Author Topic: Accelerator Pump on second carb  (Read 1576 times)

VisionaryDan

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Accelerator Pump on second carb
« on: May 08, 2005, 10:35:41 AM »
Has anyone had any experience with putting a second accelerator pump on 82 Carbs? I know there are many ways to correct the Vision bog problem but a burst of fuel in both cylinders should elliminate the bog and increase the rate that the bike accelerates. I've played around with accelerator pumps on cars in years past and was always able to elliminate a bog problem by adjusting when and how much fuel the pump shoots.

Dan
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« Last Edit: May 08, 2005, 10:36:20 AM by VisionaryMan »

Lucky

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Re: Accelerator Pump on second carb
« Reply #1 on: May 08, 2005, 03:45:15 PM »
more trouble than it's worth, Vision carbs, properly adjusted, have no stumble.
1982/3 XZ550 Touring Vison, Gold on Black

VisionaryDan

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Re: Accelerator Pump on second carb
« Reply #2 on: May 08, 2005, 06:44:54 PM »
I guess I asked this question because I see postings that suggest glueing nickels to the airbox flapper to delay it's opening. I was looking for a solution that was more technically sound.

I would be the first to admit my carbs may need some tweeking but it does seem to be one of those things that you need to keep maintained perfectly or you will experience a problem.

I even noticed an increase in the "stumble" by just replacing the air cleaner.

Dan

Lucky

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Re: Accelerator Pump on second carb
« Reply #3 on: May 08, 2005, 08:08:48 PM »
the nickel trick is only for the very early flappers that were spring loaded, not vacuume operated.
1982/3 XZ550 Touring Vison, Gold on Black

h2olawyer

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Re: Accelerator Pump on second carb
« Reply #4 on: May 08, 2005, 10:55:32 PM »
Dan -

Clean carbs cannot be stressed enough. ?My V sat in a dealership for 2 years before I bought it. ?Must have been some gelled gas by then. ?Always had a fairly pronounced stumble @ 4KPRM. ?When I finally did a complete tear down, dip & reassembly, the difference was amazing. ?Then, getting everything in synch makes the V a real smooth runner. ?After those procedures, I thought I'd bought a new bike!

After getting them clean, installing a fuel filter & properly storing it in the off season, mine starts & runs fine. ?Just need to do a synch test again. ?Have a small, intermittant stumble after the bike gets very warm. ?Nothing compared to what it used to be but enough to annoy me once in a while.

H2O
« Last Edit: May 08, 2005, 10:59:09 PM by h2olawyer »
If you have an accident on a motorcycle, it's always your fault. Tough call, but it has to be that way. You're in the right, and dead -on a bike. The principle is not to have any accident. If you're involved in an an accident, it's because you did not anticipate. Then, by default, you failed.

Glyn Pickering

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Re: Accelerator Pump on second carb
« Reply #5 on: May 09, 2005, 04:38:47 AM »

Hi Dan

I bought my Vision as a cheapo hack and didn't want to spend time fixing things constantly. I've had that with loads of Brit stuff. I cleaned out my carb really well but still had a stumble. Found the carb a real b--- to get on and off and eventually junked it all together. If I couldn't have gotten another carb to work on it I probably would have sold the bike on. I've got a Weber IDF carb on now with no YICS. Was quite a major project but have no stumble and the jets are real easy to clean / change etc.

I'm sure a well sorted and serviced Mikuni will out perform my carb but I'm happy with the ride and serviceability. I can send you info on the conversion if you're a bit of a wrench.

I'm on pickteam@xtra.co.nz

Cheers

Glyn

VisionaryDan

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Re: Accelerator Pump on second carb
« Reply #6 on: May 09, 2005, 05:02:06 AM »
Thanks Guys,

I bought this bike new and had put it in mothballs about seven years ago. I recently dusted it off, tore down, cleaned and rebuilt the carbs. It's been running well accept for about 5-10 minutes into the ride. It has a tendance to stumble a number of times when trying to accelerate (around 4000rpm). After riding about 15 minutes or so the it will clear up.

I haven't sync the carbs yet so I'll follow the procedure on Lucky's site and see if this helps.

Thanks again,
Dan

Lucky

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Re: Accelerator Pump on second carb
« Reply #7 on: May 09, 2005, 05:42:55 AM »
Dan, since you bought it new, do you know if it has the airbox/carb update? they were done at the factory midyear 82, & free to V's built before that.  the vacuume operated flapper is the way to tell.
--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

VisionaryDan

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Re: Accelerator Pump on second carb
« Reply #8 on: May 09, 2005, 07:02:58 AM »
Yes it was retrofitted with an 83 style airbox with the vacuum flap by the dealer. I sould probably just sync the carbs.

Thanks again,
Dan

Lucky

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Re: Accelerator Pump on second carb
« Reply #9 on: May 09, 2005, 07:54:24 PM »
Absolutly! and then adjust the pilot screws. if it still stumbles, the screws may still be too rich, turn them in 1/4 -1/2 turn. if it still stumbles it might be time for a thorough carb cleaning.

Tip: disconnect & block, or clamp off (with hemostats) the YICS hoses while synqing the carbs, it'll be more accurate.

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

silicon_toad2000

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Re: Accelerator Pump on second carb
« Reply #10 on: May 10, 2005, 06:14:05 AM »
Dan the second/rear carb gets a shot of fuel from the front carb accelerator pump.
I spent a lot of time following the fuel circuts on these things while i was counting to ten after trying to undo certain bolts/screws when I was cleaning the carbs.
I thought about trying to have a second pump on the rear carb and getting a bit more fuel in there. If you leave them linked you cound stagger the activation.
Like Lucky said, it is a lot of mucking about, very careful mucking about.
I'm not game enough to take it on as there are next to no parts available here in oz.
One mans clunker is another mans blank canvas.

83vtwin

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Re: Accelerator Pump on second carb
« Reply #11 on: May 10, 2005, 05:13:23 PM »
i  did this over 20 years ago along with relocating the location of the accelorator nozzle site down to the smaller brass fitting on the intake manifold,i am not sure which. but this mod helped me get the pink slip for the 83 i now have, i still have the carbs, at the time i did not think that 1 accelorator pump had enough volume to support the longer hoses and the fittings .
i also drilled out the smaller brass fitting on two intake manifolds and tapped them to accept some honda keihn air jets i did not tap all the way through them this way the jets would not fall into the manifold.
i never got the chance to run this carb on my 83 because i would have had to put a silver 82 tank on also but i think it would have more low end

Lucky

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Re: Accelerator Pump on second carb
« Reply #12 on: May 10, 2005, 07:09:41 PM »
James,
out of curiosity, what led you to these mods? was the performance of the bike lacking (as opposed to good when everything is working properly) and the mods were a way to increase performance?

I'm asking because the 'pucker' factor as you refer to it, is, for a bike of the period, not that bad, & i'm wondering if your pink slip is more the result of refined riding skills rather than mods to the bike...

it occures to me that adding a fuel shot & metered air to the intakes still would be subject to the YICS's influence (since it's downstream of the intakes) or did you remove it?

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

83vtwin

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Re: Accelerator Pump on second carb
« Reply #13 on: May 10, 2005, 07:39:51 PM »
i like to tinker and had always thought that the original location of the nozzles was to far for the fuel to enter the open valve in time before the valve closed i thought it might be part of the carb design that the 83 carbs might be differant i really had no idea what the 83 carbs looked like for 15 or so years , i had bought and sold at least 6 visions by then and always had problems with the carbs but that was the last set i kept and they were on the bike that i used as my mule to test things
 i felt that on a twin you did not have an open valve as often as a 4 cylinder making it more important to have fuel delivered to valve this bike had good torque from down low but no matter how i tuned them they would not always !pull but just most of the time , if the valve closed before the fuel mixture got into the chamber the fuel would seperate and make the next opening rich adding to the stumble

83vtwin

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Re: Accelerator Pump on second carb
« Reply #14 on: May 10, 2005, 08:01:23 PM »
i had actually stopped riding for a couple years due the loss of 2 good friends riding on the roads where we would drag the pegs.
i met the owner of the 83 and talked to him for a while, when he asked me to tune his bike i jumped at the chance. i had to build my bike from parts i had collected it took me 2 weeks after i challenged him and i still have most of the 82 bike in parts the only place the 83 had me was from about 9000 on up he did not have enough room to get all of the motor in the 1/4 i took 3 out of 3 runs and took him buy 1 to 1/2 bike , my 82  was topped out at 122 where the 83 would top 135   my bike had the bottom end but i liked the way the 83 top end