Once Again...Exhaust Pop

[kalinin]

Ok, somewhat odd issue. I keep getting popping at the exhaust when riding the bike in the morning. I took off the muffler and am currently running straight header pipes. I warm the bike for ~5 mins in the morning, ride to work about 4miles and popping (sound like little gunshots) slows from frequent to slow @3-4K rpm, no noticeable performance problems. No popping at idle (when fully warm idle is a tiny bit erratic around 1300rpm). It's 60-70 degrees here now. I just rode it around noon and popping is gone after another warm up. Popping was more pronounced a week ago when temps were around 50.

I thought it may be a carb issue but they were cleaned a couple months back at end of winter, and since the popping stops eventually (after maybe 8-10miles), I figure carbs cannot be clogged. The temp gauge can be at the halfway mark and it still can pop fairly frequenty until I've ridden ~10 miles. When looking at the sliders through the airbox, on a firm pull of the throttle all sliders open up almost synchronously. Could it be running too lean (I'd assume popping to remain fairly constant if it was a fuel issue) or does it simply take foreeeeever for all parts/carbs to warm up?

When warming in the morning I have tried to keep it full choke for like 5 seconds and no poping even when it hits 3K. Help?

 

[jfeagins]

Do your carb boots look good? Cracks? Could be an air leak when rubber is cold, and the cracks self-seal after warm up?

 

[kalinin]

It doesn't appear to be the carb boots, they feel quite rubbery all over and no cracks that I can see/feel. And the popping is at the exhaust...could the exhaust pipes be loose at the intake? Although I'd imagine that part of the pipe would be first to warm up and not take 5 miles to do so...

 

[DMAN999]

I'd think running open headers is the biggest reason for that popping.
I bet if you put some exhaust (stock or Supertrapp slip-ons) on it, that problem would disappear.

 

[kalinin]

Well I took off the muffler because of the popping, reasoning that if it's an exhaust leak it wouldn't occur with open headers....but it does. I'll check the carb boots a bit better and tighten the pipe at the intake...maybe it'll be better...

 

[kalinin]

The carb boots i'm referring to are the ones between carbs and airbox; they look good. The boots between the intake and carbs I haven't checked because I'm trying to avoid a carb resynch. Do you guys think the boots between the carbs and intake could be causing these symptoms?

 

[DMAN999]

They could be.
Have you tried turning your A/F screws out 1/2 turn or so and se if that helps ?
Also have you checked the headers to be sure they are tight and not leaking ?
Also Search this forum, there are plenty of posts about checking for Vacuum/intake leaks.

PS
A Carb synch is extremely easy to do if you have access to a Carbtune or similar Sync tool.
You should ask vmax2extreme aka Michael Moore if he has access to one if you don't own one.
He just recently did a tech day at his house and is planning another soon:
http://www.vmaxforum.net/showthread.php?t=28586

 

[kalinin]

The headers I will check, but I cannot adjust the screws because the owner before me had pretty much destroyed the screw heads. Any ideas on how to extract those screws so I can replace them?

 

[DMAN999]

I don't have any advice for removing ruined A/F screws but dannymax or Sean Morley (one2dmax) may.

 

[Traumahawk]

The headers I will check, but I cannot adjust the screws because the owner before me had pretty much destroyed the screw heads. Any ideas on how to extract those screws so I can replace them?

First spray them with PB blaster...and let them sit for about 12-24 hrs. The ones on the right side are the worst to try to turn. Use the appropriate size screw driver and turn all the way to the left, and they will unscrew. Be aware that there are little Orings that might get stuck in there. I believe that Dannymax and Sean (one2dmax) both sell the A/F screws, and can help if you cant get them out, and want someone else to do it. Otherwise I believe that an EZE-out would work....but those screws are brass and very soft.

 

[Traumahawk]

Here is the perfect sized screw driver

http://www.ebay.com/itm/MOTION-PRO-...Parts_Accessories&hash=item1e7a0bb518&vxp=mtr

 

[Traumahawk]

And if you dont want the screw driver...

http://www.factorypro.com/Prod_Pages/prody11.html

And these look interesting

 

[naughtyG]

my bike pops a bit too, and I found out that one of the the rubber boot between the carbs and the vboost assembly is all cracked and damaged.

I haven't had time to replace it yet, but I'm pretty sure that's the reason for my popping. My other issue with that bike (from the same cause I think) is that whenever I get on it, no matter if I rode it 2 hours ago or last week, the fuel pump clicks at least 20 times. Do you notice this problem on yours too? (it should only click 2-3 times if you've ridden the bike recently)

 

[naughtyG]

And if you dont want the screw driver...

http://www.factorypro.com/Prod_Pages/prody11.html

And these look interesting

I like the idea of those long A/F screws, but $80 for 4 screws, really!? :bang head:

 

[dwarf717]

The condition is worse when it's cooler out because the air is denser, and you are running a leaner fuel to air ratio

 

[bazwell]

The condition is worse when it's cooler out because the air is denser, and you are running a leaner fuel to air ratio

My missus says I weigh more than her, because I am more dense.
Do you think she is taking the piss? :ummm:

 

[naughtyG]

My missus says I weigh more than her, because I am more dense.
Do you think she is taking the piss? :ummm:

Defo! :rofl_200::rofl_200:

 

[kalinin]

Thank you guys for all the info...I think I do have a similar problem to naughty. I notice that the pops occur out the muffler, not at the front of the header so I'm betting pipes are sealed well to the engine. The rubber boots at the airbox are good, but I haven't looked at the other ones as I don't yet have a carb tool to resync the carbs. I'll definitely check the boots before messing with the a/f screws (I think one of them doesn't even have the screw head).
Although I've always thought that if the problem is a result of a cracked carb boot/seal, I would hear pops from the carbs?