Altitude jetting for GS850.

[Guest]

Looking for some experienced counsel jetting my 1980 GS850G properly when I pull the carbs for a cleaning/rebuild. I'm in the Denver area, live at 5,400 feet, and frequently ride up into the Rockies over passes that average 11,000 feet. I know it would be difficult to jet for this large a range and would settle for what would be best at 5,400' as it is my daily commuter.
The bike only has about 19,000 miles on it and is totally stock, no pods; has the original air filter set up. Many thanks in advance.

[Burque73]

I brought my 83 850 down from Denver earlier this year and it had the stock 115 main jets still in the carbs. The PO ran them for 20+ years in that area and didn't see a need to chande them apparently. I am now running with 110's in Albuquerque which is similar altitude. Going up to 11000' I dont notice any change in power. Sea level on the other hand may be an issue, but haven't ventured that far yet.Are your carbs Mikuni VM or CV type? I'm not sure when Suzuki switched over.

[Burque73]

Oh, and Welcome to the GSR! If you haven't already, look here

http://members.dslextreme.com/users/bikecliff/

[tkent02]

The 850G with it's CV carbs and with the stock airbox will compensate for elevation very well. No need to rejet anything.

[Steve]

If you DO go leaner, as Burque has, you will have to re-jet if you ever go lower in altitude. The compensation only goes in one direction.

.

[MadEyeGuy]

Many thanks folks. I'll stick with what it has and just clean everything up. I especially appreciate real, applicable experience at altitude. I don't think I'll worry about dropping in altitude yet. I'm sure it can handle the occasional short trip at lower altitude to some of the motorcycle museums in Kansas. As I stated, it's my daily ride and around home is where it has to perform best.

[Burque73]

I especially appreciate real, applicable experience at altitude. I don't think I'll worry about dropping in altitude yet.

I'm pretty sure Tkent has ridden through all of those mountains up there, and on more GS's than I will likely ever have.

[MadEyeGuy]

As a winter project I'm going to do the carbs. I've already done all the boots, but those take little time. I'll check back and let everyone know how it does once I'm done and the weather breaks in the mountains; probably April.
Again, many thanks for this and for all the handy info I've been reading since I joined.

[alke46]

As a winter project I'm going to do the carbs. I've already Sdone all the boots, but those take little time. I'll check back and let everyone know how it does once I'm done and the weather breaks in the mountains; probably April.
Again, many thanks for this and for all the handy info I've been reading since I joined.

Seriously? You should be able to ride nearly year round in Golden. Your season is a heck of a lot longer than it is 8 hrs. to the east of you. I have a daughter in the Longmont area and she constantly reminds me that when you guys get a foot of snow, it is gone within 2-3 days.

[bwringer]

The 850G with it's CV carbs and with the stock airbox will compensate for elevation very well. No need to rejet anything.

If you DO go leaner, as Burque has, you will have to re-jet if you ever go lower in altitude. The compensation only goes in one direction.

.

Yup. No need to change from stock.

[tkent02]

Seriously? You should be able to ride nearly year round in Golden. Your season is a heck of a lot longer than it is 8 hrs. to the east of you. I have a daughter in the Longmont area and she constantly reminds me that when you guys get a foot of snow, it is gone within 2-3 days.

Yeah, I ride all winter. Not every day, but certainly every week. Especially this winter:

http://www.snowbikeworld.com/2016/05/red-bulls-idaho-backcountry-snowbiking

[GSXR7ED]

I would say you could run 117 main jets but you'd have to convert your exhaust like I did on my 750T while I was living in high elevation Alamogordo, NM. Plus, I did not change my stock air box and all was well in southern NM. MrBill can testify to that!


Ed

EDIT: I've ridden in cold weather here... low 30s was tough and I wouldn't ride for very long.

[MadEyeGuy]

Yes, we can ride all year around. I tend to use my DR in colder weather as I do not have grip heaters or a fairing on the GS yet. Either way, I'm only good to around 28 degrees and dry roads, then I whimp out. The DR has great grip heaters, brushguards, and a mediocre fairing that all help deal with the cold wind. It is only nine miles or so to work and not worth the investment in time and money for heated gear.
After the GS is equipped with a fairing, grip heaters and bags, it will then be the winter ride as well.

[tkent02]

I tend to use my DR in colder weather as I do not have grip heaters or a fairing on the GS yet. Either way, I'm only good to around 28 degrees and dry roads, then I whimp out. The DR has great grip heaters, brushguards, and a mediocre fairing that all help deal with the cold wind.

Tell me about this DR please?

[MadEyeGuy]

That would be my 1998 Suzuki DR650 dual sport. While for several years that was my only bike, it is now mostly relegated to when the GS is down for service, off road, and bad weather. Still a Suzuki though.