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Hi!
I bought a CB500 the other day. Already own a CB650 that allways runs like a dream.
The 500 dont have any power at low rpm, run unsmooth at 4000, good at 6500+
I've got it new spark plugs, but they got black at an instance.
It got pod filters, they were on the bike when i bought it.
Any suggest where i find stock settings for the carbs?
I don't think i'll manage to find an airbox just like that thou.
It's been sitting for about 11 years and the pod filters don't look that free flowing. Some new filters and set carbs back to stock and go from there perhaps?
Try it without the pods, just to see if they are the restriction. What pipes are on it and are they blocked?
Unleaded always tends to leave plugs a little on the sooty side. It's not unusual to run hotter plugs with unleaded. What plugs are in there at teh moment? If they don't get hot enough to burn off deposits that could be the issue.
Retarded ignition timing can also create that problem, so check the timing as well.
Try dropping the needles one notch (raise the clip to drop the needle)
or as simple as an air mixture adjustment.....to get positive results use 1/2 turn at a time then fine tune it once u get close by reducing your adjustment to 1/4 turn.. ect. then again 1/4 reduced by half. and so one.........
The plugs are what is standard in the manual, the heat nr is 7 anyway. The old that said 8 had the exact same problem. The exhaust header goes seperatly into the muffler and have its own little pipe at the end. Cant find no blocking in them anyway.
Running without pods didnt make a differance when i checked. Air/fuel screw fully down should be rich and losen it should make it leaner, 1,3/4 or 2 turns up should be about standard?
taking a look at this chop chart should help diagnose the issue.
Also, what size jets are you currently running? Sounds to me like it's running rich. While you're riding, put the choke on half-way or so and see how the bike responds. If it runs better with some choke it's running a bit lean, if it runs worse it's running rich.
D7 should be hot enough to burn off any deposits, so that is not the issue.
For the air screws, normally from 1 full turn to two turns is the range you expect to be in. Do you have any pictures of teh bike? There may be something we can spot that way that gives us a starting point. Did you check float levels?
You mentioned poor at low revs, rough at 4000 and OK above 6500. That suggests the low end jetting or float levels. Check and adjust float levels first and then try the needles one clip position higher than stock (needle lower) to see what difference that makes.
Another issue is that old jets are sometimes not teh size they used to be. owners poke things through them and some drill them out. If you could replace teh slow jets with new ones, that might indicate whether that's a problem. Or remove teh slow jets and blow through with a can of carb cleaner or WD40 and compare all 4 jets. Then beg borrow or steal a new jet and compare the flow.
Another technique that works is to take a small sewing needle and insert it gently into each jet and see how far it goes into the orifice. Even a small difference in diameter shows up as a large change in height of the sewing needle if the needle is the right size.
The plugs are what is standard in the manual, the heat nr is 7 anyway. The old that said 8 had the exact same problem. The exhaust header goes seperatly into the muffler and have its own little pipe at the end. Cant find no blocking in them anyway.
Running without pods didnt make a differance when i checked. Air/fuel screw fully down should be rich and losen it should make it leaner, 1,3/4 or 2 turns up should be about standard?
CV carbs typically have a fuel screw on the engine side of the carb that adjusts fuel flow. Slide carbs usually have an air screw on the filter side of the carb.
So CV carbs screw out = richer
Slide carbs screw out = Leaner
I turned the point assembly to the right and the bike ran better, not so much backfire.
But the timing Gun dont flash that often an low revs, or should i say, constant.
At really low rpm the 1cylinder backfire. The timing mark shows a bit to the left both on low rpm and high so i assume that its not quite good, but with a non flashing timing gunbits hard to se any timingmark..
How do i tell that if the wires are bad?
Could i change the wires individually?
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