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drift_g35
07-21-2015, 10:09
I am looking to get my carbs tuned and maybe re-jetted. I have a project bike that I am working on that bogs after adding new exhaust. I know i can just take the bike somewhere and have it done but id really like to help and learn how to tune carbs as its a black magic to me. Does anyone here have the time to teach/help me? I dont know what the typical cost of a carb tune is so some quotes would be cool as well.

The bike is an 83 Yamaha xj750.
TFOGGER
07-21-2015, 10:28
I am looking to get my carbs tuned and maybe re-jetted. I have a project bike that I am working on that bogs after adding new exhaust. I know i can just take the bike somewhere and have it done but id really like to help and learn how to tune carbs as its a black magic to me. Does anyone here have the time to teach/help me? I dont know what the typical cost of a carb tune is so some quotes would be cool as well.

The bike is an 83 Yamaha xj750.

Hitachi or TK carbs?

The TK carbs are a nightmare to get parts for, FYI.

The Hitachi carbs are a little better, but also kind of an adventure to get parts for.

Carb tuning is only a little bit art, mostly science. The YICS Yamahas make life little more complex due to the linked intake tracts.
drift_g35
07-21-2015, 10:39
That is a good question. Without removing the carbs how can I tell?


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TFOGGER
07-21-2015, 10:43
They should have a logo cast or stamped in the side of one of the carbs, usually on the right side of the bike.
jerrymrc
07-21-2015, 15:09
A uni-sync is used to get the idle settings right on multiple setups. http://www.amazon.com/Edelbrock-4025-Carburetor-Balancing-Instrument/dp/B00062YC2E Having owned 140 Corvair's I used this a lot.
TFOGGER
07-21-2015, 15:18
A uni-sync is used to get the idle settings right on multiple setups. http://www.amazon.com/Edelbrock-4025-Carburetor-Balancing-Instrument/dp/B00062YC2E Having owned 140 Corvair's I used this a lot.

Impossible to use on this bike because of the airbox design and the YICS passage in the head. In order to sync the carbs on this one, you need an old school mercury synchronizer or a set of vacuum gauges and a YICS block off tool(I have both). The YICS system was originally supposed to yield better low end response and idle quality, but in reality just makes it more difficult to work on.