Problem starting

[anhur]

Hi, I have a 1981 Gs750e. Bike has some problem starting when cold.

I have cleaned and tuned the carb recently. I have changed new fuel petcock as well.

The starter works and from the sound of it; it is going strong.

What other issue could cause the cold starting problem? Appreciate any input or ideas. Thanks.

[posplayr]

Check voltage to coils should not be more than 1v less than battery

[koolaid_kid]

When you cleaned the carbs, did you fully disassemble them, use an ultrasonic cleaner or carb dip, all new o-rings, etc.?

[tkent02]

Difficult cold starting is a classic symptom of tight intake and exhaust valves. Have they been adjusted?

[tom203]

When you "cleaned and tuned carb", did you ensure that the "choke" (actually an enricher system) passages were not blocked. That small tube that sticks out of carb body could be blocked- it draws fuel from a small feed hole in bottom of fuel bowl that "feeds" fuel up into carb throats when "choke" is activated to aid cold starts

[Steve]

Yes, all of the above.

The most-likely culprits are dirty carbs and tight valves, but coil voltage is also suspect, as well.

.

[anhur]

Thanks for the suggestions.

Will look at the valves and coil voltage.

What is the actual meaning of tight valves?

[Redman]

....
What is the actual meaning of tight valves?

clearance between cam and valve stem shim less than spec.
Real tight means cant even get your smallest feeler guage in there.

Meaning valves open longer than should be, which you might think should help -- but it doesn't, due to how the intake nearly overlaps the exhaust valve (which does help at high rpm).
(someone other than myself might be able to explain it better).

Other difficulty in cold starting can be related to carb needing cleaning, specifically the "enricher" circuit (sometimes called choke), or the cable and mechanism not operating the all the "enrichers" all the way.

Did you have this problem before doing the work you mentioned?

But since you are asking in the electrical forum, do check the voltage to coils.

Also check to see how much the battery voltage drops when cranking the starter. SOmetimes the battery is marginal and battery voltage drops so low that ignition isn't working well. Especailly if it doesn't start at first and have to keep cranking it more.

.

.

[Nessism]

Thanks for the suggestions.

Will look at the valves and coil voltage.

What is the actual meaning of tight valves?

Free factory Suzuki service manual download here...http://members.dslextreme.com/users/bikecliff/

Also, tutorial on how to adjust the valves on your bike.

Please check the Newbie Mistakes and carb rebuild tutorials linked in my signature. The only way to a reliable bike is proper maintenance...

[anhur]

clearance between cam and valve stem shim less than spec.
Real tight means cant even get your smallest feeler guage in there.

Meaning valves open longer than should be, which you might think should help -- but it doesn't, due to how the intake nearly overlaps the exhaust valve (which does help at high rpm).
(someone other than myself might be able to explain it better).

Thank you Redman for the explanation.

I did not have starting problem before the cleaning of the carbs. I cleaned the carb because of an idling problem. After cleaning the carbs, the bike rides and idle great.

This starting problem only happened recently so it makes me feel it is some wear and tear issue like voltage or valve clearance.

Will check on the valve and voltage and post if one of these was the culprit. Thanks again for all your input.

[BassCliff]

Greetings and Salutations!!

Hi Mr. anhur,

Your immediate symptoms make me think you are having a charging issue. Test your stator, regulator/rectifier unit, and battery (i.e. The Stator Papers, and associated documentation).

Old bikes need lots of love, especially up front. Once you have all of the maintenance caught up you will have a very reliable machine. Among other things, you must attend to the charging system, properly clean the carbs, adjust the valves, ensure the air intake system has no leaks. There are other tasks but these are the most important to keep your bike running. Brakes and tires are also very important. It's all spelled out for you in your "mega-welcome" below.

If you are here you probably have a 30 year old motorcycle that needs about 20 years worth of maintenance. In the links below you'll find maintenance lists, documentation, wiring diagrams, "how to" guides, vendor links, tips, tricks, and a whole lot of GS goodness. This is your "mega-welcome". Let's get started.

Let me dump a TON of information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



Please Click Here For Your Mega-Welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

More links to helpful threads in the forum:
Help! Your Bike Won't Start
DON'T DO THESE THINGS
Help! Your Bike Won't Run Well
Oh God! Pods!


Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[koolaid_kid]

When you check the voltage to the coils, you need to check it under two conditions: with key on and engine off, with key on and pressing starter button. If the voltage to the coils is too low, so will be the spark. An easy fix with the coil relay mod.

[Redman]

When you check the voltage to the coils, you need to check it under two conditions: with key on and engine off, with key on and pressing starter button. If the voltage to the coils is too low, so will be the spark. An easy fix with the coil relay mod.

..... An easy fix with the coil relay mod.

If is difference between voltage at battery and voltage at coils. Measure battery voltage, and measure voltage at the coils to ground, should be about the same, within an volt or so.

If battery voltage goes low while cranking the starter, no rewiring will help, need new battery.

.

[koolaid_kid]

Perhaps. Could also need starter work.