Giving me a headache

[Guest]

I have a 1983 GS750E and I am having a few issue with it. Not entirely sure if this is the right section to post so I am sorry if it is not.

Long story short the bike bogs as if it is getting too much fuel and won't ride above 70mph (Bogs down as if running out of fuel) and when I release the throttle unburnt fuel gets spat out of the exhaust. I feel that it may be a main jet issue as it runs relatively nice up until around 3/4 throttle then it starts to bog.

I bought the bike "chopped" and only the front part of the airbox is in place (There is no room for filter due to the chop).

I was told the carbs were sent off and jetted to suit the setup however I am not sure if this is the case.

I have changed coils and leads as well as the CDI unit / Igniter and the bike has been serviced by myself twice a year in the two years I have owned it.

Its a real pain of a problem as the bike always starts first touch of the button without choke! Idles nicely etc.

There are no abnormal noise coming from the engine and no smoke from the exhaust when starting up.

Any help would be greatful. Thank You!

[CrazyCloud]

I think you are on the right track thinking it's a jetting issue. Do some full throttle 'plug chops' and see what the plugs look like at that throttle position. I bet they are too rich, but either way you need to confirm. Do some chops at 1/2 to 3/4 to see how the needle position is too.

[CrazyCloud]

This might help get you started:

http://www.xs11.com/xs11-info/tech-tips/maintenance/carburators/68-tuning-carbs-by-reading-spark-plugsthrottle-chop.html

http://jetsrus.com/FAQs/FAQ_spark_plugs.htm

[smilinbrad]

I suspect your carbs would benefit from a thorough cleaning and I would also guess they are not properly jetted.
I found someone's recommendation for jetting somewhere on the Internet. He suggested that K&N filters in a stock air box needed two sizes bigger and pods needed another two. 4 into one headers needed 4 more sizes, slip ons maybe two. Above 2500 ft. elevation take one or two back off. I don't remember exactly (I'm a senior citizen) but I followed his suggestion after I cleaned my carbs and my no power, super boggy GS550E runs great now.

[MavGS]

Thank you for the replies. Much appreciated.

[jdvorchak]

Make sure you have good spark on all 4 plugs. Probably is jetting as others have mentioned but you'll want to cover all bases. You also didn't mention if you have checked valve clearance.

[allojohn]

"sent off and jetted to suit the set up" LOL, he's having a laugh!
Take the carbs off, strip them down and dip them for 24 hours each. You'll also find out what jetting you have now, then you can set about fixing your bike.

[greg78gs750]

also, starting easily with no choke is not normal for these bikes.

[jdvorchak]

and they will start easily, no choke on 3 cylinders.... Found that out yesterday.