carburetor blues wtf

[TopCatGr58]

Just saw that..............hmmmm.....80 basterdized carbs to boot having the brass floats. Not particularly an issue, but yes, 25.5 float setting for the brass floats. And yes, was rich smelling with the occassinal following come to think of it.

Yep, that stood out for me also, however it may be a combination of problems(aside from ignition). He didn't mention anything about any sort of velocity mounting for the Emgo Pods (1 possible issue); Bastardized 80 carbs with brass floats so does use the ~25mm float height (issue 2); but with those intake and exhaust mods...pods and aftermarket pipes....IF the carb has the pilot jet/main jet sharing tunnel which requires the larger main jet....then the 127 mains may actually be too lean once the float is at the proper height (issue 3).

However, what I've read about the bastardized 80 carbs was that they had the sharing tunnel, and so the pilot jets were rubber capped off so that they only fed from the main jet sharing tunnel, and then once Yamaha ran out of the sharing tunnel bodies, they uncapped the pilot jet tower and then dropped the mains to 110 range.

My CRS may be acting up though, so hopefully someone with more handson experience with the bastardized 80 carbs will chime in and confirm or correct me on this? I don't know if we have this info in our carb tech tips...I'll take a look after I submit this.

T.C.

[MarkD]

Moto was maybe right on with the pick-up wires being poor conductors. When I had my first XS, it was in 2 shops for a LONG time, and the mechanics worked on non-existent carb problems ( break-up at 4500rpm). Finally , at a 3rd shop, the mechanic I took it to knew of the pick-up wire issue, and it was fixed in under an hour. Ran super after the fix. Worth a serious look.

[rdmcguy]

carbs

took a minute for me to get back,
Had to get away from it for a while.
Yes there is a tunnel from the main to the pilots.
The pilots DID have a plug which I removed.
I don't think the pods were an issue as they were not on
the bike during testing
In order to punish myself further I compared needle jet sizes
with other bank of carbs that perform correctly.
I still need to find a good set of long narrow snap ring pliers.
(would like to strangle whoever designed that whole setup )
Of course two of the springs went careening into outer space.
Spark plugs read sooty black so will have to wait for Yamaha shop to open Tuesday to get new jets.
So I bought ANOTHER 11...1980 standard. four total now.
Wiring issues...someone had "doctored"the harness,
I think it was doctor Kevorkian...lol
Thanks for the help guys

[MPittma100]

Needle Jet Snap Ring Pliers

I have a snap ring pliers set of 10 or so in it and none of them would work for those needle jet snap ring placements. So I modified one set that was close to fitting with a belt sander and it worked perfectly. This modification did not diminish the effectiveness of the tool at all. Sometimes the special tool that you need can be manufactured right at home.

MP

[natemoen]

Put the plug back in the pilot jet tower and then you need to start with a base main jet of 137.5.

[DGXSER]

So just to be sure these are truly 80 carbs is there threads on the pilot jet tower? Does the mix screw go down int the tower, or does the top stay above the "tower"? Is there three or four holes on the inlet throat of the carbs?

It could be you have 78-79 carbs on your 80 bike.

If it is the 80 model carbs, then you will want the rubber plugs back over the pilot jets. The 80 model carbs still used the 110 mains as stock, it never made any sense to me why they would not need the bigger main jets, but they do not.

[Rasputin]

I am thinking here that the more info we had the better the replies to the problem were. Exactly what I was hoping to achieve. The float setting stood out immediately if they were older carbs. Snap ring pliers that work can easily be made of a set of long nose needle nose pliers with a wee bit of filing or grinding. Makes that job much easier.
Thing is to point out all the obvious and then tell us about the intricate things we need to know to help, such as pods, exhaust, things tried and all that stuff. Then the tail chasing becomes far less and the real problem can be found.
Just small things that make no sense like the type of idle /air screws make such a difference when trying to diagnose something from far away.

[Rasputin]

So just to be sure these are truly 80 carbs is there threads on the pilot jet tower? Does the mix screw go down int the tower, or does the top stay above the "tower"? Is there three or four holes on the inlet throat of the carbs?

It could be you have 78-79 carbs on your 80 bike.

If it is the 80 model carbs, then you will want the rubber plugs back over the pilot jets. The 80 model carbs still used the 110 mains as stock, it never made any sense to me why they would not need the bigger main jets, but they do not.

Here is a perfect example. As I was one finger typing my reply, someone else was asking for more info.

[motoman]

So just to be sure these are truly 80 carbs is there threads on the pilot jet tower? Does the mix screw go down int the tower, or does the top stay above the "tower"? Is there three or four holes on the inlet throat of the carbs?

It could be you have 78-79 carbs on your 80 bike.

If it is the 80 model carbs, then you will want the rubber plugs back over the pilot jets. The 80 model carbs still used the 110 mains as stock, it never made any sense to me why they would not need the bigger main jets, but they do not.

That would be because the two circuits are pretty much kept seperate with the plug and don't draw fuel from both circuits like the early carbs do, which need the larger mains since pulling fuel from both circuits in the lower rpm ranges. Hope that helped.

[rdmcguy]

carbs

Ok.
Three round holes on carb throats.
Large oblong on top,
mixture screws are above carb bodies,
I might be on the same wave length as some of you
Though about recapping pilots and modifying needle nose pliers.
One thing I am certain of though....
I WON'T GIVE UP

[TopCatGr58]

Aha, the plot thickens.

So now we KNOW that you have 78-79 carbs on an 80 bike!

So...the brass floats are correct, and they should be at the 25.5 level afterall.
The pilot jet towers should have screwed/threaded towers, and were probaby capped by a large head screw...it needs to be reinstalled to seal the pilot jet. And the mains need to start at the 137.5 size as a baseline.

With the pilot jet towers OPEN is why you are carboning up so quickly!

You've been P.O.'d!!! It's happened to many others as well.

T.C.

[motoman]

Aha, the plot thickens.

So now we KNOW that you have 78-79 carbs on an 80 bike!

So...the brass floats are correct, and they should be at the 25.5 level afterall.
The pilot jet towers should have screwed/threaded towers, and were probaby capped by a large head screw...it needs to be reinstalled to seal the pilot jet. And the mains need to start at the 137.5 size as a baseline.

With the pilot jet towers OPEN is why you are carboning up so quickly!

You've been P.O.'d!!! It's happened to many others as well.

T.C.

U get that sorted out Joe, be careful on a test ride as I noticed even though it was being erratic while behind you, it did have an impressive zip to it.

[oldnortonrider]

The carbs are from an 80 standard,
Before I cleaned them they had 2h7-10 on the side
They are the early style with brass floats.
I set the floats at 23mm.The bike the carbs are on has a kerker header,
and emgo pods.As I live at 5280 feet elev.i jetted for altitude.
127.5 mains...42.5 pilots
I verified these sizes at my local shop and they match what I have in a different set of carbs that work fine.
I have switched and swapped the carbs with my other bikes to verify that it wasn't elec or otherwise.
same problem no matter which machine
Btw. thanks to all in advance

I thought the brass floats were to be set as follows; .25.7mm plus or minus 1.0mm ~~ 24.7mm - 26.7mm
The 23mm setting is for the "plastic" floats; ¿Am I not right on this?

[rdmcguy]

carbs

EUREKA!!!!!!!!!!!!!!1
Recapping the pilots was the solution...
unfortunately it doesn't run very well down low now.
I failed to mention that I was working on two different sets of the same
2h7 carbs at the same time.
One set had the pilots capped with no jets below
while this set had 42.5 pilots although capped
A final question Pilots in or none?
Again, thanks

[bikerphil]

Yes you want the 42.5 pilots with the caps over them.