I would appreciate any assistance

[skromfols]

I bought my 98 Valkyrie standard about 3 years ago in Minden, NV., however it was a California model that the previous owner took with him when he moved from California.  The bike had about 12,000 miles on it when I purchased it and now has around 42,000 miles.  I've had no problems with it until recently it began backfiring when I decelerate.  It has a K & N air filter, has had the piggies cut and the baffles drilled.  I added the 3 degree wheel.  I have no idea what jets it has, and even with the Clymer manual I can't find how to adjust the pilot jets.  I'm assuming that the pilot jets are what Clymer refers to as the slow jets, but I can't seem to find where they should be.

I recently had the bike run on a dynojet dyno and it showed that my max power is 90.56 between 5,500 and 6,000 RPM, with max torque at 93.99 at 4,500 RPM.  I would post the dyno chart if I could figure out how, but after reading all the instructions about how to post pictures my dyno chart is still too large to post.

My air fuel ratio is at 14 at 2,200 RPM, going to 16.5 at 3,500 RPM, going back to 14 at 5,000 RPM and staying right around there until 6,500 where he shut it down.

If anyone can give me an idea of where to start making my adjustments I would appreciate it.  I'm not a mechanic, but work on my Triumph America all the time.  I haven't worked on the Valkyrie because (a) it's had no problems, and (b) it looks way more complicated than my little 2 cylinder America.

And if anyone would be willing to resize and post my dyno chart I would appreciate it.  I can be contacted at skromfols@hotmail.com and can email you the chart.

Stan

[Garland]

Most of the backfiring issues I have had we're from vacuum leaks. Check the nipples/plugs/hoses coming off the carbs. I'll bet one or two is cracked.

[Farther]

In addition to the vacuum stuff, retorque the header bolts with care.

[Master Blaster]

Agree most likely vac leaks.  De smog will help there.  Also check that the clamps are tight that connect the carb to the down tubes.  Ive also had an O ring or two go between the down tube and the head.

[Ricky-D]

Backfiring

and

Popping

Are two different things.

Care to illuminate a little?

***

[salty1]

Take a look at a service manual for the external (to the carb) position of the pilot jets. The slow jets are internal to the carb and are probably 35s. Sure sounds like a vacuum leak. My bike had a similar problem but desmog and carb synchronization was a cure. With the exhaust mod and a K&N air filter on your bike, turn the pilots out 2 1/2 to 3 turns from a light seating. I think most of the previous post are right on. 

[skromfols]

Ricky, my bad, it's popping on decel, not backfireing.  I'll check the hoses and caps for cracks.

Salty, I'll check and see if I can find the pilots.  My guess is that they use the D adjustment tool, right?  I had one of those for adjusting the pilots on my Triumph but think I gave it away when I changed the Triumph pilot adjustments to a knob adjustment.

Thanks all for your responses

[Ricky-D]

Modifying the exhaust, as yours has been,,, is usually the greatest reason for your popping.

The first thing to do would be to synchronize the carburetors since that normally is the largest contributor to popping.

Running an additive can be helpful to alleviate some of the popping resulting from a gummed up jet or two.

Starting to change things out before getting to the bottom of the problem can cause additional headaches resulting in great frustration.

Merry Christmas!

***

[R J]

As Ricky-D said, check/replace hoses 1st, that no fix, then go to carb re-sync, that no fix it go to your internals as you want to. 

BUT, don't get in too deep or over your head as you can really screw things up.

Only make 1 (ONE) mod at a time.  If need be, put that mod back to where it was before going on.

You probably have a hose with a hole in it or a cap with a crack.   Or a loose exhaust bolt.    If ya go here, don't get tooooooo heavy on the ratchet, as they are very tender and BREAK very easy.   Break one and you will have to pull that side off to replace the stud.    Thank your maker for the way these bolts are made.  Usually there is enough of the stud sticking out to get it with vise grips.

[Patrick]

Since the bike was running fine for all those miles,, I think I would not mess with the pilots until the bike is running as before.. As the boys stated, look for vacuum leak stuff [ vacuum lines and caps, air box to carburetor clamps, and exhaust manifold retainers]..
That is, if the bike was being run regularly prior to this problem.. If the bike has been sitting for awhile, then things can be different..

[skromfols]

Thanks guys.  You've all made good sense.  Since the bike doesn't sit for more than a day or so without being ridden stale gas isn't the problem.  I've noticed the popping for quite a while.  I started riding with a fairly agressive riding group so I increased my speed and started droppping down a gear to stay in the high power/torque range, and backing off from the higher RPM's is where I started noticing the popping.  There's no hesisitation or lack of power, it runs great, and I think the dyno of 90+ hp at the rear wheel is normal, so everything points towards what you guys have suggested. 

My guess is I'll need to pull the tank and start tracing hoses and hunting for caps. 

Again, thanks loads.

[Chrisj CMA]

Thanks guys.  You've all made good sense.  Since the bike doesn't sit for more than a day or so without being ridden stale gas isn't the problem.  I've noticed the popping for quite a while.  I started riding with a fairly agressive riding group so I increased my speed and started droppping down a gear to stay in the high power/torque range, and backing off from the higher RPM's is where I started noticing the popping.  There's no hesisitation or lack of power, it runs great, and I think the dyno of 90+ hp at the rear wheel is normal, so everything points towards what you guys have suggested. 

My guess is I'll need to pull the tank and start tracing hoses and hunting for caps. 

Again, thanks loads.

before you pull the tank, check the 12 screws that hold the clamps tight for the intake to carb connection.  Most bikes have these screws scary loose

[skromfols]

That sounds like a good place to start.  Thanks.

[DarkMeister]

Do a search on here, if you haven't yet. Decel pop is covered a lot.
I chased mine down that way. Vacuum hoses, vacuum CAPS!, intake tube o-rings...and it's gone. (Includes retightening of clamps, screws and bolts, of course).
Easiest check for me was of the caps and tubes on the intake tubes. Found cracks right there.
Anyway, FWIW; but it's the place to start before getting into carb adjustements and such.

[MrBreeze]

Good read! I'm chasing the same thing & while replacing leaking oring I did find all the intake clamps loose as stated above. Will find out if fixed friday weather permitting I ride.

[salty1]

Skromfols, redeye has a reasonably priced D shaped tool to adjust those pilots.

http://www.ebay.com/itm/Stubby-Pilot-Screw-Tool-ON-BIKE-ADJUST-Valkyrie-/230710511087?hash=item35b76b05ef&item=230710511087&pt=Motorcycles_Parts_Accessories&vxp=mtr#ht_1367wt_922

[FryeVRCCDS0067]

I replace my vacuum caps on the inside of the intakes yearly. Each intake tube has them. They face towards the center and are used for carb synchronization. In particular the caps on the right side crack pretty quickly and will cause the bike to run lean when they do. I assume the right side tends to crack first because gas will sometimes condense there while the bike is on the stand. But, it could be I just check them more often because they are easier to get to.

It's worth getting the OEM caps. The auto parts store caps I've bought don't last long.

[GOOSE]

IF YOU GET THE RED EYE TECHNICAL SERVICES CAPS, YOU WON'T HAVE TO REPLACE THEM AGAIN.

[DarkMeister]

IF YOU GET THE RED EYE TECHNICAL SERVICES CAPS, YOU WON'T HAVE TO REPLACE THEM AGAIN.

That's what I got. Along with his vacuum hoses. Great to deal with, fast and cheap, great quality. So far so good.

[FryeVRCCDS0067]

IF YOU GET THE RED EYE TECHNICAL SERVICES CAPS, YOU WON'T HAVE TO REPLACE THEM AGAIN.

Thanks for the info.