why the bog on acceleration

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imgeno2

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I need some insight as to what is going on with the acceleration. I punch the throttle and whah-la nothing, can't get it to 4000 rpm. I've seen here is some topics that it could be the slides, the vacuum, the fuel filter, etc. Is this the reason that some just give up and go with the single gas guzzling carb conversion? This 83 Aspen came to me with the engine pickled and the carbs full of crap. I rebuilt the carbs with a set I purchased online, don't remember which one and got the bike to run. The acceleration is really nonexistent and disappointing after all the work put into it. Can I get a rundown of the main reasons that this happens? Is there supposed to have a vent on the gas tank? I went to put gas and there was a strong vacuum when I removed the gas cap. Just thinking that I'm missing some kind of venting and it was that simple. Otherwise the bike runs fine and wow what a smooth ride, love it. I adjusted the valves and synchronized the carbs a couple of times just to make sure. What's with this timing advance and vacuum thing? Can someone give me the scoop of how to test and eliminate the various possible situations that screws up the acceleration?
Thanks for reading and responding
Gene
 
Gene, the main reasons carbs on these bikes "bog" on acceleration is the carb slides are sticking, an intake O-ring on the intake manifold is leaking or the floats are not normally adjusted correctly. My '81 carbs did the same thing. Mainly found out of whack float adjustment and my slides were sticking on two cylinders.
 
My 82 had a brief acceleration issue but nothing as severe as you state, so it's probably another problem. But just in case.
Under W.O.T. it started to bog significantly around 6500 up but would still rev to redline 8000 rpm.
Turned out so simple, changed the evidently restricted fuel filter and wa'la it pulled again throughout the powerband like it should.

Hmm, so it idles good and synced ok? Hmmmm.

You say when you remove the gas cap you get a strong hiss of vacuum eh?
Sounds like the vented gas cap is all clogged up, a soak in vinegar or another cleaner could clear this up.
I don't know if plugged cap venting would restrict fuel flow to the mechanical pump enough to do what you describe or not.

But, those are two easy and cheap thing to check.
 
Just to add to the above info you should not have a vacuum in the gas tank, you should have pressure..the vent sucks air in and doesn't let any out...you can check your advance mechanism by unhooking the small hose an the #3 carb and applying vacuum , you may need a small piece of tubing to couple into it if it isn't long enough to test.
 
You said you rebuilt the set of carbs you had with a set you got off line, if i read that correctly. If you did this and changed out some of the carbs and mixed up the slides from the other carbs, this could affect the operations of the slides as well. Each slide that is used in a Carb has been fitted for that Carb, (as OEM) if you changed them around , you are going to have some possible issues. Also, during your carb rebuild, it is essential that the Air Pilot Cut OFF valves be replaced or checked to see if the rubber part have no holes in them. I always check the ones i take out with a small flashlight to see if they are still usable or not. It is also best to replace with new ones in my opinion. The accelerator pump should be replace also. Polish your slides with aluminum foil and the slide holes to clean all residue off and out of them. Set your floats as OEM , then i would do a leak test on the carb set before installing. Also make sure all the little holes in the carbs have been blown out, this is really important. When you are leak testing your carbs, push the throttle on the side of them to see if you are getting a stream of gas inside your carb throttle body, if not, those little holes are stopped up also, this is very important to see if your carb accelerator is working correctly too. I hope some of this is helpful, good luck.
 
great suggestions 40 yr cv carbs are a mess to get right ....compression has to be eqal to get even vacuum though out rpm zone and even gas charge ..slide resistance and springs all have to be even as well .....stock carbs have many passages o rings 90 degree turns ...and on and on ...so for a bike that has not ran forever ...getting the motor and carbs and all there interdependent parts to work good can take a long time even after runninng ...rings seating in good again for even pull on carbs ...as a test you can sycn the carbs up at higher rpm and see if this helps the acceleration if so id say there good chance things can be righted givin time and much tinkering ....
 
Speed reading- which is lazy reading- but I don't think anyone mentioned checking the vacuum canister for the advance. They're known to get holes in them. Is the hose still attached?
 
I'm looking into the repair manual but can't find the vacuum canister. Is this the small hose that's connected to carb #3?
 
Yes, it goes to the back cover, right side I think. It's probably obscured by the fuel tank. Some have had luck soldering them if this turns out to be your issue.
 
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Best I can do. See "gallery index and tech reference" banner then 80-83 1100 manual, then ch 15 page 6
 
Are you 100% sure that the float levels are correct? I didn't double check mine and ended up with the bike doing exactly as you describe.
 
I had a fuel leak and thought that it was the float height, so I checked and checked and checked. So again I will be checking the floats, but this time I shall get a professional to eyeball them for me. I'm not sure of myself anymore, though I may say that I'm very proficient at removal and installation of the carbs:) I noticed that the vacuum diagram here is of 1982 and was wondering if the 1983 is different. Boy I've got my work cut out for me. This is ok because I still have a bike to ride while this bike is more of a hobby and a learning experience. I've had a 1981-1983 Goldwing crush for some time and I found this one on Craigslist for a good price ($250) that I couldn't resist. I've personalized it a little by eliminating some parts, like no audio, don't the lower fairing, cut down the windshield. Not a lot , but enough to make me happy with it's look.
20160630_194420.jpg
 
Lowers for the fairing channel air to the radiator. If you plan to leave them off you should get the side scoops off a standard installed.
 
Imgeno, you said you synced the carbs so you obviously have the four vacuum gauges. Try hooking up the gauges again and run the throttle up and down. Watch the vacuum in each gauge and see if they remain equal. After I rebuilt mine I had a vacuum leak #2 caused by the manifold Oring leaking, replaced the 40 mm O-ring and she started running fine. A vacuum leak will normally cause the vacuum to jump around or fluctuate.
 
Learning a lot of info that could prove invaluable in the future. :good: So far though, basic cleaning, needle's with new, or cleaned seat's, float bowl gasket's, & adjusting the air mixture screw's back closer to the stock setting's. :whistling: Have taken care of most of my problem's :yes:
 
would the air mixture screw (I'm assuming this is the idle mixing screw) make a difference on the acceleration? I'm asking because the screws are new ones and the acceleration seems to feel like it's starving for fuel. Can we adjust the fuel at all?
 
well when air is cut fuel is richen ...stock carbs can be a pain ..there so many things that can cause the same thing ...a lot of times the air scres do noting indicating something else is going on ..this happens quite often with stock air mix screws ....

hmmm 83 bike so your talking screws under the carbs that hard to get to ?
 
Can we place a larger capacity jet? Seems like there's more air to fuel ratio and I was thinking of the jets.
 

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