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Carb tuning diagnosis..... (Read 133 times)
Chinaheart
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Carb tuning diagnosis.....
09/30/08 at 01:41:27
 
 I know this has been done to death, but I just need someone to confirm or refute what I have gathered....

  Bike is an 86. Brand new air filter installed, and the gentleman I purchased it from stated that the muffler is from a harley, but I believe it's a stock pipe.

  Bike was running great for a few thousand miles. It got me from Fresno CA where I bought it to Phoenix AZ where I live, without a problem.  Eventually after perhaps 2-3,000 miles, it started the typical backfire I hear so much about. So I tried changing octanes every now and then, sometimes it would help, sometimes it would get worse. It happened a few months ago, so to be honest, I don't recall which one helped.   Undecided

 Anyway, it also began showing some very slight white smoke coming from the exhaust. I didn't notice it at first because I used to ride it in the morning, but when I took it out at night, that's when I could see it as it swept past the headlight. (Mind you I'm in AZ in the summer, so it wasn't like a cold night or anything).

 Then it started giving me erratic throttle response and idling. I did what most newbies do and hoped it would go away.   Lips Sealed  

 Well, after a few more miles, on my way to work, it just died out on me. The symptoms were that of an empty tank. It would start, idle ok, go for about 15 feet, and just die. Being stuck in the middle of a busy avenue, I kept starting and going 15 feet at a time until I rounded the corner. Got off, locked it up and ran 15 blocks to work.   Sad
 When I got back, it simply refused to work. I noticed that there was a thin black/clear liquid dripping from the engine, I traced it back to the head gasket area. So I had a friend take a look, he surmised it was a blown head gasket (Possibly AZ heat combined with a LOT of stop and go traffic). He said the liquid was unbunrt gasoline seeping out.    Huh  He suggested I swap out the head gasket.

 Long story short, I did swap it out, but it took me several months to do so. (Just got busy). Well, now that it's together, it does start up, but it does take several attempts, with the throttle all the way open.  When it does start, it's now hessitant. When you give it some throttle, it bogs down slightly before picking up. To top it off, it's now emmitting black smoke (as opposed to the previous white). A big puff when I give it throttle, but it's fairly constant, it does not go away. When I just step back and let it idle, it sounds like it's going to die any minute, and eventually, it does.


  I pulled the plug to see if it had anything, all I see is pure carbon. The pic below is only after running perhaps 10-15 minutes.  I tried a different plug, and the same result.  Just a whole lot of carbon.

  So, symptoms are, Black exhaust smoke, bogs down on accelaration but picks up, hard to start (will only start with open throttle) and a whole lot of carbon on the plug after a few minutes. It's just soot; no oil or any type of liquid, it's just a lot of carbon buildup after only a few minutes. So far, it comes right off with a napkin, but I'm sure it will just build up if I don't remedy the problem.

 I am suspecting it's running to rich. (Correct me if that's not right).
Now I'm sure I can tear apart the carb   Embarrassed  and try cleaning out the jets, but I figured if I did that, it just might supply additional fuel in an allready rich situation.

Is there any way to adjust the fuel flow/ ratio without having to buy parts (Jets and so forth) in the mail or in a store, since the ones out here allways say 4-5 days?

 Has any of you seen this before, what can I (myself) do to attempt to correct the problem?

 Here's the catch.   Cool  My truck is dead (not my year I tell you), and my job depends on me having a reliable vehicle by Monday.   Shocked  So I'm hoping one of you awesome gurus out there can give me some sound, solid, prefferably experienced advice where I can begin to either diagnose the problem, or perhaps solve it.

 If you think you know what I'm talking about, please let me know what I can try. If you have links, that's fine. Prefferably with lots of pics; and anything "Step by Step" is allways appreciated, my mechanical skills arise from the modern era of fuel injection and using laptops to tune fuel ratios, so anything a-la Carb is just not my forte. The only carbs I've ever tuned were on my OS .12 engine (On a Kyosho Spider WCE II in case you're into that), but there's a lot more a stake than a tiny trophy with my Savage.


Thank you in advance to all who chime in.


(I got a message saying I can't post pics on my first post. So you'll just have to take my word for it. In the post {which I can't link} that shows all the plugs, it looks most like #3, stating too cold of a plug)
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Chinaheart
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Re:  Carb tuning diagnosis.....
Reply #1 - 09/30/08 at 01:46:48
 

OK, Here's a pic of the plug..... (After perhaps 10-15 minutes of idling and a few laps around the parking lot)




And here's a pic of the actual bike. It won't help diagnose anything, but I hope one of you will be able to help me get this fine machine back on the road where she belongs.
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LANCER
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Re:  Carb tuning diagnosis.....
Reply #2 - 09/30/08 at 04:58:05
 

You have black smoke...too rich; you have carbon on the plug...too rich; will only start with the throttle open...so rich that you need extra air before it will start;  hesitant and bogging down...too rich.  

You also have an issue with your petcock; you mentioned that when the bike died on the street that there was fuel leaking down from the top of the engine, and the only way that is going to happen is for the needle valve in the float bowl to fail and leak or for the petcock to fail and allow fuel to flow down the vacuum line (which is most likely...the needle rarely fails).

First, set the petcock in the PRIME position and try running it to see if that helps any.  If the petcock is still leaking, which will cause the excess fuel in the system, then running in prime will isolate that problem.  If it runs good on prime then just continue doing that until you can replace the petcock, rebuild it or convert it to a simple ON/OFF valve.
If running on prime does not correct the problem then go on to work on the carb.  
Your petcock, whether malfunctioning at the moment or not, is still a problem.  Since it did leak fuel before it needs attention.

So, based on the testing of the petcock, if the carb is in fact the primary problem then you need to take the puppy down to its every little screw, washer, jet and collected dirt/grit in the tiny passages from all those years.  It is 22 years old and will have some CRUD inside the tiny places.  It needs the tender loving care of a rebuild.  When doing so you need to check to see what the main and pilot jet are so you know what you are dealing with.
Doing the teardown and and rebuild is not hard to do.  You can do it in a few hours.  Get a can of carb cleaner and if you have an air compressor use that too to blow out the passages.  As you take it apart lay the parts out in order as they came off; clean every piece and passage, then assemble in reverse order.  

You mentioned needing pictorial help; do you have the CD that is available from the Savage store ?  If not,  and you are not able to get one in time then send me a PM and we will discuss options.
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Re:  Carb tuning diagnosis.....
Reply #3 - 09/30/08 at 05:07:22
 
sounds rich, but as an '86, other things may be going on.  If you have an auto parts place nearby, replace the hoses from the fuel tank to carb and check the exhaust system for leaks.  Take top off carb and check the rubber is still intact, and the needle valve is moving freely (and replace the screws with proper ones) see technical section, search carbs and carb tuning (at least 1 year) ltosa picts and thoughts there.  And then call avis/etc for backup plan. Sad  I see lancer has posted since I started..bowing out to the Guru. Grin
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Yonuh Adisi FSO
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Re:  Carb tuning diagnosis.....
Reply #4 - 09/30/08 at 10:38:26
 
Check out this thread for carb cleaning. SavageWahine did a darn good job of documenting with pictures and text. http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1191899985
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Check out Flight of Destiny http://www.amazon.com/dp/B00H9130XC
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Chinaheart
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Re:  Carb tuning diagnosis.....
Reply #5 - 10/09/08 at 01:38:55
 
Semi-Update.....

OK, so I tore apart the carb.
dunked it, soaked it, scrubbed it, everything, everywhere.

I tore apart the petcock, cleaned up a fair amount of crud on that one.
Replaces all hoses, fuel, vacum, all of them.

 It had no white spacer at all (Possible previous owner's work), fashined one from a bicycle washer, fit nicely without binding, threw that in there. I did notice that the plate/disk with the 2 screws and "U's" originally had the "U's" slightly off center in relarion to the holes in the cyclinder, but I re-installed them perfectly aligned.  If you can't tell from my lingo, I'm no carb guru, I'm used to tuning FI's with a computer so please bear with me.

 I ended up using a sewing needle to clear up several holes in one of the jets, cleared it up nicely.

 End result....
Well, it's not smoking anywhere near as bad. Still idles "oddly", but it was enough to get me to work (Save for an electrical problem I will start a new thread about).

 The engine still runs a bit hot than what it used to, so I suspect it might still be running rich. I will try varying some octanes to see what the results are.   In the mean time, I took it to get smogged and the results are as follows....

Hydrocarbons HC  77 ppm.  (Limit 1800)
Carbon Monoxide CO 0.23 (%)   (Limit 5.50)
(Edited to correct CO2 to CO)
So it passed, although it's well within spec, I was wondering if anyone has recently smogged theirs, and do these numbers match up with what it should be.  Can anyone tell if this might be lean or rich. (I still suspect it's running rich, when at a red light, all I feel is pure heat just eminating from the head, it's a thick heat that can just be felt, and it's not just because this is Phoenix AZ).

Anyways, aside from the cleaning I've allready done, is there any other way to help lean it out some? I tried turning the one on the forard right of the carb, I believe it's clockwise to lean it, counterclockwise to richen. The thing is, 1)previous owner has stripped this one beyone repair; and 2) I can turn it out, but it was allready as far as I could turn it in(clockwise).
   (Edited to correct I meant forward RIGHT of carb, not forward left. I meant the Mixture screw).

 Payday's coming up, so I suppose I could spring for new jets now, what jets and sizes should I be looking at if I plan to lean it out some?  (Or should I just try a cone filter to improve air flow instead?, currently has a brand new factory filter element in stock airbox).

   Thanks again guys.   Wink

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« Last Edit: 10/10/08 at 02:20:47 by Chinaheart »  
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Re:  Carb tuning diagnosis.....
Reply #6 - 10/09/08 at 03:36:57
 
Higher octane will only cost more and rob power from your engine. Save your money.  The bike is designed for 87 octane (due to its low compression) and as long as you buy clean, water-free fuels you'll be ok.

Forward left is the idle speed screw. It will not richen or lean your mix, it's more like simply turning the throttle giving you more of the rich o r lean mixture you set with the idle mixture screw on the right hand side. If you have not set your idle high enough the bike will die off at every stop.

Regarding the heat...Are you getting a lot of afterfiring?  I assume you adjusted your idle mixture  screw as well.  Did you adjust your idle mixture screw  with a tach or just by tweaking it by turns? Have you tightened the exhaust manifold fasteners and checked the clamps on your Harley slip-on muffler (or stock) ? With a rich mixture and air inleakage past the cylinder you could certainly expect a lot more heat.



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Re:  Carb tuning diagnosis.....
Reply #7 - 10/09/08 at 04:10:21
 
Chinaheart wrote on 10/09/08 at 01:38:55:


In the mean time, I took it to get smogged and the results are as follows....

Hydrocarbons HC  77 ppm.  (Limit 1800)
Carbon Monoxide CO2 0.23 (%)   (Limit 5.50)

So it passed, although it's well within spec, I was wondering if anyone has recently smogged theirs, and do these numbers match up with what it should be.  Can anyone tell if this might be lean or rich.



First, I recall carbon monoxide is CO, not CO2, which is carbon dioxide and you are running far too lean at idle. CO should be somewhere around 2 to 4%. This is only idle circuit so main jet or needle height has very small effect on this.
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