yamaha 70hp 3 cylinder 2 stroke carb specs

[steven brown]

hi everybody my name is steve and i live in thailand, i am a motorcycle mechanic with 30 years experience, a friend of mine has the above outboard, the boat yards in this country are not the best to say the least and after 3 different cowboys trying to fix it it has ended up in my hand, i am no stranger to boats and there engines but what i have endedup with is 2 sets of carbs in boxes and no base line to work from. does anybody have the origional specs for these carbs

pilot jet [ slow running jet] size

main jet size

air screw { mixture screw] turns out

if anybody can help that would be great also i have a lot of experince of all sorts of engines please feel free to contact me if you have problems.

many thanks
steve

[TownsendsFJR1300]

If you post the year and model # it'd be a BIG HELP.

Also, once you have that, if you look above and to the right under"Purchase Yamaha Parts" (in red) you can look up the parts fisch for the engine.

Your particular engine likely isn't in there (as your outside the US) but you can get an idea. Bring up the carb fisch, find the jet(s) and it should say the size.

Obviously the spark plug color should tell alot also...

BTW, if your fuel is as crappy as it is over here, unless someones drilled the jets(not likely), they are very small and do gum up/ clog very easily.

A simple pull the bowl, the jets, inspect and clean (make sure you can see light thru each-especially the nozzle) will likely take care of most of the carb problems.

Most Yamaha carbs (I'm NOT positive on yours) is usually about 2 turns out from lightly seated.. Syncing is fairly critical for a good idle, performance over all etc.

The OB's are generally more fussy (being adjusted correctly) than most motorcycle engines(I work on those too-mostly jap bikes).

[boscoe99]

Send me a PM with your email address.

As noted, we need the complete model identity. A complete engine serial number would even be better.

[steven brown]

seriel no

please give me seriel number location. apart from torque settings all i found was 6h 30 1 y1 on the crank case cheers

[99yam40]

Info is on a plate on mounting bracket

[boscoe99]

Here is a link to many sites that show where the engine ID can be found.

It will be found on the left side of the clamp bracket. Always begins with the number 6.

https://www.google.com/search?q=phot...FYUVkgod1RwNLA

If something exists, it is going to be found on the innerweb.