Hi gents, I recently acquired a mint 1993 Superlight that has less than 6k miles on it. Since I have received it, I have started it perhaps 4-5 times without any issue. Recently, the bike started to have a weird issue. With the enricher (choke) at the max position, the bike will start, rev to 3k then die. This is 100% repeatable. I have confirmed that the fuel pump works and fuel is getting to the float bowls. I also verified I am getting spark. Here is a short video of some cold starts. I also had my multimeter connected to the lithium battery. The first two start up attempts are without the enricher. The third and fourth attempts are with the enricher at max position. When the bike starts you can see the battery voltage does increase before it dies. Does this video shed any new light on this perplexing issue? https://youtube.com/shorts/x9FUyXo-Gss?feature=share
I am by no means an expert on these bikes, but I went through a similar experience with my 900SS. As you mention you've started it 4-5 times, but no mention of riding it, I'm suggesting the plugs are fouled. All through last summer, my bike started with a mere brush of the starter button, and behaved faultlessly throughout every ride. As winter drew in, and I stopped riding it, I did push it out of the garage and fire it up a few times, until the time it went through a similar episode to that shown in your YouTube clip. Change the plugs, and I reckon your problem will disappear. If you have been riding, rather than just starting, this advice might be useless!
I recently had the same problem, i removed the carbs myself and then cleaned by a third party, everything worked well afterwards.
When you get the opportunity perhaps a few photographs in the SS Gallery thread would help us weirdos.
Thank you everyone for your replies. I actually did replace the spark plugs. When removing the original ones, I noticed they were gapped at 0.75mm, spec is 0.6mm. The odd thing is once I changed the spark plugs, the bike started up fine but would not idle when I deactivated the enricher. I had to give it a little bit of throttle to keep the bike running. A week later, this is now happening. Nothing else has changed. I have not taken this bike out on a ride since getting her because I was working on the brakes and getting new tires. I am actually not touching the throttle at all. I am wondering if perhaps I am flooding the cylinders? I was messing around with the idle speed screw a bit but I think when the enricher is activated, the entire idle circuit is bypassed? I thought of this too but what I dont understand is that it seems the carbs are working decently. The bike will start and rev up to 3k. And just last week, before I changed the spark plugs the bike started and idled fine.
I bought the bike 4 months ago. The bike hadnt been ridden much as it was used in a display at a local motorcycle shop. The bike was demonstrated to start though it did take a few tries with the enricher on. Once started it idled at around 1k. I adjusted the idle to 1200 maybe two months ago. Since then I have started it twice without issue. Then 2 weeks ago I tried to start the bike again but it would fire up, rev to 3k then die. I replaced the spark plugs and the bike started fine but would not idle by itself without a little bit of throttle so I messed around with the idle speed screw maybe 2-3 full revolutions both directions. Then this past weekend when I tried to start the bike it exhibited the same behavior as prior to me changing the spark plugs, starting, reving to 3k, then dying. I am sure it was adjusting the idle speed screw. It is the one right below the little indent in the bottom of the airbox.
It sounds like you may have been turning the idle-mixture adjuster screw, not the idle-speed screw. I say this because you say that you adjusted it many revolutions and this would have thrown the idle mixture way out.
I am certain I was not. I adjusted the spring loaded screw in between the carbs right below the little indent in the airbox. This one:
That is my last resort. I have a set of carbs from another Superlight I am restoring that I had professionally cleaned and refurbed. I am first going to make sure there is nothing wrong with the ignition system. Perhaps I am losing spark right after the bike fires up. I am wondering if a bad voltage regulator could be the issue? However, even if the voltage regulator was bad wouldnt the battery be able to fire the spark plugs for a while? I know my battery is good, its a new lithium. Maybe its the coils or spark plug wire?
I did the same but it didn’t clear the problem A steady experienced mechanic who has the time and knowledge of these older bikes is where I went. Other more advanced garages and dealerships simply haven’t the interest or time or both, and will happily take your money for little improvement. This was my experience and it now starts and runs as it should. @Chris will get to the bottom of this issue!
I guess i got lucky then, but if they've been sitting around a while with this crap fuel these days it might make sense, i yet to start my two this year. As for Chris, he's old skool.
Thank you. How would you suggest getting close with the idle speed adjustment? What gap should I target with the throttle closed as a starting point? Anyway, I thought the enricher bypassed the idle circuit. If this is true, does it matter what the idle speed is set at if I have the enricher set at max? I actually drained the fuel from the bowls and have fresh fuel in the tank. For plugs, I have NGK DCPR8E gapped at 0.6mm. I also have some Gumout starting fluid as well which I think is close to EasyStart. BTW, I live in California so the temps are mild as usual.
SUCCESS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (sort of). So at the recommendation of those much smarter than me I bought an inductive timing gun so I can verify the spark plugs are working. I wanted to rule that out before tearing into my carbs. The first three times I started the bike with the enricher set on full, I had the timing gun connected to the vertical cylinder. Same behavior as before, bike would start, rev to 3k then die. I then put the clamp on the horizontal cylinder. Initially I was too lazy to remove the left side fairing so I connected the clamp a bit further away from the cylinder and spark plug, further up the spark plug wire. Tried to start the bike, same behavior but this time I saw that the horizontal spark plug was not firing. Hmmm...so I decided to remove the left side fairing and attach the clamp right where the spark plug wire meets the spark plug cap. Tried to start, the timing gun indicated I was getting spark and voila!! The bike started and continued to run as long as the enricher was on. Now I am not sure if the horizontal spark plug really was not firing this whole time and by attaching the clamp I somehow jostled something. Whats odd, is that I visually verified this past weekend that I was getting spark from the horizontal spark plug. So at this point, I am not sure if I was really not getting spark or by some magic my bike starts and runs now. I will check all the connections at the coils and ignitors. That being said, I think I must be getting intermittent spark because when I removed the spark plug a few days ago, I noticed that it looked relatively clean (see below). Now for the bad new, the bike wont run with the enricher in the off position. I assume I just need to keep adjusting the idle speed screw. I cant do any damage if I wind it all the way in right? Worse that could happen is that my bike revs high right?
Yes, once the bike starts and the revs start to climb I can gradually reduce the enricher (choke) and the rev will slowly drop. If I shut if off completely the bike will not idle without some throttle. So if I am understanding you suggestion, you are saying wind out the idle speed adjuster all the way so that the the butterfly is fully closed. Then slowly tighten the idle speed adjuster to open the butterflies? Should I go in 1/4 turn increments?
Thank you. But as you said, the idle may be too high now since I have been fiddling with it. Should I start with it fully backed out first then slowing wind it back in? Unfortunately for me, there is no second person available unless I count my moody teenager who seems to live in her room and only comes out for brief feedings.
