The SOHC/4 World Tour is in under way.
0 Members and 1 Guest are viewing this topic.
Yep, the condensers could...
...no idea how they came to be so far out.
If the mixture fires, it had ignition. If it has too much fuel in the mix, it will leave black deposits due to incomplete burn.Misfires are usually quite noticeable during a drive about. you are correct, when i retarded the timing, the bike became even more rich and started misfiring because the plugs were sooted up good and properly.What is the actual fuel level in the float bowls? 22mm. i have not used the clear tube method as of yet to identify the actual level unfortunately.Have your jets been drilled? i hope not, i got them from harisluv.Are you operating the choke backwards? with the choke closed/on, it dies immediately.Are the main jets still in their seats? Is the spring retainer still in place? yes, everything is brand new, sealed and in place.Are the main jet reception posts pitted enough to prevent the oring from sealing? there is pitting on the outside on the post, not inside. Explain how you know you have "stock jets and needles". they are 38 idles and 100 mains. needles are new secondhand from harisluv, i can still see the lath turning pattern on the needle and it is in mint condition. my old jets and needles cause the bike to behave in the same manner, which is why i went through the mission of importing original jets.Cheers,
Quote...no idea how they came to be so far out. How about breakerpoints gap that has changed?Intermittent grounding breakerpoints (when they shouldn't) and faulty condensers also could cause problems.In case you have the stock ignition setup, I'd first check breakerpoints and condensers. Open the ignition cover. First check if breakerpointgap is still correct and also that the forked connectors at the back of the breakerpoints aren't accidently touching the plate. Then, with engine running, see if there's excessive arcing at the breakerpoints. A tiny bit of sparking is normal, excessive sparking is not good. See //www.youtube.com/watch?v=t3cuvGVwnjIIn this vid left condensor (1+4) is bad, right condensor (2+3) is good.
can the condensers cause a weak spark and allow the fuel mixture not to ignite properly?
Quote from: Bru-tom on October 09, 2018, 06:37:21 amcan the condensers cause a weak spark and allow the fuel mixture not to ignite properly? Yes, they can. Sometimes condensers start sputtering when warm. That your points are badly pitted, to me indicates there's arcing. Unless the forked connector is intermittent making contact with the baseplate, usually the condenser is to blame. Easy fix and not expensive. Some say you should stay away from aftermarket condensers. I myself have no experience with them, so I can't tell.
Do all your plugs exhibit the same deposit pattern? You have two condensers. Rare they would both fail at the same time in the same way. However, some manufacturing defects can be that way.Did you replace the float valve needles/seats? Did you notice if the little spring pins had the same strength as originals?Have you cleared and proven the air jets and their passageways? Two per carb.Cheers,
Just to throw in an unsolicited 2 cents -- if you are truly getting 10mpg there has to be something more than a rich running condition. You should be getting about 4X that. I would think (if 10mpg is true) that there is no way that thing would run and you might want to check that gas isn't pouring out of your overflows (if you have lines connected that drop to the ground it'd be harder to notice when riding as the gas wouldn't be spilling onto your engine). And if they are overflowing, you're going to be running rich as well.
all of the plugs are identical. i was hoping to see either the 1-4 or 2-3 to be different, but they were not.
i replaced on needle and seat. the needle sprung pin was not sprung any more, so i replaced it. the new spring is a little stiffer than the rest. i can understand that the stiffer spring will cause the fuel to get cut off sooner than the rest, how would one compensate for it? clear tube test?
yes, they are spotless, i used an ultrasonic bath mixed with carb cleaner and compressed air. everything is perfect iv done this procedure several times in the past when i had the same issues, thats when i replaced jets etc from harisluv....
What are the numbers on the Jet needles? And what clip position did you select?Also, have you checked the emulsion tube jet exit for size and damage? This is where the needles regulate flow.
Yes. The spring stiffness changes the mechanical float height measurement.
Just to be clear. You verified flow from air jet entry to emulsion tube cavity for both the pilot circuit and the main emulsion tube? A cleaning process is not complete until this has been done. Please don't just assume.Just to be thorough, state condition of the carb couplers, and if you have disturbed the manifold to head connection orings.Would you expect your replacement exhaust to have more or less backpressure than the original?Cheers,
what is this forked connector you speak of? is it the wire terminal that connects to the points?
You stated "i know my carbs are 100% spot on", but then continued to describe a problem that most likely is a carb problem. Without knowing the actual level of the fuel in the bowls, it's hard to know that the carbs are spot on. You are not the first to report this exact problem on a 550F, look at this thread (there are others) http://forums.sohc4.net/index.php/topic,174062.msg2025561.html#msg2025561 It's very difficult to see the inside of the emulsion tubes and even harder to determine if they're good or bad.........Paul
FWIW, when I first cobbled my 750 together after a 25 year layoff, I was getting 17mpg, constant burbles and lousy power. First thing I did was chuck the coils and install Dyna coils, plug wires and new plug caps. Then I found that the air filter I was using was running me waaaay rich so I put in an OEM filter. Things improved radically but not quite where I'd liked. I was still running rich. I lowered my needles 1 notch and things improved a lot. It's still not the way it was out of the showroom in 1970 but it's pretty darn good. I'm getting close to 50mpg and the bike runs great. Idle is only good after the engine is good and hot.Don't look for a silver bullet. There isn't one. It's a matter of messing with things to gain a bit of improvement 'til you're happy with it.
Yes. See to it that it can not (intermittently) contact the base plate. The 2+3 breaker in particular is prone to this as there's a crosshead nearby.
Quote from: Deltarider on October 10, 2018, 01:05:39 am Yes. See to it that it can not (intermittently) contact the base plate. The 2+3 breaker in particular is prone to this as there's a crosshead nearby.thank you. but why would all four suffer from this, all the plugs are black i will make sure that these are insulated properly when i install the new ignition soon.
Quote from: Bru-tom on October 10, 2018, 06:25:53 amQuote from: Deltarider on October 10, 2018, 01:05:39 am Yes. See to it that it can not (intermittently) contact the base plate. The 2+3 breaker in particular is prone to this as there's a crosshead nearby.thank you. but why would all four suffer from this, all the plugs are black i will make sure that these are insulated properly when i install the new ignition soon. How about the airfilter? Any restriction in the air intake? BTW, if you go the GL1000 coils route, you will need a ballast resistor of say 2 Ω or your points will pit severely.