Yet another carb question.

Saturday, spent about 9 hours working on carbs, also value adjustment. Got the values in line with the exception of the number 4 cylinder, need a 250-255 shim so its sitting with a 265 for now.
Anyway, got the carbs cleaned, top to bottom, everything besides breaking the rack, replaced diaphram's because two stuck and the rubber on the other two of them had small holes. Anyway, after bench syncing we put it all back together and started it up. Ran awesome for about an hour, then the idle kicked up to around 3500 and could not get it to go down.
Today I went and checked all my cables to make sure there was no binding, and the engine started to pop, and I mean a lot of popping, which Frankie has never done before.
So, my question. What the hell did I do to my carbs, and why today is it popping?
Thanks guys, ready to put Frankie out to pasture or myself in a loony bin.
By the way, its an 82 xj650j with 82,000 on it

 

Vacuum leak? Boots still good? Air filter seated properly?

 

You have changed LOTS of stuff by cleaning/repairing the carbs and doing valve shims. you need to re bench-sync your carbs, then colortune + do a running sync.

Also, did you do a carb dip without breaking the rack?

 

jm I didn't do a carb dip, I didn't break the rack, just a very thorough cleaning, I've never colortuned it, guess I better think about doing that. I checked the boots after re attatching the carbs, and fired it up proximal, but I haven't checked the air filter to make sure its sitting right.

 

Have the throttle shaft seals been replaced? They are often overlooked when carb servicing and are very important for carb tuning.

 

Where are they throttle shaft seals located, we replaced two o rings on the outer carbs, that had serious vacuum leaks.

 

There are two throttle shaft seals per carb, located on either side where the butterfly shaft goes though them. You can only get to the two outside ones easily (2 of the 8.)

Popping indicates a lean condition (consistent with a vacuum leak.)

If you have a valve that will require a shim two or three sizes smaller then you have a way too-tight valve and it will throw off any serious attempts to vacuum sync. In spec is in spec.

If you had to replace the outer two throttle shaft seals, then the other 6 are probably in need also.

 

They are the tubes in between each carb. They need replaced. You need to break the rack and replace each and every seal in order to properly clean and rebuild the carbs. Trust me. That is the only way you will get your carbs in working order. Taking shortcuts WILL NOT work. Do it right the first time and you will save yourself from weeks of pain and torture.

 

You guys are awesome, guess its back to the work bench.

 

Actually, no; the "tubes in between each carb" are the fuel rails (that use o-rings) the throttle shaft seals are around the throttle shafts. Throttle shaft seals are NOT o-rings.

If you're breaking the rack to replace throttle shaft seals, new fuel rail o-rings are a good idea too.

 

Oh ok. Whoops. My bad. Still learning about my bike. Ha ha. Thank you for clearing that up for me.

 

Ok, looking through my Haynes book, I don't see anything on the carb assembly that's called throttle shaft seals, I also don't see fuel rail o rings. I'm I going insane or senile or both? Sorry for all the questions guys, carb work is new to me and I'm determined to see it through to the bitter end.

 

In the parts diagram, every fuel rail is called a "connector".

I haven't been able to find the throttle shafts yet...

 

quebecois,I can't even find the damn connectors on this diagram. Guess I'll wait till Sunday and pull them off again, maybe I screwed them up somehow.
by the way, checked for vacuum leak using the tried and true method of shooting Carb cleaner all over the boots, no noticeable difference in idle. Also shot it between each carb, same result, no increase in idle RPMS.

On a separate note, can the engine popping be contributed to the exhaust? I recently changed headers and muffler, and notice an exhaust leak where the muffler and headers connect.

 

Yes, exhaust leaks can make the engine pop.

Connectors are parts 49, 50 and 51 on my diagram. They are shown with one o-ring at each end of each connector. It seems that throttle shafts (also called butterfly shafts) are non listed separately because they are parts of each "carburetor assembly".

 

CORRECT.

Truth be told, Yamaha didn't offer a lot of these parts separately; if you actually wore out a carb they wanted to sell you a whole new one for $300 or thereabouts.

That's why there's a healthy aftermarket, and more importantly why we have XJ4Ever. There are garbage aftermarket parts all over eBay, including common o-rings being sold as throttle shaft seals. They're not. Throttle shaft seals have a squarish, "fat-X" profile cross section to them.

Each carburetor "assembly" has a shaft running through the middle of it that the butterfly is screwed to. Where each of these stub shafts passes through the sides of its carb, there are seals on the shaft protected by a thin nylon washer. You can easily see, and carefully remove, the outer TWO; one each from the #1 and #4 carb. There are EIGHT of them. The only way to get to the remaining ones is to break the rack; and then to get to the "final four" (one in each carb) the butterflies must be removed because the shaft in each carb is integral with linkage pieces which trap the "inner" seal.

The FUEL RAIL consists of a series of tubes between the carbs, mostly sealed by o-rings (I say mostly because some of the 550s are a tad different) and responsible for feeding fuel to each carb.

If you want to get the correct parts and do it right the first time, get ahold of chacal (XJ4Ever.) HE knows what throttle shaft seals are, even if Yamaha won't admit to their existence.

 

Ok just figured out the confusion, I'm looking at the Haynes owners workshop manual, and your using the actual xj 650 manual, am I correct?
Parts 49,50, and 51 on my diagram are spring for throttle stop screw, cold start shaft, and throttle adjuster.
Ok, now that I think we have that cleared up, give me a basic location for which you speak. Maybe I can find it in my XJ disk, if I can find the disk, just move and crap is all over the place.
Really thanks for your patients guys, I'm a long time rider, but newb when it comes to working on my bike solo. Usually I take it over to a buddies house and we divide the task, he does one thing and tells me to do another, and it works.

 

The parts diagram I referred to is on my XJCD...

 

Here are the connectors:



And the 3 out of 4 throttle shafts:

 

Sorry, here are the connectors

 

Awesome Q, I'll be finding my xj disk tomorrow for sure. Now I know where to start looking, probably is an O-ring, which would explain why the RPM's didn't shoot up when I sprayed the carb cleaner, it didn't get down into it enough.
Damn I hate when I screw up like this, I should have known, I had the Haynes book, but still should have had the CD as well.
I've learned a valuable lesson, one I'll be sure not to repeat.
Hopefully I can get it to my buddies house tomorrow and we'll tear into it again.

 

I'll try to take a picture of throttle shafts seals, I have some for my XS650 carbs (where the he** did I put them?).

Bigfitz is right, they are not the same as o-rings.

 

Ok I'm about ready to shoot my Franky in the heads.
Cleaned carbs, replace all O ring conectors, found some very minor cracks in boots, but they were superficial, only on outside of boots. Same problem is still happening. Idle shoots up to 35k after it warms up. I'm totally lost as to what to try next.
I did find a small vac. leak, but I've as yet determined where the hell it is. I've put heat resistant silicone around where the gaskets go connecting boots to head hoping that the gaskets were maybe dried out and worn.
SO guy's I'm getting very frustrated, as I'm having a sort of family crisis and the ONE way that I can clear my head and think things through without a lot of distractions is riding.
I need serious help.