Why wont my ski start without the primer? Fixed*

[Quinc]

YES, I HAVE READ THE MIKUNI MANUAL MULTIPLE TIMES. And all of the other tuning guides out there..

Ski runs perfect and has a ton of power, but I cant get it to start without a primer or idle for more then 5-10 seconds.

Single 46 on a ported and piped stock bore 61x 701. boyesen reeds, and ocean pro flame arrestor

• 170 Main
  
• 135 Pilot
  
• 2.5 Seat - 14 psi pop off. Have also tried a 2.3 Seat with 14psi pop off.
• -Coffman pipe recommends 2.3 with 14psi pop off

• Carb has been cleaned and rebuilt. New needle and new o-rings on the adjusters
  
• Engine holds 10psi for 15 minutes
• New tank valve
  
• Fuel filter is clean
• All the fuel lines on the carb are zip tied on and only 2 seasons old

I have the return line reduced to 1/8". Should I go smaller? If so how small?
Any other ideas?

 

[crazy4sand]

I would say weak diaphrams. Or the carb is off on the tuneing


When a ski has proper gone through carbs It should start with no chock or primer. I can walk up to mine on a cold start and she will fire up with no hesitation

 

[Quinc]

I would say weak diaphrams. Or the carb is off on the tuneing


When a ski has proper gone through carbs It should start with no chock or primer. I can walk up to mine on a cold start and she will fire up with no hesitation

My superjet is that way. Can go days without starting and fires up first time every time. But I cant get my damn blaster to do it... I will try switching diaphragms and see if that does it. If it does I will have a beer waiting for you at pismo!

 

[crazy4sand]

Haha no problem man. Diaphrams should do the trick, carb sounds pretty dialed but I'm no wiz at tuning carbs

 

[eastcoastjumper]

I have a wetjet 46 setup on a jetmaniac all 61x 83mm w/factory pipe . 135L 165M 2.3 n.s with 18psi pop off. Even that was a little rich. Idk your elevation but I'm at sea level. 45-75 degree water, 30-90 degree air I only have to touch the screws a tiny bit through out the season. I can run WOT for a mile. Great throttle response.

Make sure your reeds are in prefect shape. I have boysen 2 stage also. I only use my primer when I haven't ran it in a while and might have air in lines or when I'm done flushing it out I'll flood the engine out.

 

[DAG]

Does it start without a primer after you been riding for say 15 minutes. Kill the motor via stop switch and immediately get back on the start switch? How about same test if the ski idles itself off?

Have you tried increasing your idle rpm?

 

[Blue]

Could be a couple of things. Depending if ur primer is in the main fuel line it could be leaking at the plunger allowing air in and allowing the fuel to run back to the tank. Second thought is reeds. If there old and staying open you could have a loss of suction therfore not pulling the fuel from the carb. Third if the ski never wants to idle your carbs idle circuit may be clogged or not jetted properly. This is the only place the fuel comes from if the throttle is closed when you try to start it without using a primer so that could be the issue. Hope this helps.

 

[Yami-Rider]

It's normal for an engine to need more fuel during cold start up. Shouldn't need choke/primer during warm startup.

Did you check engine compression?

 

[Quinc]

Some good advice! My primer line is connected to my main fuel line so hopefully it is as easy as switching that over! =)

Reeds are Boyesen carbon two stage and only have a few hours on them.

 

[Blue]

Boyesen are famous for sticking open. Well at least the ones on the boyesen intake. I went to vforce to eliminate the problem. You can switch the primer over to the return line. Its not as good but less chance for leaks. You can bypass it just to test it too.

 

[Quinc]

Boyesen are famous for sticking open. Well at least the ones on the boyesen intake. I went to vforce to eliminate the problem. You can switch the primer over to the return line. Its not as good but less chance for leaks. You can bypass it just to test it too.

It is a 61x. But good to know for when I go to 62t cases! I had the engine apart a few weeks ago to replace the crank seals and the reeds still looked new. Also looked at them through the back and no light coming in.

 

[Quinc]

Changed seat to 2.3 and put in a lighter spring for 11psi pop off... Seems to idle a little longer but still wont start without a primer or idle for more then 20-30 seconds. I have a new diaphragm coming from JM today. If it still doesn't work I will check the reeds.

 

[jetx]

I just noticed your return line is reduced to 1/8...is this beciause there is no other restriction, as in return nipple on carb is drilled out or doesn't have one?

Every carb setup I have seen That runs a return restrictor uses a mainjet with a much smaller jet compared to a 1/8 hole...is it possible it's not restricted enough and causing not enough fuel pressure in system?

I'm no expert but thought I'd bring it up for discussion...might be the missing link

 

[Harbor]

.. Iam running a #60 jet for a restricter on the 49's

 

[kevbo]

The bottom screw controls fuel flow at idle. Tune idle mixture well rich of peak rpm on the trailer and it will be perfect on the water. I have had a carb that would idle for about 30 seconds, quit, and need prime to restart. The cause was a missing main circuit check valve. Its that little reed inside the carb. Any small air leak from the diaphragm area will cause the carb to empty at idle while working fine when riding.

 

[Quinc]

The bottom screw controls fuel flow at idle. Tune idle mixture well rich of peak rpm on the trailer and it will be perfect on the water. I have had a carb that would idle for about 30 seconds, quit, and need prime to restart. The cause was a missing main circuit check valve. Its that little reed inside the carb. Any small air leak from the diaphragm area will cause the carb to empty at idle while working fine when riding.

They can't have more then 25 hours on them, but I will check them as well. Thanks!

 

[Quinc]

Would the check valves also be why the manifold and outside of the carb is covered in gas?

 

[kswiatk]

Would the check valves also be why the manifold and outside of the carb is covered in gas?

That would probably just be a leaking gasket

 

[Quinc]

Put the old crusty internals back into the carb and now she idles... Maybe the vibrations from the blaster caused the new oem gaskets and/or check valves do go bad after only a season and half?

 

[NVJAY775]

On a side note. I'm not saying to do it. But IMO primers are one more thing to fail, or possibly cause an air leak. I keep mine simple and run without a primer. I use a little squirt of flammable brake cleaner for cold starts. Normally only needs a squirt for the first ride of the day. Zero issues, love it.