Help me diagnose this popping sound---with video

[pjm204]

After putting on a new exhaust(PO cut off the exhaust at the midpipe), new stock filter, rejetting to 122.5 main and 47.5 pilot, fuel screws to 3.75 turns out(probably too much), and cleaning/new o-rings, the exhaust is popping at idle. It also doesn't seem to like having the choke on.

Here is a short video that doesn't really catch the popping as well as I would have liked. It has good throttle response still and will maintain a constantly idle but it pops out the exhaust.

http://s267.photobucket.com/albums/ii291/pjm204/bikes/?action=view&current=DSCF0137_mpeg2video.flv

[Suzuki mad]

Its runing a bit high at tickover.

I would suggest from the noise that its running a little on the rich side. Running with the airbox lid off won't help it either.

Sounds a crisp motor when you blip the throttle though.

[almarconi]

Have you adjusted your valves?

I'd try 2 turns out on the adjustment screws.

When you had the carbs apart did you check float height?

Have you vacuum synced the carbs yet?

[pjm204]

Have you adjusted your valves?

I'd try 2 turns out on the adjustment screws.

When you had the carbs apart did you check float height?

Have you vacuum synced the carbs yet?

I haven't done the valves yet, I haven't vacuum sync'd them yet either. I did check the float height and I beleive I set them correctly to 22.4. I measured from the ridge on the carb body to the bottom of the step on the float with them inverted. So the popping doesn't sound like it is lean?

[almarconi]

How do the spark plugs look?

[pjm204]

BeforeI did the carbs and exhaust, the plugs were black and wet, I found 160 mains in the carbs so I figured it was running very rich. Now the plugs look pretty good, a grayish at the tip. I haven't changed the plugs yet.

[Griffin]

Sync the carbs and adjust the valves before doing anything else. You will never get the engine properly tuned without doing those things first. Once you get the carbs synced and you still have the tank off, adjust the mixture screws one by one so that you get the highest idle. Do a search for "plug chop" to get an idea of what different throttle settings to use to see where you are at.

I think once you really get the carbs dialed in and valves adjusted, you'll see you're not too far off from where you want to be.

[hampshirehog]

Griffin is spot on only, and I'm sure he meant it, check / adjust the valves first before synching the carbs.

I use a Gunsons Colourtune for adjusting the idle mixture - had it getting on for 30 years and swear by it (makes the job a doddle).

[pjm204]

I've done the valves on gs400's and 500's, is the 1100 difficult or should I take it to the shop? I'm half tempted to bring it in and just say, get it running right.

[Griffin]

I've done the valves on gs400's and 500's, is the 1100 difficult or should I take it to the shop? I'm half tempted to bring it in and just say, get it running right.

NO NO NO NO NO!!!!!!!!!!!!!!!

The 16 valve GSes are really easy to do valve adjustments on. No shims are required, just a feeler gauge, a wrench, and a pair of needle-nosed pliers.

There is a special tool to do them, but it's not necessary.

[Griffin]

Griffin is spot on only, and I'm sure he meant it, check / adjust the valves first before synching the carbs.

I use a Gunsons Colourtune for adjusting the idle mixture - had it getting on for 30 years and swear by it (makes the job a doddle).

Yeah, I didn't even put any relevance on the order I listed the tasks. Valves first, then carb sync, then idle adjustment.

[almarconi]

The problem with taking an older bike to a shop is that you'll end up paying alot of money and the bike probably will not run right. Most mechanics don't want to be bothered working on older bikes. With the money you save doing your own work you could buy another bike. I own two bikes so most times I have one to work on and one to ride. I can fix the bike at my leisure and not have to depend on taking it to a shop to get it running.

The valve adjustment on a 16v engine is simple. The only tools you need are a set of feeler gauges and a wrench. Z1 sells a tappet feeler gauge and a wrench set or you can use common hand tools. Replace the gasketwhile you have the cover off.

[83GSrider]

Pat, If you want to learn how to do the valves call me, it's easy. Also I have a carbtune so we could do the carbs.

[Gimpdiggity]

After putting on a new exhaust(PO cut off the exhaust at the midpipe), new stock filter, rejetting to 122.5 main and 47.5 pilot, fuel screws to 3.75 turns out(probably too much), and cleaning/new o-rings, the exhaust is popping at idle. It also doesn't seem to like having the choke on.

Here is a short video that doesn't really catch the popping as well as I would have liked. It has good throttle response still and will maintain a constantly idle but it pops out the exhaust.

http://s267.photobucket.com/albums/i...mpeg2video.flv

That's an aftermarket exhaust, obviously.

With that said, when you put it on did you make sure you put new gaskets in there??

I chased a fairly similar popping sound on my Ninja 250 (Kerker race pipe, stage III Factory Pro jet kit, UNI pod filters) for MONTHS before I finally ripped the exhaust off and found that one of the gaskets was bad. I had jetted, rejetted, cleaned, recleaned, ripped apart, reripped apart so many times I lost track. I probably ended up effectively jetting the whole bike 13 times over before I realized the gasket was bad. I was a bit embarrassed at how I could miss something so simple...but what's done is done!!!

That night I put a new gasket in it, and haven't had any popping sounds since!!!

Just something to think about if you get the carbs and valves all set and still have the issue.

[pjm204]

I did put on all new exhaust gaskets. Not saying it isn't leaking, but the gaskets are new.