Diagnostic Trivia :)

[shorthair88]

1985 Max, 16k, runs fantastic, great throttle responce, Loads of power thru all gears at all expected rpm's. jetted-k&n filter-UFO 4-2 exhaust. running a touch rich & smokes a bit under very hard acceleration.
Why does it blow harder out of one pipe than the other? not very noticable except at idle..( 1000-1100 rpm's ) Nothings broke in my opinion so I hesitate to alter anything, I just want to know why?

 

[PATMAX]

It's not blowing harder in the one pipe, it's the other pipe blowing weaker. Sorry, I couldn't resist.

 

[06VMAXIMUS]

Does the UFO have a crossover pipe? If so it could be a "path of least resistance" issue.

 

[Rhoy Carter]

I have an 85 with the same set up and a good sync and now both pipes are the same and it is putting 115 hp to the wheel

 

[naughtyG]

Carb sync?

 

[shorthair88]

I brought up carb sync last summer when I had it in the shop, mechanic told me it didnt need it, I told him do it anyways, he said I would just be throwing my $$ away because in his opinion the bike just couldnt be running any better as is..Hmmmm? whats up fellas?

 

[naughtyG]

Carb syncing is called for monthly in the service manual. It takes 5mns to do on the Max (super easy) so your mechanic's obviously full of shit and hasn't got a clue what he's talking about..

5mns @ $80/hour = less than $10.

And if you ask anyone who sync'd their carbs after not doing it for a while - it makes a HUGE difference to how smooth it idles, runs and feels.

Just my 2 cents of course..

 

[Patrick78]

Hey I am having the exact same problem on my 2003 Vmax. My bike is stock except for some Kerker slip-ons and I'm having the same issue where the sound coming out off the right side muffler is louder then the left. If I put my hand about 6 inches away from the outlet of the muffler it makes a popping sound.
I'm also having the same issue as you where the bike is running great off idle. When its cold its really rough and alot of popping from the exhaust, but once it warms up its better. Smoother throttle response off idle and great power through the whole power band.
Could this really be an issue with syncing the carbs? I was actually just getting online to post about this issue when I came across this thread. I planned on taking a video of the bike running in hopes that you'd be able to hear what I'm describing. I'll try to do this later today and post it up.

 

[Lew L]

Sync'ing the carbs is easy and you'll be better off for doing it:biglaugh::biglaugh::biglaugh:
Lew

 

[Patrick78]

Alright so we aren't going over to the in-laws house as soon as I thought so I ran back outside while the bike is still somewhat warm and took the video.

I tried to show the sound that the muffler makes with my hand in front of it compared to the other muffler and I tried to show the tach as I lightly reved the motor so you could see the hesitation at low rpm and then jump to life right after the rough area.

 

[Patrick78]

Damn guys... no comments on the video and my dueling mufflers?

 

[PATMAX]

Don't know about the hesitation as I think you should be rapping the throttle faster and farther for us. I was gonna suggest. Did you take out the baffles of the exhaust tips and check the packing for burn out/blow out? Quick and easy to do and elimnates that off the list.:ummm:

 

[Patrick78]

I can look at that this afternoon when I get home. I never really looked closely at the mufflers, but they didn't appear to easily come apart.

 

[kaboom]

There will be a different sound/pulse from one side to the other......the firing order of these engines is not even......you do not notice it with a stock or 4 into 1 exhaust......but slip-ons that split the sides it is very noticeable....

One cylinder(which one escapes me at the moment) fires out of sequence with the other 3.......:confused2:

 

[Patrick78]

Then maybe I'll be lucky and the issue will be cured with a carb sync once the tool arrives in the mail. The exhaust never made that noise difference before the bike started idling rough when cold. When it cold or atleast not fully warmed up the motor bogs down as your start to raise the rpms and then it just suddenly breaks thru the bogging and revs freely above 2k rpm. So something is obviously a miss in the idle area. I guess I could try the shotgun again to try to clean out the idle mixture screw circuit but I want to wait til I sync the carbs first and see what that does.

 

[m-cman]

The Kerker slip-on system has a balance tube so would it still have a different sound from each side?

 

[richwrench]

How many turns out are your pilot screws AND are they all the same ? Some of us set all the screws the same & others tune each cylinder individually.

 

[Patrick78]

Mine are all set at 2 turns out now. They were at 2-1/2 when it had the stage 1 jet kit installed. But after a few emails with Sean and I described the bike running rich he suggested that I reinstalled the stock jets and even drop down one size on the main jet. At first I left them at 2-1/2 turns out but it still seemed to be running rich so I turned them a 1/2 turn in so they are sitting at 2 now, and yes they are all the same.
I have no idea how to figure out how to set them on my own. Sean tried to explain it to me briefly but I don't think I really understood his direction. How do you suggest setting each carb individually?

 

[richwrench]

IMHO you need a gas analyzer to accurately set them individually. I used a tach on mine & really couldn't tell a noticeable difference so I ended up setting them all the same. 2 turns out would be way lean on mine, but I'm a stocker. I swear there's a thread from about 2 years ago describing a different amount of flow from each pipe when idling & guys were talking like it was a normal condition, just like Kaboom stated. Have you been through the carbs lately ? I had a coasting air valve hanging on mine that screwed my idle up. Had a new spark plug mis-firing as well, but that was only when fully hot. I like your idea of syncing first, then see what happens. Sync goes out pretty commonly on these bikes, but it's an easy & FREE fix once you own the tool.

 

[naughtyG]

Ya like Rich said doing the sync first is prolly a good idea. But from what you describe, the shotgun may also really help.

Of course it's also a good idea to check that all your diaphragms are in good shape - easy to do for the main (slides) ones - just remove the carb covers, pull the slides out and inspect the diaphragms carefully, looking for tears or pinholes. For the coasting enrichment ones, it's a bit more involved as you really had to take the carbs out and break'em up to get to them.