951 carb

[toolman60]

Is there any difference between the PTO & Mag carb internal ports. The reason I ask is cleaning my carbs I got the MAG carb no problem cleaned and good flow of cleaner thru the 3 small holes in the pilot circuit.

On the PTO only getting flow from 2 small holes and the big hole.



Mag carb. pop off was at 24 psi. Which according to chart if OSD sent me the 95 gram needle is good with the not so shiny looking silver original spring.

And can someone confirm that OSD1516 fuel pump Disc for 46i and OSD1517 is correct for my carbs. I had the Mag carb sitting on the table to do the check valves and of course dropped 1. Spent 30 minutes looking for that little green mark on my floor before I found it. Not going to happen again. I gonna get me a few and put in the file cabinet.

Thanks
Tim

 

[etemplet]

Put your thumb over the big hole in the barrel. if that doesn't work put the carb back in the cleaner and try to get better flow. Those 3 holes make all the difference. Don't forget to make positively sure the accelerator pump and nozzles are spraying. Good Luck !

 

[toolman60]

Gene,
Thanks I was 99.999% sure it had 3 holes also. I keep fooling with it until it open's up.

 

[etemplet]

I bought an ultrasonic cleaner just for this purpose. I fought those three holes a few times. Boy O Boy whent those carbs are clean and working properly the WHOLE ski is happy. I used to use CHEMTOOL. That stuff got expensive. I bought 2 gallons and that's what I use in the Ultra Sonic Cleaner. so I get the best of 3 different methods, HEAT, ULTRA-SONIC, and the CHEMTOOL. Good Luck !!

 

[mikidymac]

IF you put the low speed needle back in a little it will help force cleaner through the small holes.

No, the MAG and PTO carb are the same internal circuit design.

 

[toolman60]

I finally got it cleared and all good now. Pop Off 25psi so maybe between thunder storms today and tomorrow can get the carbs back on and do a test run on the lake.

 

[etemplet]

25 on the pop-off is a little on the high side. I think the tuners recommend 19-21 favoring 19.

 

[toolman60]

Carbs back on. Water test tomorrow if weather allows.

 

[etemplet]

When I did the last set of 951 carbs I went with the 80 gram spring and put the pop-off right at 19-20psi. Using the 95 gram spring had the pop-off around 24psi. I rode the ski with the pop-off at 23-24psi and it did fine during the frist break-in which is low RPM. Good Luck !!

 

[toolman60]

Gene now this to damn confusing. Looking at the Mikuni specs my 2.0 needle valve size with dull silver spring should be 25 psi. I used the springs that were in the carbs not what was in the kit.

So now I guess it needs another tear down and order different springs for them. What the heck good is an OSD back to OEM kit if it does not have correct parts for the 947.

 

[etemplet]

I'm not challenging the specs on the carbs . If you are in range and the ski runs good sobeit. I rebuild a lot of carbs and I have 20+ springs and an assortment of mikuni genuine springs they are very proud of. I fought my (2) GTXs through 5 settings. Each time I reset the Pop-Off both skis reacted the same. When I got to 36psi both skis ran much much better. That's where I set them. The range begins at 23psi. Back to the 951...If the 951 responds well at 19psi I'd rather have it a little rich. I see a lot of melted engines. Good Luck

I wouldn't waste my money on the 115 gram sprng. It puts Pop-Off through the roof and I've never encountered anything that uses it.

 

[toolman60]

Looks like I will need a Black at 21 psi or a Gold at 18 psi for mine.

 

[etemplet]

Looks like I will need a Black at 21 psi or a Gold at 18 psi for mine.

Go black... . and don't stress over it. However, if you like the way your ski runs... leave it alone unless it gives you a reason. I have way more issues with the accelerator pump system on the 951 carbs. Generally if the ski is loading up after idling for long periods or gurgles before taking off it is rich. Low Pop-Off is rich... High is Lean. Lean is bad. When you try to take off and the ski dies... that's lean or you feather the throttle and it goes... that's lean. Pull out the choke and see what happens. I know you know this stuff anyway. LOL

For us old two stroke guys, we know lean.

 

[toolman60]

Gene,
Ok will do.
Had it out on water today for hour or so. No hesitation at all from idle to WOT. No hesitation from 1/3 to WOT, 1/4 WOT,1/2 WOT,3/4 WOT. It responds every time you hit throttle from idle to mid, to idle to WOT.
It is down about 1000 rpm according to the Info tach. I going to get my brothers Fluke 931 and check it. Best I could get is 6280 rpm today. With 150 hours it may be time for a rebuild on this ski.

 

[etemplet]

Sounds like the carbs are working to me just keep an eye on your spark plugs and make sure they are at least light brown. The RPM is an issue for sure. Check the compression. Engines usually get LOOSE as they get more hours on them. Check those raves and the rave solenoid. Maybe they are not opening all the way.

Did you pull out the choke gently at RPM ? If you lose RPM you're not lean.

 

[toolman60]

Gene,

Yes I pulled the choke out a little trying to be a little while running down water. The engine lost rpm's as soon as I started to pull it out.

Right now I am running the injection and premix since it was sitting for 10 years.

 

[mikidymac]

Don’t start changing springs to chase pop off. Pop off is just a test and not how the carbs actually function on the ski. Please, just run the springs that your ski calls for.

 

[POPPS]

I'm with miki...there is no reason to change the factory spec popoffs...when i am servicing a carb, i pressure test them to see if they have leaks,,,thats it,
i would hone in on compression,,,check rav valves...

 

[etemplet]

Gene,

Yes I pulled the choke out a little trying to be a little while running down water. The engine lost rpm's as soon as I started to pull it out.

Right now I am running the injection and premix since it was sitting for 10 years.

Thats gonna hurt your RPM. Maybe not 1000 but I dunno. You're putting double the oil in the system than required. I dont think you'll get top RPM with that mixture.

 

[toolman60]

Gene yes I know. I have 7 gals. with premix in the tank. I just wanted to make sure after all the sitting it had plenty of oil. BR8ES are $2.50 each cylinders,pistons a lot more. I am going to go next week and top of the tank fuel tank with gas so that ill cut that premix down some.

I will run a compression test on it next few days and check the RAVES.

 

[1of500]

Funny thing you can run lean by having too much oil