mystery part

[lowmanj]

What is this part, pictured from the right side of the bike?
It is where the carburator vacuum line attaches at rear of engine.
What's it called, what's it do and is it expensive?
Thanks

[WingAdmin]

It's part of the pulse generator. That part in particular is the part that the vacuum hose connects to to actuate the spark advancer, which adjusts the timing of the engine when you accelerate and decelerate to prevent detonation and popping.

Pulse generator sets can be had for $150-$180, the advancer can be found for around $100-$120. You may be able to find them cheaper if you look around online.

[lowmanj]

I guess I'll let it go for now. I was going to throw a new one in since I have the bike broken down so far. But that's when I thought it was inexpensive, like an O2 sensor or something.
If it were to need replacing, what kind of indication would I see?
Thanks again.
Jesse

[WingAdmin]

The timing would not change when you opened and closed the throttle.

[littlebeaver]

Lowmanj, I have messed around a bit with these vacuum canisters, first off I will tell you that you have a leak, I can tell just by looking at your photo, let me explain, I actually took one apart to see what does what and study the thing, if a person can see that screw on the rear of the canister then you have a leak there, they are all sealed but the seal comes off in time.. so get you some epoxy or J B Weld and make a spitball out of a small piece of tissue, stuff the hole with the spitball then seal it, the reason for this is so no epoxy goes inside..Let it dry then test it, I wrote a topic on this subject here explaining this so maybe you can get more from it..Yes you can adjust the timing with this canister I have done it, you will need a timing light to do so.. If anyone ever removes one of these units be careful not to spin the arm, and mark the baseplate with a marker before you remove it in case the arm get turned.. Good luck, if it still leaks you have a hole in your diaphragm in the canister. WingAdmin. is spot on with the information he gave you..

[lowmanj]

Thanks very much. I'll resurface the issue and work on timing once I get her running again. I'm rebuilding the carbs now, so will get into synching them and adjusting idle and checking timing soon as that's done.
In the meantime, I'll take a closer look at the screw you spoke of.
Jesse

[littlebeaver]

I just checked mine and made some ajustments, if you need help I would say that you are around some really smart people here... Not me, but everyone else ha ha.. Here are a few photo's of the vacuum advance so you know what it all looks like apart, you must remove the swingarm to get it off, or remove the engine, swingarm's easier..

This is what it looks like off the bike

This unit is apart in this photo, the small nail is to remove the circlip

[rightwing]

So where do I purchase a new Vacuum unit. I now have two bad ones after buying used ones.

[littlebeaver]

Send me a pm perhap's I can help you out.. You can't buy them new anymore that I'm aware of..