Crossing over...

[jwoell]

Redefinition

OK bros, I'm looking at something totally new here at this point. I drove it home today and what my coworker said was completely true. The bike has a brief power loss right before the "shotgun goes off". I can't really explain it, the bike loses power for about half a second and then all of a sudden...BOOOM...out the exhaust. So I had thought it was maybe something simple like float level or pilot jets, but now I'm considering the pick up coil or anything else.

To define it in more detail, I'd be cruising along at about 3-4K RPM and upon any sort of deceleration (possibly just out of the blue) the bike would lose all power for about a half second (even if I tried to goose it a little) and then it would backfire (shotgun style).

So my thoughts are that I rebuilt the pickup wires for sure (never been done), replace the park plugs since they're a little old, I'm considering doing the coil upgrade, I dunno, just asking for opinions.

Thanks

[John]

Sounds like the dreaded pick up coil wires. Do a search and you'll find many a discussion about repairing them.

[skids]

Re: Redefinition

The poppity pop on deceleration can be an indication or leanness. However that big bang is unburned fuel from one or more carbs being overly rich or non atomized fuel (like a pilot jet fell out or fuel going around the float valve or intermittant spark.)

Originally posted by jwoell
OK bros, I'm looking at something totally new here at this point. I drove it home today and what my coworker said was completely true. The bike has a brief power loss right before the "shotgun goes off". I can't really explain it, the bike loses power for about half a second and then all of a sudden...BOOOM...out the exhaust.

[79XS11F]

a agree .. this sounds electoral and the BOOM is all the unburned gas in the pipes when she re-fires
Rob

[jwoell]

OK, looks like I have a project for the Labor Day weekend. I get the sense that it's an electrical issue, so i'll check the pickup coil wires and mease the resistance on the coils, maybe drop in some new spark plugs, etc. I might have a run through the carbs too if it's possible that a pilot jet fell out or something, but it runs quite well other then the backfiring. Anyway, thanks for the suggestions.

[81xsproject]

I promised a pic of the new home-jobby synchronizer I mentioned at the beginning of the thread. Here you go.

[mro]

Here you go.

B'out time

I don't know Jessie...
Think I'd a used a green liquid


mro
btw, notice your using the same kinda shelving (cinder block)
that I used in my first apartment

[81xsproject]

ha ha mro, I used the only colorful thing I had (MMO) that would mix with oil. Besides, maybe my carb synchronizer is secure enough in itself that it isn't ashamed to display pressure differences in PINK

[oldbiker648]

A couple of drops of food coloring in the water would work as well.

[fredintoon]

Hi Oldbiker,
green or yellow dish soap'd work too. It's viscosity is away more than water and that's another advantage when used as a manometer fluid. However, water or any water+dye mix has the same problem, if by some mischance it gets sucked into the carbs and into the engine it turns into a major bother. Oil-based fluids, the manly red of ATF or the delicate pink of MMO, merely mix with the gas in the carbs to make the engine run smoky for a while.

[oldbiker648]

Fred,
Yep, a little oil in the carbs beats ANY water in them. Have you ever heard of anyone actually having had the misfortune to suck mercury into their engine as a result of a rapid increase in vacuum? I've read about that being a possibility if you used a mercury manometer. I can only imagine what that would do.
John

[Ken Talbot]

Originally posted by oldbiker648
Have you ever heard of anyone actually having had the misfortune to suck mercury into their engine as a result of a rapid increase in vacuum?

That would be quite nasty, but if you use in-line restrictors like the ones that came with the set I bought, it won't happen. The tiny orifice in the restrictors also helps to dampen out the vacuum pulses so you get a more consistent sync.