06 K9 Exhaust

[SMCT]

I have these Hooker exhaust pipes and I am just about convinced that they might be an issue, meaning not even remotely matched to the engine design of the S&S 117. I just feel that they might be too large. Besides that, the back pipe has an issue for certain, and that is the band spot weld broke off leaving the chrome casing to vibrate/rattle near the cylinder head. The primary pipes seem very short and then it dumps into a very large area (2.5 inches) for a great length. They didn't have baffles when I bought the bike. The other issue I am having is a very annoying popping when the carbs throttle blade is closed during de-accel. Like gun fire. To me that back firing is not acceptable. The motor seems like it has ok power, but nothing special by any means.

I can use all the input as possible with your own experience on exhaust pipes, really thinking about getting rid of these.

Does anyone else have an issue of back firing during de-accel, throttle blade closed?

P.S. not going to accept from anyone, that this back firing is normal.

 

[SMCT]

Here is a pic of the Hooker Pipes on my 06 K9

 

[Brew]

I had issues with my pipes also. The previous owner took the baffles out of my pipes (Mean Mothers) similar to yours. I ordered some QQ Thunder Monster Baffles for mine and it sounds great. I get a little decal pop but nothing like what I had without them. I believe it was the QBL 2125 that I ordered but you need to measure your IN and OD size to know what you need. Maybe this helps!

https://www.bigcitythunder.com/

 

[SMCT]

Thanks for the link. I measured my i.d. and o.d. on my current Hooker pipes seen in the pic. The o.d. is 2.500 and the i.d. is 2.400. If I was to cross this mathematically to what we build for the race engines in the shop, a 2.5 pipe typically would require an engine, per cylinder, that would make 160HP on the average, and our typical run rpm is from 7500 to 8800. That's 320HP if you add 2 cylinders up. I highly doubt my S&S 117 makes even remotely anything near these figures. Effectively my Hookers are really a 1 3/4 pipe for about 11 inches. I bet it wouldn't make a darn difference if the remaining 3 feet of 2.5 inches where not even there. Seems that they are just absurdly too large.
Now to find baffles that will fit that i.d. I guess i'll try baffles before I bail on them.

 

[SMCT]

I stumbled on this here..... http://xlforum.net/vbportal/forums/archive/index.php/t-533171.html

 

[SMCT]

I figured it couldn't hurt to make something in the shop and give it a try. Made two insert baffles. This should give it some back pressure.

 

[Th3InfamousI]

I figured it couldn't hurt to make something in the shop and give it a try. Made two insert baffles. This should give it some back pressure.

Looks like what you would pay $80 for from Thunder City

Sent from my 831C using Tapatalk

 

[dapfunk]

Sweet. Let us know how it helps with the decel pop. I've been working to reduce mine: I'm getting close. Rejetted carb, added stock baffles (previous owner ripped them out), lower octane gas, and I only get a little bit now.

 

[Hotrod36]

Nice Job

 

[SMCT]

lower octane gas

This happens to be very interesting that you mention this. I at first was using 91 octane and then moved up to 93 with the last two tankfuls. I happened to be in an area where we stopped at a sunoco, and it was convenient to the area. Now that you have mentioned about "lower octane", my 2006 Dyna Wide Glide would run like crap on anything above 89 octane. It actually had a slight miss at cruising speeds, ran a bit rich and a lack of power.

I know that if an engine is over octaned, the engine will not have the ability to ignite all the fuel/air in the chamber and it goes into a rich condition and has a loss of power.

With the last two tanks of 93 Sunoco, when I shut the bike off, fuel ignited in the pipes, and that sound was very distinct.
I wouldn't be surprised if this engine cleans up and has more power on 89 or even 87 octane. The lower octane heats the chamber and allows for a more efficient burn, if the engine doesn't have the compression for the higher octane.

 

[TapioK]

This happens to be very interesting that you mention this. I at first was using 91 octane and then moved up to 93 with the last two tankfuls. I happened to be in an area where we stopped at a sunoco, and it was convenient to the area. Now that you have mentioned about "lower octane", my 2006 Dyna Wide Glide would run like crap on anything above 89 octane. It actually had a slight miss at cruising speeds, ran a bit rich and a lack of power....

That is interesting! Mine is popping too but if I go to 91 oct or below, engine doesen't want to shut off .Well I have shaved cylinders and 585...


Sent from my iPhone using Tapatalk

 

[cdogg556]

I don't know about the exhaust but I do know that is one good look'n K9 buddy!

 

[SMCT]

Just an update.

I installed the baffles and there was a noticeable difference. The engine no doubt needed some sort of back pressure. It runs smoother, seemed to have picked up the throttle response a little bit as well, at all areas. It got quieter, not a lot, but noticeable. The back firing is still present, although not as much and not as loud either. I'd say I knocked 30 percent of the back firing away. A little disappointed because I really thought this would cure it, but definitely glad I did it.

Here is the craziest thing about it. I've been kinda fighting this slight tick in the front rocker box, and I have done quite a few things to quiet that front box down, but no luck. Apparently that tick which sounded exactly like rockers or maybe even a guide going bad, was actually combustion in the first few inches of the primary pipe, and close enough to the head that it would give the impression that it was up in the rocker box. The baffles must have put the back pressure into it whereas now all the combustion is occurring in the chamber. WTF? The rocker box is quite now, just like the back one, not a sound out of it. Who would have thought. I'm still shaking my head, but very happy because I couldn't find anything in that top box that would amount to that rocker tic sound.

 

[Brew]

Sounds great Andy and the mods you've done are excellent. Glad that your happy with the outcome...

 

[JeffM]

This looks and sounds exactly what i have to do with the short radius Ultima pipes i put on so i can take the ol' lady for a spin. ( can't get the right rear peg on with the 2-1 V&H). The baffles i bought make it sound like a compressor.

 

[SMCT]

Kinda like this?

 

[dapfunk]

Glad it worked better for you Andy. I may still have to try new baffles to increase the back pressure.

As to the octane in the gas, I used to run 93, but it is almost impossible to find here in NM after I moved so I run 91 now it seemed to help on the decel pop a bit. I don't get any pinging, so I might even give 89 a try. The Honda slurps down 86 all day.