Poor starting tip for GS550 & 750`s

[bradleymaynar]

Well, I'll be damned! My bike's been sitting a week, plugged into the tender. Whenever I've let it sit for that amount of time, it's always been a real bear. Especially when it's cold (I think it was around 30 this morning. Pulled the seat off, puffed a couple shots of air into to each vent tube. Put the seat back on, strapped on the helmet, and pulled on my gloves. Pulled the choke and it fired instantly!\\/ Didn't even die, which it usually does.

Awesome tip!!!:-D

Brad bt

[Roland]

Poor Starting

Well it took me the better part of the day searching the forums for a solution or at least the cause that prevents my 1979 GS750 from starting without an initial shot of starting fluid.

I will give the Blowing into the vent tubes a try but from what I read on this thread is that I might need to do a thorough cleaning or at least adjust my Pilot Screws. Besides the initial starting issue the bike runs beautifully. I would hate to create more issues by taking the carbs apart during the riding season. If you are fairly Technically savvy as I am how long does a thorough cleaning including a complete removal a reinstallation replacing the typical parts.

I have searched High and Low on the forums and can't find the Carb Rebuild papers. Can someone please post a link to the thread that has the Carb Rebuild pics.


For those of you finding it difficult to find the carb vent tubes here are a couple of pics showing the tubes on my bike.

[tomo]

Roland, give the vent tube trick a try, if it works it sure saves a lot of messing about, especially if the bike runs well once its going. I`m a great believer that if it ain`t broke don`t fix it. Could be that a strip down and clean up, adjustments etc will improve things, but could also mess up the running. I think this threads been really interesting, and all the comments and advice too, but at the end of the day I don`t worry about why this works, I`m just glad it nearly always has for me. My bikes all run really well too, but are pigs to start if they sit for any length of time unless I give a couple of puffs into the vent tubes. Worth a try before pulling things apart. Best of luck,

[Steve]

I have searched High and Low on the forums and can't find the Carb Rebuild papers. Can someone please post a link to the thread that has the Carb Rebuild pics.

You have to go to the home page,, scroll down the left side to where you see the TECHNICAL section, click on In The Garage. Scroll down just a bit and you will see VM carburetor rebuild. Save the .pdf file, print it out, if you want, it's 10 pages of well-written text and great color photographs. \\/

Actually, just click on the last link in the previous paragraph to go directly there. 8-[

.

[Roland]

Blowing my bike

Well I am not a fan of "Blowing my Bike" and I really don't want my biking buddies to see me doing it but I must say it does work for my situation. I have tried it for a few days now and although it doesn't work every time it has worked the majority of the time like 80%. I do still carry my starting fluid for those other 20%.

Great Tip!! Thanks a Heap Tomo!!

I still want to address the root of the problem and determine if I can get started 100% of the time without the "Blowing the Bike" or using the starting fluid.

Thanks for the links to the Carb Cleaning pages. That is exactly what I was looking for. I also found these step-by-step-via-pictures Carb Rebuild PDF
I printed out both sets and now I just need get up the nerve to do it during riding season. Maybe I can push it till the winter.


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[Roland]

Blowing my Bike

Since Mike seems to have solved his problems on this thread let me hijack it with very similar issues.

Well I am not sure but I think my bike might actually like me blowing it.
Errr.. I mean..blowing into the vent tubes to get it going...Errr I mean..getting the engine to run without relying on Starting fluid.

<nervous look>
Trust me I am as straight as straight can be. Ask my wife she will tell you.

O.K. O.K. enough with the funnies.
I need help and guidance.

I am a better than average do-it-yourself mechanic and my bike has come a long ways since I purchased it last summer after it was off the road and garaged for 6 years. I have been riding every day since I finished my safety course and got my license this past March. Now 3-4 times a week I am doing something to address the many problems associated with actually using a classic 1979 GS750 for daily rides back and forth to work and such. All the tips and tricks you see in my post and my knowledge are all results of the Experts and those posting as they have worked through their issues. Thanks in advance to those that might provide some insight and for those of you who have helped me without even knowing it with your previous posts.

Problem #1
The blowing thing does work but my problem seems to be getting worse. I am pretty certain it is not because the bike likes for me to blow it but now I do the blow thing and it starts for about 3 seconds and then I have to do it again and maybe even a 3rd time. When I first tried the blow thing it worked most of the time after the first blow. Keep in mind this is not after it has set for 2-3 days but after shutting it off for 2 minutes or more. Does anyone know for certain what is at the root of my problem?

Problem #2
I also have a 2nd problem in which cylinder #1 keeps fouling out about every 200-300 miles. Over a period of time I can feel hesitation in the bike then sure enough when I pull out plugs 2,3,4 they look great and #1 is wet and unable to make spark. I either replace the plug with a new one or clean it and swap it with one of the others and I instantly have full power. I use a plug touching the engine to verify the coil is making spark and the Colortune test plug to verify the cylinder is firing with the correct fuel-air-mix.

I have performed an on bike carb sycn, I purchased the Colortune
and adjusted the fuel-air mixture to precision on each carb and I purchased a compression gauge and the compression is well within specs.
And finally I have been using nothing but premium gas for months. I have not removed the carbs for a complete overhaul as I don't wish to risk any loss of potential riding time if at all possible.

I did the intake leak check by spraying starting fluid around the boots on the engine side but the engine RPM did not change if anything the RPMs may have dropped a minute amount.

As I am writing this I am still thinking about the issues and what I have done to address them. I had rested my mind that it couldn't be the rings as the compression test were well above specs but now that I think about it, that isn't a test for the rings is it? The compression test is more of a test for the valves and has nothing to do with the rings. Would you guys agree?

If this is true then short of removing the engine, heads, and pistons, what is a good test for determining the quality of the rings and cylinder wall.

I have many pictures and mini-videos of the bike, engine, carb syncing, etc.. so if there are any that might help with my problems I will be more than happy to link them or take a new one to help with the details.

[petelardo]

Hi Roland,

Though I don't support thread-jacking in general, I have a suggestion that might help you pinpoint one problem you've mentioned here...

When you experience what seem to be ignition problems with one cylinder, it can help to do some basic part-swapping, to see if the problem moves to a different cylinder, if it changes (improves or gets worse somehow), or if there is NO change in the problem whatsoever, which usually indicates that the problem lies elsewhere...

First off, I'd suggest that you make sure that ALL of the sparkplug caps are in good condition. Start with the #1 cylinder; unscrew the sparkplug cap, and look for corrosion in the end of the coil wire. You MIGHT be able to trim a few millimeters of wire from the end, but if you remove too much wire, it won't reach to the cylinder, and you'll need a new coil, which can be costly.

If you suspect the sparkplug cap itself of being defective, swap it with another cap; I'd suggest you switch cap #1 with cap #4. Once you've done that, take a test ride. If the # 4 cylinder fouls the plug, and you no longer have problems with the # 1 cylinder, it's a pretty safe bet that the sparkplug cap itself is defective (or that you didn't install it tightly on the # 4 sparkplug wire).

As basic as this might seem, you'd be amazed at how often loose / defective sparkplug caps can cause this type of problem. A little detective work can go a long way in helping you to figure out which component is the culprit...

In reply to your question about compression testing, in my experience, a proper compression test DOES help you to identify ring-sealing problems. When cylinder compression is LOW, put a teaspoon of oil into the cylinder through the sparkplug hole; don't forget to rotate the engine by hand a few times to help distribute the oil evenly... You can do this by putting the bike on the centerstand, placing the transmission in gear, and rotating the rear wheel, which is the quick-and-dirty method... Putting oil in the cylinder causes a (temporary) tight seal around the rings, because the oil helps to seal the ring / cylinder junction around the piston. If compression INCREASES after adding the oil to the cylinder, the rings (or the cylinder wall, or a combination of the two) are suspect (worn or broken rings; worn or gouged cylinder wall)... Again, if (low) compression increases when oil is added to the cylinder, the OIL is causing a temporary seal between the rings and the cylinder wall. If compression REMAINS low after adding oil to the cylinder, the VALVES must not be seating properly, or, you have a hole in the piston (not as likely, I'll admit). A valve head could be damaged (burned, corroded, or broken), the valve seat could be defective... you get the idea. Adding the oil to the cylinder is the key to diagnosing basic compression problems. Of course, you could have MULTIPLE problems in that particular cylinder, but we'll leave that for another time...

Lastly, I don't know if you've started another thread to cover this problem; if so, I hope the mods / admins will move this reply to the proper place... I DID search for any other threads you've started covering this problem, but only found two threads begun by you, both of which seem unrelated to this particular issue...

Good luck; I hope this suggestion helps you find the culprit causing the problem with the # 1 cylinder... if you have more questions about this, I'd sugest that you start a new thread in the Technical Info forum, where more people are likely to see it.

[Schweisshund]

actually my carb breather tubes are under the seat in front of the battery box. (1983 GS550E) Look for the two black 1/4 inch rubber hoses that attach to your carburators that are not the gas and vacuum hose for your fuel petcock. they attach to your carburators and are connected to ... well ..... nothing. They suck in air I guess.

[Schweisshund]

whoa - I thought I was answering a question that apparently was posted some time ago.

My suggestion - as always when there is starting problems - run seafoam deep creep through your carburators when its nice and hot. Shut engine off and saturate your carbs. wait 5 minutes (try to crank it - will take a while) then stand back until the smoke clears. This just cleans out your carburator, valves and lubricates piston rings.

Is one of your carb float bowls stuck and letting fuel overflow into your combustion chamber? causing spark plug one to foul out prematurely? Get wet etc.? Maybe a carb rebuild is in order and get the darn thing synchronized when its over or you will wonder why its revving so high or too low.

[Suzuki_Don]

Great Tip Tomo. Works every time.

[QuaiChangKane]

I always keep a can of ether (starting fluid) around the shop for bikes that have been sitting longer than a couple of weeks and are reluctant to start. A couple of short spritzes into the airbox usually gets the engine to fire, and the subsequent vacuum "primes" the carbs.


I've also used a rag dipped into the fuel tank and then placed over the intake opening in the airbox to get reluctant bikes to fire - only when fuel starved on the side of the road.


Another trick that helps old bikes start in the cold - the "cold-blooded" nature old bikes develop is typically due to brittle rubber parts in the intake system somewhere - carb boots, o-rings, etc. leaking air. Couple that with the increased oxygen in cold air and you have a hard-starting bike in the cold. While cranking with the choke on, use your hand to cover the opening in the airbox to "lean" the mixture getting into the engine - for a bike whose bowls aren't dry, this typically does the trick.

And for folks in Shirley's position (old thread aside), pods will tend to make a bike waaaay more cold-blooded in the winter time - especially in an exceptionally cold clime. Try wrapping a towel around the pods when trying to start...


-Q!