Gs 850 Popping On Deceleration Need Help Please!

[Roostabunny]

I appreciate what all of you have said.

Here is what I found when removing the airbox.

The side seals are crumbling and gone. The seal on the top of the filter element that fits to the airbox is gone too. The air filter element is trashed and crumbling.

Can I buy just the foam element for the filter or do I have to buy the whole thing including the squirrel cage? These things are stupid expensive!


Jim

I think you can get just the foam element for your filter but I don't have a source off-hand. I'd think BikeBandit or Z1 or Flatout would have them. Buy a spray can of filter oil while you're at it - as fussy as these bikes are about intake, over and under-oiling the filter can mess you up as well.

Meantime, I fixed both the disintegrated foam seal on top of the filter and the side seals with $4 worth of weather stripping from Ace Hardware. The filter seal I just scraped off the housing (tight fit for your hand) and I fixed the replacement weatherstripping directly to the filter rather than trying to get a good flat adhesive seal inside the airbox. Muuuuch easier, given the tight quarters. See my pics for a little detail.

Others have had success replacing the side seals using silicone caulk and plastic wrap as a release film. If you can't re-use the top part of your side seal as I did, the silicone method might be easier. Never tried it though.

Also, when you have the airbox apart, make sure to clean out the narrow space at the top of the inside of the box. It leads to the breather hose fitting. It's real narrow - a 12" or so piece of wire from a coat hanger, with the final inch bent at a 90° angle works like a charm to "rake" the rust gunk out of there.

Welcome to the 850 club, and good luck.

[bwringer]

Decel popping is also a classic sign of exhaust leaks, too.

If you've had the exhaust off, did you replace the gaskets between the pipes and the cylinder head? Did you get the old ones out completely out? Any rust holes?

There are also a couple of places underneath where the pieces of the exhaust are clamped together. The sealing "sleeves" between these might be damaged.

And please, check the valve clearances ASAP.

[jimfj]

ARRRRG!

I sealed the airbox completely and replaced the foam on the airfilter. Homemade job but it fits the bill. I rechecked everything,
Carb boots --okay
air box boots--Okay
air box sealed--done
new plugs--done
Carb adjust, each needle turned out or loosened to get more flow and still she pops on deceleration...not as bad but its still there.

Where do I go from here?

I haven't checked the exhaust other than a visual inspection and it looks to be fine. My GS425 didn't have any gaskets between the pipes and the head. It just had the 2 little sleeves.

As always help is appreciated.

Jim

[chuckycheese]

Plugs?

I was the first one to respond to your post and asked about your plugs. I know they're new but what do they look like? You've never mentioned that.

Personally, I think air leaks are overrated, rarely found and not often the problem. I base that opinion on anecdotal information here on the forum and personal experience. I've had leaks that caused no problems and have experimented with loosening up boots to see if I could cause a problem. I'm sure leaks can be a problem, for certain, but I don't think they usually are.

If you do a search, you'll find air leaks blamed for something every day but when people follow-up with their solutions, it's usually a carb problem.

[rustybronco]

Based on my personal experience, the air box seals made a big difference as did putting the air filter back in correctly. the plus side is, now you know they are done and eliminated from the equation.
one thing I would add to what was said, when you go through the carbs, be sure that you look through all the jets, emulsion tubes, seats and make sure they are CLEAN. I use a jewelers eye loop, no need to do the carbs twice!

***check jets sizes***

[jimfj]

Here is a picture of the new plugs after a 10-15 miles ride. I live in the city so there is some stop and go, cruising at 35-40, and one short romp at 50 to 55 for about 2-miles.



What do we think?

Jim

[chuckycheese]

Lean

No surprise based on your 'symptoms'; they're very lean. These bikes seem to run best when they're slightly lean but that's too much. I'd back the air mixture screws out 1/2 turn on all of them and see what happens. If they darken up a bit, you can fine tune from there. I'd be curious to know how many turns out they are right now but the most important thing is to see how 1/2 turn counterclockwise affects their appearance.....and your overall performance. Good luck!:-D