No vacuum in Carb 2 during sync

[Guest]

Hi Fellas,

I was trying to sync my carbs for the first time today(with the Motion PRO carb sync thingy), and had no vacuum in the #2 carb line. After reading other postings I'm thinking (hoping) that this is because I didn't plug the petcock vacuum line...does that sound right. All of the other carbs were fine. (Actually, I did get a little in #2 but it was only apparent when the rpms were way up)

Just hoping I'm right so I can stop thinking about it and get some sleep....
Thanks

[gustovh]

make sure that the vacuum line is not cracked at the connections and causing a leak.

V

[azr]

Yes, plug the vacuum port on your carbs and if you didn't do a good bench sych it could simply way out on #2 and just not reading yet.

[Clockeman]

Plugged the port, I had already bench synched the carbs, but still nothing. It may be a bad carb boot. I need to check the compression too, maybe, god forbid, the problem is deeper. Oddly, it seems to run better than ever...

[Gorminrider]

In the vein of "god forbid", Did you check the valve clearances? I think it's best to check valve adjustment just before doing a carb synch.

[geol]

First thing to do is check compression in all cylinders. If a valve is hanging open you will have no or very reduced compression in that cylinder. If you have good compression, then you had best look to see if that cylinder is firing by swapping 2 and 3 plug wires. If problem then moves to cylinder 3, then you can start a thread in the electrical section. If compression is down, try adjusting valve clearances on ALL the valves.

[JJ]

The first thing that should be done when tuning a motorcycle is to adjust the valves. Everything else comes after valve adjustment.

[geol]

JJ, If the cylinder has no compression it is likely valve clearance but could also be a broken ring or a valve issue. ALWAYS check compression first and then try and pinpoint the reason... I didn't suggest a leakdown test as that is pretty much beyond novice mechanics so if there is bad compression, then see if the valve clearance are the culprit. When you roll up on a new bike and need to check things, take a COMPRESSION GAUGE and a socket to remove the plugs. If the bike won't turn over, be leery about getting involved with it unless you are also willing to do some top end work.

[JJ]

JJ, If the cylinder has no compression it is likely valve clearance but could also be a broken ring or a valve issue. ALWAYS check compression first and then try and pinpoint the reason... I didn't suggest a leakdown test as that is pretty much beyond novice mechanics so if there is bad compression, then see if the valve clearance are the culprit. When you roll up on a new bike and need to check things, take a COMPRESSION GAUGE and a socket to remove the plugs. If the bike won't turn over, be leery about getting involved with it unless you are also willing to do some top end work.

I didn't say anything about what steps to take when checking out a prospective purchase, or a newly purchased bike. I stated that the first thing to do when TUNING a motorcycle is to adjust the valves.