Petrol Vapour and drips from top of engine breather

[dobby]

Hi I have a gs1000 1980 . the first 3 cylinders fire ok but the last right one fires on and off . I At the top of the head there breather pipe gives out petrol vapour and drips with petrol . An y idea of the cause.

thks

[DimitriT]

The two symptoms are probably unrelated. Depending on how much vapor you get out of the breather hose,
it may be normal. Are you sure its gas coming out of there? It's probably water vapor with a little oil.

The causes of a non-firing cylinder is usually dirty carb (especially the idle jet may be dirty).

[dobby]

The two symptoms are probably unrelated. Depending on how much vapor you get out of the breather hose,
it may be normal. Are you sure its gas coming out of there? It's probably water vapor with a little oil.

The causes of a non-firing cylinder is usually dirty carb (especially the idle jet may be dirty).

Thanks, yes you can see the vapour coming out and its definatley gas dripping as its diluted the paint that was sprayed on the starter motor cover. I heard that it could potentially be a valve sticking?????

[DimitriT]

Spraying on the starter cover? There should be a hose connecting the breather cover ventilation to the airbox. When the bike runs, the engine vacume pulls in the vapors back through the carbs and burns them. The only stuff left over drips out the bottom of the airbox through a hose which empties under the bike.

[dobby]

Spraying on the starter cover? There should be a hose connecting the breather cover ventilation to the airbox. When the bike runs, the engine vacume pulls in the vapors back through the carbs and burns them. The only stuff left over drips out the bottom of the airbox through a hose which empties under the bike.

Ahh so you think that the hose from the head should be connected somewhere onto the air box. If there is no air box as the carbs have K&N's on them is there any where you can connect the pipe to the bank of carbs?

[DimitriT]

If the airbox is gone then you should run a hose from the breather down to someplace under the bike to vent the crankcase vapors and fluids. Some people run the hose to a resevior with a foam filter in it (try an auto parts store for foam filter material) and mount this someplace where it won't spill. This will allow the fluids a place to go and evaporate.

Maybe someone reading this thread can give more specific info on this modification.

[Guest]

Do you have a crankcase breather filter installed? The only way gas can get into your valve cover upper head area is through a valve or valve seal/guide. Check the compression for that cylinder and post the results. If a valve is stuck I don't know how the engine could create the vacuum to suck the gas into that cylinder

[dobby]

Do you have a crankcase breather filter installed? The only way gas can get into your valve cover upper head area is through a valve or valve seal/guide. Check the compression for that cylinder and post the results. If a valve is stuck I don't know how the engine could create the vacuum to suck the gas into that cylinder

hey thanks for that. no there is no filter installed just the pipe from the head and going down between the carbs and sticking out at the bottom.

Yes i'll check the compression, what should the tolerances be ? and yes gas does get in the chamber??? Well strange.

I appreciate these replies there great!!!