Author Topic: Opened up the carbs... little surprise, and some questions  (Read 1747 times)

0 Members and 1 Guest are viewing this topic.

CETME

  • Guest
Opened up the carbs... little surprise, and some questions
« on: July 14, 2005, 02:43:55 PM »
I opened up the carbs..... Found the main jet to be #100... that is right... but the slow jet is #38.... shouldn't it be a #40? Is the difference so great that I should replace them?  Remember, this is going to Alaska, carrying what will probably be a 250lb load (me and gear) what would you recommend?

I checked the FAQ on setting the floats, and it looks like you adjust the floats when the carb is upside down.  Does this mean that you measure the float height, with the float valve closed, then adjust so the pin in the float valve is barely touched when the "top" (bottom if the carbs are right-side-up) of the float is 22mm?

Reason I ask, is that if I hold the carbs right side up, the float valve is open, but resting on the float tang at all times, so it would be impossible to set them right side up right?    Does this make sense to anyone?

Offline Bob Wessner

  • "Carbs Suck!"
  • Really Old Timer ...
  • *******
  • Posts: 10,079
Re: Opened up the carbs... little surprise, and some questions
« Reply #1 on: July 14, 2005, 02:52:25 PM »
The carbs should be tilted slightly off perpendicular, not upside down. The float tang should just be touching the float valve pin without compressing it.  See;


http://www.salocal.com/sohc/tech/carb/asmpg_mgs/flthgt.htm
We'll all be someone else's PO some day.

eldar

  • Guest
Re: Opened up the carbs... little surprise, and some questions
« Reply #2 on: July 14, 2005, 03:00:13 PM »
I guess I always thought the jets were slightly larger at least for the mains. 38 will probably not cause too much of an issue but you must remember that alaska may be cooler and so will have different fuel requirements. Since I dont know what temps you have ridden in, I really could not say. 
I have a 78K and even when it is 40 degrees out, my factory lean settings work fine. Just remember, cooler air is more dense.

CETME

  • Guest
Re: Opened up the carbs... little surprise, and some questions
« Reply #3 on: July 14, 2005, 03:32:58 PM »
Thanks for the link...

I'm still not sure of where the float valve should be. Should the float valve be fully closed, but with the pin fully extended when this adjustment is made?

Offline Bodi

  • Really Old Timer ...
  • *******
  • Posts: 5,695
Re: Opened up the carbs... little surprise, and some questions
« Reply #4 on: July 14, 2005, 03:36:20 PM »
That's right. The spring pin should not be compressed..

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: Opened up the carbs... little surprise, and some questions
« Reply #5 on: July 14, 2005, 05:22:24 PM »
I opened up the carbs..... Found the main jet to be #100... that is right... but the slow jet is #38.... shouldn't it be a #40? Is the difference so great that I should replace them?  Remember, this is going to Alaska, carrying what will probably be a 250lb load (me and gear) what would you recommend?

38 is correct for your bike.  40s run pretty rich a sea level and get worse with altitude.  If you get pinging from too lean at sea level (unlikely) , then turn in the air screws a little to richen it up.
Here is the set up cahrt for your carbs.  Download it to make it larger.

Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.