Hello everyone - I'm new to the forums here. I hate to sound like more of an outsider, but I'm not much of an ATV guy, as I am a jetski and dirtbike guy. You can check out PWC Today if you'd like to see any of my posts there for credibility purposes. I moderate a forum that specifically deals with the older skis... pre-wuss-sitdown era. I'll explain why I chose a forum outside of my realm of understanding in just a moment.

I've been building the jetski equivalent of really radical hillshooter quads for quite some time, and is the niche I've found I fit into best in the PWC market. I currently have a project ski that is at it's MAX on 110 race gas, and strange as it may seem (hopefully not to all of you), I would like to make it even more... go to "11" so to speak. I know that there are TONS of alky-powered quads out there, and shops that'll assist or perform all the required modifications for such a transformation. Not so in my weenie jetski world. I've been on the phone and emailing all across the country since summer last year trying to convince someone to just *help* me learn what I need to know to do this - all to no avail. None of the great shops (CT, Trinity, etc) want to even touch a watercraft - they fear it is somehow different than any other two-stroke motor out there, which it's not! Kart, ATV's, sandrails, dragsters, monster trucks; they all run on alcohol - it seems strange that I'm pioneering new ground in the PWC world.

Trying to break out of the sticky mold that is the conforming jetski public, I've had conversations with many karters and drag racers regarding alcohol as a fuel over several years. I've come to many conclusions about how much fuel to run, the oil and mix ratios, etc. I have TONS of knowledge from years of reading about *any* type of race fuel. I am not uninformed when it comes to that. However, even those sources are at a loss when it comes to modifying a jetski fuel system for alcohol.

Which is why I've come here: I know you guys have much more experience that we jetskiers when it comes to running methanol, but the same ego-driven desire to "go to 11" that I have. You're the equivalent of me, but with wheels. Will anyone be willing to help?

Some questions I have are:
Do I need larger carbs, or will the standard bore size not matter?
Is anyone familiar with diaphragm fuel pumps (as opposed to the fuel bowls you all run) - and what mods are necessary?
I'm already very high on compression and spark advance, should I go higher on both anyway?

If anyone has some valuable alcohol experience, please share. I'm willing to learn and listen. If I am to break tradition in the jetski public, I may as well do it with a bang!

Thanks!
Ryno
XXX Racing
Prescott Valley, AZ

 

I must say I am alittle surprised to learn that Modified PWC dont already use Alcohol for thier prefered fuel.

I am not an Alky expert, but I have been running alky in my 650cc Rotax(4-stroke) for over two years, and have had ZERO problems, Infact on motors with High compression it is MUCH easier to tune,and runs much cooler. 2-strokes ofcorse require Power-jets to supply thier more powerful engines with enough fuel. Basically I dont think you can feed your PWC engine enough alky to choke it, so I would jet WAY up ,and turn your powerjets UP. I believe the best way to tune your alky would be to get a Exhaust Tempature Gage and start leaning it down to the desired exhaust temp. I dont know what the optimium exhaust temp is for a 2-stroke, but a 4 stroke is 1200 degree's.


I'm sure in a minute a real banshee guy with a BIG BAD drag quad will really tell you some good info, but thats all I have for ya..[img]i/expressions/face-icon-small-smile.gif[/img]



Good luck.

Biggerisbetter.

 

hey, I'm familiar with aky for the most part as a few others on this forum. A guy who goes by dabeechman knows alot about dragging. I ran alky for 2 years and here is some info. running alky utilizes twice the fuel, so you have to provide twice the fuel to your motor. you dont need bigger carbs but it dosent hurt. you need bigger jets, some peaple buy them some peaole just drill out the stock ones.I would try a contact FTZ racing.com for jets. depending on how long you are at full throdle, you will need to run fuel pumps witch can run off electricity or vacume. and some cut the float bowls and weld so the can hold more fuel. I think someone makes oversized float bowls, but not sure. to run vacume pumps you drill a hole in your intake close to your reeds and run a hose to the pump to the cilinder, simple. the hotter the spark the better and advancing is good.If I were you I would run a EGT (exhuast temp gauge) to dial the jeeting, depending on how far you set the egt from the piston, should be no more than 5 inches you should run at, I'm not sure but I think around 900 degrees.ftz and esr racing sell the fuel pumps and will know what temp to run on alky.Pro flow sells guages.running alky makes it very hard to read plugs.you will defenetly have to purge. purging is running race gas through your motor after every run or ride, becaus alky absorbs water into your crank and motor parts while sitting. also eats up seals and gaskets and is hard on internal carb parts. I used to fill a water bottle with a fuel line attached with race gas and pop off the fuel line and and run race gas through the moter for about 5-10 seconds.It hardly runs and you might have to give it full throdle to keep it running. you also can run evean more compression with alky. how many cilinders does your ski have and what is the displacement on each cilinder. you also have to gap your plug different.

 

sorry ran out of space, I ran my plug gap at .017. I know I left out somethig. hope this helps. just keep asking..

 

Biggerisbetter - thanks for starting out! Like I said, I've been doing the "professionally stupid" jetskis for a while, and it's surprising to me too that alcohol hasn't been at the very LEAST experimented with.

Bansheesmoker - that's a lot of great info! The carbs we run on jetskis don't have fuel bowls because the skis vibrate and bounce so much more than any land vehicle could ever hope to, plus they have to be able to run with sideways and upside-down gravitational forces (either from extreme turning or actually being sideways or upside-down!) - to do this, they have a diaphragm fuel pump (identical to the vacuum operated pump you mentioned) mounted directly to the carb body. The Mikuni SBN's have enough pumping ability to run two skis on nitromethane if you really wanted to; plus, I'm running twin carbs so my pumping doubles. I'm not sure though if *all* Mikuni jets are interchangeable with the jets in SBN carbs - otherwise, my search would be complete as far as that goes.

You said you gapped your plug at .017"? That seems awfully small - is that to keep the fuel from blowing the spark off the gap? I have an MSD ignition with a super strong spark, and have been gapping plugs around .040" which is up from .032" stock. Do you recommend going to a tighter gap, and how much if so?

The carbs I'm using now are dual 38mm Mikunis, but I could go all the way up to dual 44's if I wanted. Even though I can dump more fuel in each intake cycle, would it still act 'over carbureted' if I went that large? For reference, it most certainly would be boggy if I ran those carbs now!

I've also come to understand that alcohol is a very easy fuel to tune with, as it's less sensitive to small changes. How has your experience been with it? Were there any quirks that using alcohol revealed? How forgiving is it on motors that aren't built as well as mine? (Ha ha - just thought I'd throw that out at'cha!)

Thank you again for the replies! I look forward to chatting with you more.

 

on race gas i gap a .022 and on alky I gap .017 with a msd ingnition too,and yes it would blow the spark out. here is a good example. one time I ran lean less than 5 minutes later I had a hole in my piston the size of a quater. and one time I was so rich my exhaust was spitting raw fuel and a blue flame. SO I would start rich unlike me. you can get away with running rich as hell and hardly notice, but not with running lean thats why you should run a egt, I'm currently buying one for my cr500 quad on race gas so I can realy dial it in without the worry of detenation.the msd will work great and not having to change the fuel pump set up will buy you lots of time and head ake.AS fo bigger carbs I would also do it only if you plan on sticking with alky because like you said it wont work good on gas. your ski will have a noticable amount more power and will sound alot meaner. sounds like a bad *** project, post some pics of it. I'm currently building a 700hp big block chevy jet boat with the pump highly modified. have you considerd N.O.S., I'm going to run it on my quad. A quirk I used on jetting might sound funny but by the smell of the exaust. If it stunk real bad it was rich, or when you put your hand by the exhuast and it would get wet meant too rich. a sweet good kind of smell meant the jetting was lean or close. wish I could ride your ski,my friends sucked. and that was my only time on one.what kind of ski is it?

 

MinusB, I have some experiance with alky 4 strokes. I have no experiance with drunk 2 strokes, so my info will be generalized. Like bansheeesmoker said, you use almost twice as much fuel as gas. So to get you in the ballpark jet wise, you will have to do some mathematics. Take the jet you are running right now and figure out how many thousands the orifice is. Lets just say .050 in diameter. Now you need to double the surface area of that jet. You just can't make it .100 and call it good because of pie. If you double the diameter you will be way rich. See what I'm saying?
Another thing, alky is hygroscopic (it makes love to water[img]i/expressions/face-icon-small-wink.gif[/img]). This may be a problem with your app. Your going to have to have that fuel tank and vents sealed up real good if this thing is going to be around water.
Alky is very corrosive. Like bansheeesmoker said, it is hard on any metal, not just steel. I don't know how this will work out with a two stroke. Like I said, I have no experiance with alky two strokes. Must be hard on bearings though? Just a guess?
Alky is hard to light off. That is why the smaller plug gap.
The size of the carb will make a difference. I have experiance with Holleys. It is hard to flow enough fuel through the passages. Sure you can jet them up, but you can run out of fuel passage to flow that much fuel with a BIG airflow carb. So run a carb just big enough, don't go over board on the carb size. What I'm trying to tell you is make sure the passages in the carb are big enough for your jets.

 

yea, and what he said. Mix your alky with bean oil, I forgot the ratio. one brand that makes it is KLOTZ. Call ftz for the ratio.

 

bansheeesmoker, can you tell me if the bearings get wipped out on the bottom end alot quicker with alky? I know on a 4 stroke if you thin your oil out with alky you can wipe them out quickly. Any experiance with this?

 

you know what I'm almost positive. Its hard for me to garentee though because I went through alot of top ends, ones that exploted the piston, so metal went through the bearings. out of 10 pistons I had to do the mains 3-4 times.one time I forgot to purge and the next day the crank was so rusty you couldent see metal. you can run less oil butt purge more often like every run or ride or every 6-8 hours. I used to purge at the end of each day or before dark and it was ok. wouldent take chances in the water though.