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Looking for some advice on carb jetting

Started by grannyknot, June 24, 2011, 06:24:59 AM

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grannyknot

1984 FJ1100 with a stock air filter/air box

P/O installed a 4 into 1 Bazni exhaust and re-jetted to #38 pilot jets. He didn't like how loud it was so cut off the exhaust and welded a stock exhaust from a GXSR but left the carbs the way they were, he says it's running a little rich. (seems to me that single stock Susuki silencer has got to be more restrictive than the original double exhaust)
I'm just about to place an order with RPM and would appreciate some recommendations on what jets I should purchase that would get me into the ballpark, a base that I could fine tune from. The prices for the jets are very reasonable so I could order a set one size smaller and larger as well to experiment with.
I'll be doing a complete carb overhaul this winter but just want to get her running this summer.
Thanks,
Chris
84 Yamaha FJ1100L
82 Honda CB450T
70 Suzuki T500
90 BMW K75S

JMR


grannyknot

Yes sir, can't say I have ever heard of them before, must be my sheltered life.
84 Yamaha FJ1100L
82 Honda CB450T
70 Suzuki T500
90 BMW K75S

racerrad8

Quote from: grannyknot on June 24, 2011, 06:24:59 AM
1984 FJ1100 with a stock air filter/air box

P/O installed a 4 into 1 Bazni exhaust and re-jetted to #38 pilot jets. He didn't like how loud it was so cut off the exhaust and welded a stock exhaust from a GXSR but left the carbs the way they were, he says it's running a little rich. (seems to me that single stock Susuki silencer has got to be more restrictive than the original double exhaust)
I'm just about to place an order with RPM and would appreciate some recommendations on what jets I should purchase that would get me into the ballpark, a base that I could fine tune from. The prices for the jets are very reasonable so I could order a set one size smaller and larger as well to experiment with.
I'll be doing a complete carb overhaul this winter but just want to get her running this summer.
Thanks,
Chris

Chris,

I have never heard or seen a 38 pilot jet. They are stock at 37.5 then step up to 40 & 42.5.

The 1100 with a stock air box should be 115 max with a 112.5 being the most popular. When you get rid of the air box you will then need to go up to at least the 40 on the pilot and possibly higher on the main jet with a shimmed needle as well.

I see you are in Canada and with the Canada Post strike; UPS is the only shipping option. Right now the cost of shipping will make the purchase of the jets to high.

I know several other Canadians are holding off on orders until the strike has ended.

Randy - RPM
Randy - RPM

grannyknot

Quote from: racerrad8 on June 24, 2011, 05:03:25 PM
Quote from: grannyknot on June 24, 2011, 06:24:59 AM
1984 FJ1100 with a stock air filter/air box

P/O installed a 4 into 1 Bazni exhaust and re-jetted to #38 pilot jets. He didn't like how loud it was so cut off the exhaust and welded a stock exhaust from a GXSR but left the carbs the way they were, he says it's running a little rich. (seems to me that single stock Susuki silencer has got to be more restrictive than the original double exhaust)
I'm just about to place an order with RPM and would appreciate some recommendations on what jets I should purchase that would get me into the ballpark, a base that I could fine tune from. The prices for the jets are very reasonable so I could order a set one size smaller and larger as well to experiment with.
I'll be doing a complete carb overhaul this winter but just want to get her running this summer.
Thanks,
Chris

Chris,

I have never heard or seen a 38 pilot jet. They are stock at 37.5 then step up to 40 & 42.5.

The 1100 with a stock air box should be 115 max with a 112.5 being the most popular. When you get rid of the air box you will then need to go up to at least the 40 on the pilot and possibly higher on the main jet with a shimmed needle as well.

I see you are in Canada and with the Canada Post strike; UPS is the only shipping option. Right now the cost of shipping will make the purchase of the jets to high.

I know several other Canadians are holding off on orders until the strike has ended.

Randy - RPM
Randy, it doesn't surprise me you have never heard of a 38, the P/O is proving to be a real BS artist.
As I start to go through the bike I'm finding all kinds of things that don't add up to what I was told.
I guess I just bought a fixer upper.
Canada Post is going to be legislated back to work early next week so I'll place my order then.
You say "when I get rid of the air box" is it really that restrictive? I'm not looking for more power and I trust paper filters.
Do you think I can get away with your stock carb rebuild kits?
84 Yamaha FJ1100L
82 Honda CB450T
70 Suzuki T500
90 BMW K75S

grannyknot

Update, I pulled the carbs to find out what is actually in there, they were filthy.
Main jets 112.5
pilot jets  40
pilot air jets 160

I did through cleaning of everything and I'll try to get it running today.
84 Yamaha FJ1100L
82 Honda CB450T
70 Suzuki T500
90 BMW K75S

andyb

Shouldn't be terribly far off then.  Get things cleaned up and float heights relatively close, and you should have a good base to start tuning from.