Author Topic: Some '83 questions...  (Read 10845 times)

QBS

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Re: Some '83 questions...
« Reply #20 on: April 03, 2015, 04:41:54 PM »
PoD, so the 120 recommendation would richen the pilot circuit?  What does "backing off" the accel pump do?

Rikugun

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Re: Some '83 questions...
« Reply #21 on: April 03, 2015, 05:48:56 PM »
Yes, I have an '82 Vision, with '82 carbs. Converted the carbs to '83 style. Didn't know the fuel pump was different.

So, '83 front carb top and '83 airbox with flapper.

The fuel pump is an '82.

What problems, if any, would I have with this setup? --Steve

There are as many as 2 1/2 different types of '82 carb sets  :) with the newer variants having the vacuum flapper capability. Most parts interchange on these. To my knowledge there is only one variant of '83 carbs and they have the vacuum flapper. There is no significant interchangeability between any '82 carb and the '83 carbs.

The bottom line is you'll want an airbox with the "vacuum" actuated flapper. To make that happen you'll also need a late model set of '82 carbs with those ports or a new style front carb top fitted to an old set plus the little filter thingy. Oh, and some slight jet changes too. Simple, eh!?  Again, '82 and '83 carb parts don't interchange so if you have successfully fit a new style top to your front carb it is from a newer '82, not an '83.

The '82 pump will work fine with the '82 petcock/tank combo. I have no experience fitting the '83 airbox to an '82 frame but there may be interference on the rear cylinder's head-to-frame engine mounting bracket. If it clears, you have an '82 box, not an '83.

Amongst other things, the two years' carbs have different venturi sizes BTW but I'm unsure if the air horn side are similarly sized. If so, the rubbers to fit the airbox to carb air horn would potentially be an issue. To my knowledge, all carb outlet OD are the same so there is essentially one size of rubber intake manifold despite the venturi size difference.

Some pictures of your carbs from a few angles may clear up what you actually have.
« Last Edit: April 03, 2015, 06:17:36 PM by Rikugun »
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Prophet Of Doom

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Re: Some '83 questions...
« Reply #22 on: April 03, 2015, 06:52:21 PM »
PoD, so the 120 recommendation would richen the pilot circuit?  What does "backing off" the accel pump do?
Yes, it richens the pilot circuit, but that never turns off so you will get a slight enrichment at wider throttle as well.  The 120/120 is standard jetting for Euro and Australasian models where emissions testing in the 80s was not so vigorous as USA.

On downdraught carbs (and the vision is no exception) a shot of fuel is squirted in to help with rapid acceleration - particularly when coming off idle.  The goal is to deliver the right amount of fuel at the right time. You don't want to deliver too much fuel too soon (bogging), or too little fuel too late(poor throttle response).  We don't have any control over the overall volume (that's done by the diaphragm size) or the volume/duration (controlled by the nozzle) but we can adjust the point at where it kicks in, which is done by the rod length.  Backing it off 5mm was required in the Yamaha TSB for the flapper mod. 

Don't just set it to 60mm but experiment a bit at a time.  The optimum will change depending on configuration, weight, altitude etc.  Mine is currently set and locktited at 58.5mm, but that will change with the new intake and exhaust

Prophet Of Doom

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Re: Some '83 questions...
« Reply #23 on: April 03, 2015, 07:05:28 PM »
The bottom line is you'll want an airbox with the "vacuum" actuated flapper.
Why? This has been interesting me lately.  I know lots of people say the flapper is necessary but can't think of a good reason for it other than decreasing induction howl. 

dingleberry

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Re: Some '83 questions...
« Reply #24 on: April 03, 2015, 11:04:36 PM »
I had a cb900 (hornet) a while back that had the flapper on the throttle body side of airbox. The induction noise was the only reason it was there, just to meet emission regulations. It was removed with no noticeable effect on performance. In fact after I had removed all emission gear my bike would leave my mate's bike (also low km cb900 hornet that I had ridden and deemed equal performance to mine pre modding) behind even though I was 25kgs heavier and 6 inches taller sitting upright on a naked bike. 
You like, oui?

turbosteve84

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Re: Some '83 questions...
« Reply #25 on: April 04, 2015, 07:18:35 AM »
'83 front carb top fit just fine. Only difference I could see was the hose fitting on the front on the carb for the flapper box.

Replaced the butterfly valve seals.

I'll take your advice on the other two items.

--Steve
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Rikugun

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Re: Some '83 questions...
« Reply #26 on: April 04, 2015, 07:56:17 AM »
The bottom line is you'll want an airbox with the "vacuum" actuated flapper.
Why? This has been interesting me lately.  I know lots of people say the flapper is necessary but can't think of a good reason for it other than decreasing induction howl.

I do appreciate you thinking outside the (air) box on this one.  :) In answer to your question "why?" my answer is admittedly because that seems to be the conventional wisdom. I have no practical experience with the early style flappers or no flapper but I'm sure someone has tried it successfully. It seems many more have used the vacuum actuated setup with success so I thought that would be the most straightforward way to get Steve up and running.

Since we are theorizing about the flapper purpose I'll disagree with you since it wouldn't be much fun otherwise.  :angel: From what I've read, the Visions ended up in the configuration they are because they ran poorly and stumbled badly as first delivered. Everyone has their theory for the stumble but I feel part of it is cured with the addition of the vacuum flapper.  My personal feeling is the carb's unfortunate design makes for inherently clumsy and slow response - especially at low to moderate engine speeds. They react badly to momentary signal loss when the throttle is opened quickly and if not for a functioning and well adjusted accell pump the stumble is more pronounced.

My feeling is the flapper functions similarly to the diaphragm controlled slides on a CV type to buffer signal changes. Getting air in doesn't seem to be the issue. It's getting fuel to flow through the lengthy maze of passages that seems to be the trouble. The flapper modulates air until the fuel can catch up. That's my very un-scientific and completely un-tested theory anyway.
« Last Edit: April 04, 2015, 08:41:41 AM by Rikugun »
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Ken Williams

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Re: Some '83 questions...
« Reply #27 on: April 04, 2015, 08:24:08 AM »
As an experiment I once ran my 83 with the air box flapper removed.  This resulted in a tremendous off idle bog. 

Rikugun

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Re: Some '83 questions...
« Reply #28 on: April 04, 2015, 08:25:55 AM »
'83 front carb top fit just fine. Only difference I could see was the hose fitting on the front on the carb for the flapper box.

The airbox connector port is on the carb top facing the camera. In addition, the "new style" carb top has that grey air filter hanging from the small hose. Note the carb bodies are of an earlier design prior to the second cross brace being added.
« Last Edit: April 04, 2015, 08:28:27 AM by Rikugun »
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turbosteve84

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Re: Some '83 questions...
« Reply #29 on: April 04, 2015, 05:50:18 PM »
Rikugun -- ask and ye shall receive.

Here are some images of my "hybrid" setup. New '83 front carb top fit neatly with no MacGyvering.  --Steve
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Prophet Of Doom

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Re: Some '83 questions...
« Reply #30 on: April 05, 2015, 12:01:12 AM »
Rikugun -- ask and ye shall receive.

Here are some images of my "hybrid" setup. New '83 front carb top fit neatly with no MacGyvering.  --Steve
Isn't that an 82 carb top?

fret not

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Re: Some '83 questions...
« Reply #31 on: April 05, 2015, 12:58:58 AM »
Yes.  '83 carbs have those holes along the top of the rim farther apart.  So that is the updated flapper valve model for the '82.
« Last Edit: April 05, 2015, 01:01:01 AM by fret nut »
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Rikugun

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Re: Some '83 questions...
« Reply #32 on: April 05, 2015, 08:22:44 AM »
Steve, Prophet and Fret are correct - what you have there is a set of run-of-the-mill '82 carbs. They may be an early body type as the second cross brace is not present like the photo I posted above. If someone sold you the carb top claiming it is an '83, they are mistaken and lucky for you as it wouldn't work if it was.  :)

The picture below shows an '83 bowl gasket fit on an '82 carb body. The brass enrichener circuit tube and float arrangement are different amongst other features.

What's of particular interest is what looks like the cam chain tensioners sitting on the bench....
Why aren't they on the bike where they belong!?   :'(  :laugh:
« Last Edit: April 05, 2015, 08:32:18 AM by Rikugun »
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

pullshocks

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Re: Some '83 questions...
« Reply #33 on: April 05, 2015, 03:18:45 PM »
When my '83 petcock crapped out, I was surprised to discover it was available from Yamaha.  That was over a year ago, availability may have changed, but appparently it was used one or more other models.   And yes it was spendy, but what a relief.

turbosteve84

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Re: Some '83 questions...
« Reply #34 on: April 05, 2015, 05:50:39 PM »
You're right. It is an '82 top.

I checked the part number of the box it came in (see attached images). Bought it OEM NOS. But it has the vacuum port on the front for use with the upgraded airbox so I'm using it. One of the images below shows the new carb top and the old. Another shows the airbox I'm using.

Cam chain adjusters: Yes, I tore the top end down to check everything and paint the cylinders. BTW, all 8 valve clearances were tight! Luckily I was able to use 3 of the shims to adjust some of the valves, and my local shop swapped shims for the others I needed. Those were the DAMN TIGHTEST VALVE SHIMS that I've ever encountered on any motorcycle I've ever worked on. No way I could have popped them without removing the cams! Even then I had a problem.

So, now you've seen my setup. I'm going to run (hopefully!) with it. Everything is super clean inside the carbs.

Fingers crossed.  --Steve
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Rikugun

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Re: Some '83 questions...
« Reply #35 on: April 06, 2015, 02:12:57 PM »
I absolutely agree, use the updated carb top. My understanding is once they developed that upgrade, later units were delivered with the parts from the factory. Dealers may have upgraded units still on the floor and the kit was available to install yourself if one were so inclined. POD provided a PDF of the kit instructions on his resources page here: http://ridersofvision.net/rovforum/index.php?topic=12221.0 It's the first item under Service Guides.

Of particular interest is the recommended accel rod adjustment on page 4 of the PDF. I think this adjustment was referenced by POD earlier in this thread.

I'm glad to hear how clean the carbs are as your chances for success improve greatly the cleaner they are. Clean carbs seems to go without saying but can't be stressed strongly enough with respect to these carbs in particular.

Shim removal can be difficult with the tool as it sometimes rides too far over the lip of the bucket interfering with removal. They may never have been checked which is why so many were out of adjustment.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

munkyfistfight

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Re: Some '83 questions...
« Reply #36 on: April 09, 2015, 04:25:16 PM »
Wow! Sorry for the delay in getting back. I'm glad this thread got so much attention. The carbs will always be a point of contention. I can tear my '82 carbs apart and put them back together in under 20 minutes. It wasn't until I actually had a giant fan to cool the radiator while I synced them that I actually was able to dial them in. These '83 carbs are still a complete mystery to me. Should I remove the plugs for the mixture screws? I also can't seem to get the float pins out so I don't really want to risk breaking a post (done that before). Any tips on removing stuck jet? Two of them have the heads broken off.
Those who play by the book will always be beaten by those who write their own. -Travis Pastrana

Prophet Of Doom

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Re: Some '83 questions...
« Reply #37 on: April 09, 2015, 05:20:20 PM »
Of particular interest is the recommended accel rod adjustment on page 4 of the PDF. I think this adjustment was referenced by POD earlier in this thread.
If you read any of the tuning guides for Holley or Weber carbs, they go on and on about the accelerator pump adjustment for fixing stumbles coming off idle. 

Should I remove the plugs for the mixture screws?
Yes indeed.  How else do you adjust or replace them?  If you live in California I believe that will get you thrown into gaol though.

I also can't seem to get the float pins out so I don't really want to risk breaking a post (done that before).
The trick is to use a pin punch, not a standard nail punch as these get thick too quickly and you end up hammering on the top post.  I made a pin punch by grinding a nail punch down so it's parallel for the first cm.  Place the bottom post over a slightly open vice then tap tap.  Gently at first till you get the feel of it.  You need more force than you think, but with the pin punch and vice you aren't putting any force on the posts.
To replace the pin, use pliers between the bottom post and the pin end till it just pops in place.

The procedure is in Haynes


Any tips on removing stuck jet? Two of them have the heads broken off.
I drilled and used a screw extractor. Worked well for me, though I know a lot of people hate ez-outs because they break and leave you even more in the crap.  I don't know what a better alternative would be.

QBS

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Re: Some '83 questions...
« Reply #38 on: April 09, 2015, 09:07:09 PM »
If I'm remembering correctly, V float posts are a tricky deal that, at least to me, is counter intuitive.  It seems that the pin is slightly larger in diameter at the spread end than it is at its' other end.  This means that if the punch force is applied to the smaller end of the pin without supporting the post that the bigger end is stuck into, that post will be broken off.  This is because the force applied to the punch's' smaller end will be transferred without resistance to where the large end of the pin is stuck through the other post.  The unsupported post then breaks off and the owner needs to apply the miracle of J-B Weld.

jefferson

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Re: Some '83 questions...
« Reply #39 on: April 09, 2015, 09:40:19 PM »
I was able to use a small screwdriver to twist in between the head of the pin and the post. That way the force is applied where it needs to be and not to the post. Just worked on the XS carbs and they have the same setup on the float pins.

 

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