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Cone filters on gs850 with CV carbs

  • Thread starter Thread starter melanoluca
  • Start date Start date
M

melanoluca

Guest
I have been toying with the idea of fitting these filters on my GS850.
Understandably the standard jets would be no good with the free flowing air etc
I have been asking some of the local guys in my area but i am getting a few conflicting opinions so i figured let me get an opinion from the big boys in the business!
Exactly what has to be done to the carbs in order to use Cone filters and if you could clarify; will i need to change the needle as well, i have been told if i dont then i will get quite a flat spot when i open it up. i have also been told that a lot of the cone type filters tend to have difficulty handling the vacume and end up collapsing.
 
What an interesting mix of mis-information you have received. :shock:

You will not likely have to change the needle, but you may have to raise it. If your needle has multiple slots for the clip, just lower the clip one notch, which will raise the needle. If you don't have multiple slots, you will have to shim the needle. Many have used small washers, a flat washer size 4-40 should work.

"Cone-type filters can't handle the vacuum and therefore collapse"? A properly-maintained 'cone' filter has less restriction than a stock filter. (That is why you have to re-jet the carbs.) The only way they are going to collapse is if the filter material physically breaks down or is totally clogged. Neither one is likely.

Yes, you will have to re-jet the carbs. How much to change will depend on whether you have a header or a stock exhaust system. With stock exhaust, you might get by with going up two sizes. I don't know about your bike, but the 850s I have worked on here have had 115 main jets, so you might start with 120 mains. If you have a header, you might be looking at 125 or 127.5 jets. If you go with the larger jets for the header, you might also have to change the pilot air jet and go up one size.


.
 
header?

header?

Please excuse my lack of knowledge in this department but what is a header?
 
Trail of bread crumbs...

Trail of bread crumbs...

Mr. melanoluca,

As has been mentioned, to get the most out of modifications like pod air filters and 4-in-1 exhausts, the carbs will take a bit of tweaking (more than I have the expertise to perform). I just wanted to suggest that you hang on to all of your stock parts just in case it becomes too much trouble and you want to go back to the original equipment. Good luck and happy wrenching!

Thank you for your indulgence,

BassCliff
 
isnt a header just the pipes that direct the exhaust gasses away from the engine, or have i been lied to all of my life?:shock:
 
catbed said:
isnt a header just the pipes that direct the exhaust gasses away from the engine, or have i been lied to all of my life?:shock:
Click to expand...

A "Header" typically references the exhaust tubes attached to the head. In the motorcycle world the entire exhaust system is often called a header.
 
Well, it just goes to show you how little we should take for granted. :oops:
When I made this statement:
Steve said:
...will depend on whether you have a header or a stock exhaust system.
Click to expand...
there is at least a hint there that a "header" is a non-stock exhaust system.

And, yes, some bikes (but none of our GSs) came from the factory with a 4-into-1 exhaust system.

Now for further explaination for Melanoluca: The carbs are jetted from the factory for what the put on the bike. When we change to less-restrictive air filters or freer-flowing exhaust sytems, more air can flow, which requires more gasoline (petrol) to be mixed in, as well. The only way to do that is to increase the size of the jets that regulate fuel flow. There are several sub-systems in the carbs that control the mixture at different speeds, so there are several places that changes can be made, but each one concerns particular throttle openings, not just engine speeds.

.
 
All good advice so far.

This is sort of one of those "If you have to ask, then don't do it." type of questions.

If you're not already VERY comfortable with the concepts and components involved in rejetting, then stick with the stock intake system. You'll spend a lot of time and get very little added performance.

Have you made absolutely sure that your 850 is running up to snuff with the stock components? Airbox sealed, carb boots and o-rings fresh, valves adjusted every 4,00 miles, air filter oiled juuuust right, idle mixture screws exquisitely twiddled, carbs rebuilt, o-ringed, and synced to perfection?

Even if you're a jetting expert, without knowing how it's supposed to feel, sound, and run, you'll have a lot of trouble understanding the results of the many test rides it takes to dial things in.

It's certainly possible to rejet an 850 -- it's still only a motorcycle, after all -- but they run so nicely when dialed in and stock, it's generally just not worth the trouble.
 
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