Motorcycle Repair: Carberator, suzuki gs400, carb synchronizer

Question
Hi.

I asked you a question previously about an overspeeding idle.  Your response was very helpful and I solved the problem at least partially.  I have a '78 Suzuki GS400 with Mikuni twin-jet carbs with a large diaphram attached to a needle style.  I rebuilt and dipped the carbs and replaced all the rubber.  I was very careful not to tamper with anything unnecessary.  The gaskets from cylinder block to the spacer which leads to the carbs were missing, so I carefully cut some from fuel-line gasket material I got from NAPA.  I tore them up the first time I installed them which caused them to leak, and I detected the leak with your method of spraying carb cleaner.  Thank you.  I fixed the leaks which newly hand-cut gaskets.  Before I fixed them was overspeeding all the way to 7000.  I also replaced the throttle return cable and the throttle cable.  The bike used to idle really well at around 1500 when it was cold but would overspeed to around 5000.  

Now that I replaced the 2nd faulty gasket, it just starts up, revving way up to 5 or 6000 with the choke on, and then dies when i turn off the choke.  It also backfires some.  I have the point's timing pretty close to perfect.  ALso, new spark plugs, points, etc.  I got a carb synchronizer and synched the carbs.  I haven't synched them sinced I fixed the second leak, but I have hooked it up and tried and they aren't terribly off.  My diaphrams didn't seem to have any holes in them when I took them out, but I did let them sit on their sides some.  I didn't think it was excessive or the cause of a permanent deformity.  Could that be the problem?  THe spacers have a notch in them which, if I remember correctly from the parts breakdown I saw at the parts store, goes to the outer top.  It doesn't show in the haynes or clymer.  Just speculation.  I put them in so the notches faced out and up rather than in and down.
Thanks for taking the time to read this and help me, I really appreciate it.  Could you also resend your carb troubleshooting writing?  It was very helpful last time and I appear to have lost it.

Any follow-up diagnostic questions for me?

Thanks again
Jeremy John  

Answer
Hi Jeremy,

Cut and paste your question and send it to me as an email. My email address is: mshively1@woh.rr.com

I'll return carburetor files via email.

Visit Bike Bandit's website and indicate to me by part number the parts you're making by hand. Cut and paste the following link:

http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_de...


Respectfully,
Mark Shively