XJ1100 Mikuni Carb Problem

I have had my carbs off about 4 times so far and they still are not right. I only want to do this one more time if possible. So I am looking for some advise. I first got the bike the carbs were pluuged with the typical brown goo and dryed gas and such. No water Thank God. I cleaned the float bowls in carb cleaner let soak for about and hour. They came perfectly clean. Spray carb cleaner and it shoots out about 10 feet. So moved on to clunk test and breifly soaked the carb bodys for about ten minutes. Should not have hurt the shaft seals in that little of time. Blew out and checked float levels al seemed ok installed on bike and carb syn'ced The bike seemed lean. Rode it several times. Noticed popping in the exhaust when backing off and down shifting when coming to a stop sign. I just knew it was not right. Pulled the carbs off again and found red rust in the little wells in the bottom of the float bowls????? the tank was cleaned and I'm not sure where that came from. Cleaned again and installed new needles and seats since the carbs were off again. Checked float level with clear plastic tube its right at the lock washer under the bowl screw. Should be OK so I got the idea if I were to start pulling plug wires to see how it effected the idle maybe I could Isolate it to the culprit. it was # 3 cylinder not working. So I pulled the plug and it is snow white the other ones are slighty brown but they are for sure on the lean side. and compression is good. So it brings me back to that carb. I pulled pilot jets and they are good. Sprayed carb cleaner up the little brass tube and the vent holes are clean. Blew out with air and reinstalled them again. Same problem. What the heck am I missing. I pulled the little tamper proof plugs out and have tryed to adjust the mixture. ( I also took them out and blew out with carb cleaner and compressed air) My other bikes have the Hatichi Carbs and I have been able to get those to work really well. These are alittle different. Would or could the enrichement circuits be causing trouble. I only cleaned them the first time I had them apart. I think the enrichement only works when you push the choke lever over to start it or could that circuit be in play with the needles closed.
As a Note: we set the valves and they are on the loose side. I know I can't get a good carb sync if the # 3 carb is not working correctly since you have to set the other three to it. Also Checked for vacuum leaks with a propane torch (unlit) to see if the idle picked up. It did not since the carb boots were replaced with new gaskets the first time I had the carbs off. I'm running out of ideas on this one. Thanks for your help in advance.

 

Update:

Went through the carbs again tonight, Pulled the intake manifolds off and checked gasket & sealing surfices. Checked #3 manifold and the gasket looked like it may not have been sealing right around the 7 oclock position. I sealed the intakes with permitex ultra black to be sure I don't have any leaks. Put it all back togeather and it runs better but it still pops slightly at high RPM with throttles closed much better than before. It idles better and responds to the throttle. But if I crack the throttle and let off quick it dies. I can start it right back up with no problem. I beleive it is still lean. I have the stock jets in there. It should be ok because I have not modified the exhaust at all. I do have a small crack in the right outer pipe where it goes into the muffler. I wouldn't think that that would have anything to do with it dieing out after a quick throttle rev. all carbs sync'd at about 10 in hg with out YICS tool. ( I still need to make one to dial it in ) Thanks for looking

 

Did you remember to put the booster sensor hose back on?

and... are you using the octopus or did you chunk it?

 

The booster sensor (little black box with vacuum line attached) hose was attached to the #2 carb and it is in place. The octopus I assume that that is the vacuum diaphram that contols the fuel flow to the carbs. I put a rebuild kit in it and it is in place and plumbed as per the diagram under the seat.

I worked on this thing last night I got #3 to fire now but if I turn the mixture screws out it gets rich with any more than 3 turns out from bottom. It has to be real hot before you can crack the throttle and close it quick for it to stay running. I think its close but I'm at a loss as to why it seems lean. It idles rough but smooths out at anything above 1500 RPM. So I can add some propane to the air cleaner and it idles so nice. Take the propane away and it goes back to rough. I went all around the carb bodys again with the propane to see if the idle picks up and checking for more places for vacuum to leak. All seems to be good

I did not use the YICS tool to sync. I need to get one or make one and see if that helps. There seems to be a big debate on tool or no tool when you sync. I'm also going to try a infrared thermometer to see what the exhaust temps are to see what that might tell me.

 

Any update on this one please?

 

Its running good but still pops in the exhaust when I let off at higher RPMs Starts and runs fine. I think the next step would be for me to lower the float levels just a touch. My plugs are ok but when I shut the bike off when its hot the carbs seem to overflow alittle and its hard to start if I don't leave it sit for awhile. Otherwise the idle quality is good and driveablity is great. Crack the throttle and hang on thats for sure.

MN

 

Hey guys have a 83 1100xj and was just reading up on this thread I do not want to JACK it lolol but I was wondering where was the booster sensor I did the carbs and fuel line but the only thing attached to my lines was the vacuum diaphram so am I missing something in the lines . Maybe thats why 'm getting no top end

Thanks

 

The boost sensor is located under the tank. It looks like a black plastic box (Similar to the Ignitor) with a vacuum connection coming out the bottom.

MN

 

Well seems like I do not have that booster.....Trying picture it but don't recall it being there. Can I see it with not removing the tank.

Thanks

 

You'll have to lift the tank up in the back and you might get it up high enough to see it.

MN

 

Does not having the booster affect the bike performance.

 

I'm sure it changes the advance for the ignitoin at higher RPMs

MN

 

Well you see I get good performance out of the bike just went a few long trips and no problems but I know I'm not using all of the xj1100 power thats for sure

 

The thing is I get high rpms till 4th gear then shifting into 5th I cant reach the 7500 rpms

 

That booster would affect all gears woulnt it ...

 

I get the best results:

Syncing with Tool.
Increasing rpm's until the Throttles transition to Off-idle.
Leaving the Tool in and "Tweaking-out" the Poppity's.

You can hear the Bike miss as you smooth-out the idle.
It will ... Purr, purr, purr, purr, poppity-poppity, purr, purr.

Get rid of the poppity, ... then ... pull the Tool.
Now, tune it like you'll be riding it.
Lower the Idle ... close your eyes and listen to it.

Once again, find the Poppity if its doing it.
Lose it.
Set the idle.
Run it.
Check the Plugs and Cop Tweak.