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More carb questions

  • Thread starter Thread starter Spyder
  • Start date Start date
S

Spyder

Guest
Ok,

I've searched everywhere on this great site, and can find no specific info on an 83' 750T model carb rebuild. The picture tutorial is awesome, until you come to reassembly. how do you reset everything?!?

I see the term bench sync. but, what's the procedure? what are you syncing up, and to what spec?

Does anyone just know what jet kit I should have for this bike with K&N Pods and a D&D 4 into 1? ( i.e. stage-1, stage-3 )
Does the jet kit come with EVERYthing I need to re-jet?

I'm sorry if these are dumb questions, but I just don't understand the spec sheets. ( not that I can find one for this bike) Measurements don't mean much if your not sure what your measuring or where to measure it from.

I was an automotive technician for 9 years. I really don't want to farm this job out to anyone. I should be able to accomplish it. But I need proper info before starting.

Any info is appreciated, thanks for this site keep it up.
See you in Brown County...
 
The four carbs need to be synced to each other for the bike to run properly and for best performance. The bench sync is just gets you in the ballpark, after they are on the bike and running you need a manometer to set the vacuum from each carb the same.
 
...the only adjustments possible on the carbs are the pilot screws, start at 2.5 turns from lightly seated and tune for best running, and the float height. The factory service manual will provide info on setting the floats.

For your setup you will want a Stage 3 kit. The jet kit should have instructions on any fine tunning necessary.
 
Hey Spyder

Hey Spyder

I think you can find a factory manual here http://members.dslextreme.com/users/bikecliff/
At least there is a 750T there.

I also have a carb question: I started tearing the carb of my 1980 850 G. I guess someone who did not know what they were doing messed with them (found a broken air screw, two orings from the intake were missing) Now, I took apart # 4 and 3. First, in #4 I found a little cup-shaped screen/ filter in the fuel inlet. When I got to carb #3 there was none. Instead I found a similar screen/ filter in the fuel inlet needle valve seat. I like the idea of having those extras screens, but don't exactly know were they go (guess I will find out when I get to #1 & #2)Has anybody seen these before and, are they necesary??

Thanks
 
filter screens

filter screens

cruz del sur said:
I think you can find a factory manual here http://members.dslextreme.com/users/bikecliff/
At least there is a 750T there.

I also have a carb question: I started tearing the carb of my 1980 850 G. I guess someone who did not know what they were doing messed with them (found a broken air screw, two orings from the intake were missing) Now, I took apart # 4 and 3. First, in #4 I found a little cup-shaped screen/ filter in the fuel inlet. When I got to carb #3 there was none. Instead I found a similar screen/ filter in the fuel inlet needle valve seat. I like the idea of having those extras screens, but don't exactly know were they go (guess I will find out when I get to #1 & #2)Has anybody seen these before and, are they necesary??

Thanks
Click to expand...

In the parts fiche those are very hard to identify because the picture doesn't look like what you'd expect. They are fuel filter screens and one goes on top of each of the needle valve seats. Not sure why one would be on the fuel inlet, or even how that could be done. Those are available as replacement parts:
http://www.yamahasuzukioftexas.com/...&category=Motorcycles&dc=2354&name=CARBURETOR

In that picture it's part number 51. You can get 50 while you're at it: the O-Ring , although they are available for less as a set from http://www.cycleorings.com/
http://avherald.com/h?article=41370ebc/0005
 
Awesome

Awesome

Thanks so much Larry. I found that screen jammed at the end of the fuel inlet. It did fit nice and snug (and now that I think about it it could be added another set there for extra protection). I recently bought this bike, ($350 at a bike shop so imagine the condition I got it:0) and I guess the previous owner messed with it or some butcher wannabe mechanic got hire and fired after messing with this bike. (a broken air screw says it all. The tip of the broken needle was stuck in there)

I willl be ordering those o rings as soon as I finish taking all the carbs apart so I can order what I need and put it back together.

Thanks!!
 
Thanks so much Cruz,
that's exactly what I needed to know.
See all of you in brown county!!!
 
Screwed !!

Screwed !!

I think I am screwed by the air screw :0(

I thought I had removed the tip of the air screw that is broken inside. today I took a look, and affter a while, I shined a light through the airscrew hole, and nothing comes out. I already tried everything, even bent a needle and tried to push it the other way. Anyone has a saving suggestion ???
 
I have extra fuel inlet screens if you need them.
You need to tap out those tips. Use heat if there is no fuel present.
 
broken tip

broken tip

Thanks Chef!! The screens that I have seem intact. Do you know how often they should be replaced?? As for the tip, I tried everything I could, even submerged the carb in hot water, bent a needle to have somthing sturdy to push it, and nothing. Today I will go to a shop I used to work and the guy there is the best mechanic I know see if he has any solution. However I pretty much think I should start looking for a new carb :0(
 
Finally got the sucker out !!! I went to my friends shop, and what I did was to drill in the inside of the carb where the small hole comes out, until I made a big enough "crater" :0) and then pushed with my test light and it finally came out. I asked my buddy if the bigger hole would had dammaged the carb, and he said no, that the air vaine was above the hole so it was OK. Now lets rebuild the sucker :0)
 
so you drilled a hole from the "inside" of the carb facing out towards the screwpoint?
I'd be very wary with that. and your sort of right, as long as your drilling didnt interfere with the tapered hole that is used for metering you should be ok.

I only just saw this thread now, but my first thought was to go find a mate with a compressor and blast the tip out from the inside and push it out the way it went in.
 
HI Mike. Believe me, I did try the compressor, and gave it a full 120 PSI. I even put a rubber tip in it so it would shape to the curve of the carb, and the sucker didn't budge. I think someone tightened it with a 1/2 inch air gun :0)

We'll soon see how it runs.
 
Hey Chef.I am ready to replace it if needed. However, this buddy of mine is a great mechanic. I do take his word when he says it will be fine (although I am a bit wary and probably will be till I fire that puppy up)

At any rate, I am ready to buy a new one (use of course since the are discontinued) if I have to. But I am sure it will be fine. I will let you guys know as soon as I get it running
 
Spyder said:
Ok,

I see the term bench sync. but, what's the procedure? what are you syncing up, and to what spec?


-> When they talk about bench synch they mean using a usually round guage to measure the gap between the bottom of the barrel of the carb and the throttle plate. Sometimes there are specs for this gap, and sometimes not. The idea is to make sure all the throttle plates are open exactly the same amount prior to installation so that the actual vacuum sync goes more smoothly.
In automotive in my experience one is taught to look at the relationship between the edge of the throttle plate and the hole in the throttle bore which lets gas in at idle. Sometimes there are pictures in service manuals which tell you what you are looking for. My bike has such a picture but I have no idea whether yours does.
In any case, setting the throttle plates of all the carbs on an engine to the same place in relation to any known fixed point, and knowing what that point means, will go a long way to making vacuum synching a carb a pleasure rather than a pita. If you know how it should look in relation to the idle inlet, so much the better.
S
Click to expand...
 
Thanks guys. All of this sounds complicated but seems easy enough. Are there any of you in the Chicago region, maybe willing to physicaly help and or do this carb build? I don't have the greatest carberated track record.
 
Hey Spyder, what part of Chicago are you at???

I MUST have a worst record with carbs than you do. Believe me when I tell you that they are very easy to do (of course I haven't gotten to the sync part yet :0) I guess the hardest part is taking them apart (screws that don't come out etc) then all you have to do is, basically, adjust the float.

If you still haven't taken them apart, you could take one part. by the time you are done, you'll probably decide you can do them.

And, if there is no one more experienced than I am in this area, I will help you (I am right by Devon and Clark:0)
 
Hey cruz, I'm down in Bradley. It's down 57 by Kankakee.

Hey Chef, I accidentally deleted your message. Please resend it.
 
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