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General Discussion => Tech Tips => Topic started by: boggy on May 10, 2013, 05:16:26 pm

Title: "Popping" off throttle, deceleration
Post by: boggy on May 10, 2013, 05:16:26 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.
Boggy
Title: Re: "Popping" off throttle, deceleration
Post by: AgentX on May 10, 2013, 07:09:43 pm
Did you check the rubber between the carb and the head?
Title: Re: "Popping" off throttle, deceleration
Post by: barenekd on May 10, 2013, 07:10:00 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.
Bare
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 10, 2013, 08:23:12 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.
Title: Re: "Popping" off throttle, deceleration
Post by: Blltrdr on May 10, 2013, 08:29:43 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.
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 10, 2013, 09:54:11 pm
PWK flat-slide, metal flange mounted.  It's on there.  I'll try the spray.
Title: Re: "Popping" off throttle, deceleration
Post by: ace.cafe on May 12, 2013, 12:29:30 am
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.
Title: Re: "Popping" off throttle, deceleration
Post by: baird4444 on May 12, 2013, 05:43:48 am
points slip, close up a little?
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 13, 2013, 06:19:55 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.
Title: Re: "Popping" off throttle, deceleration
Post by: ace.cafe on May 14, 2013, 11:06:56 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.
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 14, 2013, 03:42:55 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.
Title: Re: "Popping" off throttle, deceleration
Post by: ace.cafe on May 14, 2013, 07:32:39 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.
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 14, 2013, 08:45:00 pm
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

Title: Re: "Popping" off throttle, deceleration
Post by: AgentX on May 15, 2013, 04:40:58 am
You could also use an exhaust pipe expander tool, no?
Title: Re: "Popping" off throttle, deceleration
Post by: ace.cafe on May 15, 2013, 11:50:46 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.
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 15, 2013, 04:25:18 pm
Resourceful, and maybe my only option.  None of the bike shops around here, or any of the Auto-zone/Advanced-autos have it.  Not the sort of grey, metal looking tape I was looking for anyways.

Ace, so just cut a strip off of the beer can and use it like a collar around the header-pipe's end?  I'd imagine a little air would still sneak out, but maybe that's no big deal.
Title: Re: "Popping" off throttle, deceleration
Post by: barenekd on May 15, 2013, 05:27:26 pm
Auto-Zone has an aluminum tape that will do the job. I used it on my pipe/muffler joint. It worked quite well. I think it's called muffler tape.
For a better gasket, go here
http://www.aircraftspruce.com/search/search.php?s=crush+gaskets&x=0&y=0
Bare
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 15, 2013, 06:05:48 pm
I think I'll try those gaskets.  Can I use 3m Alluminum tape?

http://www.shop3m.com/70006006525.html?WT.mc_id=GoogleProdSearch&gclid=CNbYkcTKmLcCFUHe4AodMTcAIQ

Says up to 600 degrees.
Title: Re: "Popping" off throttle, deceleration
Post by: baird4444 on May 15, 2013, 06:21:42 pm
I always used the hi-temp rtv sealant...
     just gotta let it cure fer 24 hours.
               - Mike
Title: Re: "Popping" off throttle, deceleration
Post by: boggy on May 15, 2013, 06:26:38 pm
Baird, what was your method of application?  My header diameter is quite a bit smaller than the port opening.  You just lather it up around the header pipe?  Easy to clean out if you need to remove the pipe again?

Thanks.
Title: Re: "Popping" off throttle, deceleration
Post by: baird4444 on May 15, 2013, 06:41:42 pm
thoroughly clean port and pipe with small brass brush and then wipe down with rubbing alcohol.
run about a 3/16" bead  around outside diameter of pipe at end, then insert and tap in with rubber mallet....
I guess I should say that the rest of the exhaust should be attached but loose....
then start aligning and tightening everything werking your way back. Should only take a few minutes...
then if there is too much excess sealant or it is uneven, it can be smoothed.
now fer the hard part; use some self control and let it dry and cure for 24 hours.
           - Mike
Title: Re: "Popping" off throttle, deceleration
Post by: Blltrdr on May 15, 2013, 09:41:37 pm
I think I'll try those gaskets.  Can I use 3m Alluminum tape?

http://www.shop3m.com/70006006525.html?WT.mc_id=GoogleProdSearch&gclid=CNbYkcTKmLcCFUHe4AodMTcAIQ

Says up to 600 degrees.

You can take the header pipe to a local muffler shop and have them expand it a bit or use a strip of pop can along with some silicone.