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Running Lean 1980 GS850L

  • Thread starter Thread starter banditblom
  • Start date Start date
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banditblom

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So I have a 1980 gs850l that I wanted to turn into a cafe racer. I put the bars on upgraded the suspension and it ran great! The only problem was that dreaded 80s exhaust sound... I did something drastic and ended up cutting the exhaust off so it is essentially just running open headers now. Now it doesn't run so good. It will start right up but as soon as I try and give it gas it nose dives and loses all power. On deceleration it has some nasty pops also... If I keep on it it will take off in the higher revs but only in the higher revs. Should I re jet the carbs? Or would I be able to adjust the air/fuel screws to so I can avoid re jetting?
 
Just keep persevering and running it the way it is.
Eventually, it will cease to run at all and your neighbours will thank you.
 
Hi Banditblom. Welcome to GS land. In case you haven't found it yet http://members.dslextreme.com/users/bikecliff/

As you may have guessed open headers will not win many friends.
It's not just the noise either. Fuel metering is done by jets and needles matched to specific intake and exhaust flow characteristics. Change either and the carbs don't work properly any more. Wide open exhausts, or intakes for that matter, will generally let too much air through and the carbs can't keep up.
Rejetting can improve running on non stock mufflers or pods. Wide open headers ? I don't know for sure but I suspect that without some back pressure you will lose a lot of charge air out the exhausts no matter what.
 
Thanks for the input and the manual! Even if I get exhaust though I feel as it wouldn't have enough back pressure being most slip ons are usually pretty wide open. This is why I think a jet kit will probably be needed
 
banditblom said:
Thanks for the input and the manual! Even if I get exhaust though I feel as it wouldn't have enough back pressure being most slip ons are usually pretty wide open. This is why I think a jet kit will probably be needed
Click to expand...

I run close to stock on all my bikes. Many guys here don't and have lots of experience rejetting. If you let us know what filter and exhaust you have I'm sure you could get some pointers.
Many after market mufflers are well packed and won't require rejetting provided the stock airbox is still there.
 
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The stock box will be staying! So if all I need is some new tips that would be great! What do you recommend?
 
Get a muffler back on :)
A lot of thought went into the stock setup. With clean balanced carbs, hot sparks, yada yada yada the 850 is no slouch.
 
That "dreaded 80s exhaust sound" was not due to the 80s, it was due the fact that you have an "L".

The shorter "L" mufflers have sort of a "motorboat" quality to them, they don't sound like the "E" or "G" mufflers.

Grimly's sentiments were a bit harsh, but they were spot-on. Nobody like open pipes, except possibly the one riding the bike, and we motorcyclists are already looked upon as second-class citizens, so why aggravate the situation? Please put SOMETHING on there. Even a pair of EMGO slip-ons will help a bit, but regardless of what you do, you WILL need to re-jet the carbs. Simply turning the mixture screws will only tune the idle and low-speed settings, not the half-throttle and above, where you will actually need the better mixture.
 
Datsa Noydb said:
That "dreaded 80s exhaust sound" was not due to the 80s, it was due the fact that you have an "L".

The shorter "L" mufflers have sort of a "motorboat" quality to them, they don't sound like the "E" or "G" mufflers.

Grimly's sentiments were a bit harsh, but they were spot-on. Nobody like open pipes, except possibly the one riding the bike, and we motorcyclists are already looked upon as second-class citizens, so why aggravate the situation? Please put SOMETHING on there. Even a pair of EMGO slip-ons will help a bit, but regardless of what you do, you WILL need to re-jet the carbs. Simply turning the mixture screws will only tune the idle and low-speed settings, not the half-throttle and above, where you will actually need the better mixture.
Click to expand...

Buy yourself a replacement exhaust. If you need a stock system contact me
 

Cafe builders favorite tool in action....:-#

mighty-miter.jpg
 
Datsa Noydb said:
That "dreaded 80s exhaust sound" was not due to the 80s, it was due the fact that you have an "L".

The shorter "L" mufflers have sort of a "motorboat" quality to them, they don't sound like the "E" or "G" mufflers.
Click to expand...

Truth. I ride a 1980 GS850GL and after owning an 82 750E, I can't say I approve of the L sound at all. Only thing I don't really like about the bike. Besides the tiny gas tank. And the relatively uncomfortable seat. And the brutal suspension. And all the rust everywhere. And... well it is actually a crap-ton of fun to ride so it'll have a home in my garage a little while longer.
 
Just my 2 cents but a lot of inline 4's sound great with Harley Sportster stock mufflers. They are cheap 'cause the HD guys pull them off and get new. Check Craigslist or even drop into the local HD dealer and see if they don't have some take offs they'd sell cheap or even give away. Those mufflers remove all of the high pitched "crack" that open headers let through so only the low rumble of your engine will come through and not all that loud.
 
jdvorchak said:
Just my 2 cents but a lot of inline 4's sound great with Harley Sportster stock mufflers. They are cheap 'cause the HD guys pull them off and get new. Check Craigslist or even drop into the local HD dealer and see if they don't have some take offs they'd sell cheap or even give away. Those mufflers remove all of the high pitched "crack" that open headers let through so only the low rumble of your engine will come through and not all that loud.
Click to expand...

They also don't allow much airflow, you will get very low power and poor gas mileage.
 
Thanks for the input! I ended up buying sportster mufflers just like you said and it instantly brought it back to life. Sounds good and all my power is back!
 
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