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Author Topic: "Popping" off throttle, deceleration  (Read 1403 times)

boggy

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"Popping" off throttle, deceleration
« on: May 10, 2013, 04:16:26 PM »
Just want to reality check this.  Carb was in good tune when I put it away.  Few weeks ago I pulled the bike out and did a few things, but nothing to the carb.  I did have the exhaust off for a new gasket.

I'm getting massive popping when I pull the lever in to shift, and especially when I decelerate.  My carb has always run on the rich side.

Before I even think about messing with the carb, I'm going to assume I have an air leak somewhere and the exhaust is the most likely candidate. I don't see any soot coming out of the head, but does that sound like the suspect of this type of behavior?  I might try doubling up on the gaskets.  Let me know if that's a bad idea.

Thanks.
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AgentX

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Re: "Popping" off throttle, deceleration
« Reply #1 on: May 10, 2013, 06:09:43 PM »
Did you check the rubber between the carb and the head?

barenekd

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Re: "Popping" off throttle, deceleration
« Reply #2 on: May 10, 2013, 06:10:00 PM »
Doubling up on the exhaust gaskets is OK. Or there are some hi-temp sealers you can use to stop any leaking. Try your local auto parts store.
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boggy

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Re: "Popping" off throttle, deceleration
« Reply #3 on: May 10, 2013, 07:23:12 PM »
Did you check the rubber between the carb and the head?

Visual inspection, yes, but not very thorough.  I wonder if I could put some water or other liquid on/around it to see if there are any visual indications... like checking a rubber roof leak?

Any suggestions for exhaust gaskets other than our host just so I can take care of business quickly?  I know they have some in stock now so no big deal if I have to wait.  I need a spare-spare clutch cable anyways.
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Blltrdr

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Re: "Popping" off throttle, deceleration
« Reply #4 on: May 10, 2013, 07:29:43 PM »
Visual inspection, yes, but not very thorough.  I wonder if I could put some water or other liquid on/around it to see if there are any visual indications... like checking a rubber roof leak?

Any suggestions for exhaust gaskets other than our host just so I can take care of business quickly?  I know they have some in stock now so no big deal if I have to wait.  I need a spare-spare clutch cable anyways.

Spray carb cleaner or starting fluid around the joints to see if there is a crack or loose connection. Also if you are running an aftermarket filter you will want create a metal mounting tab that tucks under your hose clamp and then is secured to a nearby frame stud or bolt. The carb is to heavy to let it dangle out there unless the carb is actually flange mounted like the Amal or PWK.
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boggy

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Re: "Popping" off throttle, deceleration
« Reply #5 on: May 10, 2013, 08:54:11 PM »
PWK flat-slide, metal flange mounted.  It's on there.  I'll try the spray.
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ace.cafe

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Re: "Popping" off throttle, deceleration
« Reply #6 on: May 11, 2013, 11:29:30 PM »
PWK flat-slide, metal flange mounted.  It's on there.  I'll try the spray.

That PWK is JB Welded together at the mounting flange. It has been known to lose its grip.
I'd check to be sure that it isn't coming apart there. That would cause an air leak.

But I do agree that since it happened after you worked on the exhaust, it is likely that something there would be the culprit. But not always. There are coincidences when something else goes bad right at that time.
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baird4444

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Re: "Popping" off throttle, deceleration
« Reply #7 on: May 12, 2013, 04:43:48 AM »
points slip, close up a little?
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boggy

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Re: "Popping" off throttle, deceleration
« Reply #8 on: May 13, 2013, 05:19:55 PM »
That PWK is JB Welded together at the mounting flange.

I don't know if you remembered Ace, or if that's how they come stock but you just reminded me that I actually JB welded a replacement flange on myself.  However, I can FEEL the air leak coming out of the engine where the header goes in.  Quite a large leak... like a pulsing hair-dryer. I'm going to try 2 new gaskets. 

Because that Goldstar header isn't stock, when you get it on and the mounting bolt behind the foot-peg lined up, there is VERY little wiggle room to adjust. It kind of lands where it lands on my AVL.  I'm hoping an extra gasket will seal it up otherwise I'll have to try a sealer of some kind. 

-If I use a sealer does it make header replacement difficult? Or does it scrape off?

-Do you still use a gasket with a high temp sealer?  Or is IT the gasket at that point?

I'm assuming you sort of line the exhaust port with a hefty amount and then place the header pipe in.
« Last Edit: May 13, 2013, 05:24:04 PM by boggy »
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ace.cafe

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Re: "Popping" off throttle, deceleration
« Reply #9 on: May 14, 2013, 10:06:56 AM »
If you use regular automotive silicone sealer, it will hold for a pretty good long time. It takes the heat very well. You have to let it cure the full 24 hours, so that it sets up good and hard, or the exhaust can blow it out.
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boggy

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Re: "Popping" off throttle, deceleration
« Reply #10 on: May 14, 2013, 02:42:55 PM »
I ended up buying the copper Permatex.  I was reading some other leak threads here and now I've realized this: My header pipe is a good deal smaller than the exhaust port.  It seems like the FIRST thing I should do is wrap up that pipe so the fit is nice and snug.  It's pretty clear now that it wouldn't seal up, as-is. 

I'm going to try that first with my old gasket before I try permatex'ing, as I'm reading it's tricky with that avl port and the smaller diameter headers.  The flange on that header doesn't sit flush to the port either.
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ace.cafe

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Re: "Popping" off throttle, deceleration
« Reply #11 on: May 14, 2013, 06:32:39 PM »
I ended up buying the copper Permatex.  I was reading some other leak threads here and now I've realized this: My header pipe is a good deal smaller than the exhaust port.  It seems like the FIRST thing I should do is wrap up that pipe so the fit is nice and snug.  It's pretty clear now that it wouldn't seal up, as-is. 

I'm going to try that first with my old gasket before I try permatex'ing, as I'm reading it's tricky with that avl port and the smaller diameter headers.  The flange on that header doesn't sit flush to the port either.

I wrapped my Iron Barrel header pipe at the head joint, and it worked real good.
I don't have the bolt-on thing like the AVL has, but wrapping seems to be a good part of the equation.
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boggy

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AgentX

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Re: "Popping" off throttle, deceleration
« Reply #13 on: May 15, 2013, 03:40:58 AM »
You could also use an exhaust pipe expander tool, no?

ace.cafe

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Re: "Popping" off throttle, deceleration
« Reply #14 on: May 15, 2013, 10:50:46 AM »
Is this the stuff? Exhaust tape. Up to 400 degrees.
http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_cool-tape-1-1-2-x-15-design-engineering_16120023-p?searchTerm=exhaust+tape

I just cut a piece of aluminum roofing flashing metal, or you could cut up a beer can or whatever, and wrap it around the end of the header pipe that goes into the head until it just barely fits in with a friction fit. That should fill up all the extra room. Cheap and easy, and you can adjust it to get the fit you want, and it doesn't blow out or burn out, and doesn't make a mess.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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