82 GS650G Won't start!

[Darazuu]

I guess it's been so long since I last posted that I had to make a new account.

I was having trouble getting the bike running last fall and now this spring she refuses to start at all.

Some background info (note: Little to no proper maintenance was done on the bike before I got it.) :
2011

• Acquired bike
• New Battery
• Carbs cleaned, carb boots and O rings replaced at reputable bike shop
• Replaced petcock with new
• adjusted valves

2012

• Overhauled the rear brakes

Last fall the bike started to lose power on a ride over to a friends house. It's hard to describe from memory but it felt like I was running out of gas. I limped it to my destination where it wouldn't start again until I added gas to the tank. By the way there should have been plenty of fresh gas in the tank (guessing I was 1/3 of a tank). I rode it a few more times that fall with no issues during my rides. If the bike sat over night I would have trouble starting it. Sometimes I could only get it started by rolling it down my driveway and popping it into first. Since it was rapidly getting cold out and I didn't have much time I treated the fuel and left it in the back of the garage.

This spring I can't get it started with a freshly charged battery or rolling it down my driveway. I know there's a lot of overdue maintenance to do. But I would like to at get it running first then tackle the other projects one by one with a running bike in between. My first guess is this problem has to due with the fuel system. I was thinking about tackling the carbs first and replacing every rubber hose along the way.

Does anyone have any ideas as what might be wrong?

 

[BigD_83]

On my 650G, the reserve pickup is very high in the tank, and I find I have to switch over way earlier than one would think was necessary, way more than half a tank of gas still in it, so that part of the story makes some sense.

However, the rest of the story sounds like a classic case of charging problems. Time to go through the stator papers and figure out the state of repair of your electrcial system. That in itself shouldn't be the whole story though, as a freshly charged and known good battery should still start the bike.

When you try to start the bike, is it turning over strongly? Have you pulled the plugs to see if you are getting spark? Are the sparkplugs getting wet?

 

[jeffgs]

So is it a crank no start?

Ok my first thought is you need to be sure the carb bowls are full. If you remove anything from the fuel system and get air in the line between the petcock and the fuel T or you drain the bowls, they are gravity fed and the fuel will not displace the air. I will crack the bowl drains slightly and let the air be pushed out. I use lot's of rags so I do not make a mess.

I have had my carbs off a bunch of times re-jetting and I have to do this every time. Even on prime fuel will not move down the line if it has air. I have a clear glass fuel filter and on prime nothing will happen until I either A pull the fuel line just slightly off the T at the carb or crack the bowl drains.

 

[tom203]

This last fall stuff......."If the bike sat over night I would have trouble starting it."
To me this sounds like gunked up carbs, especially the "choke" circuit . So you had the carbs cleaned back in 2011 and it ran ok till last fall? Did you use it much in that time period?

if you still got the factory airbox on, carb removal is challenging the first time, but it can be done.

 

[eil]

I know there's a lot of overdue maintenance to do. But I would like to at get it running first then tackle the other projects one by one with a running bike in between.

Heh, I hear you, but these old vintage motorbikes don't work that way. It's like your parents told you when you were young: work then play, in that order.

I would suggest getting it caught up on all of the maintenance, then riding it and taking it for a spin. Chances are, it will run perfectly and there will be nothing left to do but ride off into the sunset.

 

[Darazuu]

Alright, I finally had some time to work on it yesterday. I went though I tried out everyones suggestions here as well as the Help! Your Bike Won't Start (http://www.thegsresources.com/_forum/showthread.php?t=183245) thread.

Basic info:
The bike cranks well.
The plugs aren't wet.
Looking at in line fuel filter there's no gas going through the line even on prime.

Ok my first thought is you need to be sure the carb bowls are full. If you remove anything from the fuel system and get air in the line between the petcock and the fuel T or you drain the bowls, they are gravity fed and the fuel will not displace the air. I will crack the bowl drains slightly and let the air be pushed out. I use lot's of rags so I do not make a mess.

Following this I pulled the bolts from the float drains. Good tip on the rags cause I noticed the gas coming out smelled bad and didn't appear to be very clean. While doing this I realized I may have caused my own problem. Last fall when I was having trouble starting I decided to replace the inline fuel filter. Though I think things may be worse that my own stupidity. When I pulled the bolt to carb #4 nothing came out and I noticed there was a good amount of rust dust following the bolt. The bolt appears to not be standard either. It took a size 11 wrench when the other 3 took a size 10. It also looks like it was cut down from a longer bolt.

Should I look at doing a full carb cleaning and find out whats inside or just try to get gas back into the system? Which I realized I don't know how to do. Do I leave the drain bolts off and put the petcock on prime?

Heh, I hear you, but these old vintage motorbikes don't work that way. It's like your parents told you when you were young: work then play, in that order.

I would suggest getting it caught up on all of the maintenance, then riding it and taking it for a spin. Chances are, it will run perfectly and there will be nothing left to do but ride off into the sunset.

There's so many things I want to take care of on this bike that I've thought about buying a second bike to ride while working on this one. It's really been abused by the past owners.

 

[Redman]

.
.
The plugs aren't wet.
Looking at in line fuel filter there's no gas going through the line even on prime.

..

That seems to be your main "no start" problem.


Try disconnecting the line there at the petcock or at the inline filter, check fuel flow then, just as a double check.
If no fuel flow even in prime, then suspect the petcock, or the intank filter (comes out with the petcock).


Ah, you are looking at the bigger line, correct? (not the smaller vacuum line).

.

 

[JTGS850GL]

There should be no need to leave the drains bolts off to prime the carbs. The vent lines (2 of them) should allow the float bowls to fill. Always use the prime position if the bike has sat for an extended period of time. Put it on prime and let it set for about 30 seconds and then put it back onto the ON position. If you want to, leave the #4 drain screw open just to make sure that gas is getting in.

If it were me, I'd go ahead and plan on a fresh rebuild. I always have a complete set of O-rings on hand just in case.

 

[bonanzadave]

Eliminate the easy-to-do first. Take off the tank and dump all the gas out. Go buy a couple fresh gallons. Now there is no question if the gas is good. Get some fuel line and eliminate that fuel filter. Do as others suggest and switch to PRI to verify fuel delivery. Get a meter,switch on the key,check for 12vdc at both coils.

Keep us posted....

 

[knewel]

I'm having same issue on '79 GS850. Carbs redone last year. Bike sat over the winter with carb bowl plugs opened (and conditioner in tank).
Wouldn't start this year. Put petcock on PRI, fuel runs out of hose. Reattach fuel line, open plug on carb and no fuel runs out. I'll try leaving plugs open part way with petcock in PRI position.

 

[JTGS850GL]

I'm having same issue on '79 GS850. Carbs redone last year. Bike sat over the winter with carb bowl plugs opened (and conditioner in tank).
Wouldn't start this year. Put petcock on PRI, fuel runs out of hose. Reattach fuel line, open plug on carb and no fuel runs out. I'll try leaving plugs open part way with petcock in PRI position.

Try giving the carbs a light rap with a hammer while the petcock in in the PRI position. Might just be stuck floats.

 

[tom203]

When you say "carb bowl plugs" , you do mean the fuel bowl drain plugs, right? If fuel runs down fuel line in "PR", it should make it to fuel "t" between carbs and find its way to each fuel bowl. Of course, floats might be stuck down after sitting like this all winter, but fuel should pour out!

 

[Darazuu]

Eliminate the easy-to-do first. Take off the tank and dump all the gas out. Go buy a couple fresh gallons. Now there is no question if the gas is good. Get some fuel line and eliminate that fuel filter. Do as others suggest and switch to PRI to verify fuel delivery. Get a meter,switch on the key,check for 12vdc at both coils.

Keep us posted....

I dumped the bad gas and filled the tank with good gas. Verified the petcock works and gas comes out on prime when nothing is hooked up. Then I put everything back together, loosened the float drains, turned the petcock to prime, and gas only drips out of the interior two carbs. After about 20 seconds gas will stop going into the carbs. Any ideas? Or should I do a full clean of the carbs? Since good gas is going into at least 2 carbs should I try starting the bike to see if it will "pull" the gas into the other carbs?

I haven't bought new fuel lines yet. Is that something I can get from any auto shop, cut to length? Why should I get rid of the inline fuel filter? So far it's allowed me to see when gas is actually flowing.

 

[William Groebe]

It's painful figuring out a no-start situation. There are so many things that could be going wrong, and even when everything is in working order a bike that has been sitting for a while can have a hard time "waking up."

I took my engine apart recently and when I put everything back together (5 months later) it had a hard time starting too. I tried a little starting fuel and she started up fine and has been running well ever since. Sometimes a bike just needs to be "encouraged" to wake up. Your situation sounds more rough, though. Good luck.

 

[Guest]

I had a similar problem with mine after trying to start it after 20 years. I had done all the work, stripped the carbs, cleaned them and it would turn over but not fire up. I got a small insulin syringe and put a tiny bit of gas down the first and fourth cylinder through the spark plug holes. It fired up right away and has been firing ever since. Can't explain it other than to say that it might have been an air lock and just needed a bit of priming to fire up.

 

[chuck hahn]

Have you tapped on the bowls to see if the floats stuck? Have the edges of the bowl gaskets made the floats hang up and not open...its happened before to me and many members as well. If the petcock is on PRIme and no fuel will come out the drains..then whats the next logical thing in the stream.....floats

.If the petcock is on PRIme and fuel will come out the drains....then follow the path upstream....clogged jets.

 

[eil]

Clean the carbs. Here's your guide: http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

 

[Darazuu]

Have you tapped on the bowls to see if the floats stuck? Have the edges of the bowl gaskets made the floats hang up and not open...its happened before to me and many members as well. If the petcock is on PRIme and no fuel will come out the drains..then whats the next logical thing in the stream.....floats
.If the petcock is on PRIme and fuel will come out the drains....then follow the path upstream....clogged jets.

Fuel comes out of two of the carb float drains when on prime. I'm at the point where I'm just going to do a thorough cleaning. I already got new o-rings from Robert Barr.

Clean the carbs. Here's your guide: http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

Thanks Eil! I'm planning on going through this on my next free day (probably next year!? haha). By the way, I like your youtube channel. I think it helped convince my girlfriend to ride with me when the bike is working again. She had her fears due to media always showing extreme stunts or accidents. She enjoyed seeing a rider buzzing around town rambling about the average day.

A general question to everyone: When I clean my carbs should I replace the diaphragms or the float gaskets since they are still stock?

 

[BigD_83]

The diaphragms shouldn't need replacing if they are in good shape. If they are not leaking, the float bowl gaskets can be reused if you are careful. A little smear of engine oil will help keep them from sticking the next time you go to pull them.

Make sure you keep any plastic or rubber bits out of your carb cleaning solutions.