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Return to stock jetting?

  • Thread starter Thread starter demark
  • Start date Start date
D

demark

Guest
After owning my 1980 GS1100 for almost two years, I've finally found the time to clean and dip my carbs. Upon doing so, I've discovered that my jets are not stock. Based on Haynes, they are supposed to be:

Main Jet: 107.5
Main Air Jet: 1.2

what I found is:

Main Jet: 122.5
Main Air Jet: 1.6

When I purchased my bike, it had a 4-to-1 exhaust in poor condition. When that failed, I replaced it with a stock 4-into-2 from an '83. Do I need to replace them with stock, or at least something smaller?

Note: The only intake modification is that the air box lid has been removed.

Also note: Via synchronizing and color tuning prior to the dip, I had never been able to get a smooth idle or exhaust free from popping. There was a lot of gunk in the carbs, so I'm hoping those problems can now be dealt with.

Thanks,
- Tony
 
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Stock

Stock

I think if you replaced the air box lid and put in stock jets, your bike would run just great. After all, it would then be a stock setup with squeaky clean carbs!\\:D/
 
Also...

Also...

But....you should also check the schematics to make sure the jets specified for your 1980 model are the same as the ones used in the 1983 models.:?
 
It looks like an '83 uses either 110 and 112.5 jetting (depending on model).

Since the airbox top is gone (never got it from the previous owner) and the exhaust is slightly more open from the '83 (vs stock '80), I should probably go up from stock '80 jetting of 107.5, right?

I'm thinking about going to 112.5.

Thanks,
- Tony
 
Argh. No one seems to have 112.5 or 110 in stock.

I tried a bunch of different places (local and internet) and have been told 7 - 10 days at each of them.

I'm looking for a Mikuni N100/604 #112.5 main jet, right?

Anyone know a good source for them that might actually have them in stock?

EDIT:
One place did tell me that it would only take a day or two to get them, but they're price was so low, I was a little concerned. Everyone else was telling me $5 to $8, this one place had them for $2.80. Is there any reason this one place would be so much cheaper?

Thanks,
- Tony
 
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Make sure the previous owner didn't install a DJ kit before you go this route. If he did, you may have slides that were drilled out and diaphragm springs that are stiffer than stock. This makes a HUGE difference in drivability.

I've never gotten Mikuni jets cheaper than $4.50 each.

Did you try www.motorcyclecarbs.com ?
 
Jethro said:
Make sure the previous owner didn't install a DJ kit before you go this route. If he did, you may have slides that were drilled out and diaphragm springs that are stiffer than stock. This makes a HUGE difference in drivability.
Click to expand...

Good call. I happen to have a PDF copy of the eBay auction where I got my bike and it does list "Carburetors have been Dynojetted".

I probably should just put the newly cleaned carbs back on the bike and see how well she can be tuned before making additional changes.

Jethro said:
Did you try www.motorcyclecarbs.com ?
Click to expand...

Yep - I actually put an order in. When they called me for my CC info (they don't have a secure checkout), they told me it would be 10 days before they get the jets in. So I told them to cancel the order and I would call them back if I couldn't find it elsewhere sooner.

- Tony
 
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