Vumad
Super Hero, with a cape!
- Location
- St. Pete, FL
I just left the sensor hooked up, coiled it up nice and zip tied it beside the box.
Pop off psi, what should I be aiming for?
- Thread starter superjetincairns
- Start date
I just left the sensor hooked up, coiled it up nice and zip tied it beside the box.
- Location
- Cairns Australia
ok, it think ive solved it, finally....
I pulled the ebox out, cleaned and reseated all the connections, double checked the coil resistances and checked signals from the charging coil and pulse coil, all looked good. reinstalled it all and the problem then degenerated to no spark at all. I then replaced the msd with a stock cdi, spark came back, went to the boat ramp, ran it on the trailer, still no revs past about 3500rpm. crimped the fuel line from the primer and away it went, revved to 6000rpm for the first time since the engine rebuild. woohoo!
The primer is less than 12 months old but must be leaking fuel once the pressure in the tank builds up at high rpm and floods it out. I have it plumbed into the return line as recommended so it cant leak air into the fuel supply so I assume its leaking the other way and dumping fuel into the carb throat.
Now I'll put everything in the carbs back to jm recommendations and start tuning from scratch. wish me luck!
If this damn cyclone would hurry up and clear away I may even get to go for a ski soon!!!!
I pulled the ebox out, cleaned and reseated all the connections, double checked the coil resistances and checked signals from the charging coil and pulse coil, all looked good. reinstalled it all and the problem then degenerated to no spark at all. I then replaced the msd with a stock cdi, spark came back, went to the boat ramp, ran it on the trailer, still no revs past about 3500rpm. crimped the fuel line from the primer and away it went, revved to 6000rpm for the first time since the engine rebuild. woohoo!
The primer is less than 12 months old but must be leaking fuel once the pressure in the tank builds up at high rpm and floods it out. I have it plumbed into the return line as recommended so it cant leak air into the fuel supply so I assume its leaking the other way and dumping fuel into the carb throat.
Now I'll put everything in the carbs back to jm recommendations and start tuning from scratch. wish me luck!
If this damn cyclone would hurry up and clear away I may even get to go for a ski soon!!!!
- Location
- Cairns Australia
Ok, I started with 75 pilot, 135 main and 95gm springs with 1.5mm needle and seat. ls screw 1 turn out and hs screw 1.5 turns. running on the trailer, the bog from hell was back, starts fine idles nice but dies at around half throttle.
I swapped springs back to 65 gm and tried again, much better but still a bog when I snapped it open quickly. I wound the hs screws out to 2 turns and the bog pretty much dissapeared, sounds pretty clean and crisp but I am yet to ride it as there is a cyclone knocking on the door in the next day or so. I will have at least a week until I can ride it again so I want to get my carbs running on the slightly rich side for run in and go from there.
I don't really want to run in my new engine or risk seizing it due to being too lean on the main jet so I'm considering going up a size to 137.5 or maybe 140 at least until I get some time on the fresh motor.
I am going to replace my needle and seats as well as they didn't always pop cleanly when I was testing them, sometimes they just fizzled slowly, even when wet with wd40. I'm told this is not really desireable, they should pop!(they did sometimes)
I am considering going to a 2mm n/s combo as I see a lot of people seem to run this size. Are there any benefits to going up to a 2mm n/s or is it better to stay with a 1.5mm and just richen my mains up a size or 2 so that I can try to get the high speed screw back into around 1 turn.
the mikuni manual says a 1.5 can flow more fuel than the carb can use so im leaning towards staying with a 1.5.
I realise all this may go out the window once I start riding it but ive always been a 'start rich and lean off slowly' kind of guy and ive never blown up an engine using this method.
Any thoughts?
I swapped springs back to 65 gm and tried again, much better but still a bog when I snapped it open quickly. I wound the hs screws out to 2 turns and the bog pretty much dissapeared, sounds pretty clean and crisp but I am yet to ride it as there is a cyclone knocking on the door in the next day or so. I will have at least a week until I can ride it again so I want to get my carbs running on the slightly rich side for run in and go from there.
I don't really want to run in my new engine or risk seizing it due to being too lean on the main jet so I'm considering going up a size to 137.5 or maybe 140 at least until I get some time on the fresh motor.
I am going to replace my needle and seats as well as they didn't always pop cleanly when I was testing them, sometimes they just fizzled slowly, even when wet with wd40. I'm told this is not really desireable, they should pop!(they did sometimes)
I am considering going to a 2mm n/s combo as I see a lot of people seem to run this size. Are there any benefits to going up to a 2mm n/s or is it better to stay with a 1.5mm and just richen my mains up a size or 2 so that I can try to get the high speed screw back into around 1 turn.
the mikuni manual says a 1.5 can flow more fuel than the carb can use so im leaning towards staying with a 1.5.
I realise all this may go out the window once I start riding it but ive always been a 'start rich and lean off slowly' kind of guy and ive never blown up an engine using this method.
Any thoughts?
- Location
- Cairns Australia
Ok, after a few hours of tinkering at the lake I ended up with 25psi pop off, 2mm n/s 95gm springs, 75pilot, main jet started off at 135, went to 140, better but still bogs when snapped open, then went to a 142.5. Got stronger and more responsive with less bogging every time I richened up the main. I did a few short full throttle plug chops and the plugs still look too white for my liking. Still feels very flat with no torque above half throttle. If I hit some chop and it free revs for a second it revs out and flies but doesn't want to rev up properly when it's hooked up on flat water. I've gotta get a hold of some bigger main jets and try again. It seems to be wanting more fuel than most people's jetting combos on here. I haven't seen many posts with 145 mains in dual 38's but I think that's where I'm gonna end up.
- Location
- Charlotte, NC
carb settings will be different for every ski.. i see youre in australia, your more south location could cause the need for more fuel.. ive worked in the automotive field in the past and seen several instances where different brand spark plugs cause driveability issues.. Chryslers should only use champion plugs as well as Toyota should only use NGKs, and many of the toyotas use iridium tip plugs from the factory.. i would only use the ngk bres plugs in a jetski.. thats what the ignition was designed to use and its best to used oem specs..
Sounds like the carb tuning is going in the right direction.. id step up to the 145 mains.. one jet size doesnt make much difference.. i feel the safest tune is having a larger main jet to keep the high speed jet open no more than one turn.. some seadoos are set from the factory with the high speed screw completely closed..
Sounds like the carb tuning is going in the right direction.. id step up to the 145 mains.. one jet size doesnt make much difference.. i feel the safest tune is having a larger main jet to keep the high speed jet open no more than one turn.. some seadoos are set from the factory with the high speed screw completely closed..
the reason seadoos came with the hs closed in later models was because of guys like us who raced the earlier models and turn them in to run leaner and fast with a homemade pipe jetting setup for water injecting
we would sometimes seize it and we would put the stock water injection back on and reset the screws back to stock then have the dealer warranty it
we would sometimes seize it and we would put the stock water injection back on and reset the screws back to stock then have the dealer warranty it
Fro Diesel
creative control
- Location
- Kzoo
I am pretty sure i am at 145 main on my 38s. But i may have since reverse jetted for fun. Ported cyl 82mm, bpipe, 185psi.
- Location
- Cairns Australia
Well im up to 147.5 mains now and the thing is starting to drive me nuts. It seems for the 1st ten minutes or so it has heaps of power and no sign of bogging whatsoever. Revs out easily but if anything sounds a little rich but I'm still running it in so im trying to stay away from full throttle apart from the odd squirt here and there.
After 10 minutes or so the lean bog returns. It will only handle about 1/3 throttle. Anything more and it dies. It will cruise along on the plane at 1/4 throttle effortlessly but crack it open or open it up gradually and the fire goes out completely. I pulled the plugs and they look too lean still. Not burnt but a bit on the grey side of tan. I've tried stock br8es and iridiums, both gapped nice and tight with no difference between the two. I Have several areas to target.
1. My earth terminal on the battery is a bit dodgy. I've had to clean and reseat it a few times to get it to start, it's a new batt but the previous owner damaged the terminal. I suspect it could be intermittent causing breakdown under load but doubt this is the cause of my problem, just a rare possibility.
2. Fuel switch is leaking air into line causing a lean out intermittently.
3. Wsm carb kit is causing fuel pump issues and not pumping enough fuel at wider throttle openings. I've put most of the original mikuni parts back into the carbs but not the fuel pump side. I have no external fuel leaks to speak of.
Anyone have any ideas which is going to be the most likely culprit here.
After 10 minutes or so the lean bog returns. It will only handle about 1/3 throttle. Anything more and it dies. It will cruise along on the plane at 1/4 throttle effortlessly but crack it open or open it up gradually and the fire goes out completely. I pulled the plugs and they look too lean still. Not burnt but a bit on the grey side of tan. I've tried stock br8es and iridiums, both gapped nice and tight with no difference between the two. I Have several areas to target.
1. My earth terminal on the battery is a bit dodgy. I've had to clean and reseat it a few times to get it to start, it's a new batt but the previous owner damaged the terminal. I suspect it could be intermittent causing breakdown under load but doubt this is the cause of my problem, just a rare possibility.
2. Fuel switch is leaking air into line causing a lean out intermittently.
3. Wsm carb kit is causing fuel pump issues and not pumping enough fuel at wider throttle openings. I've put most of the original mikuni parts back into the carbs but not the fuel pump side. I have no external fuel leaks to speak of.
Anyone have any ideas which is going to be the most likely culprit here.
are these stock carb bodies? if not they might not have enough restriction in the return line. Novis like to have the return restricted to maintain enough fuel pressure. stock carbs a lot of times had a restricted hole in the last carb but not always. you may try adding a inline restrictor and see if it helps.
I guess if my computer would have loaded the whole page i would have seen others talk about this my bad. just curious when you built the carbs did you change all the little plastic check valves and stuff?
- Location
- Cairns Australia
Yes I did but they were a an aftermarket product. I think I'm going to put all of the original mikuni parts back into the fuel pump and see if that helps. I think I have a dodgy fuel tank check valve as well. It was stuck open. I cleaned it with contact cleaner but it takes a lot of blowing through it before it will close off. I doubt the fuel pump would flow enough volume to ever make it close and build up tank pressure. I'm still trying to get a definitive answer on whether they need pressure in the tank or not to work properly. I had suspected it was blocked but when I checked it, it was stuck open.
This is a problem.
Yes it requires pressure, you will get opinions here but it needs that valve to work.
You killed it with the contact cleaner.
Replace it with a proper ski oneway valve (OEM is best) not a MX breather like I see on skis that don't run properly all the time.
That pipe in OZ on skis will run well with 140 high, 77.5 low. 1.5ns and 95. Pop of around 40 is desirable with 38's.
Check the return line as others have said, it needs to flow, the line out of the carb to the tank has a small hole that gets blocked, check it and clean it out with a fine pick and blow out.
Get the WSM carb kit and throw it in the bin.
All of it.
WSM produce some great bits, this in not one of them....
Replace the in line fuel filter if not done too.
Your problem is not jetting
- Location
- Cairns Australia
Im with you on everything you said. It goes well for 10 min which has me confident that the jetting is close. In theory engines will richen up as they warm up as the fuel atomises better in a hot engine so I doubt its jetting causing me to lean out after 10-15 min riding. I'm confident it was lean at the start of this saga but feel it's fixed in that department now. I've cleaned and checked the return line restricter and put on a new filter and fuel lines and drained and cleaned the tank out. I'm hoping the check valve is the cheap fix to an expensive test of my patience here. Will a normal fuel rated one way valve do the job or do I need a genuine yamaha valve. I can get much more blingy looking billet alloy valves for less than the ugly plastic yamaha one but read somewhere the yamaha one opens to vent at around 5psi. Is there any merit to this? It appears to be a normal one way ball valve to me.
Quinc
Buy a Superjet
- Location
- California
Any one way valve will work.