Pulls hard then dies out at 5500rpm

[Missile99]

I had this exact problem, I was missing one of the plugs on the breathers inside the carbs. Did you replace them?

If you are referring to the rubber pilot jet plugs then we are thinking the same thing. Without them the bike will run way too rich.

[GSNewbie]

Still working on this problem.

I just correctly ran a compression check and they are all within 5lbs. and at 130lbs with #1 at 125. (Hot w/ WOT).
Does this mean it needs a full rebuild or just the valve seals since it smokes a little at startup? It lists the compression new at 142 and I can't see 12 lbs low being a reason for rebuild...

I have not run it with the pipes off as there doesn't appear any way to get the cans themselves off of the head pipes and I can't see taking it down the road without any headers at all. They seem to be putting out a lot of exhaust and I can see no debris in them looking down them with a light.


The ignition advance appears to be working correctly. There is some resistance with the springs and turns 3/8" on the shaft without binding.

All the carb rubber plugs were intact and looked good in the carbs. I can pull them again and will soon if nothing else comes up as the problem.

Still stumped...

[TheCafeKid]

Did you actually disassemble the carbs and dip them and replace the orings?
Not just take them out and inspect them, but really follow the tutorial and clean them??

[GSNewbie]

No, I have not completely dipped 'em. I got them disassembled and they were super clean, synced, (checked that). I saw nothing that would lead me to go through dipping them and looking for all the rebuild parts. After trying about everything else, I'm back thinking there must be a passageway in there that is not a jet, needle, plug, or or vaccume diaphragm that might still be the cause.
Now to find carb parts (money) and dig in...

[TheCafeKid]

No, I have not completely dipped 'em. I got them disassembled and they were super clean, synced, (checked that). I saw nothing that would lead me to go through dipping them and looking for all the rebuild parts. After trying about everything else, I'm back thinking there must be a passageway in there that is not a jet, needle, plug, or or vaccume diaphragm that might still be the cause.
Now to find carb parts (money) and dig in...

You gotta dip em bro. You can't see inside every passage. The orings must be replaced etc. This is essential stuff. For as many times as you've had the carbs out and such you could have stripped em and dipped em and likely been riding trouble free this whole time.

If your diaphragms have any pinholes or tiny tears they're trash. If you need em, I have a like new set for sale in the parts for sale section.
If you bought them new they're nearly $100 each...

[tom203]

After trying about everything else, I'm back thinking there must be a passageway in there that is not a jet, needle, plug, or or vaccume diaphragm that might still be the cause.
Now to find carb parts (money) and dig in...

Oh yeah, there's lots of little passageways that you can't see -lots of places for gunk to hide and interfere with the carbs intended operation. Hopefully, your diaphragms are OK, so all you likely need is the new o-rings- avoid rebuild kits, your present stuff just needs cleaning.

[GSNewbie]

Ordered the carb "o-ring" gasket set. I've got the dip. We shall see...

[GSNewbie]

I got them stripped tonight. So far so good. Diaphragms look good. Pretty clean inside overall. No plugged jets. The connecting o rings are cracked and should have started leaking soon. The manifold gaskets were flat but not cracked yet. The rubber plugs were missing on the pilot jets so that would be a big problem. I was wrong about that. I had them apart 8 times messing with them and at some point had left them on the bench. So, that was a big part of the problem (but maybe not the only one). I tried to put them back in the carbs but they fall out. I'd guess that the rubber has shrunk (and they are cracked up too) so I'll have to find new plugs. It looks like the GS needed the overhaul. I don't have the funds to sync them at a shop (probably just bench sync) so it may be awhile before I can properly check it after the rebuild. Thanks for the help.

[tom203]

Flat lifeless "manifold" gaskets are likely to leak after reinstall, so get the stuff you need at cycleorings along with carb oring kits. Those rubber plugs will likely swell up if dropped in gas-might be useable. The bench sync is adequate, so wait till you find someone with the deluxe tool. Get this bike running right- you'll be amazed at it, and yourself.

[GSNewbie]

I did buy the kit from cycleorings. What a deal finding everything (minus the rubber plugs) in one place!
I had purchased this kit (when I posted "gasket kit" it was really this one). I bought the manifold gaskets at the time too. I bought the rubber plugs new oem on ebay last night. So, may be going within the week...

[jwhelan65]

Dont forget the rubber plugs, I think that is where the problem lies

[GSNewbie]

So she is back together and running better than before. Many o-rings were lifeless, brittle and cracked. The plugs are in and it revs up the rpms.

I think that it revs too slowly as it seems sluggish and has a slight miss at idle. I'm thinking it's possibly running rich...

[tom203]

So she is back together and running better than before. Many o-rings were lifeless, brittle and cracked. The plugs are in and it revs up the rpms.

I think that it revs too slowly as it seems sluggish and has a slight miss at idle. I'm thinking it's possibly running rich...

Run it some more, pull plugs to make sure they all look similar. Did you just bench sync carbs? "revs too slowly"- the 650 shafties aren't rocket sleds, they need some revs to inspire them.
Put bike/model/year in your signature to help those of us with memory problems.

[salty_monk]

I chased a problem like this for months on my 1000G. Turned out to be nothing to do with the carbs & fueling... was a fault with the ignitor box. Symptoms were pretty much identical.

I did the test in the Clymer manual & it tested bad (the one where you supply a charge with an AA battery etc) but I don't think you can always see the fault in these tests.

Fix was to fit a Dyna S.... $120 well spent.

[tom203]

Might be igniter, but I'd make sure my advance mechanism isn't sticking- pull off signal generator cover and check for free movement.