Runs like a deer walks like a dog with a peg leg

[slipstreamer]

My bike has been doing a lot of backfiring on deceleration but has been running like a deer on the highway. Yesterday I went for a four hour ride and it even started stalling before I got stopped at the lights so I had to keep the revs up just to keep it going. I have not got a clue where to begin but I guess I should be starting with the diaphragms and carb slides. I am also thinking that plug wires and plug caps should be replaced: The plugs are new. Any particular type or brand recommended? I see some on e-bay on a pretty regular basis. Any clues would be helpful and appreciated. I am sure this has been discussed before so a link might be helpful too. I suppose a valve adjustment and carb synch would also be in order.

[Squeeze]

Hi,

 

clean the Carbs complete and briefly and be done with it.

 

New Plugs are also a good Idea, if they where not done recently.

[slipstreamer]

Thanks squeeze. The plugs are new a few weeks ago. By clean the carbs complete and "briefly" what do you mean? Do you mean carbs off, dismantled and soaked in carb cleaner and all the little ports cleaned out? I have never done that before and I am told it is pretty complicated. Is there a step by step instruction somewhere to do that?

[Squeeze]

Thanks squeeze. The plugs are new a few weeks ago. By clean the carbs complete and "briefly" what do you mean? Do you mean carbs off, dismantled and soaked in carb cleaner and all the little ports cleaned out? I have never done that before and I am told it is pretty complicated. Is there a step by step instruction somewhere to do that?

 

Hi,

 

yes, that's what i've meant.

 

imho, using Seafoam, is a temporary Fix and won't help on the long Term. It's also good as a preventive Measure, but not if you're suffering Problems already an want it fixed for along Time.

 

If you don't want to mess around for Weeks and learn how to take the Carbs out in 15 Minutes, a complete Cleaning is the only Way to assure that the Carbs won't be Problem in the Future. Also, if an other Problem occurs in the near Future, the Carbs would be out of Question.

 

If you're mechanically inclined a bit, it's more a Question of Wrench Time and some Money for good Chemistry, but overall it's the best to get it done once and have more Fun with the Bike later.

 

MBrood has a writeup in the Tech Section. http://www.venturerider.org/forum/showthread.php?t=54

 

One Thing i would add, is to use some Valve grinding Paste on the Tip of the Screwdriver or the Bit you're using. Otherwise, those damned Phillips Head Screws can really be a pita.

 

If you want to go a Step beyond manual Cleaning, take the Carbs out and tear them apart. Now, take all the Parts to a Shop and have them cleaned by a Ultrasonic Cleaner. Might cost some Bucks, but after they blowed them out with compressed Air after the cleaning Process, there ready to be put together again.

 

Also, check the Float Hight on each Carb to ensure the proper Setting. This can be done with placing the Carb without mounted Floatbowl in an old fish Bowl, for Instance, and a fresh Hose on the Fuel intake. You can see the Float moving and when blow some Air in the Hose you can check if and when the Valves shuts the Intake.

[slipstreamer]

If you're mechanically inclined a bit, it's more a Question of Wrench Time and some Money for good Chemistry, but overall it's the best to get it done once and have more Fun with the Bike later.

 

Thanks again Squeeze. I have never worked on carbs before, is this the kind of thing a novice should be taking on . I read that link by MBrood that you provided and I guess it all sounds easy to those who already know this stuff but, a lot of the terminology presumes some knowledge that I don't have. Seems like quite a challenge.

Which parts would one take to a shop to be ultrasonically cleaned : I am assuming that would be just the carb bodies.

[Squeeze]

Hi Cliff,

 

i think everybody with a clear Mind and who is willing to learn and understand is capable of repairing anything on these Bikes. It needs some Tools and Time, but with the Help of the Workshop-Manual and all those great People here, anything is possible.

 

That is not Rocket Science, we're talking about. Ok, you're not familar with Carbs and their particular Parts, but if you look at the Manual and the Yammi Internet Parts-Catalog IPC, you will learn the Names of all the Parts and what they do. If you do not understand, how things work, you just need search the Board here, read and ask afterwards and you will have a Bunch of Descriptions and Explanations and you will understand. If not in first Place, ask again and there will be other Answers. On the other Side, there is a Lot of Space to screw Things up, but with a good Portion of Patience you will get around these Rooms.

 

Imho, People who want to take the Bull by the Horns earn a Lot more Respect than those who take out their Checkbook and sign whatever the Guy behind the Counter asks for. I really don't want to pick Swifty here, but as an Example, search for the 'Help Swifty' Thread here, i'm sure there were many People who grined a Lot while reading the Postings during the ongoing Process, but in the End, he did make it, and that's what counts.

 

As for the Parts and the Ultrasonic Cleaner, every Part can and should be cleaned by the Machine, except the two Diaphragms and the Floater.

[slipstreamer]

OK Squeeze, I am convinced. I will give it a go but it may be a week or so until I get around to starting. Thanks for your help but, as Arnold says, I have not doubt that "I'll be back".

[mbrood]

Taking stuff apart isn't all that tough (once you get the carbs off and separated). You WILL want to make some SPECIAL notes about WHICH brass jet came out of WHICH little hole. I think there's markings (flow rating) on them but it would be CHEAP to mark each one as it comes out if they aren't... and yes, a couple tiny and large metered jets ARE the same thread and mount size. The main idea is to get anything with rubber OUT before a good bath... idle mixture o-ring, rubber plugs on the main jet housing, choke valve and primary and enrichment diaphragms.

 

Then the carb housing and the jets would just LOVE a good ultrasonic bath... that is truly better than just basking in a tub of cleaner!

[Squeeze]

I do not mark the Jets, they are marked with their Size already near the Slot where the Screwdriver fits into. I use a magnifying Glass while mounting the Jets.

[slipstreamer]

Thanks Squeeze and MBrood. I will embark on this adventure with a whole lot of trepidation with full knowledge that it aint rocket science. However, less complicated things have been challenging to me. We'll see. Maybe I need to buy a set of carbs just to experiment with

[Guest Popeye]

I had rust mess up my carbs last Spring on my 86, but ran fine the 13K miles before.

Engine actually ran 'perfect' until it just stalled, last May.

Carbs redone, diaphragms, sliders, new plugs, gas lines, filter, sync, etc., etc.

 

It's running quite well, but it now backfires some during deceleration, but it never did that before all the fancy carb work. [??]

 

Like Squeeze says, carbs are a very good bet & doubtless need the work, like mine did, but may not fix the backfire-during-deceleration....like mine.

[slipstreamer]

Popeye, at one point, I read an item here that listed reasons for backfiring. I can't recall them but let's both do a search and get back here with the link if we find it. Thanks for your input. i think i still want to do my carbs just for the experience though.

[helomech]

One Thing I came up with on several web searches is that deceleration backfiring is usually caused by idle mixture being too lean. I could try to explain it, but I'm currently climbing up the steep learning curve on this stuff too and I don't want to get it wrong. Suffice to say it has something to do with unburned lean mixture entering hot exhaust pipes, and I'm trying to get my brain wrapped around it. Mine was backfiring BEFORE I cleaned my carbs. It doesn't anymore, but from what I gather, my current setting of 1 1/4 turn out from bottom on the idle richness screw is much leaner than most end up with. From the responses I've received recently, 2 to 2.5 turns out from bottom is more common. If you've gone through the carbs, I'm assuming all is well with your deceleration diaphrams. The effect of what they do, from what I see in my shop manual diagrams is to richen the mixture further whenever the throttle butterfly closes rapidly, causing a change in pressure in the throat which, in turn, moves the bleed valve in the decel' circuit. Anyone jump in and correct me if that is not the case...

[Squeeze]

Hi Folks

 

I had rust mess up my carbs last Spring on my 86, but ran fine the 13K miles before.

Engine actually ran 'perfect' until it just stalled, last May.

Carbs redone, diaphragms, sliders, new plugs, gas lines, filter, sync, etc., etc.

 

It's running quite well, but it now backfires some during deceleration, but it never did that before all the fancy carb work. [??]

 

Like Squeeze says, carbs are a very good bet & doubtless need the work, like mine did, but may not fix the backfire-during-deceleration....like mine.

 

Did you plug your Exhaust one Time to test for Leaks ? Two Potatoes might do the Job. If you're sure of a non leaking exhaust, then i'd look for the Coast Enrichment Diaphragm. Or just richen the Mixture by half Turn CCW on the Mixture Screws.

 

...Maybe I need to buy a set of carbs just to experiment with

 

Well, if you could get one cheap, this is undoubtful also an Approach. Buy a Set, clean them and rebuild them and afterwards, just exchange the Carbs Sets. You might not get a Set with good Diaphragmn, but that would not hold me back.

 

One Thing I came up with on several web searches is that deceleration backfiring is usually caused by idle mixture being too lean. I could try to explain it, but I'm currently climbing up the steep learning curve on this stuff too and I don't want to get it wrong. Suffice to say it has something to do with unburned lean mixture entering hot exhaust pipes, and I'm trying to get my brain wrapped around it. Mine was backfiring BEFORE I cleaned my carbs. It doesn't anymore, but from what I gather, my current setting of 1 1/4 turn out from bottom on the idle richness screw is much leaner than most end up with. From the responses I've received recently, 2 to 2.5 turns out from bottom is more common. If you've gone through the carbs, I'm assuming all is well with your deceleration diaphrams. The effect of what they do, from what I see in my shop manual diagrams is to richen the mixture further whenever the throttle butterfly closes rapidly, causing a change in pressure in the throat which, in turn, moves the bleed valve in the decel' circuit. Anyone jump in and correct me if that is not the case...

 

Your Description is perfect.

[k7mdl]

My bike started to back fire some on deceleration suddenly one day. Found the choke was not all the way off, just enough to run good, just enough to cause backfire. Maybe check your choke cable alignment and that all 4 carbs choke mechanisms are moving in sync and freely.