#4 is cutting out on me????

[natemoen]

Now I'm confused over here. After checking the specs for the 78 carbs, 210 is listed as the correct air jet. Now the 79 carbs specify a 180 air jet. I think we need a carb super guru to chime in on this one.

Yes a carb guru would be necessary cause my clymer manual says that a 78 has 180 air jets in it.

[bikerphil]

Yep, all the Yamaha parts fiches say 210's for the 78.

These should be the correct type air jets (small round type main jet).

http://www.jcwhitney.com/cv-carb-jet...x?skuId=399856

[natemoen]

In the product description of that link it states they are 180's

[bikerphil]

In the product description of that link it states they are 180's

Yep, just showing you what the correct air jet type is for your bike. They are available in all different sizes. The link for the jets you posted didn't look like the right type for the BS34 carbs.

[natemoen]

Well then if 210 is the correct air jet then I am still on the hunt for a solution to the bogging between 1500 and 4500.

[petejw]

hi natemoen,
be real particlar with your fuel height settings,
as little as .1mm makes a difference to how the
engine runs,
i wouldnt personally rev the engine to 7500rpm in neutral, its
not good for the engine, and you wont be able to read
the plugs for a main jet setting, the bike needs to be ridden
under load at wot for the slides to fully open.
are the 145 pilots stock for the 210 pilot air jets or are the
142.5 the stock ones? the 145 could cause it to bog down.
also when your riding take note of the throttle location as well
as the rpm that will help determine what circuit of the carbs are
being used.

[natemoen]

hi natemoen,
be real particlar with your fuel height settings,
as little as .1mm makes a difference to how the
engine runs,
i wouldnt personally rev the engine to 7500rpm in neutral, its
not good for the engine, and you wont be able to read
the plugs for a main jet setting, the bike needs to be ridden
under load at wot for the slides to fully open.
are the 145 pilots stock for the 210 pilot air jets or are the
142.5 the stock ones? the 145 could cause it to bog down.
also when your riding take note of the throttle location as well
as the rpm that will help determine what circuit of the carbs are
being used.

42.5 is the stock pilot jet Mine currently has 45 for the pilot (could this be causing the problem)
the 210 is the air pilot jet which according to the Yamaha parts fiches 210 is correct for it but my Clymer manual say it should be a 180????

Now when I am looking in my manual its lists an "air jet-main" and says it should be 140. I dont know where this thing is. it does not show it in the exploded diagram either

[natemoen]

Ok, next part of the puzzle. Plugs 1 and 2 are a nice tan gray color and 3 is getting there and 4 is still a bit black so i will probably have to continue to play with the float in that carb (still looking for an original brass float if anyone has one). The thing still pops (might even have some backfire not sure) like SOB though and it happens pretty much any time, constant speed, decel, and even a little sometimes on accel. I get a lot of stares when I drive through the residential areas by my place. I don't want to be put into that category of the Hardly guys

The bogging is happening between 1500 and about 3500 RPMs and not 4500 like I had said before (I was watching a little closer this time). I have found that if I roll on and off the throttle when it is happening it seems to help it through a little better.

So I am still looking for help if anyone has any ideas!!!

Thanks

[bikerphil]

Now when I am looking in my manual its lists an "air jet-main" and says it should be 140. I dont know where this thing is. it does not show it in the exploded diagram either

The main air jet is pressed in and non-removable, that is why it is not listed.

If 3 of your 4 plugs have decent color, then I'd just focus on that #4 with the bad float. I'm sure someone on here has an extra brass float they'd part with.

[natemoen]

The main air jet is pressed in and non-removable, that is why it is not listed.

If 3 of your 4 plugs have decent color, then I'd just focus on that #4 with the bad float. I'm sure someone on here has an extra brass float they'd part with.

How hard would it be to adjust the #4 float when it is still on the bike??

[bikerphil]

How hard would it be to adjust the #4 float when it is still on the bike??

I couldn't tell you, I've never tried. I'm sure you will let us know.

[Ken Talbot]

How hard would it be to adjust the #4 float when it is still on the bike??

I would have to say pretty much impossible. It is tricky enough trying to bend the adjustment tab by just the right amount when the bank is sitting upside down on a clean workbench with good light. I can't imagine how you would even begin to measure the height when gravity is pulling the float down.

[natemoen]

I would have to say pretty much impossible. It is tricky enough trying to bend the adjustment tab by just the right amount when the bank is sitting upside down on a clean workbench with good light. I can't imagine how you would even begin to measure the height when gravity is pulling the float down.

We the thing is though measuring it does me know good. Its not the right float so its pretty much just guess and test. I dont want to pull the carbs adjust it a little and find out its still not right and have to pull them right back out to go over it again. thats the only reason I ask. If I were measuring I know I would have to pull them out.

[TopCatGr58]

Remember, I'm no CARB GURU!

Hey Nate,

You've gotten alot of good help recently. The mismatched float is a PITA to adjust/test. I think the bowls have a drain and bolt. Folks have gotten a tube fitting from LOWES or hardware to screw into it, and the connect a clear tube looped back up to the side of the carb body, and you can then mount the bank on a LEVEL rack, connect to a fuel supply, fill and check the fuel level that way....see the manual for the technique for the later model carbs. Would be the easier way than having to R&R them on the bike so many times!

As for the carb body disassembly and cleaning..you said the slide NEEDLE, but I was talking about the MAIN JET NOZZLE that slide down into the middle of the carb body. The MAIN JET screws into it's end and holds it in along with the washer. Once the main jet is removed, then you can gently tap that NOZZLE up thru the carb body for thorough cleaning to get all of the fine aeration ports clear..they are small and clog easily!

Glad to hear that the pilot jets are the right type/style, and since the other 3 carbs appear to be working properly, looks like most of the problems are with the #4 carb and float.

BUT...are the PILOT SCREWS tips nice and sharp/pointed, and there are no tips broken off in the holes? With one carb flooding/running rich, it can cause the bike to BOG....you say pumping the throttle helps the transition, but it's hard to say for sure what's helping, opening the throttle plates more to let in more air, or backing off? IIRC Prom posted about how if it lags when you open the throttle that it's usually LEAN because as you turn the throttle you're letting in more air, and therefore leaning it out more, so it doesn't have or gets enough gas, and lags until the engine catches up.

SO....after you get the float height thing fixed, then just testing with turning the pilot screws out 1/2 turn each, and then retest the throttle response, may require additional turns. If it worsens though, then need to turn inwards, but I'm thinking you're a little lean overall...Once you get into the MAINS....it seems to pick up, so it's the pilot/idle circuit that mostly needs tuning! Keep at it!
T.C.

[natemoen]

Well then tomorrow I will have to try and limp myself over to some (hopefully I can find it at the first place I go) hardware store (bike is all I have for transpo at the time). I have seen pictures of other people who have set the float level this way so I can figure out how to set it up but my question is how do I measure the level so it is still set at the 25.7 (heck I am not even positive I was measuring it correctly in the first place).

Yes I did remove and clean the main jet and emulsion tube as well. The pilot screws and nice and sharp (or at least they were when I had them out the other day) and if something happens to them I have a spare set anyways (hopefully I dont need them though).

Once the bike get caught up it does definitely take off. Right now when I take off from a stop I have to slip the clutch a lot to keep the RPMs up over 4000. Yesterday I was trying to do to many things at once and had it up a bit too high and ended up with the front wheel like 2 -3 feet off the ground. I would much prefer to not do that again, so I need to get this fixed. At least then it would be easier for me to control

Thanks guys!