1979 GS 750L resurrect

[Crake]

Spring sucks

Spring sucks

So I've named my bike Stinky because of the ever-elusive gas leak stinking up my shop. I pulled the carbs again and gave the floats and needles a close inspection, as I suspected the bowls are overflowing. Did a meticulous cleaning and reassembled it. There seems to be some sort of stealth leak as I'll let the bike sit for a few days - it would seem fine however after a day or two a bit of gas would puke out randomly in the middle of the night all over the floor. I don't get it. You'd think if there was a leak, it would immediately leak when the fuel hit the carbs.

I suspect the petcock might be dribbling a bit and one or more of the carbs are gradually overflowing. Possibly even forward into the cylinders. :-& This was verified when I tried rerouting my fuel line (what a cursed tight space to work!) and gas would trickle out the petcock as I cursed and fumed.

I pulled the bike out on a warm day and drained the oil - it was looking pretty cloudy and I suspected it was contaminated. New filter, new oil - and a nice brand new fuel cut-off valve between the gas filter and carb. That should stop excess fuel flow, I'll make a point of running the bike a few minutes after I shut the valve and that should empty the fuel system. Take that, leak.

Stinky now sits outside 'cause I don't wanna get high on gas fumes anymore. Took her for a spin around the bay and she seems to run fine, all systems are go. A new development, however - now there's a black oily gunk leaking out of the exhaust drain. Not much (whenever I start it and let it run, about a teaspoon dribbles out) and a wee bit out the rear exhaust. Could be unburnt oil (leaking past the rings when the oil was contaminated?) or possibly just the excess of penetrating lubricant I used to free the cylinders getting ejected out the exhaust. I did use quite a bit of Fluid Film so I hope that's all it is. Will watch the fluid levels closely.

So now I wait patiently for May 1 to go pick up an antique plate. More to follow...

 

[Crake]

All done (almost)

All done (almost)

Today I picked up some bar end mirrors at my local motorcycle salvage shop. The guys talked me into some decent handlebars for $30. I figure I'd probably pay that in shipping to get something shipped in, so I went for it.

The end mirrors needed a bit of flat black paint but otherwise were in great shape. Picked up an antique plate over my lunch break ($78 for 6 months - wow!) Came home and installed the new handlebar. It looks great and feels a lot more natural than those ape-hangers. What did the guy call them at the salvage shop? "Wheelbarrow handles"...

Took her down to Husky to fuel her up - $12 of premium to fill. She ran really well for the 5km test drive. I did notice the occasional stutter now and then but otherwise the bike had good acceleration and seemed to run and idle just fine. Tach is still sluggish - I'm gonna ride her for awhile and see if it loosens up before springing on new gauges.

I cut the fuel supply about 100 meters from the house and parked it in the garage. Put a tub underneath her - lo and behold, the black ooze seems to be gone. I guess all she just needed to blow out a few cobwebs.

So here she is. Gonna spend my next allowance on a new set of tires. I'll take some better pictures when it isn't gusting 70kph winds and blowing dust and sh*t all over my neighborhood. Cheers!

"Crake"

 

[keepsailing]

Right on!! Congrats, glad to hear it made the trip. Wish I could say the same about my current build. Keep us updated

 

[Crake]

put-put-put

put-put-put

Well the first 20 km went well. Then she started bogging down like she was running out of gas. Managed to limp her home (barely) and observed the fuel line from the filter to the carb was bone-dry. After a few cranks there was barely a trickle down the line. Soooo. Plugged filter or plugged petcock. I'm betting it's the filter. Should be an easy fix - and here I was all sad there was rain forecasted for the rest of the week!

 

[keepsailing]

Well the first 20 km went well. Then she started bogging down like she was running out of gas. Managed to limp her home (barely) and observed the fuel line from the filter to the carb was bone-dry. After a few cranks there was barely a trickle down the line. Soooo. Plugged filter or plugged petcock. I'm betting it's the filter. Should be an easy fix - and here I was all sad there was rain forecasted for the rest of the week!

Shouldn't be too bad of a fix. Should probably swap out petcocks on my bike as well. :-\\\

 

[Crake]

Petcock

Petcock

Shouldn't be too bad of a fix. Should probably swap out petcocks on my bike as well. :-\\\

I stripped my petcock and cleaned it. Had about 29 years of solidified resin and crap plugging it completely. Once it was cleaned it seemed to function well.

 

[keepsailing]

I stripped my petcock and cleaned it. Had about 29 years of solidified resin and crap plugging it completely. Once it was cleaned it seemed to function well.

I'll have to look into that instead, could probably save me a little coin. It would probably be safer to run a new one though. Hopefully the bike makes a full trip for you in the near future!

 

[Crake]

Petcock cont

Petcock cont

I'll have to look into that instead, could probably save me a little coin. It would probably be safer to run a new one though. Hopefully the bike makes a full trip for you in the near future!

After a bit I suspected my petcock might be leaking a bit of gas over time (mine only has an "on" and "reserve" setting, no "off") so I installed a fuel cut-off switch a bit further down the line to resolve that.

 

[keepsailing]

It should have a vacuum line then? At least mine does, which allows the ON position to basically be an OFF position when the bike isn't running.

 

[Crake]

It should have a vacuum line then? At least mine does, which allows the ON position to basically be an OFF position when the bike isn't running.

Yes sir, there should be a vacuum line running to the petcock. When the motor runs, the vacuum pulls a diaphragm back which opens a rubber stopper inside the petcock, allowing gas to trickle through. Turning the petcock lever rotates a small plastic fitting that redirects fuel flow from either the top end of your in-tank filter ("on") or the bottom ("reserve").

 

[Crake]

Wheel change

Wheel change

I decided to spring on some new tires. Seeing as the ones on it are 30+ years old. I was having nightmares of a sudden and violent blowout in mid-traffic. Couple guys down at Regina Motorcycle Salvage are going to change them for me on Monday.

So I pulled the wheels off this afternoon. Was a lot easier than I expected. God bless the service manual, forever and ever, amen. Kinda looks like a hover-bike now...

 

[Steel Toed Tank]

How have I never seen this thread before?
Not many of us from Saskatchewan on here.

Good job getting it going while spending as little as possible!

That's how my first GS worked out too, although I didn't paint it or pretty it up.

 

[Crake]

How have I never seen this thread before?
Not many of us from Saskatchewan on here.

Good job getting it going while spending as little as possible!

That's how my first GS worked out too, although I didn't paint it or pretty it up.

Yup - St. Walburg I see. I've been up in that neck of the woods awhile back for work. Mostly hang my hat here in Regina these days.

 

[daturat100r]

while the wheels are out i would recommend pulling out the swingarm and giving the bearing a clean and a grease.lack of use is very hard on those bearings and also the steering head ones too.My bikes ones were history and expensive to replace after it had been in storage for years then taken out and ridden by the PO

 

[Crake]

All done - for now...

All done - for now...

Its been a bit since my last update. I've had the 750 out of commission for a bit until I could work up the ambition to sort out the fuel line issues. Turns out the gas tank wasn't as clean as I expected. Fuel filter was plugging solid with crud after only about 45 km. Fuel economy was also terrible - a little better than 20 miles to the gallon!

I expected the poor fuel economy and the leaking carbs were likely related. Pulled the carbs off for what I hope is the last, last time, and re-checked the floats. Sure enough, two were set a bit too high. I evened them all out to spec and tested the needle seals by blowing into the fuel line. They all looked like they were sealing tight. Scrubbed a bit of powdered deposit out of the bowls and attacked the gas tank. After a good soak with CLR I flushed a goodly amount of rust and crud out of the tank. Followed up with a vinegar bath, a soda flush and a good splash of isopropyl alcohol to dry it out. The tank appears much cleaner now.

Re-installed everything and had a hell of a time getting her to start again. Once she was running she was pretty boggy and didn't want to hold idle. I expected some solidified crap in the carbs that had to dissolve as I had it laid up for a few weeks. Sure enough, after a few days she started and ran easily after a few puts out the exhaust. Took her for a run tonight and it looks like all systems are go.

For now.

So the wife asked me the other day, "I suppose our front step is your bike's new home?" Yes, my dear, noone has built a big Pillar of Awesome on which to perch my resurrected bike for the world to see, so for now, the front porch will have to do. After which I said, aloud, "just for a little while, honey..."

Cheers all...

"Crake"

 

[Crake]

July 2014 - Final fix

July 2014 - Final fix

Well after a couple of months frustration I narrowed down the horrible fuel economy/gassy exhaust issue. I'd driven it for about a month and burnt a terrible amount of gas (one day I burnt 10 liters of fuel in only 50 km). The bike would typically leave a thin blue smoke trail in the mornings until she warmed up. And she always stunk of gas.

I'd assumed the gassy exhaust was a fuel/air mixture issue. Also, #3 carb had consistently refused to fire, which I figured was the cause of the poor gas mileage. After some good advice from a motorcycle salvage yard guy, I remembered finding a bit of trace gasoline in the vacuum line running from #3 carb to the petcock during one of my many carb disassemblies. Sure enough - there was a crack in the petcock diaphragm, just enough to siphon gas down the vacuum line to choke up #3.

Finding replacement innards for a 750L petcock was damn near impossible, so I elected to mod it. I already had a down-stream on/off petcock installed into the fuel line, so I pulled the old petcock apart, cut out the center of the diaphragm to make a half-assed gasket, epoxied the vacuum port shut, plugged vacuum line with a golf tee, reassembled everything and the bike fired right up (including #3 - yay!) I took the bike for a spin around the block - completely different bike!

I never would have thought these issues would require a 0$ fix - unless, of course, you count the golf tee...

A few days later - the gas stink has completely disappeared. There's no more smoke coming from the exhaust and I'm getting about 33 mpg (mostly inner city driving and a bit of tearing down the highway on the odd weekend ride). No drips, no leaks, and the bike's got plenty of jam. Just cracked 5500 original km on the odometer! - "Crake"

 

[eil]

Good temporary fix. It's always a great feeling to resolve long-standing issues like these. Now save up the pennies for a new petcock.