- Location
- kent island maryland
I recently discovered after spending countless hours on here searching for advice and trying every logical jetting combo known to man I started to see a lot of people post issues similar to the problems I was having and struggling to get their ski tuned properly and it always seemed to ended up with some "expert" on here steering someone to what they think is right cause that’s all they know. It blew my mind how much of a difference the correct fuel pressure made in my ski!! If this doesn't speak as to how far of a difference it made this is my first post on here after being a member for several years hopefully this tip can help someone else out too!!
So a little background on my setup I have a CPT 836 lw 4mil stoker engine with duel 48 novi-tec's MOD B pipe bored to 50mm and enhancer with 62T stator. So I finally had enough I was at the point of throwing a match in the gas tank I was so pissed with the how badly my expectations of this brand new setup was performing and no matter what the jetting it burnt more fuel in the same amount of time just riding around throttle blipping and trying to tune then my 1200 blaster running WFO with buck shots!!! I knew something wasn't right so I made a call to Tim at novi tec I told him my jetting and engine setup he instantly knew my issue was due to too high of fuel pressure due to the fact my engine is a stroker and cause of that the pulse signal that runs the fuel pumps is going to be a lot higher causing the pumps to pump more than they should aka too much fuel pressure. So he strongly advised me before I fool with any of the carbs jetting I need to get the fuel PSI in spec cause when it’s not you will do nothing but chase your tail with tuning.
So here’s how you can do this and after setting it up I was blown away on how easy it is to test and how HUGE of a difference it made!! now i cant speak for every carb mfg. but a drilled return is a drilled return and the industry standard is a 60 return jet but what iv learned is thats for a stock stroke engine which alot of us don't have... Every engine is going to be differant so it doesn't hurt to test it out and you don't even need to pull your carbs to check it!!!
heres the link from novi tec to show you what it will look like... ish
http://www.novi-tec.com/images/installationmanuals/yamaha/DY-XRF-SS.pdf
so You need to rig up a fuel pressure gauge a typical 0-15psi carb fuel pressure gauge that most auto parts stores sell will work, you need to tee into one of the carbs return line the tee needs to be in between the carb and the return jet then you need run the hose up the pole (or if your confident enough to ride your ski with your hood cracked with i strongly don't reccommend you can sneek the line out that way) so you can ride the ski and watch the numbers. make sure the hose is bleed and there is no air in the line to give you false readings you need to run the ski in the water. One thing Tim stressed is it's important that whenever your tuning your ski the pump needs to be loaded and preferably ridden and not nosed up to a pier hence running the line up the pole. You want to have 1-2 psi at idle and 4-5 psi at 3/4 to wide open throttle once you find out the return jet size you need you can remove this setup and keep it in your tool box like a pop off gauge.
It was quite interesting to see how stepping up the jet size how much of a difference it made with just the skis idling I started at 80 and no matter what it wouldn't idle for more than 10 seconds when I switched the return to 85 it would idle for a little while but still shook like a paint mixer so I tried the 87.5 it still shook at an idle but not nearly as bad as before with the 85. It was about 3-4 psi at idle and 5-7psi wide open it actually felt pretty good if I didn't have the gauge hooked up I would have called it done and would have been happy with that but since I knew it was too much psi I popped in the 90 return jet started it back up and it idled just as smooth as my 06 superjet when it was bone stock. I was really floored how smooth a light weight 4 mil stoker with a light weight fly and couplers could idle. I was sitting at about 2psi at idle and 5psi wide open. Let me tell you that engine and carbs came to life like Jesus on the 7th day!!! lol So after seeing how amazing it started to run I wanted to keep going. unfortunly I do not have a 92.5 jet to try so I popped in the 95 jet and at idle it started shaking again. I was running 1psi at idle and 3-4psi wide open I will say it ran good but not nearly as good as the 90 jet.
I can't thank Tim enough for his advise it's such an easy test to do and what a difference it can make.
So a little background on my setup I have a CPT 836 lw 4mil stoker engine with duel 48 novi-tec's MOD B pipe bored to 50mm and enhancer with 62T stator. So I finally had enough I was at the point of throwing a match in the gas tank I was so pissed with the how badly my expectations of this brand new setup was performing and no matter what the jetting it burnt more fuel in the same amount of time just riding around throttle blipping and trying to tune then my 1200 blaster running WFO with buck shots!!! I knew something wasn't right so I made a call to Tim at novi tec I told him my jetting and engine setup he instantly knew my issue was due to too high of fuel pressure due to the fact my engine is a stroker and cause of that the pulse signal that runs the fuel pumps is going to be a lot higher causing the pumps to pump more than they should aka too much fuel pressure. So he strongly advised me before I fool with any of the carbs jetting I need to get the fuel PSI in spec cause when it’s not you will do nothing but chase your tail with tuning.
So here’s how you can do this and after setting it up I was blown away on how easy it is to test and how HUGE of a difference it made!! now i cant speak for every carb mfg. but a drilled return is a drilled return and the industry standard is a 60 return jet but what iv learned is thats for a stock stroke engine which alot of us don't have... Every engine is going to be differant so it doesn't hurt to test it out and you don't even need to pull your carbs to check it!!!
heres the link from novi tec to show you what it will look like... ish
http://www.novi-tec.com/images/installationmanuals/yamaha/DY-XRF-SS.pdf
so You need to rig up a fuel pressure gauge a typical 0-15psi carb fuel pressure gauge that most auto parts stores sell will work, you need to tee into one of the carbs return line the tee needs to be in between the carb and the return jet then you need run the hose up the pole (or if your confident enough to ride your ski with your hood cracked with i strongly don't reccommend you can sneek the line out that way) so you can ride the ski and watch the numbers. make sure the hose is bleed and there is no air in the line to give you false readings you need to run the ski in the water. One thing Tim stressed is it's important that whenever your tuning your ski the pump needs to be loaded and preferably ridden and not nosed up to a pier hence running the line up the pole. You want to have 1-2 psi at idle and 4-5 psi at 3/4 to wide open throttle once you find out the return jet size you need you can remove this setup and keep it in your tool box like a pop off gauge.
It was quite interesting to see how stepping up the jet size how much of a difference it made with just the skis idling I started at 80 and no matter what it wouldn't idle for more than 10 seconds when I switched the return to 85 it would idle for a little while but still shook like a paint mixer so I tried the 87.5 it still shook at an idle but not nearly as bad as before with the 85. It was about 3-4 psi at idle and 5-7psi wide open it actually felt pretty good if I didn't have the gauge hooked up I would have called it done and would have been happy with that but since I knew it was too much psi I popped in the 90 return jet started it back up and it idled just as smooth as my 06 superjet when it was bone stock. I was really floored how smooth a light weight 4 mil stoker with a light weight fly and couplers could idle. I was sitting at about 2psi at idle and 5psi wide open. Let me tell you that engine and carbs came to life like Jesus on the 7th day!!! lol So after seeing how amazing it started to run I wanted to keep going. unfortunly I do not have a 92.5 jet to try so I popped in the 95 jet and at idle it started shaking again. I was running 1psi at idle and 3-4psi wide open I will say it ran good but not nearly as good as the 90 jet.
I can't thank Tim enough for his advise it's such an easy test to do and what a difference it can make.
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