Author Topic: 78 invader carb questions. 30 Pilot jet and a 40!?!?!  (Read 184 times)

0 Members and 1 Guest are viewing this topic.

chaddyg8

  • Newbie
  • *
  • Posts: 38
78 invader carb questions. 30 Pilot jet and a 40!?!?!
« on: November 28, 2017, 07:24:23 AM »
I am rebuilding the sled.  And finding out I have a lot of weird stuff going on. Just did a stock rebuild and crank seals. Pulled the carbs again to clean. Pulled both pilot jets and found a number 30 and 40. I should have two 30ís Correct? The reason I pulled the carbs again is Iím having an issue idling. Thanks

mswyka

  • Hero Member
  • *****
  • Posts: 797
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #1 on: November 28, 2017, 04:41:59 PM »
What issues are you having with  the idle?

While there are quite a few things to check, one of  the places that can be fussy are the moats in the top of the main jet.  There is a air passage in this jet that helps atomize fuel at idle.  These moats can be clogged with crud.

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #2 on: November 30, 2017, 08:02:13 AM »
The motor was just rebuilt new pistons rings and crank seals. Iíam running premix and the oil pump. When it starts. It will Idle around 3 and then randomly start running away (idle higher) so I shut it down. The air and idle screw seem to have no effect.  Iím going to check my pulse line and put two clamps on that.  Also check the new car boots I just bought.  I feel like itís an air leak. Just getting a little discouraged. Thanks

rminier

  • Sr. Member
  • ****
  • Posts: 392
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #3 on: November 30, 2017, 08:41:57 AM »
 You did get another #30 pilot jet so they are both the same, right?
I agree it could be an air leak.
The rubber carb boots can be a likely culprit.
If you have replaced them with some new, aftermarket boots, it is easy to over tighten the bolts and distort the rubber boot.
I usually use the same sealant that I use for the crankcase halves and spread some on the surface where the boots attach to the engine, then snug down the bolts without distorting the rubber.
Are the rubber gaskets in the top cap of each carb still in place and good condition?
 Yep, the impulse line needs to be absolutely perfectly air tight from end to end.
Some people use ether, but I prefer to use Gumout Carb Cleaner (maybe a little safer) and spray around likely trouble spots for a potential air leak.
 If you find one, the Gumout will let you know in a hurry.
75 SnoJet Astro SS, 79 Kawasaki Invader 440, 81 Scorpion Sidewinder, 82 Blizzard 9500, 83 Yamaha Vmax 540, 97 MXZ 670....and holding...for now.

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #4 on: November 30, 2017, 09:00:21 AM »
# 30 pilot jet is on order. Just waiting....on that!  In the meantime I will check over everything you just described. Now that you mention it Iím pretty sure I tighten those carb boots way too tight.  Gaskets were brand new but I did not use any sealant. Thank for the reply!  I will report back when the new pilot jet arrives.

gixxer6

  • Hero Member
  • *****
  • Posts: 941
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #5 on: November 30, 2017, 10:08:31 AM »
I refuse to use the aftermarket boots.  They are crap...If you get them to seal, it won't be for long!  These are like crank seals, if they leak too much it will cause major engine failure. 

I have found even the "Mikuni" brand ones seem to have switched to they cheapo plastic like rubber.  I buy OEM Arctic Cat boots, they are pricey, but worth it in my opinion. 

From the parts interchange thread:  "36mm Carb Flange: Kawasaki pn# 16065-3007, Arctic Cat pn# 0670-197"

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #6 on: November 30, 2017, 10:54:16 AM »
Dang! 33 and some change a piece!!!  I may need to save up. Lol. I did follow your advice though and get the two piece head gaskets. Those are awesome and no leaks. 🤘

mswyka

  • Hero Member
  • *****
  • Posts: 797
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #7 on: November 30, 2017, 11:33:14 AM »
Just a question on the comment about "running away"  Do you have the drive belt installed?  We have some engines that tend to run up above the idle set point but when they hit the point where they engage the clutch they settle back down.  I have run the engines without the drive belt and the engine does just run away with nothing to stop it. 

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #8 on: November 30, 2017, 11:40:49 AM »
At first no belt.  Then after reading in this form I put the belt on.  It would still run away But at the point of engagement it would come back down. But even with the belt on it just has a very erratic idle.

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #9 on: November 30, 2017, 11:43:51 AM »
 But that is also with the 30 and 40 pilot jet.  Which I really donít understand.... New pilot jet should be here Wednesday.

kawhead

  • Sr. Member
  • ****
  • Posts: 440
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #10 on: November 30, 2017, 04:22:54 PM »
I pull up on the choke cables [lightly] one at a time.....tells me what side is lean....

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #11 on: December 07, 2017, 05:56:47 PM »
Ok guys. I have the Correct pilot jets in both carbs. Made sure the Pulse line and oil lines are correct. Went out and Choked it. Gave it a few primer shots and she starts and idles. Let it idle for a few then turned off the choke. It climbs to about 4 then slowly dies. If I give it some coke it will Recover and idle at about 2-3.  I shot some starting fluid onto both choke plungers and both seem to not leak? Any suggestions would be great? Thanks

Interceptor398

  • Administrator
  • Hero Member
  • *****
  • Posts: 940
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #12 on: December 08, 2017, 07:50:55 AM »
Do you see any air bubbles in the gas line?  A leaky enricher is very common.

chaddyg8

  • Newbie
  • *
  • Posts: 38
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #13 on: December 08, 2017, 08:17:08 AM »
I posted this. Then I think I found the problem with the carb boots! While idling I sprayed starting Fluid I each carb boot.  It immediately wanted to die. Stop spraying at it would recovery. This is with the Choke on. So itís looking like a air leak. I have some OEM artic cat boots ordered now.

gixxer6

  • Hero Member
  • *****
  • Posts: 941
Re: 78 invader carb questions. 30 Pilot jet and a 40!?!?!
« Reply #14 on: December 08, 2017, 10:36:39 AM »
Those cheapo crappy carb boots should be illegal!   >:(

Glad you got it figured out!   ;D