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99 Monster doesn't like to cruise (has pod filters)

Started by s14unimog, May 19, 2011, 06:31:54 AM

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s14unimog

May 19, 2011, 06:31:54 AM
So I picked up a 1999 Monster 900S the other day for a smoking deal and need some advice. The bike is currently equipped with a pair of K&N pod filters, some DP slip-ons, apparently re-jetted, removed carburetor vent pods, and a little filter on the crank vent. Now all things considered, I'm sure this has to play hell on the cruising area of the throttle but I wanted to see what you guys thought about using those filters. From what I've heard it seems the carbureted monsters don't respond well to the absence of its air box.

As for symptoms the bike just hates that "middle" area. When under load (acceleration) it seems fine, pulls hard and doesn't break up. It's when you reach that desired speed, ease off on the throttle and I get this fast "kick-drum" break up that clears up with a bit more/less throttle. I put a brand new set of plugs in it and have tried to keep it out of that range; staying high in the RPMS, and the plugs don't look THAT bad. Is there a trick to re-routing the lines that previously went to the air box? Is it just the reality of using pod filters? Would it just be the jetting?  What about the absence of the carburetor vent pods?  Possibly a synchronization issue?

Any advice would be helpful. Thanks!

ducpainter

#1
May 19, 2011, 06:36:40 AM
Could be any of the things you mentioned.

You need to get the vent lines in still air. That affects the way the slides lift.

Your description sounds more like the wrong needle position or wrong low speed jets or a combination of the two.

Were your plugs dark or really light colored?
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


s14unimog

#2
May 19, 2011, 07:11:40 AM
the ones I pulled were fouled out.  As I've riden it lately they are still more rich than lean and that's with me attempting to avoid that area.

ducpainter

#3
May 19, 2011, 07:19:33 AM
Quote from: s14unimog on May 19, 2011, 07:11:40 AM
the ones I pulled were fouled out.  As I've riden it lately they are still more rich than lean and that's with me attempting to avoid that area.
First thing is to get the vents to still air. If the slides don't lift correctly it will mimic a rich condition because the cylinders don't get enough air.

I got rid of the vent pods on my bike and tucked the lines up between the battery box and airbox.

If they are still dark you can turn your idle screws in a bit, but with stock pilot jets I have mine adjusted at 4 turns out.

Any idea what brand of jet kit is installed?
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


avizpls

#4
May 19, 2011, 07:40:00 AM
depending on how bad it is....

my diaphragms were torn and caused this same issue. I had to really crank on it to get them to lift. These are under the TOP of the carbs and checking/replacing them doesn't require any fuel release.
#11

s14unimog

#5
May 19, 2011, 07:49:36 AM
Quote from: ducpainter on May 19, 2011, 07:19:33 AM
First thing is to get the vents to still air. If the slides don't lift correctly it will mimic a rich condition because the cylinders don't get enough air.I got rid of the vent pods on my bike and tucked the lines up between the battery box and airbox.
If they are still dark you can turn your idle screws in a bit, but with stock pilot jets I have mine adjusted at 4 turns out.
Any idea what brand of jet kit is installed?

no but I could contact the previous owner and ask.  I need to look at those vent lines and see where they are going, or how they were modified.  Any one have a picture of these lines and their standard routing?  Is that what the vent pods do, just isolate them to still air atmospheric environment?  Since mine doesn't have the air box, I don't have many places to "hide" them.  Maybe I should just reinstall the vent pods?


Quote from: avizpls on May 19, 2011, 07:40:00 AM
depending on how bad it is....my diaphragms were torn and caused this same issue. I had to really crank on it to get them to lift. These are under the TOP of the carbs and checking/replacing them doesn't require any fuel release.

Oh there is an idea.  I'm quite comfortable splitting carbs apart and inspecting a diaphram is as easy as 4 screws IIRC.  I'll check those tonight.

Thanks for the help so far guys.  I did borrow a carbeurtor sync-ing tool from a buddy, do you guys know the procedure for a Ducati?  couldn't hurt to check that I suppose?

ducpainter

#6
May 19, 2011, 07:56:11 AM
Yes, the pods just isolate the vent lines from moving air.

You could lengthen the lines and ziptie them to the battery somehow. As long as they're up under the tank it seems to work.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


s14unimog

#7
May 19, 2011, 08:17:47 AM
^okay, I'll try that.  I'll also inspect the diaphragms this evening.  How many lines are there in total?  And what about the larger lines with the double barb ended plastic piece?  At the moment they are just extending down from the barbs on the carbs. 


Maybe a picture is in order.  I'll take some close ups tonight and see if anyone can spot something.

ducpainter

#8
May 19, 2011, 08:24:37 AM
Quote from: s14unimog on May 19, 2011, 08:17:47 AM
^okay, I'll try that.  I'll also inspect the diaphragms this evening.  How many lines are there in total?  And what about the larger lines with the double barb ended plastic piece?  At the moment they are just extending down from the barbs on the carbs. 


Maybe a picture is in order.  I'll take some close ups tonight and see if anyone can spot something.
Those are the lines I'm referring to.

A large hose from the top of each carb.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


s14unimog

#9
May 19, 2011, 10:30:46 AM
Quote from: ducpainter on May 19, 2011, 08:24:37 AM
Those are the lines I'm referring to.

A large hose from the top of each carb.

oh okay, yeah at the moment they are just hanging down beside the carb, so they are quite exposed to forward movement air.  When I was looking at the vent pods I have it seems there are smaller lines meant to be connected.  Are there others?

ducpainter

#10
May 19, 2011, 10:32:50 AM
Quote from: s14unimog on May 19, 2011, 10:30:46 AM
oh okay, yeah at the moment they are just hanging down beside the carb, so they are quite exposed to forward movement air.  When I was looking at the vent pods I have it seems there are smaller lines meant to be connected.  Are there others?
It's been so long since I've seen mine I forget to be honest
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


greenmonster

#11
May 19, 2011, 12:15:04 PM
There are 3.
Relocate to f e behind battery.
M900 -97 
MTS 1100s  -07

s14unimog

#12
May 20, 2011, 12:58:47 PM
Where is the third one?  I saw the two, one for each carb, but can't seem to locate this third one.  Also, what lines would have ran into the carburetor vent pods?

greenmonster

#13
May 20, 2011, 04:04:55 PM
M900 -97 
MTS 1100s  -07

s14unimog

#14
May 21, 2011, 11:27:56 AM
^thank you for that link! Very helpful.  I rerouted them last night and took it for a quick ride this morning.  That has DEFINITELY improved that off throttle area.  For those who come across this later, I've realized why those need to be relocated.  If you blow into the vent lines, you'll raise the slides.  So if they're exposed to forward movement air, they are effectively blowing the slides open.
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