NITROUS OXIDE ( nos / n2o ) advice forum

I've been working on a pretty heavily customized XJ750 (re-built w/ a Hossack front end, among other mods) that, for various reasons (mostly shits and giggles and the fun of further customizing an already mad-science type vehicle) I'd like to get ~100hp out of. Stock, it made about 75hp, so that seems do-able without to much fuss via a n20 system, yes?

After a fair bit of research, I like design concepts behind the pulsoid valves a lot, although I wish maybe there was a smaller one that pulled less than 10 amps... is such a thing available / sensible?

The bike has CV carbs, which (I assume) means I need to run a wet system. That means I'd need a fuel pump, yes? Instead of a fuel pump, what about packing a propane tank alongside the nitrous? I'm thinking the typical camping stove size, which means it would discharge gaseous propane, not liquid, probably at ~25psi. Not sure how I'd figure out how much flow I need (maybe use a scale and see what size jets / pressures give what flow rates in terms og grams / minute, and find the gasoline equivalent). Also not sure the pulsoid fuel valve would handle gaseous propane, and if so, if it would flow enough of it, given the lower density. If gasoline can be used without a fuel pump, that's probably a better option, although the added octane from propane is (in theory) a nice bonus.

Also wondering, is it a good / bad idea to inject the nitrous & fuel downsteam of a CV carb? I'm figuring this would give quicker response, but runs the risk that you can't close the throttle and block off the flow of N20 (in a mechanical sense - there would be a sensor that prevented the valve from opening at part throttle). If its not a bad idea, its very appealing in this case, because the XJ series heads have a head design (called "YICS") that would make it rather easy to pipe n20 and fuel directly into the intake tract, bypassing (and avoiding any alterations to) the carbs & carb boots.

I thought that might be the case... what do you think you could get the amps down to, and would the cost be comparable to the normal pulsoids? I assume they wouldn't allow as much max boost as, say, the pulsoids in the SB75 kit?

To be honest, something like you old Dou-noid design sounds like it would ideal for my situation... maybe because the bike is of similar vintage.



Ah, The metering jet info in you FAQ makes a lot of sense in this light.
Would be happy to guinea pig, but am in the USA. Perhaps once I gain a bit of experience with a conventional (grav fed fuel) system, I could look into what you've learned if still curious, or try some experiments with remote oversight. TBH, if its not needed to avoid fuel pump use, the added complexity isn't all that appealing, except to curiosity.



You can add n2o and fuel downstream of a set of carbs without putting a hole in the carb boot (or boot replacement) or body? The instructions for various systems indicate drilling holes in intake components, which is what I was aiming to avoid. You are right about added complexity- in essence I'd be making my own custom, engine specific injectors. However, its highly appealing in a cosmetic sense if possible (not just to avoid damage to aging components, but as a potentially good looking feature in its own right).

The low amp pulsoid mod you mention sounds good; keeping the whole system on one 10 amp circuit would be nice. If I wanted to go past +50hp, I'm doubt the cash for a new pulsoid (or maybe just new internals?) would be the main factor holding me back.

Any progress on the micro pulsoids you mentioned in the SSIS thread? Would they maybe be suitable?

The intake setup you mention (fuel via vacuum ports, n20 in airbox) sounds quite well suited to my case. I'm planning a custom (or at least heavily modified) airbox anyhow, so have no concerns about alterations on that end. Probably superior performance wise (especially under NA conditions), given the YICS system would be un-impeded.

Not sure when the budget on this will free up (there's an outside chance of build sponsorship, otherwise its out of pocket on a typically tight family budget) but having this info will keep me going in a direction that makes implementing the system easy down the road. Like I said initially, everything I'd learned makes your system seem a better choice than competing brands despite higher (initial) cost, and your helpfulness only confirms that.

Fog the airbox
bore the rubbers for fuel.

Even when your budget is low , go with the pulsoids , as one pulsoid is cheaper than buying engine parts when the usual
solenoid keeps open (N2o) or wont even open (on fuel) or even buy another "normal" solenoid when you find the issues BEFORE damage.

Nitrous is a damn honest tuning . If done right its the cheapest way to get HP. But its not forgiving if done wrong.

Do it right the first time ,and dont spend your money twice.

Very good advice