Hello,

I went out today to water test my GP1200 and at idle it was fine but when I tried to give it any gas it had no power and felt like it had to much gas.
I have 130 mains, 110 pilots.1.5n/s....Ckoke is out along with the linkage and throat plates.It was blowing alot of smoke as well.
When I got it home I took off exhaust to gain access to carbs. When I took off the exhaust it seemed like there was to much oil in the pipe. I checked all my lines and everything is good. I repositioned my jets Highs at 1 1/4 out and lows at 7/8 out. Please help....Getting frustrated...

Hi,
I took someones advice and performed a pop off test and was able to get all three carbs to 148psi, I did have to snip a couple of springs but they are all the same and maintain pressure. As for the gauge I used I can thank Phil and Fernando's links.
I water tested today and had a major improvement,1/4 throttle still bogging but WOT almost through me off the ski. I still need to dial in the carbs a little because when I pulled the plugs they were very wet....Thanks to everyone...My ski hit its highest speed ever today in an 1 foot chop hit 66mph. AWESOME!!!!

I am guessing you meant to say the pop-off is 48 lbs???

When you say it is loading up, does the motor 1) die or does the motor 2) load up (it runs, it just stumbles badly)

If the motor dies you are lean. If it loads up you are rich.

If it dies (lean) you want to lower the pop-off - try a 95 gram spring or even an 80 gram spring.

If you are rich you want to raise the pop-off - try the 115 gram spring

The Mikuni manual includes a chart which shows the pop-off pressures using different springs.

The manual also explains the different fuel circuits.

The low speed screw has very little effect at 1/4 rpm range. So fixing your problem is not as easy adjusting the low speed screw.

http://www.mikuni.com/pdf/sbn_manual.pdf

I think 130 main is too large. Next time the carbs are off you might try a 122.5. (main screw at 1.5) In the meantime you might try turning the main screw in 1/8 turn at a time. Make sure when doing a WOT run the rpms do not drop. If RPMs drop this means the motor is getting too hot because there isn't enough fule. Fuel cools the motor. You need an aftermarket tach in order to monitor the rpm. Do not try turning in the main screw unless you have an aftermarket tach.

If you simply pull a plug to check it it will always be dark and oily. To check a plug you have to stop the motor at the rpm range you want to check and pull the plug out on the water.

This message has been edited. Last edited by: Philip_GPR,

You have a PM

Thanks Philip,
I swayed from your original advice and regret it I am going to go back to 120 mains 95 gram springs and go from there. I think I will have much better luck this weekend. If it is my oil injection (being to rich) how in the heck can I adjust it without taking the oil pump out and making sure it is lined up correctly. I do not think I could have mis aligned it by simply disengaging it at the carb rack bracket.

the oil injection is fine, they rarely fail

test it the way you have it now, if you are still rich you may have to put in 115 springs

Philip,

Thank you for all your help...I will let you know how the ride goes this weekend. Fingers Crossed...

philip,

I hooked everything back with k&N filter and am going to water test this Saturday. I started it and the throttle response seemed very good, but still seeing more smoke than usual. However I know it will be the water test that will be the deciding facter. I do know that the last time I had it all together the throttle response was sluggish. So I think we are on the right track. you were right when you said to have patience.
I have a feeling I might need to go with the 115 gram springs. But the water test will tell all.

Thanks again Philip....

Update,

Water tested today and it went a lot better with the 120 mains and K&N back on. Also, I would like to thank Philip, and TCR for their help, I will dial my lows to what TCR recommended along with a couple other recommendations that he made and report back tomorrow afternoon...I hit some nice surf today and it felt awesome to get back out their again...That salt water sure clears out the sinuses...

I went out today and rurned my lows out 1 1/4 and it ran much better but it is still not right, very close but not quite their. Their seems to be less snap at idle to when I pinch the throttle.