[jddwls]

OK so little background:

Bike is a 2003 vt750dc

39t rear sprocket
upgraded the clutch springs
advanced timing 3º
and synched the carbs to withing 1/2" using the homemade mamometer method

now the bike runs like crap. I started with the a/f adjustment screws at 3 1/2 turns out (as per vt750dc.com) I have slid them in from there in gradual 1/2 turn increments. Choked the bike will start and run fine, but any movement of the choke the bike quits on itself. Any suggestions before I start adjusting again?

Before I used the mamometer to synch the bike did run, albeit a little "off" but it was rideable. It was just a pain in the ass to start cold, I would have to turn the idle stop all the way down, start it choked, let it warm for a few minutes and then turn that idle stop knob to the max as the choke was released. Now I cannot get anything to work. Also, when the bike was first started with the mamometer the rear cylinder had almost all of the pull. Now that it is synched/balanced, I cannot keep it running at all. Any help would be appreciated? Am I missing something?

 

[John Hopkins]

First thing to ask is when you decided to sync the carbs had you already replaced the fuel and air filters, stripped the carbs, cleaned them, fitted new repair kits, leveled the floats and checked the diaphragms for splits or pinholes and lubricated the choke and throttle cables..If not then you probably wasted your time.

John.

 

[adlowe]

Put the screws back into the holes used for carb synching.

Seriously, though: Carb synch means little when RPMs get above idle, less and less as the throttle opens wider. You've probably got something else wrong.

I started with the a/f adjustment screws at 3 1/2 turns out...

IIRC, your service manual instructs starting 2 3/8 turns out.

 

[jddwls]

Yes carbs were torn down, checked and reassembled. Synch was done to try and rectify cold start issues. I'm going to crawl all over the bike again tomorrow hopefully

 

[jpr1968]

sync has nothing to do with cold start issues. The cold start issues are idle jets and choke/enrichener.