Diagnosing a weird issue

[Fix]

Hey folks,

I've got a bike issue I can't figure out. For the last few weeks, when upshifting at low rpms (short shifting) or when I let the rpms drop too much without down shifting, my bike acts like it's only partially in gear. It doesn't lug in the traditional sense. It seems like it's half in gear. If I roll on throttle in these situations, it doesn't have any power. If I pull in the clutch, increase rpms, and release the clutch it goes away.

I pulled the clutch apart and measured the springs and plates. Everything was well within spec according to the great tech tip. I adjusted the clutch cable when I was done in accordance with the tech tip as well.

But it was doing the same thing when I rode in today.

I can ride it as is, just make sure to keep my RPM's up, but I'm worried I may be doing damage.

Would a gear issue cause these symptoms? It doesn't pop out of gear, and has no issues when I accelerate hard.

Any help is appreciated.

[DAVINCI]

Look up the pickup wire fix here on the site.

[Fix]

No kidding? I thought for sure it had to be mechanical. There's a reason I'm not a mechanic, I guess. I'll check the pickup wires tonight. Thanks!

I assume this tech tip is the one you're talking about? http://www.xs11.com/xs11-info/tech-t...pictorial.html

[dpotter58]

No kidding? I thought for sure it had to be mechanical. There's a reason I'm not a mechanic, I guess. I'll check the pickup wires tonight. Thanks!

I assume this tech tip is the one you're talking about? http://www.xs11.com/xs11-info/tech-t...pictorial.html

I chased what i thought was a carb issue for over a year. Fixed the pick ups and it's perfect.

[DAVINCI]

Yeah, you did a bang-up job on those, Duwayne! How you doin, pal?

[DGXSER]

my bike acts like it's only partially in gear. It doesn't lug in the traditional sense. It seems like it's half in gear.

First, what RPM range are you talking about, below 2k these bikes typically do not have alot of power.

Can you elaborate on "acts like it's only partially in gear"or "only half in gear"? You say it is not skipping, do the RPMS seem to go up, but the speed does not change? Does the engine or bike seem to sputter or stutter?

[Fix]

First, what RPM range are you talking about, below 2k these bikes typically do not have alot of power.

Can you elaborate on "acts like it's only partially in gear"or "only half in gear"? You say it is not skipping, do the RPMS seem to go up, but the speed does not change? Does the engine or bike seem to sputter or stutter?

Below 2k, but I'm used to the normal low torque in this range. RPM's will go up if I roll on throttle, but slowly and the bike shudders very slightly and acts like it's going to stall. Since it's only done it while I'm in traffic (stop and go stuff) I quickly pull in the clutch and rev it up, so I don't know if it would eventually climb out of whatever state it's in. Plus it just feels really strange, so I worry it might cause damage. I'm not talking about the "I missed a shift" feeling, or the "lurching about to stall" feeling. The best way to describe it would be like the clutch is half-in but with a weird engine sound. Not a metallic grinding gears sound, just that the engine sounds...weak.

It's one of those things that's hard to explain, and since it's only while in motion, I can't really video it.

[GLoweVA]

Not to add any more confusion, but what about a fuel issue in the pilot circuit. At the lower RPMs the pilot/idle circuit drives most of the fuel and if one or more of these is clogged up, then the bike would be 'weak' at lower RPMs. When the RPMs get up there, then the mains take over and the cylinders would get the fuel they need and then go.

The pick up coils could also be cutting out at the lower RPMs, then when the vac advance pulls the plate over, the coils cut back in, so that could be the issue too.

The best way to troubleshoot, is the process of elimination. One possible issue at a time. Once that's ruled out, move to the next possiblity.

[Fix]

As soon as I touch the blue pickup wire the bike dies. May have found our culprit!

[GLoweVA]

Hope that's all it is. Find the tech tip here for the repair.
http://www.xs11.com/forum/showthread.php?t=543

And

http://www.xs11.com/forum/showthread.php?t=122

[Fix]

Thanks, I have to wait til the wife gets home from work to take the bike out and test the fix.

[Fix]

Good news, the wire fix seems to have solved the bikes poor running issue.
Bad news, I pinned the throttle for just a second...and it stayed there!
I pulled the clutch in, hit the kill switch, and pushed her home a mile uphill.
After that, I was too tired to take it apart. I figure it's either a kinked/stuck throttle cable, or something amiss at the carb throttle lever spring.

Hopefully it's a quick fix. Looking back I do recall just a tiny bit of resistance at the throttle the last few days, but I thought nothing of it. That'll teach me.

By the way, I don't know if it's adrenaline hazed recollection or not, but I'm pretty sure I got the front tire up last night before I killed the motor.

My sphincter may not unclench for days.

[GLoweVA]

It's amazing how much power these old bikes have when they're running on all 4!
I've seen that the 78-79's are a bit more powerful than the 80-81's.
Kinda of wish I had done some research into that before I picked up my SG project.
However, it has been nice to have a readily available parts bike sitting right next to me when ever I needed a part, it's right there!

[DAVINCI]

Fix,

Glad you got it.

Gee, I love being right

[Fix]

Fix,

Glad you got it.

Gee, I love being right

You nailed it in one, despite my half-assed description of the problem!