Vacuum leak--o-rings replaced still an issue

[Guest]

I've been fighting an apparent vacuum leak in my GR650. I tracked it down to the o-rings in the Intake boots, but I am still having an issue after putting the new ones in.

The bike starts an idles well if the choke is on. Stalls if the choke is turned off.

[Steve]

How new are the boots?
It's possible that the rubber is pulling away from the metal.
It's also possible that there is no more "squeeze" left in the old, hard boots, so the clamps are not sealing properly.

Have you cleaned the carbs?
If it won't idle, you either have dirty pilot passages or the idle speed is simply too low.

Where are your mixture screws set?
Not sure about your bike, but most of the GS bikes came rather lean from the factory, with about 1 to 1 1/4 turn on the screws. Most of us agree that it needs to be closer to 2 full turns, but will start at 3 turns to ensure a properly rich mixture for easy starting, then adjust in from there.

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[mustangflyr]

I've been fighting an apparent vacuum leak in my GR650. I tracked it down to the o-rings in the Intake boots, but I am still having an issue after putting the new ones in.

The bike starts an idles well if the choke is on. Stalls if the choke is turned off.

Make sure that the carb manifold o-ring surface is true, they tend to warp and leak past the o-rings. Can be as simple as using a flat file it worked on my 1000.

[jwhelan65]

This is a great source, download and save it.

http://www.mediafire.com/?zx5unr1sxq0cvvx

[oldrookie]

Thank you for the suggestions.

I think the boots original to the bike, but they seem to be reasonably flexible.

I haven't yet cleaned the carbs, but the PO had it done in September. I haven't messed with the mixture screws yet.

The manifold surface could be an issue. I'll lay a flat edge on it an see how it sits.

It is possible that the o-ring moved out of the seat area.

The bike idles nicely with the choke on. Not at all without it.

Thanks again.

[bwringer]

Carbs can and will gum up in less than three weeks, let alone the nine+ months since last September!

Clean the carbs... it's your only hope.

[tom203]

I've been fighting an apparent vacuum leak in my GR650. I tracked it down to the o-rings in the Intake boots, but I am still having an issue after putting the new ones in.

The bike starts an idles well if the choke is on. Stalls if the choke is turned off.

I would think a air leak in boot/ o-ring area would give you an erratic idle no matter where choke was. As Steve said, try openning up mixture screws. Hopefully, PO did thorough carb cleaning, but idle problems usually signal incomplete cleaning. Was fuel stabilized last fall??

[OldVet66]

Clean the carbs. They can not be cleaned any other way except by soaking in a good carb dip to melt the "molasses like" crud that blocks the passages. If they weren't dipped, you will find all sorts of trash in there now that they have had gas in them. What most people consider a good cleaning with spray carb cleaner and compressed air is just enough to loosen up the junk in there a little so it blocks something else up later.

[oldrookie]

I've reached the same conclusion and will be tearing into them shortly.

It may still be the intake boots are involved. Griffin has offered to stop by take a look when he gets a chance. He doesn't live too far from here.

Been ten years without a bike, a few more days/weeks won't kill me, but I really want to get this ol' gal on the road.

[oldrookie]

Have ordered new intake boots and a spare set of intake o-rings. Ordered a set of o-rings for the carbs from Robert Barr. Ended up buying the set for four carbs, even though mine is a parallel twin. Figured it couldn't hurt to have spares in my inventory.

Figure I'll tear into the carbs and have them disassembled and clean by the time the o-rings and boot arrive (3-5 days.)

Will be taking another more serious look at the tank as well. It looked pretty good, but that was a pretty cursory inspection. I think a drain and strain to look for rust is in order as well.

[Nessism]

When the intake boots are bad, or the O-rings leaking, the symptom is a high idle, or hanging idle (engine rpm's hang up and doesn't drop to idle when reved). The symptom you describe, no idle or idle set too low, is unlikely to be related to the boots and/or boot O-rings.

Sounds like you are on the right path now regardless. Clean the carbs w/fresh O-rings is always good.

[oldrookie]

Well, the boots were only moderately pliable and I can still change the idle by spraying electrical contact cleaner around the right boot. Something fishy there, but clearly not the whole story. Won't hurt (until my wife hears the price) to replace them while I am trying to recondition this old bike. (Sounds like a great idea for a podcast, but This Old House would probably sue for trademark.)

The carbs are the most likely problem. I admit to trying to avoid tearing them apart. Last time I cleaned carbs was about 12 years ago. I'm still surprised the bike ran.

Far better tutorials available now, so my comfort level is a bit higher

[Nessism]

If the idle changes like you describe the boot is bad. No doubt. Part Shark usually has good parts prices.

[oldrookie]

Well, Part Shark would have saved about $8.00 per boot, but I'd have shipping costs...so might have saved a few dollars. I'll remember them in the future.

[bwringer]

Well, Part Shark would have saved about $8.00 per boot, but I'd have shipping costs...so might have saved a few dollars. I'll remember them in the future.

Just FYI, http://PartShark.com is based at Flat Out Powersports' location in Martinsville, Indiana, so if you buy from them, you have to pay Indiana state sales tax. This pretty much erases any price advantages for us. They instituted a minimum "handling" charge and stopped allowing in-store pickup a while back, so I stopped ordering from them. (Cheapcycleparts.com is based in Southern Indiana, so ordering from them presents the same issue.)


These days, I order most of my Suzuki stuff online through my nearest dealer, Westfield Yamaha Suzuki (I live on the NW end of Indy). Bit of a haul for you, but they ship free for orders over $100, and you'll get it the day after they do. They've always been very prompt for me. I've almost always gotten my stuff in less than a week.

Or, you can always choose "in store pickup" for free and they'll call you when your stuff shows up. (Really! Very good service.) Then you get to go slobber on some new machines, paw through the gloves, sneeze in the helmets, etc. Always a good stock of gear, tools, supplies, gewgaws, etc. too.

The parts cost a wee bit more than Partshark, and there is that damn state tax, but free shipping almost always makes it a wash or better.


Unfortunately, your nearest Suzuki dealer, Dreyer, doesn't offer online ordering, and I've never really had a productive visit there. Sky-high markups and some very bad attitudes from the teenage hood rats back in the parts department... YMMV.