elevation change

[dustin]

I just moved from 300 foot elevation to 4200 foot elevation. I was told that the change in elevation is going to make my 1981 gs750e run pretty rich. I was wondering what I could do to fix this? Is there a simple fuel mixture screw I could turn or am I going to have to do something bigger.

[Spyderman]

I just moved from 300 foot elevation to 4200 foot elevation. I was told that the change in elevation is going to make my 1981 gs750e run pretty rich. I was wondering what I could do to fix this? Is there a simple fuel mixture screw I could turn or am I going to have to do something bigger.

it'll require something bigger you'll need to rejet your carbs and that can be a real PITA with the CV's
if you want help from the wonderful people here then you need to give us more info

we know it's a 81 750E
is it????
bone stock (no mods)
if there are mod what are they (be specific)
chances are that some one has done what you want to do and will give you a good starting point to work from
but each bike is different and will not react the same as another so a good starting point is just that a point that you can work from to get it to where you want it
we look forward to seeing more info so that you can get the help you want and need

[Steve]

Even more important than what mods have been done to the bike, ...

are you going to STAY at 4200 feet, or is there a chance you will EVER come back down? If you re-jet for 4200 feet, you will be running LEAN when you come back down and that is much worse than running a bit rich where you are. And, the little bit that you will be running rich should not be enough to really matter. There is a certain amount of jetting necessary for different elevations, but I don't think that 4200 bumps it into the "must change" category.

.

[jbs80106]

650g

My 650 came from WY, now lives at 7000 ft, no changes made to carbs and runs fine.

[simon kuether]

Even more important than what mods have been done to the bike, ...

are you going to STAY at 4200 feet, or is there a chance you will EVER come back down? If you re-jet for 4200 feet, you will be running LEAN when you come back down and that is much worse than running a bit rich where you are. And, the little bit that you will be running rich should not be enough to really matter. There is a certain amount of jetting necessary for different elevations, but I don't think that 4200 bumps it into the "must change" category.

.

What Steve said . I live at close to your altitude but regularly ride at sea level.I find that my 'S runs a wee bit rich at home and a wee bit lean on the coast.Neither seem to affect the old girl too much but she runs a bit "crisperlerly" down be the flatlands.I guess that I should move to the middle . Trouble is the land around here is all wrinkley and I'd only have about a metre to ride around on. Cheers,Simon.

[BassCliff]

Greetings and Salutations!!

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[bonanzadave]

Punch a hole in your air box at altitude. When you come back down put a plug in the hole.

[tkent02]

That bike has CV carburetors, they are somewhat self compensating for elevation changes. It should run fairly well at 4,000ft or higher.

In comparison, the older VM carburetors react very poorly to changes in elevation, 4,000 difference makes them run like crap unless they are rejetted.

Try it and see, you may want to do the hole in the airbox trick but you probably won't need to do anything at all.

[dustin]

so thankful

Just wanted to thank everyone for your input. Several of you said that the elevation change shouldn't effect it enough to change anything, and it has been running good and I haven't noticed any real difference. I smell a little fumes on start up but that is about it. From what I've read on some other post I guess I'll have to check my spark plugs. If the spark plugs look ok could I fine tune it by messing with the mixture screws? About being able to give more info I'm sorry, but this is my first bike and I don't know anything. I got the bike from my brother inlaw and he didn't tell me about any mods he did to it. I'll see him this weekend and find out for sure but I don't think he did. I am really glad I have found this site, you have all been really helpful and I appreciate it immensely.