Carbs popping off

I have a 1979 xs 650. I have rebuilt the carbs and greased the advance rod due to poor idling and trouble starting. This has corrected many problems but still a problem is that once ridden and warmed up when kick started the carbs will pop out of their boots. I have changed all the fuel and vac hoses. I have just experienced that the vac hoses are blowing off there boot.

Any suggestions?

not tryin to be a dick but are you using clamps? are the boots original? do the boots still have the metal shroud? the shroud helps keep the clamps from cutting into the rubber and gives the boots more strength to help hold the carbs.

when the carbs do pop out do you notice them being blown off from little backfire?

J Allen

I can tell you right away what your problem is - I had the same thing happen to me several times last year. It's simple: your maching is not set-up right, so go through the tried-and-tested process:

1. check cam chain adjustment to spec. (if you can't get it correctly tensioned you will need a new one.
2. set the valve clearances to spec (set and check, turn engine, check again);
3. set timing (it will need to be re-set to new chain tension/valve clearances)
4. then, and only then, get to the carbs.

Be thorough, be patient.

Carbs - hang on, there are guys on the forum with muchg greater knowledge, but here goes:
If you haven't done so already, remove, clean, check all parts are serviceable. Adjust float heights to spec. If you have stock set-up, uses stock settings (read the Carb Guide - a must). Custom set-up you will need to jet accordingly (read the carb guide).

Finally, then you can get to what Deadchef has said above. Clamps wear so they do not tighten as they should, and boots wear so air can get in for that blow-back effect.

The likely scenario is this: the machine is incorrectly set-up so valves are not opening and closing as they should. Blowing the carbs off (they go with a big pop, don't they!) is fuel igniting and blow back through the inlet.

Come on J Allen, let's get that sorted. Plenty of guidance on the forum and the YouTubne videos.

Let us know how you get on.

ANLAF

Thank you both for your responses. I will go through the steps of timing.

Have you adjusted the timing any since you had it running previously?

no I have not adjusted anything the chain needs to be readjusted but I want to be sure of the problem before I made any adjustments.