Slash five tuning help

[Frog]

First off, I want to thank you all for the in depth efforts to help.

Here is what I have to report:

I was lucky enough to catch Duane working in my area, so I roped him into coming over for some diagnostic fun and catching up.

We first started by going over the symptoms of the bike. Duane noted right away that the carburetors were poorly tuned and out of synch. I knew this, as my previous carburetor tuning efforts had had to be aborted due to this ignition issue. Duane did as much carburetor tuning as was possible and managed to make it run a little better.

Please note that the bike does fire right up and idle/run well enough to ride. If you did not know these bikes, you might even think that it is normal.

Then I put the timing light on the bike and showed him how the left skipped, while the right sparked without hiccups. Even at higher rpms (2,000 or so), the pause in the light (spark) is long enough to really notice. We determined that this was equivalent to missing much more than one spark, but instead a whole series.

o The first test that we did was to swap the ignition leads, but keep them on their original coils. We had the left coil running the right side and vice versa. The problem remained on the LEFT.
o The second test that we did was to swap the spark plugs. The problem remained on the LEFT.

At that point, we assumed that we had eliminated ignition/coils as the culprit and decided to put things back in place and move on to swapping the left side carburetor with the one on my bike (which runs great).

But, while under the tank, I decided to install by other spare (used) coil, so that both of my spare coils would be in the bike. I figured that this would not mess up our testing and would possibly teach us something else.

Well, that seems to have fixed the problem. We put the timing light back on and tried both sides. We could not find a miss and the bike seemed to by running properly (minus some needed carburetor tuning).

It was too late for me to go for a ride and until I do so, I don’t want to break out the champagne.

After our testing, I decided to put the bike on the lift and install a grounding wire from the diode ground, to the coil mount and finally to the battery negative. With all of the powder coating on the engine mounts, I figured that this would insure that the systems would be properly grounded. I have not run the bike since, but plan to today.

I know that our conclusions do not really explain all of the symptoms. Did I have bad coils? Did they need to be grounded and my removal and installation of the right one improve its ground?

It seems that the two nicks in the coil mounting brackets, that dig into the coil case, must serve to ground it. Duane also remembers that when he used to set up the ignition system on the bench for demonstrations, they had to run a grounding wire to the outside of the coil. This seems to contradict what is being said here. I did a little coil reading online and it seems that the mounting to a good ground is important.

I do think that the powder coating of the frame compromised the grounding of the frame.

I hope that this does not add to the confusion.

[Frog]

I hope my tone wasn't that of talking down to you. That certainly was not my intention.


Ken

Not at all. I appreciate your serious efforts to help and assure you that it is helpful. In my time on this forum, I have learned that you are one of the members that is able to present things with much respect for others and you have a keen sense of how to do so.

Besides, I am French and don't offend easily

[Ken in Oklahoma]

. . . It seems that the two nicks in the coil mounting brackets, that dig into the coil case, must serve to ground it. Duane also remembers that when he used to set up the ignition system on the bench for demonstrations, they had to run a grounding wire to the outside of the coil. This seems to contradict what is being said here. I did a little coil reading online and it seems that the mounting to a good ground is important . . .

Well, damn! I guess now that means now we have to do the discussion all over again.

Uh, y'all wanna go on ahead then. I'll catch up with ya later.



Ken, ungrounded in Oklahoma

[Major Softie]

Yeah, it's hard to know exactly what the problem was from just that. It could be the ground, it could be one of the other connections to the coil that was fixed by the disconnect/reconnect procedure, it could be the coil itself. The only way you will be sure what the problem was is if you can figure out exactly what you need to do to repeat the problem.

But, hey, why stress about what's working, right? Ride it and be happy!

[Frog]

Yeah, it's hard to know exactly what the problem was from just that. It could be the ground, it could be one of the other connections to the coil that was fixed by the disconnect/reconnect procedure, it could be the coil itself. The only way you will be sure what the problem was is if you can figure out exactly what you need to do to repeat the problem.

But, hey, why stress about what's working, right? Ride it and be happy!

I just took it for a ride and it is definitely fixed. I still need to fine tune the carbs, but Duane got it pretty close (despite the stuttering ignition).

As I was riding, I was thinking about all of the debate on the forum and my not really knowing the answer. I will tune the carbs tonight.....and then if the question is still eating away at me....I will put in the old coils to see what happens. I think I owe you guys an answer.

[Ken in Oklahoma]

As I was riding, I was thinking about all of the debate on the forum and my not really knowing the answer. I will tune the carbs tonight.....and then if the question is still eating away at me....I will put in the old coils to see what happens. I think I owe you guys an answer.

For what it's worth Frog, I don't feel like I'm owed an answer. To me this is kind of what we do on the forum. We ask for help if we need it. We offer advice. We kid around. We get to know each other. And we learn things in the process that we don't necessarily know that we're learning.

A few years ago, when the forum history was still available, I went back as far as I could to take a look at my oldest posts. I was amazed at the things I was asking about, things that for me now is pretty much common airhead lore. For example, I had dropped third gear simply by grabbing a handful of throttle and torquing through the gears. I wanted to know if this was likely to be an isolated failure or if I need to be careful in the future how heavily I get into the throttle while getting on the freeway. I now know that our transmissions are far from bullet proof, especially the 5 speed transmissions.

The thing is, by participating in the forum, doing the things we all do, I had gained a hell of a lot more than I recognized.

And this topic that you started has furthered the process. That and the friends I've made here is what keeps me coming back.


Ken

[Major Softie]

As I was riding, I was thinking about all of the debate on the forum and my not really knowing the answer. I will tune the carbs tonight.....and then if the question is still eating away at me....I will put in the old coils to see what happens. I think I owe you guys an answer.

For what it's worth Frog, I don't feel like I'm owed an answer.
Ken

Me either. I'd stick with the "if it ain't broke, don't fix it" adage.

[sterob]

. . I also agree with your other secert thought about 2 12V coils in parallel should work like 2 6V coils in series. But they don't, and I can't tell you why.


Wow, you do have a good memory. I had almost forgotten about my two-12V-coils-in-parallel-ought-to-work idea. Still seems to me like they should.

My first thought was the current may tend to circulate around the coils instead dis-charging and creating a spark.....
Would be interesting to find out if that is true or not.
Sterob

[robtg]

Path of least resistance may be a clue.

[Deleted User 62]

Path of least resistance may be a clue.

Do you think a dodgy jumper wire connection between the two coils could be the culprit? Would that change how the right coil fires too?