Gs 450 ´81, engine refuse to start

[carlos020465]

Hi:
My bike is a Suzuki gs 450 E ´81, and the engine refuse to start. I have a valve adjustment, new spark plug, new battery.
When I push starter button, the starter motor run then I listen intermitent detonation, but the engine don´t run...!
Any one may help me..?



Oh.! thank´s friends, I go to try..! then comment you

[thevillaindylan]

Sounds like a fuel problem. Are your carbs clean?

[davidduarte]

check the vacuum line to the petcock from the left carburetor, and also the gas line, make sure it has no kinks that would restrict the flow of fuel.

[tfb]

The essential ingredients for any multi-cylinder engine to run are:
1. adequate spark,
2. adequate & even compression across the cylinders,
3. fresh fuel,
4. correct spark timing, and
5. correct valve timing.

As you can see, considering each one of those aspects introduces about 100 questions we could ask, that you should consider... Is your fuel clean? no water? Is the fuel fresh? ie. not 6 months old? Is fuel getting through to the carbs? Have you cleaned out the carbs? Are the plugs getting spark? Is the timing of the spark correct? Is the valve timing correct? Do you have good compression? And so on...

What you need to do is approach things in a methodical way, ie. start with the easiest/ least expensive things to check, and work your way from there.

[spyug]

As already mentioned, it sounds like a fuel issue although the battery could also be at fault despite it being new.

From the picture of the bike, I'm thinking the carbs likely have not been serviced in a while and it could be that your primary circuit jets are plugged. This is very common in older bikes especially if the bike sat for any time. Gas goes bad and can become like a varnish plugging up the tiny holes in the jets and pasages. You likely should begin by cleaning and rebuilding them as per the carb tutorial on the main page.

As I mentioned, It could also be the battery. If it is not fully charged or has a bad cell, it may put out enough charge to turn the starter but not enough to cause a healthy spark. If the battery shows 12.5 volts or under (at rest) it may not be powerful enough. Have you checked your spark? Make sure the battery is fully charged ( put it on a 1.5 amp trickle charge until it shows 13 volts or better) pull one plug and lay it on the cylinder to ground it. Turn over the engine and look for spark. Ideally it should be fat and blue. If not something in your electrical system ( i.e. wires, coils, points, battery etc.) needs looking into. To help the small battery when trying to turn over a hard starting bike you can use jumper cables and connect it in series to a larger auto or truck battery. Just make sure the car or truck is not running as you can and likely will fry the electronics on the bike.

Like TFB says you need to make sure you have good gasflow, properly working carbs and a healthy electrical system to get the bike running. If you go about it systematically you will find the fault.

Good luck with it and let us know how it turns out for you.

cheers,
spyug