Topic: Accelerator pump driving me crazy.

[Ira]

I just took my carbs apart and cleaned the jets.  I'm trying to figure out why the bike sputters and bogs under 3k rpm, and a lot of threads seem to point to the accel pump.  I took off the airbox to observe for squirts of fuel, and noticed they seemed sporadic- sometimes 3 would squirt, sometimes 2, sometimes none.  I figured this was a problem and took the carbs off the bike.  I took the pump assembly apart and shot carb cleaner through all the passages.  it was able to squirt through pretty strong.  i shot it into the opening on the #2 carb and cleaner sprayed out of the accel pump jets on every carb. when i pumped the assembly by hand, it squirted fluid.

i put it all back together, after cleaning the bowls and other jets.  back on the bike- nothing.  it's doing the same thing, except i don't see any fuel coming out at all- maybe a fine mist, but not a squirt.  the bike runs the same.  it idles much better after the cleaning, but it still stumbles and bogs for a second when the throttle comes on, then roars to life at about 1/4 throttle or 3k rpm.

what should i be thinking about that i'm not?

i've read all the pump threads i can find.  it seemed like the pump was clear and mechanically sound when i sprayed cleaner through the circuit and worked it by hand, but there's not a noticeable improvement.....

[piute]

    1977 F2 stk.key tops
  I'm no mechanic but my Mechanic(Paul/cousin)
 When the juice shot out all #2 leaked,(bowl/looked like rubber tube NOT)
  Paul suggjested using a bigger diagpham rod "O"-ring ,that set out-side the rod contersunk hole(witch it belonged in)Ithen tightened as even as could.Smashing that "O"ring .
  HEY it worked NO leaks Shoots juice every were/every time

[lucky]

If the check ball in the bottom plate of the accelerator pump is corroded ( and they get that way )
The accelerator pump will never work right. Just have to get a new one($65.00)
Also make sure the little rubber hoses that distribute the fuel to each carb from the accelerator pump have the little brass restricters in them. It raises the pressure.
If the hoses were replaced the little bras restrictor tubes could have been thrown away.

But if you have a 4 into 1 exhaust  it still may not help the hesitation problem even with a stock air filter box and filter.
Put in #42 mm idle jets and set the mixture screws to 3/4 turn. Main jets #120.

On the top edge of the float bowl there is another check ball and that keeps fuel from draining back down into the bottom of the accelerator pump. Make sure to blow through that with a straw (from spray can) and that air will only go one direction.
That check ball is usually OK. Water does not sit in it.

When you test the system ENGINE off and give it throttle while you look in the intake with a bright LED flashlight and see that each nozzle is giving a squirt of fuel.
That still will not help the hesitation without changing that idle jet.

The best thing is if you can get some 1977 needles and lower the clip one notch.
The 1976 needles are the same as the 1978 needles except they are adjustable.

My advice is put 1972 carbs on it OR What I like is the 1969 carbs to get rid of the throttle shafts,and levers and all hat other stuff. Then you can change and adjust everything on the carb while the carbs are on the motorcycle.

Just my opinion. Now let the comments start flying.

But once you work on the 1978 carbs and that accelerator system you start to see all of the nonsense. Even the CR racing carbs do not have accelerator pumps.
Almost NO motorcycles have it.

[Ira]

I have a kerker 4-1 and stock airbox with a k&n filter.  I recall an old article someone posted about that specific setup, which I'll need to reread and make sure my jetting is right. 

I read the chopper forum tutorial on cleaning the check ball. I was hoping that since i could spray fluid through the valves with a straw, they were ok, but i guess i'll take the valve out of the bottom plate and see what it looks like. 

The rubber hoses are stock and even have the little wire clamps on them.

I'd like to avoid purchasing new carbs, but I appreciate the advice.  If I can't figure this out I'll go that route.

[Imago]

My biggest improvement occurred after I followed Two Tired's advice and took a small drill to the "Mickey Mouse" ear holes on the accelerator pump diaphragm. One in particular is critical to the operation of the pump. One hole feeds gas from bowl to the pump, the other hole is the discharge path from the pump to squirt jets. Night and day improvement in my case. The size of the holes must mirror the size of the openings.

This was after I cleaned my PD carbs twice, including pulling and cleaning the slow idle jets and ensuring the two small brass blocks that hide the tiny spring and ball valves were passing air in only one direction.

My set up is stock except for a MAC 4 into 1 exhaust. 105 main, 35 slow idle jets. Mixture screws @ exactly 1.5 turns from seated.

Another improvement came after setting the points and adjusting the timing.

Give the "ear hole" trick a try.

[Ira]

Thanks, I haven't done that yet. I'll report back.

[lucky]

I have a kerker 4-1 and stock airbox with a k&n filter.  I recall an old article someone posted about that specific setup, which I'll need to reread and make sure my jetting is right. 

I read the chopper forum tutorial on cleaning the check ball. I was hoping that since i could spray fluid through the valves with a straw, they were ok, but i guess i'll take the valve out of the bottom plate and see what it looks like. 

The rubber hoses are stock and even have the little wire clamps on them.

I'd like to avoid purchasing new carbs, but I appreciate the advice.  If I can't figure this out I'll go that route.

Some owners have taken out the check ball out of the bottom plate and cleaned it were able to get a good result. I agree that is worthwhile to do.
Some of those bottom plates had a plastic plug holding in the check ball and some had a brass plug holding in the spring and check ball.

Put it on a big towel so that you do not lose the little spring  You can use a very small flat blade electronics screw driver to pry that little plug out and up. Once it comes out a little ways then you can grab it with a needle nose pliers.
Once the little steel ball is out you can roll it around on a piece of 800 grit sandpaper and get it clean if it will not clean up with carb spray.

Let us know how you do.

[TwoTired]

Since details count, I'll make these comments:

I read the chopper forum tutorial on cleaning the check ball.

There are Two (2) check balls.

I was hoping that since i could spray fluid through the valves with a straw, they were ok, but i guess i'll take the valve out of the bottom plate and see what it looks like. 

Fluid must be able to pass, but only in one direction.  The other direction must block fluid passage.  This proves their function as a check valve.

Do heed the advice about the diaphragm "Mouse ear" holes.  They must not impede fluid passage.

Cheers,

[lostmykeys]

 My accelerator pump dind't work right until I took the three hoses between the bowls that feed the brass nozels off.
 Then I sprayed carb cleaner into each conection on the carb until each nozel had a strong stream.
 If i remember I had to block one of the nipples on #2 and 3 carbs to increase the preasure.
Then I put new clear tubing with the brass restictors inside back on the carbs.
 When I got this bike it had some very rust in the tank so I changed all fuel related tubing.

[Ira]

Thanks for all the replies.  This forum really is the best.  I'll check this stuff out and post some before/after pictures.

[flybox1]

Ira, that tiny oring at the top of the accel pump bowl..... If your Carbs are put together and you are testing spray out of the carb squirters, and they don't all squirt, gently loosten the carb bowl mounting screw closest to that tiny oring. I had the issue that my new oring there, when compressed, covered the hole preventing gas to flow upward and into the tubes to the squirters.  If loostening that screw a turn or 2 allows better squirt, wrap a drill bit with some 600, and.spin the oring on it to open it.up a bit.

[Spanner 1]

Yeah, bloody corn gas will cause all the rubber parts in your carb to swell.... and swell shut in some cases. Need to go ahead and open-up the mickey mouse ears holes in the acc. pump ...and check the small o-ring between bowl/body is not squeezing shut 'cos it's all soft and mushy.... 

[Ira]

But if you have a 4 into 1 exhaust  it still may not help the hesitation problem even with a stock air filter box and filter.
Put in #42 mm idle jets and set the mixture screws to 3/4 turn. Main jets #120.

Quick question about this.  I re-read the '81 Motorcyclist magazine article about jetting for a 4-1.  This is what they recommend:

Jetting for either of these pipes is rather easy. Simply install the K&N stock replacement filter, change the pilot (idle) jets to No. 35s, go up two sizes on the main jets and adjust the pilot-air screws out one to one and one-eighth turns. Be sure to synchronize the carbs.

What is "two sizes up" on the mains?

My carbs are jetted w/ #120 main and # 35 idle, pilot at 1 1/2 turns.

This is what the squirt from the pump looks like on each carb.  Sorry for the bad lighting and shaky video, I was holding a flashlight and my phone at the same time.

Accelerator pump in action.

[Ira]

I realize that before I said none of the accel pump jets were squirting.  I don't know if I just couldn't see the squirts before (without a light) or if the carbs are behaving differently today for some reason.  I haven't touched them since the first time I posted in this thread.

Either way, does my video look like the correct behavior, or should they be squirting more fuel?

[Ira]

top for today- any opinions on the video?

[flybox1]

if all 4 of them squirt like that, you should be ok.
mine squirt a little more forcefully. i went with the smallest ID clear fuel line i could get on the 'between-bowl" connectors to up the pressure out of the squirters.  this might have helped.
Tonight i will road test my setup for my 4 into 1's(minimal baffle) after a vacuum sync.
35/120 jets.  stock airbox.  fuel mix screw at 1.5 turns out.
i'll keep you posted on how that goes.

[bollingball]

One thing you might consider is do all your test on the bench no need to put them on the bike. Most every thing can be tested before you put them on the bike.

Ken

[Ira]

Ken-  thanks, that is extremely useful advice. I would have wrestled them on an off a few more times before it occurred to me.

[TwoTired]

Sorta seems weak, to me.  I recall when I finally got mine working properly, it would shoot clear to the opposite end of the carb throat with slide snapped fully open.

[lucky]

The video shows me that they are not working.

Were the float bowls full of fuel???

They were not working.

[flybox1]

Sorta seems weak, to me.  I recall when I finally got mine working properly, it would shoot clear to the opposite end of the carb throat with slide snapped fully open.

Really?  The only other parts of that system I can think of which would change squirt distance, would be to decrease the size of the  exit holes of those little squirters. ( or increase the length of the stroke of the pump to move more fuel, faster)
Mine do squirt better than a pee, but suggestions are welcome for enhancements.

[TwoTired]

Sorta seems weak, to me.  I recall when I finally got mine working properly, it would shoot clear to the opposite end of the carb throat with slide snapped fully open.

Really?  The only other parts of that system I can think of which would change squirt distance, would be to decrease the size of the  exit holes of those little squirters. ( or increase the length of the stroke of the pump to move more fuel, faster)
Mine do squirt better than a pee, but suggestions are welcome for enhancements.

The check valves have to seal so as not to allow pump pressure to flow fuel back towards the bowl.
The pump diaphragm rubber need to be supple.
The Diaphragm "ear holes" mist be the same size and the passageway holes they seal.
The pump rod must be allowed to move freely in it confinement.  There is a rubber dust boot that should not have hardened.

I haven't seen them, since I didn't de-rack the carbs on my examples.  But, there are reportedly restrictors that are in the tubes between carbs.
Restrictors would increase pressure and jet stream among the carbs.  They should neither be clogged, reduced in diameter, or removed from the system.

The actuator spring and linkage should have no fatigue or binding.  The pump return spring may need to be stiffer if the diaphragm rubber has hardened from ethanol pollution.  Weak spring and stiffened rubber will reduce volume and pressure.

Cheers,

[flybox1]

Those tiny restrictors dissapeared with one of my POs long ago.
My Diaphragm looked soft, orings seal, check valves spray nicely...my system seems to function as it should, but now I can't help but wonder if a fresher diaphragm would help move things along.
Does anyone have specs on the restrictors?  It might be worthwhile to find some brass hobby tubing and fab some.  I'll try it.

[millerza]

http://www.hondachopper.com/garage/carb_info/accelpump_valve_repair/page1.html

If you follow this procedure you can at least get peace of mind that it is not the check valves, clean the seat with steal wool. I replaced the ball with some small ball bearings I found at my local Ace hardware perfect size no need to clean old balls. BB sized stuff in there(tiny spring) so be careful.
It was really easy.

[lostmykeys]

 Flybox,I think Lucky went to the trouble to measure the specs of the original restrictor brass tubes.
 If I remember right,he came very close to tossing them in the trash as he didnt know they were in the original lines.