gas tank pressure

[rossthaboss11]

i did change the fuel filter a couple times. i have a huge one on now which is meant for boats so it allows optimum flow. i really should drain the gas tank and make sure theres no crap in the bottom. but i still need this question answered: are your plugs wet/black at idle and in the driveway? or are they completly dry and a brown color? im just so lost on this low speed setting now

 

[stanton]

no they shouldnt be wet that is way too rich.

 

[Mile9c1]

but i still need this question answered: are your plugs wet/black at idle and in the driveway? or are they completly dry and a brown color?

Hard to say, I don't think you can tell much about how the carb is tuned based on idle in the driveway, there is no load on the engine and it's not at operating temperature.

 

[Mile9c1]

FWIW, here is what Group K says:

It's interesting they wrote that, but it doesn't make any sense, since again, nothing pressurizes the gas tank. The vent just prevents a vacuum condition from happening when the fuel level goes down.

 

[rossthaboss11]

hmm then i guess ill have to get a smaller jet. somethings up with my low speed. i tuned it exactly how group k says with it idling on the trailer and then when i go to ride it at that setting it sucks. it was a 127.5 jet at 3/4 turns out. so i richened it up and it ran better and better then at 2 turns out i blew my top end. fixed it then i richen it up and turn it all the way to 3 turns out and thats where it rides best at that jet. so i figured it wants to be richer so i went to a 130. when trying to tune that one on the trailer it only started to idle higher at 1/2 turn out and less so it wants a smaller jet. but when i ride that at 3 turns out it rides pretty decent. it rides better and better the richer i make it. but according to group k's low speed tune i should lean it out. i put in a 120 today and i couldnt get that dialed in at all.

 

[rossthaboss11]

and at the 127.5 and 130 size jets the plugs are very wet at idle. im going to get a 125 and 135 and see if i can tune with either. its a 61x motor with a riva red pipe, 180psi, msd, prop, lightened flywheel, 15psi pop off, 2.3 N/S, 46mm mikuni wetjet carb, motor is bored to 733cc, riva intake, boyeson carbon reeds

 

[SharkB8]

Its been a while since I've read their jetting instructions, but I think when they say "on the trailer", I think they mean "and backed into the lake". I think the pump needs to be immersed in water. Hopefully someone more knowledgeable than me can comment on that, but after reading the article, I backed mine into the lake rather than running it on the hose. Even now that mine is jetted correctly, it still runs so weird on the hose (erratic idle) that I only run it long enough to wash the salt out. I don't think I would attempt to jet it like that. I could be wrong though.

 

[Mark44]

p

hmm then i guess ill have to get a smaller jet. somethings up with my low speed. i tuned it exactly how group k says with it idling on the trailer and then when i go to ride it at that setting it sucks. it was a 127.5 jet at 3/4 turns out. so i richened it up and it ran better and better then at 2 turns out i blew my top end. fixed it then i richen it up and turn it all the way to 3 turns out and thats where it rides best at that jet. so i figured it wants to be richer so i went to a 130. when trying to tune that one on the trailer it only started to idle higher at 1/2 turn out and less so it wants a smaller jet. but when i ride that at 3 turns out it rides pretty decent. it rides better and better the richer i make it. but according to group k's low speed tune i should lean it out. i put in a 120 today and i couldnt get that dialed in at all.

Follow this right up and take the guess work out of it your motor will thank you.

http://www.x-h2o.com/threads/39846

Mark44

 

[SharkB8]

Someone should edit the "50 kilometers" part of that article. He meant 50 meters. I don't think my ski would go 50 kilometers on a tank of gas.

 

[rossthaboss11]

hahaha, mine either. when i said on the trailer i did mean backed into the water as well.

 

[rossthaboss11]

Mark44 i was reading that way of tuning but im confused on one 2 parts. first on the tackometer part. what exactly am i looking for on the tach? for peak rpm and to see if it holds it steady? and for the low speed screw it says put it at 1 turn out, then it jumps into "after you find the correct low speed setting, write down how many turns your are at". i thought im supposed to keep it at 1 turn out, or do i play around with it till it feels good?

 

[jMike]

*** If no matter what you try, it still won’t leave the line without falling on its face "lean bog"... Then try the next size lower pop-off spring in the carbs... Don't be afraid to try #95 or even #80 gram springs..***

Sounds like something to look into.. what spring are you running with the 2.3n/s to get the 15psi pop?

 

[rossthaboss11]

i think its the smallest size spring. but i dont think its pop off cause ive tried 3 different pop off settings and they didnt change much. the ski doesnt fall on its face. it just cant tune perfectly and the jets and screw turning dont really have that big of an effect on it. im going to try and do some leak down tests and stuff to make sure nothings wrong

 

[rossthaboss11]

well i did an air leak test and my motor passed. so thats not the problem. next ill check pop off but i doubt thats the problem and are there any sites or videos that really show how to put a mikuni wetjet 46mm carb together? im pretty sure mines right but just to double check. most diagrams only show the 38's and 44's

 

[SharkB8]

Just curious on a couple things... why are you running a wetjet 46 rather than a 44? AFAIK, the only reason to go to a bigger carb is if you have a motor and/or pipe that requires the extra flow. I could be wrong, maybe a 46 will let you go faster than a 44, all other things being equal, but IMO you should make all the other mods you want to your ski, and then choose the carb for those mods, and jet accordingly.

Also.. at first I thought your ski was running perfectly and then suddenly started running weird. Is that right, or are you going through the jetting process for the first time?

Also, have you read the Group K jetting articles (I think you might have said before that you did, I forget now). Anyway, I find them a little more clear and "step by step".

But to answer your question about the low speed adjuster, yes you start at 1 turn out and basically frig around with it until you get the highest idling RPM possible. That's the easy step. >

 

[rossthaboss11]

i have a 46mm carb on cause i wanted more power and more airflow for my bigger motor. my ski was running perfect untill i started having fuel problems with clogged fuel filters and such and the gas tank pressurization issue and during this i put in a new carb kit. after the carb kit my tune was off and i blew my motor. since then i could never get it tuned right. ive read all the articles and i try the group k thing but something doesnt work right. it idles highest and wants to be set exactly where i had it set when it was tuned b4 but when i ride it it runs crappy. and other jet i try to do the idling thing and it only idles higher when the jet is just about closed. it runs best by my feel whenever the screws are turned way out. no matter how big or small of a jet i put in

 

[BruceSki]

when you say you had clogged fuel lines i know you changed, or blew them out/cleaned them

did you clean out the fuel selector? blow compressed air through it?

 

[rossthaboss11]

umm im not sure what the fuel sector is. i took the carb apart to make sure there wasnt anything blocking the jets and cleaned the internal fuel filter ect. used a Q tip here and there

 

[Johnny340]

umm im not sure what the fuel sector is. i took the carb apart to make sure there wasnt anything blocking the jets and cleaned the internal fuel filter ect. used a Q tip here and there

Fuel selector on your dash. On-OFF-RES. Take the lines off and blow it out. Also, did you spray carb cleaner through all of the carb passages when it was totally apart?
IMO that pop off pressure seems way to low which makes it overly rich and hard to tune down low.

 

[rossthaboss11]

i took that fuel sector completly out i just run a straight line off of reserve. yes i completly cleaned the carb. that pop off does seem low to me to but thats what other guys with similar setups are running. i tried 3 different pop offs and i didnt notice much of a difference while trying to tune with any of them. i think i tried like 32, mid 20's, and 15