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Carb Sync

Started by Dan88, February 21, 2016, 10:53:37 PM

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Dan88

Hi, I want to sync my carbs using a Vacuum gauge kit. I hooked it up but then noticed there are only three (synchronizing screws) on the carburetors. . .I expected to see four!! Does one screw adjust carbs 1 - 2 while the other two screws adjust carbs 3 - 4 ?? There doesn't appear to be any info in the manual on this topic, so if someone could help us out outlining the best procedure to use for this task I would be externally grateful.

Dan

Pat Conlon

Hello Dan, you are correct, looking down from the top you see 3 screws, left, center and right, that adjust the throttle plate openings.

Remember what you are trying to do is match the throttle plate openings between all 4 carb's.
The process is simple, with the vacuum gauge hooked up to all 4 vacuum ports
1) balance carb's #1 and 2 with each other by adjusting the left screw
2) balance carb's #3 and 4 with each other by adjusting the right screw
The center screw adjusts both 2 left side carb's(#1/2)  and the right side carb's (#3/4)
So your last step is to
3) balance carb's 1/2 with carb's 3/4 by adjusting the center screw.

Work quickly. Don't let that big air cooled inline 4 cylinder idle too long. You can cook your exhaust valves. Our FJ engines need air flow to stay cool. If you need more than 4 or 5 minutes, get a box fan to provide air flow.

Hope this helps...Cheers Pat
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

Capn Ron

Hey Dan!

Welcome to the forum!  What you're seeing is a screw between carbs 1 & 2...You sync those two carbs.  Then you're seeing a screw between cabs 3 & 4...you then sync those two carbs.  The screw in the middle of it all then syncs the carb 1 & 2 pair to the carb 3 & 4 pair.  When you're done, you'll get a close-to-same reading on all four carbs.
Cap'n Ron. . .


There are two types of people in the world...Those who put people into categories...and those who don't.

Pat Conlon

Ha!
I got the Capn by 1 minute 29 seconds... :greeting:
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

Dan88

Thanks a lot guys . . . Unfortunately I had a go at syncing the carbs prior to posting this blog ( silly bugger . . .) and now need to get things back on track. Pat will you steps still work? the bike starts and will rough idle. Cheers

Dan

Capn Ron

Quote from: Pat Conlon on February 21, 2016, 11:42:09 PM
Ha!
I got the Capn by 1 minute 29 seconds... :greeting:

First time for everything my friend!   :biggrin:
Cap'n Ron. . .


There are two types of people in the world...Those who put people into categories...and those who don't.

Pat Conlon

Fist time?

Ouch....I'm afraid to ask....you are one kinky dude.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

Pat Conlon

Quote from: Dan88 on February 21, 2016, 11:45:06 PM
Thanks a lot guys . . . Unfortunately I had a go at syncing the carbs prior to posting this blog ( silly bugger . . .) and now need to get things back on track. Pat will you steps still work? the bike starts and will rough idle. Cheers

Dan

Yes Dan, both Ron and I said the same thing. Follow the steps 1/2, then 3/4, then center to match left two carb's to the right two carb's.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

Capn Ron

Quote from: Pat Conlon on February 21, 2016, 11:52:58 PM
Fist time?

Ouch....I'm afraid to ask....you are one kinky dude.

Damn...thanks for the heads up...fixed it!  Phew!   :good2:
Cap'n Ron. . .


There are two types of people in the world...Those who put people into categories...and those who don't.

Pat Conlon

Good...I was starting to get concerned :sarcastic:
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3