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Discussion Starter #1 (Edited)
I have a 2009 and was looking to upgrade pipe and a/c. I installed a Supertrapp IDS2 with the quiet baffle so it wouldn't be too annoying w/ a K&N a/c element. I left the air box stock. I modified carb with a 45 slow jet, 2 washers under needle, drilled air hole in slide to 1/8", cut 1 and 1/2 rounds off slide spring, and turn fuel mixture screw out 2 to 2 1/2 turns. I run the Dyno at local Harley shop and a/f ratio looked to be dead on. It made 35 lbft of torque and 37 hp. The pipe and a/c was less than $400. Plus I still get over 48 mpg riding between 60 and 70 mph on highway. If you need a slow jet stop by your local harley shop and ask. 45 is the stock jet in carbuerated twin cam models. If you can't find one shoot me a message I have a ton of them!
 

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I have a 2009 and was looking to upgrade pipe and a/c. I installed a Supertrapp IDS2 with the quiet baffle so it wouldn't be too annoying w/ a K&N a/c element. I left the air box stock. I modified carb with a 45 slow jet, 2 washers under needle, drilled air hole in slide to 1/8", cut 1 and 1/2 rounds off slide spring, and turn fuel mixture screw out 2 to 2 1/2 turns. I run the Dyno at local Harley shop and a/f ratio looked to be dead on. It made 35 lbft of torque and 37 hp. The pipe and a/c was less than $400. Plus I still get over 48 mpg riding between 60 and 70 mph on highway. If you need a slow jet stop by your local harley shop and ask. 45 is the stock jet in carbuerated twin cam models. If you can't find one shoot me a message I have a ton of them!
Hello Webb.

What is a 45 slow jet?
What was the thickness of the washers?
The IDS2 comes with 12 plates. What is the quiet baffle?
Where did you get the information for the 1/8" drill and cutting the slide spring?
What was the A/F ratio?
What counter sprocket are you running?
What are your valves set at?
Have you completed the Doohickey and Torsion spring?
Are you having fun?
 

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Simple REALLY Cheap Upgrade:

Talledega Nites (legend of Ricky Bobby),

My '01 Dyna came with 45/190, '96 Sporster at 42/ 150.
The mains have different threads for the KLR! I didn't mess with the low speed
(which is fine as-is imo.) I got a 150 at Honda and left the 42 in there.
The cylinder size for the EVO engine and KLR is the same, only 20cc difference.
With the twin cam setup on the CV40, I think you are a bit rich, not that is any
problem, plus you said AFR is fine. Your mileage is in the ballpark.

I thought I knew everything CV when I got here from my HD experience and learned
otherwise. These waterheads are fine leaner than HD, but richer than stock. Nearly
everyone who mods their carbs here just does the #4 ss or brass washers (2), and
turns out the mixture screw 2 1/2 to 3 turns from gently seated. The cut spring
and larger hole can make the slide go up too fast. You'll be on the main too soon
and run rich during acceleration.
The sponge element flows fine, and most dudes don't like the K7N unit. The KLR
problem is the restrictive airbox. Remove the rubber snorkel. Some, me included,
drilled holes in the top of the box in an "L" shape known as the L-mod here. I did
5 1/2" holes along with the snorkel. Some do 1" holes that can be reversed with
1" plugs if they don't like it. My bike woke right up and I haven't tried the K&N, nor
an aftermarket muffler. Cored my stock baffle instead for a nice bark yet it's neighbor-
friendly at steady cruise and idle. I get 50 mpg and spent about 4 dollars on my mods.
Including the pcv valve added to the crankcase breather line, the cost went up another
$4.99. If ya take a look on the right side of the carb where the cables attach, now
there's a stopper that prevents the butterfly from going past 80 degrees. It won't
open the full 90. I still don't know what to make of that, but it's gotta be hurting top speed.
I bent the tab out of the way and it ran like CRAP at WOT. Came up with a new
stopper that won't let the 'fly go too far, but goes further than before, and I went from
the stock 142.5 to a 150 main.
The Dynojet kits and Thunderslide recommend drilling the slider but I never have done
it, nor ever clipped a coil winding. I think the extra turbulence helps with the mixing
and performance.

Sounds like you know what you are doing, and welcome to the site. Don't be afraid
to learn new tricks here. I hadda eat some crow. Thought I'd come in here as a
teacher, but am an apprentice. Some of the guys here have been working on KLR's since
they came out in 1987. I've been working on them since 2009 and have had
to relearn the art of mixing. The spark advance is more aggressive than HD's too.
Probably attributed to the waterhead once again. These babies don't go over 190,
where we had to try HARD to stay under 250 in the past and were really taxing our oil.

Once again, enjoy the site and welcome aboard!
CheapMark
 

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Heh cheap you mentioned spark advance and it got me thinking I haven't seen any advancer devices for the KLR. As I live at mile high, I can run tons of advance and it really helps with the throttle response. I have an adjustable Muzzy advancer on the GPZ, set it to max when first installed and it works great up here. On the vrod I adjusted the advance via a laptop on the thundermax ECM. So I need to look into KLR spark advancers, anybody know of one?

John
 

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I think one of the reasons that we don't see some of these more aggressive mods on the KLR has to do with the nature(s) of the beast.
The KLR has a very nice torque and power curve. While it doesn't make loads of either, it has really good low-end grunt and a broad power curve . That's really desireable for most riders.
While there are things that can/could be done to improve the power, it may come at the expense of the low end, with most are loath to lose.
The tried and true mods are inexpensive and improve throttle response while preserving that beautiful low end.
And, after having picked that low-hanging fruit, if people want more power and will spend some money, they go for the 685. Even that doesn't add a lot of power, but what power it adds is very broad and useful.
A road bike that is making 100hp can afford to lose a bit of low end to get more top end, as that's where it will be useful on the road. The KLR does't have low end power to throw away, especially when that's where it needs it when it's in it's element, off road.

That's just my 2 cents, of course, and I'm a bit of a Luddite anyway ;^).

Tom
 

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Do the 2009 models need the Doo Hickey upgrade? I thought that was solved with the newer model..??
RBW, sorry for the thread jack. I am still interested in your response(s).

HB, this was not the thread to ask this question but since you asked...the Gen2 OEM balancer lever is made better than the Gen1 but not good enough. It fits loose and is made of weak material. The spring is good for MAYBE 500 miles then it is through doing its job. Kawasaki is aware of the problems. There is another MAJOR problem KAWI created during the remanufacturing of the KLR650 engine. To be discussed at another thread.

RBW, again sorry for the thread jack.
 

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Better, yes.
Good enuff? Yes for awhile.
There's a thread on it with a pic, and mine was the same.
The adjustment screw bit into the slot and made an indent.
Loosening the screw wouldn't let the adjuster slide due to
the indent it made. The casting itself has a rough surface.
It's not machined smooth to slide back and forth.
Also my '09 spring was fully relaxed. It had pulled the doo
as far as it would EVER go without ever once adjusting it.
We're talking 1244 miles on the scooter. Not excactly old.

I bought Eagle Mike's and would again in a second.
On the plus side, the new stock unit is unlikely to fail or come apart in the engine case
so it's ok to relax. Once the chain relaxes,tho, there's nothing (tension available)
to take up the slack. If you get extra vibration or hear a chain slapping the case
it's time indeed for the upgrade.

Metallurgically speaking, the casting is iron, and has aspects of both gray and ductile.
It's soft like an auto engine block, not hard like an automotive head or railroad wheel.
The softness is what lets the screw bite into the thing instead of just clamping it in place.


Reason for editing: Afterthought on Tom's paragraph.
My very first mod:

With the power coming on soon and low on the tach, I wanted an extra tooth countershaft sprocket.
I wanted to bring down the rpms at highway speeds back into the powerband. Something to
consider if you do 90% commuting and open road, and the occasional offroad blast.
I have no problems in the dirt with the 16. Only need first and second gear anyway. Well,
3rd on the looooooooong Indiana straight railroad beds. Ye hah baby!
 

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RBW, sorry for the thread jack. I am still interested in your response(s).

HB, this was not the thread to ask this question but since you asked...the Gen2 OEM balancer lever is made better than the Gen1 but not good enough. It fits loose and is made of weak material. The spring is good for MAYBE 500 miles then it is through doing its job. Kawasaki is aware of the problems. There is another MAJOR problem KAWI created during the remanufacturing of the KLR650 engine. To be discussed at another thread.

RBW, again sorry for the thread jack.
Thanks... and sorry, didn't realize I was in the wrong thread.
 

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Thanks... and sorry, didn't realize I was in the wrong thread.
Not a real problem HB. You were in the correct forum though the subject is "Simple Cheap Upgrade" which referred to carburetion mods.

Now about those Carburetion Mods. I am interested in knowing what some of the mods do and where they came from. Sounds like RBW knows his way around a motorcycle and can handle a wrench. I have never heard of cutting the spring and the usual slide drill for a KLR is 7/64th. I have never heard of a 'slow jet' but I want to know what it is.
 

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...Sounds like RBW knows his way around a motorcycle and can handle a wrench. I have never heard of cutting the spring and the usual slide drill for a KLR is 7/64th. I have never heard of a 'slow jet' but I want to know what it is.
He certainly does sound like he knows his way around a bike. I'm also intrested in the spring cut.

Pretty sure that "slow jet" is synonymous with "pilot jet". When I was wanking with Webers it was oftern referred to that way.

Tom
 

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Timmater',
There's 4 fuel circuits. Idle that we all know about and use at idle.
The throttle isn't being touched.
The low jet is a tiny thing with holes in the sides of a slender emulsion tube.
At cruise we are on the low jet and just starting into running on the needle,
which is nothing more than partial main. On the main, the needle is fully outta
the hole and the engine is taking the full amount of fuel the main can deliver.

Shimming the needle gets us to that point sooner, and a larger main is used
for a juicier mix when gettin' on it, or stayin' on it.

Cutting the spring lets the diaphram up easier, less vacuum can pull it up.
The larger hole lets the slide fly up faster when we yank it wide open.

The last two trick the carb into "thinking" the engine is under more of a load than it is.

Please help or correct me RBW if you don't agree or have another angle.
I know this is close, but my knowlege is limited to that I learned at HTT.
(Harley Tech Talk) It was msn's largest group at 25,000 members before they
cancelled groups. HTT's still around tho, and set up like this site now.
Bunches of dealership techs were on the site as well as hotrod dudes that also
had HD's. I picked up TONS of info in 5 years there.


......And what's this other major problem with the new casting????????????????
 

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...
Cutting the spring lets the diaphram up easier, less vacuum can pull it up. ...
Mark -

Now yer makin' my head spin. Cutting a spring makes it shorter and stiffer, doesn't it?

Tom
 

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I'd like to hear about what the MAJOR problem is as well. Did a search on the site for MAJOR and it came back, buy a honda :)

Also, all this carb talk got me going so I'll be putting a Dynojet kit in my bike when it gets here to go with the full FMF system that looks so "purty and trick". I ordered the special "high altitude" kit 'cause of my location and am looking forward to getting it leaner so it doesn't smell like unburned fuel at idle.

John
 

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Tom,
The whole spring is weak, very weak. The long flimsy one ya took out when doing
the .22 mod. It's not progressively wound. Cutting out a coil makes it shorter
and just as weak. It's only holding down the diaphram and vacuumm pulls it right
up out of the way. (While lifting the needle outta the main.) One less winding
length and it comes up further. The .22 mod lifts it another .052" (or so) at all
times. The diaphram and spring come into play only under vac and load.


Now my head is spinning. LOL
 

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..
Now my head is spinning. LOL
Yeah, I was trying to get my head around what chopping a coil off of a 5" long spring made out of .020" wire was really going to do.

See, in SU carbs we play with the viscosity of the oil in the dashpot...

Tom
 

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Discussion Starter #18
I think I have attached a Dyno print out to this reply. The afr (air fuel ratio) table is very lean at low rpm because the supertrapp only allowed me to probe up to the end cap about 3 or 4 inches into the pipe. The afr is right on about 13.5 to 1 at the big end though. I have not had any spits, spudder or hiccups, rapidly twisting the throttle from low to high rpms, and the starting sequence for the m/c is unchanged which shows me nothing to believe that it is rich. This is the exact same "git kit" we put in carb harleys. 3 up on slow jet size I believe the stainless washers we use are the same as in your 20 cent fix I will let you know what size. This setup works better than the Dyno jet kit (for harleys) and I think it's working great on my KLR. I am a master of service technology through H-D and work at Albany H-D. I am impressed with the knowledge in this forum as a lot of people come into the dealership with a lot of wrong info from the Harley forums. You guys have got my wheels turning and with a Dyno at my disposal I ordered another end cap today that I can drill a hole in so I can better probe my exhaust. Reading the replies I believe I have left some free torque and h.p.'s on the table. I am going to try taking off my air box lid and tuning for that I will have a new Dyno graph of the way the bike is now with the afr for the low rpms as soon as the end cap gets here. Thanks for the feedback, and I'm having a great time sharing ideas with you guys. I couldn't wait to get home from work to write this.
P.S. I have not changed my doohickey YET and I have 2,000 miles on my bike. It's time huh?
 

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Nice data! On another thread somewhat like this one, it was noted (and I don't know as my HD is fuel injected) that the HD Kehin has an accelerator pump whereas the KLR does not. Drilling the slide, cutting the spring, plus having an accelerator pump may cause a rich condition during quick throttle transitions upwards imho. You're pretty much at sea level so your HP should be a good as you get on these things.

Enjoy,

John
 

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I am just learning though I would like to know if HD mods are the same as KLR mods? I know they have the same brand carburetor but their vacuum characteristics and powerbands are different.

- When is the hole drilled in the slide too big?

- When is the pilot jet size to large?

- When is the main jet too large?

- Why isn't float level discussed?

- What do you have to do to make a silk purse out of a sows ear?

- Does a penguin have knees?

Note: 1987-2007 KLR650: CVK40 40mm carburetor: in the past I referred to the pilot jet sizes as 38, 40, and 42. I am sure I read that somewhere (maybe the service manual) but the Clymer manual shows the 38 and 40. The 38 is above 4,000 feet. The 40 is 4,000 feet and below. The Clymer also shows main jets as 145 and 148. The 145 is above 4,000 feet. The 148 is 4,000 feet and below.
These specs are most likely different for the 2008-2010 KLR650.
 
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