Author Topic: Accelerator Pump Settings  (Read 15564 times)

Rikugun

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Re: Accelerator Pump Settings
« Reply #20 on: May 29, 2012, 05:45:24 PM »
Quote
Kudos to whoever bent that bar up though, nice work

The more I magnify it the more grainy it gets but I can't see much in the way of tooling marks. Sorta' looks factory made.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

Lucky

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Re: Accelerator Pump Settings
« Reply #21 on: May 29, 2012, 05:59:24 PM »
Your replacement rod is on it's way, it went out in this mornings mail.
--Lucky
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Jimustanguitar

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Re: Accelerator Pump Settings
« Reply #22 on: May 29, 2012, 07:23:54 PM »
Thank you very much! Lemme know what I owe you.

Lucky

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Re: Accelerator Pump Settings
« Reply #23 on: May 30, 2012, 07:19:50 AM »
nothing although.. (que Godfather music here) I may one day ask you to do me a favor... lol  no we're good. :)
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Cdnlouie

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Re: Accelerator Pump Settings
« Reply #24 on: May 31, 2012, 11:44:19 AM »
Here is a procedure that I discovered recently to be quite effective on the 82's.  It should be helpful for setting up an 83 as well.

I usually use the 60mm measurement with the stock diaphram (but the Keyster kit necessitates shortening it, or the delay will cause a serious stumble).

You can start with the 60mm (assuming everything else is perfect on your carbs) and adjust the rod on the bike after a few test runs. There is a slight hesitation when the pump delay is too far behind the throttle plate opening. Yamaha had you set it visually to clear the throttle plates, but this only get you close and cannot realistically anticipate the venturi air flow effect.

I think I did about 7 turns (thread revolutions, shortening the rod) and it consistently improved in response. You can pull the rod out of the throttle actuator and while holding the shaft from turning rotate the bent end a full revolution each time.  I started with four turns, then went to two turns and finally one more (for good measure and stopped).

I know Ken (motoracer) suggests the volume measurement, but I have not found that method particularly useful with any of my setups (with due respect here), because I find that timing is a more signficant issue than volume.  My 82's don't have any bogging problems because of too much fuel, rather they tend to get too much air, too soon, and create lean conditions.  Getting the fuel delivery into the venturi at the correct timing with the air flow has made the most difference in my tuning situations.


QBS

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Re: Accelerator Pump Settings
« Reply #25 on: May 31, 2012, 01:07:55 PM »
Cndlouie, that makes great sense.  Thank you very much.

Cdnlouie

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Re: Accelerator Pump Settings
« Reply #26 on: May 31, 2012, 01:32:49 PM »
I sort of "stumbled"  ::) upon that one when I was fitting a new keyster diaphragm that has a shorter actuator rod than the original, so I didn't have a clue what I should set it at.  A bench test with fuel to see if the nozzles open up and cleared the throttle plates as early as possible is a good start, and what I usually did before coming upon this idea.

Everything was brand new in the carb set so I knew what I was dealing with, I started with 60mm and it still had a bog when first opening the throttle.  I went right to the pump adjustment and started shortening the rod. Each time it improved the throttle response.  I stopped when any hesitation vanished.  I should have continued to see if further shortenings created any other issues, but hey, when you get things right you stop.

This makes for a good procedure for ensuring the rod adjustment is optimum under running conditions.  Start at 60mm (from right bend to plunger arm) and if you have hesitation, shorten it until your hesitation goes away.  This 82 procedure was done on the flapper controlled airbox.  Now, this "assumes" that your carb set is perfectly set up in every other manner, because this will not compensate for clogged passages, or leaking throttle shaft seals and the like.  This is like the last thing you would do to perhaps clear up anything less than fantastic throttle response.


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QBS

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Re: Accelerator Pump Settings
« Reply #27 on: May 31, 2012, 01:54:29 PM »
What are the symptoms of leaking throttle shaft seals?

Lucky

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Re: Accelerator Pump Settings
« Reply #28 on: May 31, 2012, 02:14:46 PM »
same as other vacuume leaks. uneven idle, runs lean, hard to tune, hard to start, backfire on decel, etc
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Jimustanguitar

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Re: Accelerator Pump Settings
« Reply #29 on: May 31, 2012, 04:52:46 PM »
There are a few different methods and opinions for adjusting the linkage rod's length, but I've not read much about adjusting the stop screw... I've found that the general consensus is "don't touch it", but am a little too curious to stop there. One could control the timing of the pump by adjusting the linkage-rod's length and the overall volume that the jets squirt could be adjusted with the stop screw, right?. Obviously it's a sensitive balance and you would have to dance back and forth with both of these adjustments to get things just right, but it does sort of work that way, right?

QBS

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Re: Accelerator Pump Settings
« Reply #30 on: May 31, 2012, 06:07:11 PM »
Regarding your last two questions, that's definitely how I see it.  If both variables are set perfectly, off idle flat spots should, at the very least, be greatly minimized.

As an aside, my '83 has/had a significant off idle flat spot.  For many years I worked around it by coming off the line with a little bit of high idle and a little bit of clutch slippage.  I'm convinced that this chronic minor clutch abuse resulted in shortened clutch life.  The fact that the factory clutch lasted 72k miles is due in large part to many of those miles being rolled on the highway.

Lucky

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Re: Accelerator Pump Settings
« Reply #31 on: May 31, 2012, 09:16:32 PM »
any adjustment that you can turn it with your fingers, a wrench, a screwdriver or heat and a hammer, you should play with!
1982/3 XZ550 Touring Vison, Gold on Black

Jimustanguitar

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Re: Accelerator Pump Settings
« Reply #32 on: June 01, 2012, 08:03:53 AM »
Jim, Your rod is FUBARed. it's not supposed to have that bend in it, it should be straight like the drawing. you need a new one.

maybe that IS the correct rod for the rare 82 carb with the stop screw on the accelerator pump... no?


Lucky sent me a replacement rod that arrived in the mail yesterday. After taking a closer look, perhaps I do have the rare '82 version... The rods are the exact same length. If a "stock" rod were bent up like mine, it would be shorter as a result. It's also evident that it was manufactured differently because the threads aren't the same length. I think that my rod was manufactured the way it is instead of being modified by a PO. I uploaded more pictures comparing the two.

Is there a VIN lookup or some other way to tell what I've got? Perhaps it holds more secrets :)

Jimustanguitar

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Re: Accelerator Pump Settings
« Reply #33 on: June 01, 2012, 08:04:55 AM »
I also can't find "homemade" marks on it. The bends appear to be machine made.

Rikugun

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Re: Accelerator Pump Settings
« Reply #34 on: June 01, 2012, 08:13:24 AM »
Quote
Kudos to whoever bent that bar up though, nice work

The more I magnify it the more grainy it gets but I can't see much in the way of tooling marks. Sorta' looks factory made.


Very interesting. It seems theses bikes still have some surprises  :)
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

Lucky

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Re: Accelerator Pump Settings
« Reply #35 on: June 01, 2012, 04:15:33 PM »
If it's factory made then I have some other thoughts:
1)that it came out of something else because it would present quite an angle change from stock. I wouldn't be surprised that the end would pop out when the green plastic gromet wore out.
2) when you put the one i sent on, is the angle way off on that one? if not then the linkage is different, or... might not be vision carbs??..
1982/3 XZ550 Touring Vison, Gold on Black

Rikugun

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Re: Accelerator Pump Settings
« Reply #36 on: June 01, 2012, 05:04:17 PM »
A picture of the carbs may help clear up the mystery.

I considered the rod is from another set of carbs but can't think of any other Yamaha's that had accel pumps. Anyone know of any possible applications? Only two other Japanese bikes I'm aware of  had accel pumps but the parts were different and they were from inline fours.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

JohnAMcG

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Re: Accelerator Pump Settings
« Reply #37 on: June 06, 2012, 12:23:10 PM »
I have it too!

I recognized the bent rod immediately but wanted to check before posting, in case I had lost it (my mind).  From a quick glance, I do not think the straight bar will fit as a replacement.  I have a lot of other things to do at the garage but I will try to look into it a little deeper. 

If you guys remember, I had accel pump problems, and with used guts from here, it works just fine.  I haven't seen anything else to suggest I have anything other than original 82 carbs on an original 82. 
-JM

JohnAMcG

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Re: Accelerator Pump Settings
« Reply #38 on: June 06, 2012, 12:33:20 PM »
Oh, and it has the stop screw adjustment, which IIRC works pretty much as described by jim
-JM

Lucky

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Re: Accelerator Pump Settings
« Reply #39 on: June 06, 2012, 02:04:17 PM »
I'd say this qualifys as another carb varient now known...
1982/3 XZ550 Touring Vison, Gold on Black