GR650 running woes - can you help

[Barneycanoe]

As the owner of three GS850 bikes, I trust you won't mind a question about a 1983 GR650 Tempter.
I had recently got low on gas and put 2-3 litres in from our lawnmower supply. I went out for a ride and the bike started bucking and hesitating, so I thought I was running out and put the fuel cock onto reserve.
The bike was barely running but I nursed it to a gas station and filled up with mid-grade gas.
It still ran quite badly, especially around 4000rpm. I bought a can of seafoam and things have improved to the point where sometimes I have full throttle and everything is normal, but then I will get the hesitation again.
I conclude that I either put dirty gas in (I've only ridden about 30 miles since then so it may still be affecting it) or I have a carb problem.
The bike starts and idles fine as it always did. It has 22,000km (15000miles). Has been on the road last year and this.
My questions are:
1) Can I take off the carbs and pull the jets and spray with carb cleaner and be reasonably sure of getting any dirt out without having to completely dissassemble the carbs?
2) If I pull the carbs tonight, do I really have to worry about a carb sync when I put them back on as I don't have the tool to do that and have never done it myself.
3) Do people ever balance carbs by ear just to get them close?

Regards

Dave in Ontario, Canada

[rustybronco]

Try draining the float bowels first and refill it with fresh fuel.

carb balancing by ear, no. benching synchronizing by eye, yes.

[spyug]

Sorry but the only way to clean carbs is by a full strip, dip and rebuild with new o-rings. There are no short cuts. Seafoam may buy you some time but you will need to pull them.

As mentioned, You will get them to run after bench synching by eye using a small feeler guage like a paper clip. You might also get them running fairly well by listening closely as you adjust the airscrews to best idle but ultimately you will need a manometer to properly synch them.

The bike will likely run ok and perform better than it has but without synching your performance will not be optimised and the gas consumption could be way off.

Good luck with it.

Cheers,
spyug

[Dakotakid]

I just sold my GR 650 this spring. I really loved the engine and transmission. Sure wish they would have put that engine in a realistically-sized frame with good brakes and seating arrangement!!!
To me, this sounds like some water in there. I would do as Rusty said and drain the bowls. Then, turn the spigot to "prime" and run some gas through the carbs. (Of course, use a big rag to catch the fuel and put out your cigarette....yada, yada....). Stored gas can be a problem especially if you have the container out in the sun or have a lot of humidity, etc.

[rustybronco]

To me, this sounds like some water in there.

That was my reasoning as well.

[Barneycanoe]

Thanks for your ideas, will drain the float bowls first and see what's what.

Not sure I know what this means "As mentioned, You will get them to run after bench synching by eye using a small feeler guage like a paper clip"

Is bench synching some procedure without using a manometer?. And do you DIYourselfers consider a manometer a must-have for fettling old bikes like these.

I do like this bike, I put a lower handlebar on it and I find it quite comfy, I'm 6'3". Yes, the brakes are not the greatest (just bled them the other day) but I use this one for toodling around the back roads and it matches my wife's 1979 Suzuki 425e.

Dave

I found Ed's tutorial and now know what bench synching means!

Dave

[rustybronco]

And do you DIYourselfers consider a manometer a must-have for fettling old bikes like these.

I my opinion it's not a total must have.

more important is the engine is mechanically sound with even compression, no vacuum leaks, valves adjusted, good spark and the carbs "properly renewed'. then if you pay careful attention to the bench sync, it will run reasonably well.

keep in mind you don't 'need' to spend big bucks on a synch gauge. if you have patience something like this will do nicely...



***edit***

Thanks for your ideas, will drain the float bowls first and see what's what.

Capture what's draining out of the bowls and inspect it for rust, dirt, ect.

[LarryC]

If you do some digging u will find a homemade syncing guage using clear tubing with transmission fluid inside. I forget where I saw that.... but it gets good remarks. On the other hand I saw one with 4 vacuum guages, tubing, carb attachment fittings, etc for sale online for $72.

[kirkn]

Sync-ing and full carb OH's don't seem to be what's needed at this point, IMHO.

The way I read it, the bike was running great yesterday, then it got a batch of gas, and started running like crap today.

I don't see the full remove, disassemble, dunk, new O-rings, vacuum sync route as being needed to deal with what sounds like a batch of bad gas.

I, too, would start with draining the bowls to see what's there, then even going further and draining the whole tank and starting fresh...

Good luck, and keep us posted.

Kirk

[1_v8_merc]

No need to dip them right now.
Although you could try a quick carb spray job, I've definitely gotten results doing that before...usually when there's some really funky gas or slight dirt in there.

Bucking and kicking usually means your starving of fuel.
So check your fuel lines and flow.

Remember, the lawnmower gas could be a coincidence.
These old bikes tend to have a lot of those Coincidence situations, lol.

Some stale gas might give you a Kick here and there, but if you've got 75% Good Gas in the tank.....you'll be fine.

[Barneycanoe]

Results! Bike works again!

Well, I drained the bowls for a while, some small dirt particles were in the bottom, kind of like if you were mining gold in a pan, very small and from both carbs.
Took it for a spin and no improvement.
So, took a deep breath and prepared to take off carbs.

First thing I notice when removing the tank is that the vacuum line has a split at the end about 3/16" long, and neither it or the fuel hose were clamped to the gas tank. Maybe that was the fuel starvation right there.

Anyway, proceeded to partially disassemble carbs, sprayed everything. There was some dirt in the passages nearest the air cleaner, and small stuff here and there. None of the orifices seemed to be blocked but I blew everything out anyway (With my own breath!).
Couldn't get out the Pilot Jet, hope that one's not too important.
Bench-synced the carbs (yeah!), they were very, very slightly out.
Checked spark plugs and both were showing a little lean.

Re-assembled all (it was dark now, naturally) and fired it up. Took for a five mile spin and it ran well. It's smoother now, and there is no hesitation at any throttle opening. Idle is smoother, too.

Feeling good, and as I was driving the car to work this morning realized with total clarity that I forgot to tighten the lock nut on the balance screw! Will have to see if I can get a hand in there to hand-tighten. Grrr.

The screws for doing the air fuel mixture are exposed on my carbs (Canada?). I didn't touch them at all.

Thanks for all your help and suggestions.