
I think I even saw a company that makes a supercharger for the Honda z50 but the price tag is more than the bike..
Can it be done? Yes, definitely, but is it practical? Not really, but if budget allows and you got a few engines to experiment with, it sure would look and sound cool... I have seen people successfully turbo charge a small 12hp diesel tho... that was cool on all counts.
I have seen successful turbo applications on 2 strokes. I know it seems impossible but from the way I understand it the stronger the explosive pulse coming out of the cylinder the stronger the echo coming back in the expansion chamber and so on so boost actually works. I have looked at the tiny turbo for my Briggs Vtwin but again that's a long way off. The Predator 212 getting NOS though I can do now so I am working in the extra parts during the build. Silly, yes. Fun, I hope so ha ha.