another carb problem/carb synch

[petejw]

Im getting air leaks thru the throttle shaft of the carbies,
i spray carbie cleaner on them and the motor nearly dies.
ive never torn down the carbies completely b4, so im wondering,
in the clymers it states theres a seal that sits in the throttle
shaft, number 42 in the carb diagram. does any one know if this seal is a rubber o ring, or is it like a plastic bush, r they hard to get, do they come in the carbie kits?
there all leaking pretty bad to the extent i cant get proper vacuum readings.
thanks again 4 all ur help


pete

[randy]

Pete,

Those seals are available from

motorcyclecarbs.com

[petejw]

cheers

thanx randy

[petejw]

i just stripped down my carbies 2day,
what a pain, someone had locktite the screws
holding the rail to the carbies, out comes the impact
driver, got them out eventually but it wasnt pretty.
pain also was unscrewing the screws holding the
butterflies, the ends of those are tapered over,
eventually got them all out.
just waiting on the seals, hopefully monday arvo.


pete

[Ken Talbot]

Originally posted by petejw
i just stripped down my carbies 2day,
what a pain, someone had locktite the screws
holding the rail to the carbies

Yup, that's the way Yamaha put them together when they were built. Quite a chore..

[TopCatGr58]

Hey Pete,

Don't forget to use Locktite on the butterfly screws when you put it back together. Even though it's a pain to take apart, you shouldn't have to be taking those off again, and it's no fun having them work loose and get sucked into the intake....munch, crunch!
T.C.

[petejw]

yeah i definately know that.
they are normally bevelled over at the factory
which makes them hard to get out,
but like u said once the seals have been replaced
there should b no reason to have to strip them apart again.
u would think they couldve used spring
washers for the carb rails.

[Winterhawk]

If you take them off of the rails, be sure to assemble them on a surface plate such as glass.

[petejw]

Carb Sync

Just put all my carbies back together after replacing the
throttle shafts seals, the old seals were dry and hard with plenty
of air able to leak by them, i doubt that they had ever been replaced b4, I read a lot about checking 4 leaking carb manifolds
BIMHO i think the chances of the seals leaking would b greater
especially if they have never been replaced, these seals being over 25 yrs old. To check just spray carbie cleaner on the throttle
shafts on each side of the carbie, ull soon hear a difference in the engine if there leaking.

I sync the carbs also, but instead of using the bread tie method, i used a lamp.
I found using the breadtie had several disadvantages, being that the breadtie still scratched the carb throat, the breadtie would bend and flex, the breadtie had to be exactly in the middle bottom of the butterfly, it was more time consuming, u also had to be precise with the 'feel' of the wire moving in and out.
The method I used was with a lamp shining at the front throat of the carbies, looking at the 'light gap' between the butterly and throat.
Not sure if this method has been mentioned b4 but
For those interested in knowing, ill describe how i sync them.
remove carbs from manifold, remove air filters, i had pods,
loosen the idle adj screw all the way so that no3 butterlfy is completely closed, hold carbies up to the light looking thru the air intake, if all butterflys arent closed, the carbs need to b sync.
adjust carb 1 - 2, adj carb 4 -3 then adjust carbs1,2 - 3,4.
remembering 3 has no adj and all carbs are to match the 3rd carb
u want to hold the lamp at the back and adj all butterflys so they are all just closed, no light shining thru, u can readjust all carbs as necesary. IMHO this was the first time i adj the sync in this way and found it much more accurate than the bread tie.
U can still use the bread tie and then try this method following.
i hope ive made sense and this can help someone.
its a good alternative if u dont have vac guages or mercury sync.

[81xsproject]

I like the idea for a good pre-sync. It is probably a good idea to still do a vacuum check on the running bike afterwards to compensate for all the other variable that could differ from one hole to the next.

[bandet01]

yeah i think it is a good idea too since alot of people say the break tie makes it idea alittle to high

[John]

You don't leave the main idle screw turned in as far as it needs to be when doing the twist tie method. That just opens the plates enough to use that size of wire to sync the carbs. You should have counted the number of turns the main idle screw was set to, and then turn it back to that setting when you were done syncing them. That's why your bike idles too high, I'll bet. I just did a set a couple of weeks ago on my 79SF project, and I had to turn the main idle screw in four turns in order to open the throttle plates far enough to get the wire under them. When I finished syncing them, I just turned the screw back four turns, and that was pertty close once I had the carbs back on and the bike running. I then tweaked the pilots, and set the curb idle at 1100 rpm. It idles well, but it needs to be adjusted with some gauges, and I don't have any.

[GNEPIG]

.. petejw, could you give us the part #s for these throttle shaft seals you have used, also what year is your bike?. do you think it matters between the two models of carbs?

[TopCatGr58]

Hey Petejw,

I merged your thread with your earlier one, helps folks to follow a problem and it's solution!! Also helps keep down the number of threads when they are from the same person on the same subject.....hint, hint.....

Gnepig,
As mentioned in the above replies that you might NOT have seen since it wasn't merged, they are gotten from Rob Reil's Motorcyclecarbs.com.

They are listed by Yamaha as:2A2-14997-00-00 SEAL from 79SF.

I checked the #s for the Yamaha XS650, but it doesn't match, so the ones from MikesXS probably won't work!
T.C.

[GNEPIG]

.. i did notice from the other thread where he got the parts from, but didnt see a part # .. Thanx TC
.. i was going to try for a set from mikes xs, instead i will get them from Rob Reil .. Thanx again TC
Gene