CSC TT250 Exhaust Popping - Page 2

chuck · 08-15-2016, 02:02 PM

Quote:

Originally Posted by '16 TT250

Did you remove it or do they not come with it?

I don't think that the Hawk is equipped with one.

celswick13 · 08-18-2016, 09:32 AM

I'm in Tacoma, 250' above sea level.
After removing the airbox lid and putting on that exhaust I had to go to a 115 jet.
I also replaced the exhaust gaskets at the head.
With the 112 jet I got a serious amount of pop on deceleration. I get very little development pop with the 115, but it's there.

Mudflap · 08-18-2016, 10:25 AM

To prevent annoying popping, many carbs used on bikes of the past had a vacuum operated valve that cut off the fuel during deceleration. These small and simple carbs don't have one so it can be difficult to eliminate it.

2LZ · 08-18-2016, 10:39 AM

Do you still have the stock PZ carb? Can you open the idle mixture a half turn and see if that helps?

Azhule · 08-18-2016, 11:02 AM

"Pumper Carb" anyone?

Just like Mudflap said... without an expensive pumper carb or EFI setup, your exhausts will have some "pop" while decelerating... and in most cases a properly tuned carb/engine with an open exhaust will have that "popping"... it's the amount it "pops" and how loud it is will usually tell you what to do with jetting on a cheap carb/open exhaust set up

Ariel Red Hunter · 08-18-2016, 09:59 PM

Quote:

Originally Posted by Mudflap

To prevent annoying popping, many carbs used on bikes of the past had a vacuum operated valve that cut off the fuel during deceleration. These small and simple carbs don't have one so it can be difficult to eliminate it.

In the fifties and sixties, we used to set the idle speed adjustment so the carburetor shut completely off to get away from that noise in the exhaust. Other guys who had no idle speed adjustment (they adjusted idle speed by shortening or lengthening the throttle cable) used the kill switch for the same purpose. You could do the same, I suppose. Leave the key on, and manipulate the red buttons on the right handlebar, leaving the clutch engaged until you are almost stopped. At that point, push the other red switch to turn engine back on and pull the clutch. If you practice doing this for a few days, it'll seem like the most natural thing in the world to do. Learning this little routine will really help you on off road descents of steep hills.

2LZ · 08-19-2016, 10:09 AM

It has to be a mixture condition. I can decal from 6k and no pop on the Phoenix with the same pipe.
Can you adjust the mixture screw?

PNWDualRider · 09-19-2016, 01:35 AM

Quote:

Originally Posted by '16 TT250

That's a common issue. Disable the exhaust air injection and it'll probably stop. Tuning the carb to stop a deceleration issue is likely to be fruitless.

I have very little mechanical knowledge. For this exhaust air injection, what exactly am I looking for?

mtiberio · 09-19-2016, 06:57 AM

It is an idle mixture issue, but can be due to being too rich or too lean. too lean, and there is not enough gas to ignite, so unignited gas gets in the exhaust. Too rich, and there is unburned gas left over after combustion and it burns in the exhaust. diddle you idle mixture screw to see if you can affect it.

As far as the air injection goes, I was looking at that the other day after I removed my carbon bottle. Like most I have seen, to remove it you have to fabricate a block off plate to cover the hole left in the cylinder when you remove the air injector. Simple small rectangular plate made from Aluminum. Easy to cut. With two holes. Use the flange off of what you remove as a template. The other thing you must do is trace the vacuum line from the air pump proper back to the carb manifold. That is where the pump gets its power. Get a small rubber "vacuum cap" from your local auto parts store (they usually sell blister packs of various sizes), make sure you cap the fitting at the manifold, or you will have an air leak and really eff up your jetting.

08-18-2016, 10:39 AM	#19
2LZ Join Date: Mar 2010 Location: Volcano, Ca Posts: 7,102	Do you still have the stock PZ carb? Can you open the idle mixture a half turn and see if that helps? __________________ "Light a fire for a man, and you heat him for a day. Light a man on fire, and you heat him for the rest of his life." 2007 Suzuki DRZ400S (SM convert) 2009 Q Link XP 200 1967 BSA B25 250cc Starfire 2022 Royal Enfield Interceptor 650 2023 Royal Enfield Scram 411 1948 Royal Enfield Model G 350
	0

08-18-2016, 11:02 AM	#20
Azhule Join Date: Dec 2015 Location: CO Posts: 1,525	"Pumper Carb" anyone? Just like Mudflap said... without an expensive pumper carb or EFI setup, your exhausts will have some "pop" while decelerating... and in most cases a properly tuned carb/engine with an open exhaust will have that "popping"... it's the amount it "pops" and how loud it is will usually tell you what to do with jetting on a cheap carb/open exhaust set up __________________ "Think as you like... but this self proclaimed Professor is always right" - Buckshot "You never know what someone is hiding beneath their smile..." - NinjaTom - R.I.P.
	0

08-19-2016, 10:09 AM	#22
2LZ Join Date: Mar 2010 Location: Volcano, Ca Posts: 7,102	It has to be a mixture condition. I can decal from 6k and no pop on the Phoenix with the same pipe. Can you adjust the mixture screw? __________________ "Light a fire for a man, and you heat him for a day. Light a man on fire, and you heat him for the rest of his life." 2007 Suzuki DRZ400S (SM convert) 2009 Q Link XP 200 1967 BSA B25 250cc Starfire 2022 Royal Enfield Interceptor 650 2023 Royal Enfield Scram 411 1948 Royal Enfield Model G 350
	1

08-18-2016, 09:32 AM	#17
celswick13 Join Date: Jun 2016 Posts: 19	I'm in Tacoma, 250' above sea level. After removing the airbox lid and putting on that exhaust I had to go to a 115 jet. I also replaced the exhaust gaskets at the head. With the 112 jet I got a serious amount of pop on deceleration. I get very little development pop with the 115, but it's there.
	1

08-18-2016, 10:25 AM	#18
Mudflap Join Date: Sep 2014 Posts: 1,894	To prevent annoying popping, many carbs used on bikes of the past had a vacuum operated valve that cut off the fuel during deceleration. These small and simple carbs don't have one so it can be difficult to eliminate it.
	0

09-19-2016, 06:57 AM	#24
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	It is an idle mixture issue, but can be due to being too rich or too lean. too lean, and there is not enough gas to ignite, so unignited gas gets in the exhaust. Too rich, and there is unburned gas left over after combustion and it burns in the exhaust. diddle you idle mixture screw to see if you can affect it. As far as the air injection goes, I was looking at that the other day after I removed my carbon bottle. Like most I have seen, to remove it you have to fabricate a block off plate to cover the hole left in the cylinder when you remove the air injector. Simple small rectangular plate made from Aluminum. Easy to cut. With two holes. Use the flange off of what you remove as a template. The other thing you must do is trace the vacuum line from the air pump proper back to the carb manifold. That is where the pump gets its power. Get a small rubber "vacuum cap" from your local auto parts store (they usually sell blister packs of various sizes), make sure you cap the fitting at the manifold, or you will have an air leak and really eff up your jetting.
	0