Easiest way to check for leaks - Harley Forum

unfknblvbl · #1 06-05-2008, 09:26 PM

What is the easiest way to check for exhaust leaks?

Being the newbie I am, when I changed out my pipes I overlooked the exhaust port gaskets. Well, I didn't overlook them, but when I pulled off the stock pipes I didn't see any gaskets (was picturing header gaskets like you put on cars, only with one hole) and when I pulled the bag 'o goodies that came with the new pipes I didn't see any gaskets (again picturing/looking for header type gaskets). Then I thought to myself, hhhmmmm that's strange they don't use gaskets on motorcycle exhaust that doesn't seem right, but I'll roll with it. Well I've been riding back and forth to work all this week and completely unhappy with the way my bike sounds, the occasional backfire on decel and some distinct popping at speed. I put the intial blame on my fuelpak, called V&H yesterday, got some advice made the changes they recommended. The ride to work this morning was absolutely painful, the bike sounded like crap. So at lunch I put the fuelpak back to the initial settings.

As I was riding home, getting even more mad, I was thinking about the whole gasket issue. So I got to the house pulled out the service manual and then it smacked me in my face....EXHAUST PORT GASKET!!!! I called a local dealer, sounded like an idiot and the tech explained to me what was suppose to of been done and what I needed to. Now I'm lead to believe that I have exhaust leaks and regardless the port gaskets need to be changed, but I want to go ahead and check for leaks before I do that.

Thanks

frisco-rigid · #2 06-06-2008, 03:28 AM

Hey UN

First off, if you did not remove the gaskets that were already in the port then they are still there.. I guess you did not see them.. I have used exhaust gaskets many times over without having to change them,, lucky???,, maybe, but I have gotten away with it for years.. Doesn't mean others always can..

Start the motor in an enclosed garage or at least make sure there are NO drafts or very little at least..
Then with a flame such as a Bic or a long BBQ lighter or something similar reach in to the exhaust port as close as possible without burning yourself..
If there is a leak it will play havoc with the flame--- pull it away and the flame will settle down.. No diff in the flame then no leak.. Simple
Go ahead and rev it up and notice if it leaks..
Do it to all connections.. If there's a leak it's usually very obvious..
If all it took to have a de-cel back-fire was exhaust leaks then my 93" shovel should sound like a fire-fight.. I can see the puffs coming out from the connections..

We talked about de-cel back-firing in a very recent thread..
I've always gotten rid of if by fattening the idle jet.. Everytime but this time.. I too have been fighting a back-fire in a 127" motor.. Changed exhaust twice, and Carbs twice.. And 3 diff ignitions.. This time with a Dual-fire Dyna I think I whipped it.. The first 2 were single-fire..
I personally have never seen any advantage to single fire..

In my experience, back-fire through the pipes is usually (but not always) caused by lean Idle jet..
Back-fire through carb, or intake, is usually an over-all or specific RPM lean condition..
Some very open-low restriction pipes encourage de-cel back-fire..

unfknblvbl · #3 06-06-2008, 09:44 PM

Frisco- As always knowledgable. I will try to "fight fire with fire".

I've already dropped the pipes and put in new gaskets. It helped alot, but not all the way. When I pulled off my pipes I noticed the rear pipe is really blue and the front pipe has a yellow tint to it with a little bluing, but nothing like the back one. They are V&H big shots staggered with power chamber. I find that really strange. After I put everything back together I took it out to see how it sounded under speed. It sounded a lot better, but what has me really thrown off is the top (which is the rear exhaust) pipe sounds really good at speed, the bottom (front pipe) sounds like a d@mn lawn mower. There is a very distinct sound between the two.

If I'm reading the color of the pipes correctly the back is really lean and the front is rich (makes sense with them technically being a 2-1), but doesn't seem right. What would make more sense is they were same color.

Once the bike cools off I'm going to re-tighten everything and then give it a shot tomorrow, but I will definitely try the flame thing first (after I re-tighten everything). If all else fails I'll take it to a shop (not a stealer) have them drop the exhaust re-install it and then tune the bike, even though I really don't want to. We'll see what happens.

frisco-rigid · #4 06-06-2008, 11:59 PM

Hi UN

Is this PowerChamber actually a cross-over connecting the pipes.? And are they Straight pipes,,,,,, no baffles or muffs,, if so , shame on you..

Ok,, I gotta ask--How can you tell which pipe is souding good and which is bad when you're ""at speed""??

It is an EFI right.?

The bluing is heat related but not always A/F mix.. However in this case it prob is part of the prob..
Timing can also color pipes real quick..
Too little ignition (retarded) is a heat builder and of course too much ignition can cause detonation especially if A/F is also lean..
And don't forget about intake leaks..

I would be sure of the timing before doing A/F mixture adjustments..
Timing is universal,, Pre-twinky or post.. If it's EFI I have no recommendations other than (in all my pre-twink motors) I always have a gentle rate of advance and only to 26* to 32* total advance at about 1800 to 2200 RPM's depending on the motor.. Now dig it-- if the rate of advance is tooo slow then it's retarded (for load and RPM) for tooo long..

A little something I always do when re-tightening exhaust for instance..
Loosen all exhaust support brackets, tabs, etc.. Then re-tighten--- then tighten (and shim if neccessary) the supports back up.. You see-----
Sometimes while re-tightening the exhaust port fasteners, the pipes will slightly "pull" up, down, in or out..
No reason to create a new stress-point pull,, heck there's enough of them already..

unfknblvbl · #5 06-07-2008, 12:23 AM

Hey Frisco- Let me try to answer all of these questions....

The powerchamber is a crossover connecting the pipes. They are straight pipes with baffles, but no muffs. So only half of the shame on me

As for the different sound at speed you can just hear it....hell maybe I'm just hearing things, because at an idle they both sound good and when in N or at a stop they both sound the same, even when I pull in the clutch and downshifting they sound the same. Maybe I'm just not use to sound of these new pipe over the stock ones.

It is an EFI, closed loop from what I understand. Doesn't mean a lot to me either....

I haven't forgot about the intake either. I need to pull the air cleaner and double check the connections. I have no idea how to check the timing on a bike,,,sounds like it is time to go the shop (to check timing, A/F, etc).

I have never thought about loosening up the support brackets and then re-tightening. Makes perfect sense to me. I'll have to do that.

Thanks bud!

frisco-rigid · #6 06-07-2008, 02:41 AM

Hi UN

With baffles and a cross they should be OK..

I believe all timing and A/F is computer controlled on your sickle,, so yes, it's something done at a shop,, but, best done at a shop that will re-map correctly not just according to HD's and the Pinko-Commie EPA's specs..

I have fought the Closed-loop EFI in my car tooth and nail..
Believe me,, I will NEVER willingly own an EFI sickle.. So good luck..

Even though there is little you can do about A/F mix you can still do a plug check reading.. Then at least you will have an idea how lean it is..

Well, we've touched on alota things here,, keep us informed on your findings..

unfknblvbl · #7 06-08-2008, 11:51 AM

Frisco- The timing and A/F are both controlled via a computer. I have found an independent shop who will dyno my bike and give me my A/F ratio. They should be able to tell if my timing is advanced or retarded, too. If I understand all this correctly the "map" that I loaded in my fuelpak is controlling all of this and over riding my stock ECM settings. I have contacted V&H and explained all of this with as much information as possible so they can hopefully give me a solution. If V&H comes back stumped I'm hoping they may let me bring my bike to their facility, they are only an hour and 1/2 up the road from me.

I've pretty much ruled out exhaust leaks now. I didn't find anything when I tried the flame concept. I loosened all support tabs and re-tightened the exhaust flanges. I need to do the same with the air cleaner just to double check.

As more comes about I will keep you informed. Thanks for the help and ideas.