How to baffle the Rocketman?

[Rocketman]

All very good points, and I expected nothing less from you guys. Compression check done, and almost perfect. Mixture screws/needles turned to richen up a previous lean condition, and I think they're right on now. Carb boots on both sides are soft, pliable and sealing fine, and just to make sure we used adhesive to make 100% sure (don't freak out). Carb screens and needles checked for crap-no issues. Later this week, I'm going to have the stock ignition pickup re-installed, which had been replaced by a brand new Dyna-S unit when I did the coils. Maybe since I think I've exhausted all fuel issues, it might be smart to go back to stock ignition. But AGAIN, if the ignition was bad, two simultaneous cylinders would stop working, as the pickup is sending signals to coils 1&4, and 2&3. This would not account for one dead cylinder migrating randomly. Maybe BillyBoy hit it on the head, and I need an Excorcism to scare the demons out of this bike. Sometimes when logic doesn't work, BillyBoy prevails!

[focus frenzy]

dude change where you are getting gas at!
the only thing that adds up and can explain a wondering cylinder cutting out is water.

the moving around is from changes in the angle of the bike determining where the water flows to.

it straightens out at the mechanica cause he has it sitting still on the side stand or center stand (the water will run to the front of the tank on center stand)

also open the bleed air mixture screw a half turn, you are lean.

[bonanzadave]

This is a stretch but it worked for me with my brother. We both drove the same make truck and when I was having engine trouble I started swapping parts from his.

Find someone with another 850 that runs well. Buy him (or better yet her) lunch and beer. Offer to watch the beloved machine while hes (or shes) on vacation and then start swapping. Sooner or later ya gotta figure it out. Good luck

[bwringer]

A couple of thoughts....

Tthe one thing I haven't seen mentioned is the foam seals under the chrome covers on the the left and right sides of the airbox. Apologies if you've already done this...

These covers MUST be sealed for an 850 to run right. Basically, the airbox must be sealed airtight so that air only gets in through the snorkel on the back and the vent holes on the bottom.

You can use self-adhesive weatherstripping in place of the original foam, which is probably completely gone by now. I also glue the edges of the weatherstripping together to ensure no extra air is getting in. You have to do both the cover on the right (the one you remove to replace the air filter) and the one on the left.

You also need to place weatherstripping on the top of the air filter carrier so that it seals against the top of the airbox. Again, even on a low-mileage bike, the original foam will have crumbled and vanished long ago.

There are generally two thicknesses of weatherstripping available, and I use the thicker -- I think it's 1/2 inch or close to that. The 1/4 or 3/16 is usually too thin. Use brake or carb cleaner to clean off the mounting surfaces, stick the weatherstripping on, then use yellow weatherstripping glue (gorilla snot) to seal the corners where the pieces meet. Once that's all dry, smear a light coat of grease on the top of the foam to keep it from sticking. You should also have a hard time installing the air filter the first few times because you have to compress the foam -- make sure this foam has a little grease on the surface so it can slide into the airbox without ripping off.

If you're having trouble getting the weatherstripping to stick, glue it down using the gorilla snot as contact cement -- apply a light coat to both surfaces, let dry for a minute, then stick together.

One of the symptoms of leaking intake o-rings is exactly what you are experiencing -- problems that seem to move from cylinder to cylinder and drive you absolutely crazy. Even with very few miles on the bike, your original o-rings are done for. These o-rings need to be replaced ASAP with the heat-resistant o-rings from Suzuki. Your intake boots will likely be OK for a while longer if they're not separated and still pliable enough to get the carbs off and on without two men and a boy to help. I'd still replace the boots before a long trip if it were my bike.

Please note that you usually won't notice anything with the WD-40 or water tests until the o-ring problem is really bad. Despite their large effect, the air leaks are very, very small, and problems will seem to move randomly from cylinder to cylinder as the engine warms up and cools down.




Two other things I'll mention just in case, although I don't think these are related to your current problem. Just things to be aware of that I've encountered and corrected.

Too much oil on the filter is a common mistake, although it's probably not your problem at the moment -- use the lightest possible coating of spray filter oil, or if it's already soaked, use paper towels to blot off as much oil as possible. It should be as dry as possible.

Also, I just corrected a friend's 850 (also a pristine '82 GL) that had the float heights set incorrectly when he bought it -- somebody had set them using the top of the float, not the "notch" in the top of the float. We corrected the airbox sealing and intake o-rings (and adjusted the valves), and the bike was absolutely transformed.

These are incredibly rewarding and reliable motorcycles when they're set up correctly, but it can be admittedly tough to get all the details right in the face of 23 or more years of neglect and unknown alterations. Fortunately, you've got the resources for the correct information right here on the forum!

[Rocketman]

BWRINGER,

Are the O-rings the clamped on 4 boots that connect the carbs to the engine, and the 4 that go to the airbox, and are clamped on? Or something else like the intake O-ring shown as part #29 on this schematic?



Larry

[Dink]

No 29 is the o-ring everyone is talking about, a tiny leak here may give exactly your symptoms.

Dink

[Rocketman]

Well for $1.19 a piece, I think its a no-brainer that they will be replaced (as an excorcism I think is kind of pricey these days!.

[txironhead]

Well for $1.19 a piece, I think its a no-brainer that they will be replaced (as an excorcism I think is kind of pricey these days!.

Not if you can find a priest that drinks!\\/

[Dink]

Well for $1.19 a piece, I think its a no-brainer that they will be replaced (as an excorcism I think is kind of pricey these days!.

Not if you can find a priest that drinks!\\/

You mean you can find one that doesn't!!!:shock:

Dink

[bwringer]

Yup, part #29.

You've, um, seen this, right?

http://bwringer.com/gs/intakeorings.html

Lotsa pictures and everything.

If you haven't already removed the intake boots, there's a 99.9999% chance you'll need to resort to extreme measures to remove the cheesy philips head screws holding the boots on. You can cut a slot with a Dremel tool and use a chisel or impact driver to get 'em started. Once they crack loose, you're home free. Other than that, it's easy. The original o-rings are likely hardened to resemble ceramic -- more than one person has mistaken old o-rings for metal pieces!

If you drill the heads off the screws, you might nick up the intake boots a bit. If you're replacing them anyway, you may or may not care.

The screws are 6mm diameter X 20mm length, and you can get tasty stainless steel allen head replacements at most hardware stores (you need a hardware store -- large home stores do not have them).

[ifly85]

I think BWRINGER's comments are right on, but I am pretty sure that one other thing that could do this would be if your electrical system wasn't putting out 12V+. Then the coils could work somewhat randomly. I admit that I wouldn't expect to have one cyclinder that was the only cool one on each ride.

Good Luck!

[tconroy]

I really appreciate your advice. The boots on the air box side and the engine side and o-rings are original but are in nice pliable condition. Even if there was an air leak (which I've already checked numerous times) , I can't imagine how this would cause an inermittent combustion problem that migrates randomly from one cylinder to the other. It seems to me, it would constantly affect the one cylinder with the leaky boot, not all 4 randomly. Same holds true for the idle circuit; assuming the carbs have been torn down and rebuilt and cleaned numerous times, including blowing compressed air through the fuel line to almost force fuel injection into the carbs, and blowing out any specks of residual crap, and then cleaned out again, why the heck does the cold header keep moving form one place to another? It's odd that I never have any wet plugs either. You would think after riding for a while on 3 cylinders, that the 4th non-running cylinder would be soaked, but its not. And its not like I'm dropping a cylinder only at idle when I stop; its just that's the time I notice it, and on acceleration after that.

Are you missing any washer on the carb intake boot calibration screws.I would spray wd-40 behind the intake boot where the fins meet the boot.I would go ahead and replace the o-rings anyway.They are cheap and if they are original they are shot..Make sure your air intake side boots are also not leaking.

[49er]

Intake air leak, or intermittent electronic ignition fault?

If I was a betting priest, I'd have another beer. After a second, I'd probably lay money on the air leak.

[Rocketman]

Yes, I saw the intake o-ring article and should have tatooed it on my forehead. If the o-rings were my problems all along, I will smack myself a few times (but not too hard). O-rings are definitely in my bike's future, as well as re-checking the "packing" in the airbox.

[Dave8338]

Use a Vice-Grip on the screws, Tconroy set me up with this advice and it works too good to be true. Start at the top screw, clamp the grip on as tight as you can get it and tap with a small hammer to loosen it. It works!! Then, using a samll piece of wood placed on the metal flange of the intake boot, grab the hammer and hit the wood in a counter clockwise direction...the boot itself will back the screw out. If it doesn't come out on the first try, rotate the boot clock wise and repeart. All of mine came out using this method and didn't even scratch the boots. It works that easy, no drilling grinding nothing! Give it a try!