Accelerator pump rod travel

Re: Accelerator pump rod travel

Postby cross » Wed Apr 17, 2019 5:34 pm

daves79x wrote:Aris:
Doing some quick math, I see that 6mm is about 1/4 inch, which I can more easily visualize. I'm sure I've assembled carbs to nearly that spec also. Yes, you do have to bend the limit tab to get that much travel. I suppose there is such a thing as too much 'squirt' from the pump, but most times that does not seem to be a problem. Just as long as you are getting a good healthy shot with each 'blip' of the throttle.

Dave

I have a bit of difficulty trying to adjust accelerator pump as well. Accelerator pump was working and squirting fuel when i removed the carbs, just wanted to adjust it a bit. It is few years old pump diaphragm from randakks.
I have about 5mm on the accelerator pump travel. That's measured on the rod with fuel bowl removed. I tried adjusting it (once back on the carb) to as close to 5mm travel but can't and rod now has travel to about half a throttle. No matter what i do i can't get it to move more than abt 3mm or so. It is difficult to measure though too.
Up to how much throttle should the accelerator pump be working or rod be pushed? Mike Nixon mentioned here that half throttle is not recommended. So if pump rod is supposed to be pushed abt 6mm, that should equal to how much throttle travel?
Another question i have is about the spring and linkage. There is a plastic seat, spring, washer and pin. But below the linkage is another washer, is ti supposed to be there? It seems that the lever just sitting there is pushing against the pump rod and actually pushing it abt a mm. I'm not sure if this is the way it's supposed to be.
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Sasha
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Re: Accelerator pump rod travel

Postby daves79x » Wed Apr 17, 2019 6:54 pm

Second washer above the rod bracket is correct, for the late models. Early ones had a clip through the rod. Biggest trick is to stretch the spring about half again it's length. If you want more travel, make sure first that the tab hitting the pump rod is not 'pre-loading' the rod. Bend it until it just touches the tip of the rod. If all that does not give you the travel you want, just pinch further together the limiting fork of the actuator lever, as described in the shop manual.

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Re: Accelerator pump rod travel

Postby cross » Wed Apr 17, 2019 7:01 pm

Dave, I’ve been doing all that but I’m afraid that I have too much travel on the rod now. I think it’s moving up to abt half a throttle now. That’s not too much?

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Re: Accelerator pump rod travel

Postby daves79x » Wed Apr 17, 2019 7:34 pm

Then simply open the lever fork to limit travel.

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Re: Accelerator pump rod travel

Postby cross » Wed Apr 17, 2019 8:01 pm

Thanks Dave

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Re: Accelerator pump rod travel

Postby Rick Pope » Wed Apr 17, 2019 8:10 pm

Holy Cow... I don't think they looked nearly that nice when new. :bigthumb:
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Either garage is too small or we have too many bikes. Or Momma's car needs to go outside.
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Re: Accelerator pump rod travel

Postby cross » Tue Jul 16, 2019 6:12 pm

daves79x wrote:Then simply open the lever fork to limit travel.

Dave’s


I've assembled everything back and bike runs very good and is nicely responsive to the throttle.
One thing though, i was adjusting the throttle cable after ride one day and was twisting it several times while testing and the bike wouldn't start after that. I had to keep the throttle wide open while cranking and it eventually started and smelled like fuel out of the exhaust as if it got flooded.
Before i could twist the throttle many times and this would never happen. Is this because acc pump has greater travel now and is squirting more fuel or it has too much travel?
My friends that were riding behind me said that my bike has an un-burned fuel smell.



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Re: Accelerator pump rod travel

Postby daves79x » Wed Jul 17, 2019 6:32 am

Of course you flooded the engine when you twisted the throttle. Every touch of the throttle should squirt fuel if everything is adjusted correctly. You may indeed have a bit too much travel however. It will decrease over time - they all do. Do you now see how this new-found accelerator pump operation can greatly aid cold starting?

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Re: Accelerator pump rod travel

Postby Larry Zimmer » Wed Jul 17, 2019 7:03 pm

Just a somewhat side note along the same that Dave said, Sasha: a properly adjusted acc pump will squirt quite a jet of fuel into the carb mouth with one twist. So, more than one twist will get things flooded. Especially if the engine is already 'warm'. That is most certainly the cause of your difficult start and the fuel smell. Good to hear that your carbs are working well!
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Re: Accelerator pump rod travel

Postby cross » Wed Jul 17, 2019 11:09 pm

daves79x wrote:Of course you flooded the engine when you twisted the throttle. Every touch of the throttle should squirt fuel if everything is adjusted correctly. You may indeed have a bit too much travel however. It will decrease over time - they all do. Do you now see how this new-found accelerator pump operation can greatly aid cold starting?

Dave


Yes, it definitely starts easier when cold. When warm, I just briefly touch the start button and it fires right up without throttle action.
I think that pump rod has travel to about half a throttle, I’ll try adjusting it better next time

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Re: Accelerator pump rod travel

Postby cross » Wed Jul 17, 2019 11:10 pm

Larry Zimmer wrote:Just a somewhat side note along the same that Dave said, Sasha: a properly adjusted acc pump will squirt quite a jet of fuel into the carb mouth with one twist. So, more than one twist will get things flooded. Especially if the engine is already 'warm'. That is most certainly the cause of your difficult start and the fuel smell. Good to hear that your carbs are working well!



Thank you sir, I like how smooth it is now
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Re: Accelerator pump rod travel

Postby herdygerdy » Mon Sep 09, 2019 5:35 pm

Lovely job Aris, I am very envious, esp. now I am CBX-less. Great to see you in person and so happy in the first start video too.

You write very well btw, and your questions, responses to the answers offered and your own suggestions (I'm thinking the excellent work you did with an oscilloscope on the switching activity of the OEM OKI ignitors) are very interesting, well thought through and most engaging. Every post is a worthwhile read. Thank you.
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