1981 XJ650 finally getting right!

Had a hell of a time figureing this one out.
Started out when I bought it would foul the plugs real quick.
The PO had had the carbs rebuilt by a "race guy".
I was looking into piss poor fire for the plugs after assuming the "carb guy" new what he was doing. I rebuilt the fuse box, added pod filters to try to get it lean. Swapped out ignition control box. Replaced spark plug "caps". Went to a hotter plug. Swapped out Ignition coils. All to no avail.

Rode it for ~3000 miles back and forth to work (80 miles roundtrip) while getting 20 miles to the gallon. While still trying to figure it out.

I removed and cleaned the carburators 3 times or so. I talked to Rickcomatic on the phone for pointers. Tried adjusting the air fuel mixture.

Finally getting some better. Still extremely rich surges at low speeds. Cleaned out the starter circuit in the carbs. 3 of 4 were plugged up. Getting so the start lever functions but still rich as hell!

Took carb rack off this weekend and rechecked float height. set it to 1/2" from the carb body to the bottom of the float. Installed new stainless steel Allen headed drain screws. Had to drill and easy out 2 of them (could have been 4 I guess?).

I finally opened up the top of the carbs, removed the diaphrams and the plate covering the main and pilot air jets. Something didn't look right!javascript:emoticon('post', 'message', '')
Surprised

I inspected a carb from my spare rack and discovered that the main and pilot jets were swapped when compared to my spares!javascript:emoticon('post', 'message', '8O')
Shocked

I then researched on this site and found a reference to there being a misprint in one of the aftermarket manuals where the main and pilot air jets were labled wrong!javascript:emoticon('post', 'message', ':idea:')
Idea

I installed them they way my spare set was set up .
I then reassembled everything. Cranked it up and it idled real high ~ 4500rpm . I backed off on the idle adjustment and low and behold I have a decent running 27 year old XJ650 with 6,000 miles on it. javascript:emoticon('post', 'message', '')
Very Happy

Idles as it should, plugs look good, can go 25mph in 5 gear with no surging or "spitting back".
I am impressed with this thing! I got 51 miles per gallon on my most recent cruise to work this morning. Used to have to fill up 2 a day. Now I think I fill 1 in 2 days!javascript:emoticon('post', 'message', ':!:')
Exclamation

Thanks for the info on this site the good people and especially Rickcomatic for his advice and expertise. (Rick I have not forgot you, wife did however I rectified that this morning)javascript:emoticon('post', 'message', '')
Embarassed

I would say it is running at ~ 90% efficency. Now I need a color tune and a carb sync and I think she will be 100%.

 

good to hear you got that worked out. Sometimes it is just that simple.