1981 GS 850GL loses power and dies in 5th

[dwickham]

1st time it died I was able to downshift to 4th, 3rd, and second but it lost power in those gears right away too.
After that we fixed the electrical issue and I rode it for about 20 minutes through heavy traffic to work and then back home again. Would it have had time to vapor lock? Especially since it was mostly 1st and 2nd gear?

The second time it broke down I downshifted to 4th, rolled down on the throttle, and it died in gear. I really need to find a friends garage to break down the tank and petcock as it does seem like it just ran out of gas. Its too damn cold to keep doing this outside!

When I get the new tank a friend of mine suggested taking it to a radiator shop to have it stripped and dipped. Has anyone had any success with radiator shops before?

Thanks!

[DanTheMan]

If your "mechanic" shop hasn't yet sourced a tank for you, and your tank is the 3.2 gal single bolt tank (GLT) have them contact me. I have a perfectly good one with the petcock (no gauge sending unit or cap) I'll let go for $60 plus shipping cost.

[dwickham]

Thanks for the offer Dan, that is super cheap, but my tank attaches with 2 bolts, which I guess makes it the GLX model.

[Big T]

When I get the new tank a friend of mine suggested taking it to a radiator shop to have it stripped and dipped. Has anyone had any success with radiator shops before?

Dipping is no longer available due to DEQ rules. Plus, it takes the paint off the tank. Mac's Radiator on TV Hwy can send it over to the main shop and have it blasted.

But, it's easier just to clean the interior with Evaporust or vinegar or electrolysis. Check BassCliffs site

If the interior is rust free, then you're in business

Have you ever checked the interior of your damaged tank?

What shop is jerking you around?

I typically order parts from Beaverton MC via their website and check the "i will pick up" box

[DanTheMan]

Thanks for the offer Dan, that is super cheap, but my tank attaches with 2 bolts, which I guess makes it the GLX model.

Yep, you're right, that's the '81 model. If you can get an '82 tank, it holds 4.5 gal instead 3.2 which the 80 and 81 tanks hold.

[Steve]

In the very first reply, Tom R suggested checking the cap vent. Have not seen any reply about that.

Sounds like it's starving for fuel. Check the vent on the fuel cap for starters - if that's not it, check the petcock and the carbs. Fuel filter?

Easiest way to check that is to go until it starts to lose power. Stop, open the gas cap. If you hear a "WHOOSH" as you open the cap, your vent is plugged.

.

[dwickham]

I just finished up recharging the battery but I have to cop to being lazy. Just need to convince my wife to drive behind me for when it breaks down. She hates this bike and wants me to buy a newish bmw oil head but I love the way these GS bikes look. That plus freezing my butt off while my bike wont start is depressing. I'll get to that sometime this week and let you know.

[dwickham]

So I took it back out today for a real short hop just to get gas moving through it, 4.5 miles one way. Went to pick up some new aftermarket brake pads and an inline fuel filter. By the time I got there it seemed good and warm. Pulled the gas cap and listened very carefully but heard no sucking sound from vacuum. I am guessing at this point its A. the petcock, B. the fuel line, C. the vacuum line, or perhaps D. junk in the carb getting moved around and clogging my jets? The shop says my "new" tank is on the way so I'll treat and coat the tank, check those lines and maybe check the carb while I'm at it.

One the way down, by the time I got there it seemed like it was starving for fuel again, died super fast when I pulled up before I even hit the kill switch. On the way back up it seemed fine.

Big T, its RoadHawk Cycle thats taken over 3 months to get me a new tank. Next time I'll try Vicious Cycle.

[dwickham]

So I took it over to my friends today and we took the tank apart and inspected it. Seemed fine with no crap coming out so the tank is pretty clean. We broke down the petcock and found nothing wrong, clean filter, all parts with very low if any wear. Inspected the gas and vacuum lines and they both looked good. They were new as of a month ago so I expected that. The last thing I can think of is the manifold boots. You guys all say replace them as a first step and these are old if not the originals. I'll order them, swap em' and let you know if it makes a difference.

[Dogma]

That inline fuel filter may make things worse. Since these bikes rely on gravity instead of a pump, a restrictive filter can create a fuel flow problem. There have been some people who had success with a high flow filter (For mowers, I think - also gravity-fed.). Most go with the factory configuration of no filter other than the petcock's screen.

In today's post, you mention cleaning a filter. Does it already have an in-line filter? If so, get rid of it and see if your fuel flow problem goes away.

[dwickham]

It had an inline fuel filter when I first got the bike but it hasn't had one since the shop I took it to,Roadhawk cycle, broke its gas lines and replaced them. I can't think of another reason besides loss of vacuum at the manifold boots that it would die in 5th gear. My buddy told me that the more I roll on the throttle, the less vacuum I have and the more gas I need. So by the time I'm in 5th and rolled all the way on it has almost no vacuum due to broken or poor sealing at the boots. Does that sound about right? Thanks for your help.

[banditom]

vac leak?

Hi,

If youre wondering about a vacuum leak, the quick way to tell is run the bike , and spray some carb cleaner or propane from an unlit propane torch around where you think the vac leak is, if it picks up engine speed immediately, that is the location of the vac leak. Most recommend changing the inlet o rings regardless, I believe the carb boots can be rehabbed on zukis similar to the yammies that Ive done with spray on rubber coating if the boots are actually worn thru the inner walls. Just because the boots may look cracked on the outside, is not proof that they are leaking on the inside. Take em off and look carefully. If there is any inner cracking whatsoever, its best to just get new ones, but spray on rubber coating on the outside may delay the need to buy new ones if you dont want to go the new route.

[Big T]

My buddy told me that the more I roll on the throttle, the less vacuum I have and the more gas I need. So by the time I'm in 5th and rolled all the way on it has almost no vacuum due to broken or poor sealing at the boots. Does that sound about right? Thanks for your help.

His reasoning is backwards

The more you open the throttle, the more vacuum is created. The increased vacuum lifts the slides more and more gas flows out of the jets

It looks like you need to go back to your Megawelcome and check the 10 common things.

New O rings in the carbs and at the head are manditory. New intake boots may be needed

However, I don't think your problem is fuel related. Looking over your initial post, the problem seems to be electrical due to the 30 amp fuses and such. I don't think changing the fuse box cured that issue.

Gave you checked for spark when it died?

[dwickham]

The one thing I haven't checked I guess is the spark. I'll check them when I swap the new boots in this weekend hopefully.

The first time it died in 5th I couldn't turn the electrics back on, we cut out the old fuse box for modern water proof stuff. The second time it died the electrics didn't die and when I tried to restart it the motor kicked over till the battery died trying. I shouldn't have figured the spark plugs were good because of that and I'll make sure and check them.

My starter is weak and I was thinking of replacing it but my buddy said it was easy to fix an electrical motor. Easy for him as he is an electrical engineer, I'm just your average-to-low end mechanical knowledge type guy and that is way over my head. How hard is it to find new brushes to fix it instead?

[BassCliff]

Hi,

Many of the vendors in your "mega-welcome" sell starter rebuild kits. Some of those vendors specialize in electrical stuff.

Thank you for your indulgence,

BassCliff