How to get a 79 GS850 to run in Denver

[Guest]

paging tkent02... So I just moved here from Iowa and my 79 GS850 which ran great at 1000ft barely runs at all up here at 5800ft. It stinks because I just had the carbs professionally cleaned/tuned last summer. Can I just put some new jets on there and ride again? Any suggestions on size or where to get them?

[tkent02]

PM coming.

[slt]

For future altitude searches, per tkent02's recommendation, I dropped my main jets down two sizes. Stock mine were 102.5, I replaced with 97.5's. Bike runs like a champ again!

Got them here: http://www.z1enterprises.com/ search for "mikuni main jets"

[chuck hahn]

point it down hill??????

[Highway_Glider]

Hi slt.

Welcome to the forum.

Just curious. Is your bike stock or has pods?

I tought I could travel to a high altitude without problems.

[Steve]

I tought I could travel to a high altitude without problems.

If you take your GK, you will have no problems.

A little less power, but no jetting problems.

The original poster (slg) has a '79 850 with VM carbs, they don't compensate like the BS carbs so.

.

[Highway_Glider]

Ha.

I tought so.

BS being CV carbs and VM being "Classic carbs". Gotcha.

Thank you steve.

I was starting to think that I had to rebuild my bike somewhere before Denver.

[Steve]

BS being CV carbs and VM being "Classic carbs".

"VM" is the name of the series of carbs.

"BS" is the name of the series of carbs.

"CV" is the type of carbs. It stands for "Constant-Velocity", which is a result of the variable venturi, provided by the slide attached to the diaphragm.

Many different manufacturers made CV-type carbs, so if you simply say "I have CV carbs on my bike", nobody will know what you have.
You might have Mikuni, Kehin, Bing, SU or any of several others.

.

[mrbill5491]

I'm at 3,800 ft here and I ride my bike alot at altitudes of 6,000ft up. My bike runs fine, only thing I've notice is the idle at higher elevations tends to drop. So, I have my idle on my bike set a bit high then what it calls for. Usually around 1.200-1,500 rpms.

[KEITH KRAUSE]

My '79 GS1000 runs fine at higher elevations than 5800'. There's a little "sluggishness" but that's all. For your bike to barely run I think there's other issues.
Changing your main jets wouldn't make your bike right again. The mains only regulate fuel at 3/4 throttle to full open. You spend the most time riding on the jet needle so if elevation was the true problem then you'd have to adjust the jet needles too, along with pilot circuit changes.
The VM carbs will handle higher elevations with simple air screw and possibly pilot fuel screw adjustments. At 5,800' properly running carbs/motor won't need anything more.