Is it carbs, or is it electrical, or is it exhaust?

[Tracer]

I have a 1980 GS850L that I have been tinkering with over the last couple years. I have it running, and even went on a local ride this last Saturday with a Rolling Wheels Vintage Motorcycle Club. However, I still have a few, possibly minor but recurring, conditions I'd like to iron out.

First, when I start the bike, I have little or no evidence of the cold-blooded heritage of these bikes. In the past, with full choke it fires right up and then revs up to 3000 almost immediately until I work with the choke to bring the idle down. Sometimes, after a ride and after the bike's been sitting an hour or so, I don't need any choke. Part of me assumes it is still sufficiently warm, but I also wonder if the jets are a little too rich (they're stock).

Second, I have what I think is an exhaust tick. It sounds like a valve tick, but I've checked all shims and they are within specs, though I replaced one. Afterward, the tick is still there. I've had the pipes off once. Are the metal exhaust gaskets re-useable, or should I look at investing in a new one(s)?

Third, I have some popping. Usually there is a little poping during warm up, but there is also some consistent popping after I've been riding in midrange and I let off on the throttle to shift down or slow down.

Last, I am getting some periodic loss off power when riding in midrange (60-70 mph around 4000 rpm.

I was wondering if my main jets were too big, therefore sending too much fuel during midrange riding causing flooding and popping. My brother thinks I may be letting air in at the exhaust end leading to the popping, and things a plug wire may be periodically faulty causing the losses of power.

THoughts?

Much thanks!

[dtkid]

Quick thoughts off the top:

The pops during decceleration are more than likely due to a small exhaust leak. YOu need to "dig" those old exhaust gaskets out and replace them.

YOur episodic loss of power in the mid-range is difficult to diagnose with any confidence. You may have a plug wire/cap that fails when it gets hot or I have heard that a "weak" coil can start to founder when it is hot (I think you said it only happens when the machine has been run for a while).

If your mains were too big than the bike would falter all the time and in the same throttle position.

At least it sounds as if your problems are minor and extremely fixable.

Good luck

[chef1366]

Petcock

I agree the popping is an exhaust leak. These 80s petcocks are NOT one of Suzukis finest. I had the same problem and It turned out to be fuel starvation from a faulty petcock.

[dtkid]

Yeah, fuel starvation is something I didn't consider. I replaced my fuel line and filter once and used a relatively long piece of fuel line. The line had a tendency to crimp under the tank and it was causing exactly what you explain (but only episodically).

Make sure your lines are laying/running in the correct positions. Although it seems too simple to be true it will definitely shut you down.

[jrciamacco]

Are you still running with the fuel filter? That could be part of the fuel starvation problem too. I know a lot of people think ill of them...

[Jethro]

Are you still running with the fuel filter? That could be part of the fuel starvation problem too. I know a lot of people think ill of them...

They are not nessecary. The bike already has 5 inline fuel filters, you don't need a 6th.

Anyway, to more constructive topics, popping on deceleration is generally attributed to a lean condition, caused by either exhaust leaks, air intake leaks, or poor fuel mixtures. If your bike has stock jets, keep in mind that if anything they came lean from the factory for emission reasons.

Is your exhaust system stock?

[Tracer]

Sorry for taking so long to reply to all the great suggestions. It was the end of the semester and grading, etc. was on the table.

In terms of the midrange issue: I did some poking around the plug wires, and lo & behold, #1 wire popped right out if its cap. Inside the cap I notices that the connector was pointed and threaded, so I slid the boot back, "corked" the cap back into the wire nice and secure, and then slid the boot back on. Since the boot had some cracks in it, I did what any Red/Green fan would do, and I wrapped the boot in electrical tape. (I know, duct tape would have been more Red/Green, but a man, even a handyman, can only go too far. Anyone know of a good source for those wire/cap boots? The local parts stores have been clueless.) End result: No loss of power in midrange, or ever for that matter. My guess is that before the fix, my 850 was operating as a 640 whenever the connection at #1 opened up.

As for the popping, I am looking into some new exhaust gaskets to replace the ones in the bike right now. I did pull the headers and pipes last year at this time to replace the oil pan gasket, and I just stuck the old header gaskets back on and thought nothing of it.

Concerning the general leanness of these early 80s bikes, I've considered going up a size in the main and pilot jets, and down (?) a size on the air jet in order to rich things up a tad. (Normally I would just adjust the mixture screws, but two are seized ever so tightly, thank you EPA.) Any experience and/or thoughts?

Much thanks. This group and forum rules.

[dtkid]

Ahh: End of semester grading.....you must also be a relatively impoverished educator. Myself as well.

Concerning your plug boots: If your coils are stock you may have some trouble simply replacing the boots. I think a thread does exist to assist with this task, although from experience I have found it much easier to purchase a new/used set of coils.

If you so desire, I have a number of coil sets that will fit your bike and if you send me a message we can discuss this. Actually, I think I have 8 sets so they won't cost you much.