Hit pothole....now it doesn't idle

1977 kz750b twin. Stock carbs, stock airbox, good condition rubbers etc. 

Was riding today all day. Bike was running. beautifully. Not far from home a car almost merged into me, forcing me to swerve and this gigantic pothole was unavoidable. 

Hit so hard the tailight lens broke off the bike, rear shocks bottomed out and damaged the remote shock resevoirs, no other obvious damage. 

Immediately pulled over to check and the bike idled ok while I assessed the damage.  A few blocks closer to home it wouldnt stay running without some throttle. Decent amount of exhaust popping when revving the bike. Idle was inconsistent.

Im gonna start in the morning by setting my idle speed and pilots to stock as a fresh baseline, any ideas what else to look at or why a hard hit like this would mess with my carbs?

Pipes  flattened under the bike perhaps?

Exhaust pipes appear to be undamaged, I will be checking them in the morning for any loose connections

Exhaust popping is usually timing issue or lean exhaust. If lean, popping is usually when you close the throttle. On cars with distributor, if you install distributor, say 2 tooth off, it'll pop. One tooth off usually rough idle.

Hope this helps in some way.

It sounds like you have unmetered air getting in between the carbs and engine. Given the violence of the impact had it displaced the carbs in the inlet rubbers ? Or has a vacuum pipe come off?

Might be some rust or other crud in the fuel system got knocked loose and is partially clogging the carbs.

After checking all the obvious, it seems like the carbs are flooding. I'm gonna guess the most likely cause is crud knocked loose from the impact and clogging some carb jets or stuck float. 

I've managed to get it to a point where it will idle, not that well but it does hold an idle. Seems to idle high for a few seconds at a stop then idles down to around 1k. 

You might try draining the carbs into a clean container and looking for any silt, rocks or pterodactyl bones.

For a conclusion to this problem. I got it running enough to head out and enjoy the rare 80* ohio sprong day. Carb was flooding at low speed or idle, was manageable. 

I drained the carbs this morning just using the bowl drain, flushed them by just running fuel through them, one or two extremely small flecks of rust came out of the left side carb only. Somehow small enough to get past my filters, guess I will look for smaller micron filters. (Not unexpected, my tank was rusty as can be last season when I bought it, even though I evapo-rusted it last fall I'm sure there are still tiny particles stuck places) 

That all said.......bike runs great now with just that simple fix. Idles better than it did before the pothole. Gonna road test some this morning before it rains but I think it's fixed. 

Thanks everyone, always appreciate how responsive this group is. 

wrote:

Pipes  flattened under the bike perhaps?

This was a great guess. I wouldn’t of thought of asking it. Makes great sense. 

Research the ideal filter size. Gravity feeds don't like too tight of a filter. I looked it up awhile back I just can't remember the micron size.

These filter down to 10 microns and have a washable filter media, so it basically never needs replacing. I have one on my ZRX and have been pleased as punch with it.

golanproducts.com/product-category/filters/super-mini-filters/