Carb problems? Something else? I'm lost...broke down, and need help! - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 36 Old 05-04-2010, 12:50 PM Thread Starter
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Carb problems? Something else? I'm lost...broke down, and need help!

Ok, I got deep into a world of modding over the past 2 weeks. Here is exactly what I did to get to this point.

Starting from bone stock (1999 650)

Supertrapp IDS II Exhaust (Is used and needs repacking, but I also tried straight pipe with the same results)
Repainted Exhaust header/pipes with high heat black paint
Removed air box
Added K&N filter
Cleaned Carb
Changed stock 148 main jet to a 160
Still running the stock 40 pilot jet
drilled and shimmed the slide with 2 #3 washers
I'm also out 3 1/2 turns
Choke is seated too

After the carb rebuild (I made sure the rubber boot was free of holes and created a seal), I start the bike.

What happens is this:

I can rev at idle like normal, can easily hit 5k.

A slow rev though, I can't get about 3-4k without hesitation. If I hold the throttle, it will hesitate, drop a hair, then catch up with the higher rev.

However, upon load, I can't get above 3500, after that, I get severe lugging and bucking. I can only get to about 45mph before she hits a wall.

I originally thought I was running too lean (which is still possible), and I have to special order the #50 Pilot Jet that I want.

I'm just racking my brain as to what it could be.

Additionally, at the coast enrichener, there is a small gap where it sits on top of the "O" ring. It is sealed at the "O" ring though, and not leaking.


Also...

I tried another slide assembly from another carb (from a KLR). It does sit better in the groove, however, now here are my symptoms.

a) No tach, it will bounce like crazy or stick at 3k
b) Nothing more than 45mph (It will start puttering, bucking, and lugging)
c) Low end is fine, I can start out, accelerate at a normal pace, and shift just fine...If I punch it though, I will get lugging and rough acceleration.

I am putting my original slide back in after the engine cools.

The original slide does not have a hole.

My valves are lightly tapping, which is normal.

I don't think it's a jet issue...I can't get above a certain rpm...AT ALL.

Should the slide be lubed up? I don't remember if mine was.


Again, it revs just fine...the low end is fine...but when I try to punch it, or go about 50mph, it starts lugging, bucking, and puttering...


Please, I'm at a loss here...
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post #2 of 36 Old 05-04-2010, 12:53 PM Thread Starter
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Also, here's a youtube video with the problem...

youtube .com /watch ?v= gk5bADKAQH8
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post #3 of 36 Old 05-04-2010, 01:02 PM
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toasty hoodie -

Why a 160 jet? That sounds like it would be quite rich. Pukey rich.

Your symptom of being able to rev to 3-4K and them having it hesitate and catch up sounds like the idle circuit is working correctly, but then the crossover to the main jet may be too rich. The stumbling and bucking sounds like an overly rich problem, too.

Now it could be other stuff (like you really didn't get the carb cleaned out right), but for easy diagnosis reasons I would try going back to a stock jet ('cuz you have one) and seeing what happens.

How many discs are you running in the IDS2?

You've made quite a few changes simultaneously here. If the smaller jet doesn't help, figuring this out may take some time. I know you don't want to hear this, but any chance you can go back to stock and wrok things out one thing at a time? Something to consider if the stock jet doesn't return the bike to some semblance of civility.

Tom

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post #4 of 36 Old 05-04-2010, 01:13 PM
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toasty hoodie-

Now allow me to be critical, and don't take it wrong. What follows is my opinion. It's worth everything you've paid for it .

Removing the airbox, from a performance persepctive, didn't do anything for you that about 4 one inch holes poke in the box would do.

Installing the K&N is probably reducing the airflow over what the stock filter or a Uni filter would do.

The IDS2 is pretty well opened up when you have eight discs in it. After that it doesn't flow more, but it just gets louder. It's already way louder than stock at four discs, which is equal to the opening on a stock muffler.

What I'm leading up to is that you may not be flowing as much as you think you are, and are therefore not nearly as lean as you think you might be.

Tom

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“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


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post #5 of 36 Old 05-04-2010, 01:19 PM Thread Starter
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Quote:
Originally Posted by Tom Schmitz View Post
toasty hoodie-

Now allow me to be critical, and don't take it wrong. What follows is my opinion. It's worth everything you've paid for it .

Removing the airbox, from a performance persepctive, didn't do anything for you that about 4 one inch holes poke in the box would do.

Installing the K&N is probably reducing the airflow over what the stock filter or a Uni filter would do.

The IDS2 is pretty well opened up when you have eight discs in it. After that it doesn't flow more, but it just gets louder. It's already way louder than stock at four discs, which is equal to the opening on a stock muffler.

What I'm leading up to is that you may not be flowing as much as you think you are, and are therefore not nearly as lean as you think you might be.

Tom
While I appreciate your opinion, I have already run straight pipe, and no K&N and have the same problem.
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post #6 of 36 Old 05-04-2010, 01:54 PM
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Quote:
Originally Posted by toasty_hoodie View Post
While I appreciate your opinion, I have already run straight pipe, and no K&N and have the same problem.
Which is no sign of anything, other than confirming that the engine requires measured amounts of back pressure on the exhaust, and measured air flow at the intake to operate as tuned.
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post #7 of 36 Old 05-04-2010, 01:59 PM Thread Starter
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Originally Posted by vatrader View Post
Which is no sign of anything, other than confirming that the engine requires measured amounts of back pressure on the exhaust, and measured air flow at the intake to operate as tuned.
Ok, if you could explain to me is stupid simple terms, I'd appreciate it.

I have only a basic idea of what I'm doing here. I'd love to figure this mess out, lol.

I'm not willing to go back to the stock muffler, and I'm not dropping down the subframe to put the box back in.
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post #8 of 36 Old 05-04-2010, 02:09 PM
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Quote:
Originally Posted by toasty_hoodie View Post
Ok, I got deep into a world of modding over the past 2 weeks. Here is exactly what I did to get to this point.

Starting from bone stock (1999 650)

Supertrapp IDS II Exhaust (Is used and needs repacking, but I also tried straight pipe with the same results)
Repainted Exhaust header/pipes with high heat black paint
Removed air box
Added K&N filter
Cleaned Carb
Changed stock 148 main jet to a 160
Still running the stock 40 pilot jet
drilled and shimmed the slide with 2 #3 washers
I'm also out 3 1/2 turns
Choke is seated too...


I originally thought I was running too lean (which is still possible), and I have to special order the #50 Pilot Jet that I want...


Again, it revs just fine...the low end is fine...but when I try to punch it, or go about 50mph, it starts lugging, bucking, and puttering...


Please, I'm at a loss here...

You proabably allready know this but for the benefit...

Motorcycle carbs work on throttle postion not RPM. The jet circuits in the carb overlap somewhat. The low speed circuit is the pilot jet and air screw. You say the bike is fine at low throttle so that's not the problem (BTW if you need to be out more than about 2.5 turns on the air screw the pilot is too lean).

The stock bike is generally lean on the low and mid circuits (<1/2 throttle) and rich on the high speed circuit (3/4 to full throttle). When you twist the throttle wide open your on the main jet primarilly. You've made that circuit even richer than stock so I would go back to the stock main and see how it runs. Also you may need to take one of the washers off the slide needle as that overlaps onto the main jet circuit somewhat.
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post #9 of 36 Old 05-04-2010, 02:16 PM
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Originally Posted by toasty_hoodie View Post
Ok, if you could explain to me is stupid simple terms, I'd appreciate it.

I have only a basic idea of what I'm doing here. I'd love to figure this mess out, lol.

I'm not willing to go back to the stock muffler, and I'm not dropping down the subframe to put the box back in.
Interesting position to be taking for someone in trouble!

All i can do is wish you luck then. My suggestion is to go back to stock exhaust and air box to isolate the "wall issue".

I'm also out 3 1/2 turns

That is about one full turn more than I have ever set the main jet to.

In listening to the engine on the video, I do not hear any popping on decell, which would indicate a lean setting.

K&N air filters on KLR 650's have created far more problems than solved any. You need to get a controlled air system back on the bike to isolate the problem.

A KLR 650, well tuned, can be turned into a stumbling nightmare simply by putting on a straight pipe.
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post #10 of 36 Old 05-04-2010, 02:21 PM
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Quote:
Originally Posted by toasty_hoodie View Post
Ok, if you could explain to me is stupid simple terms, I'd appreciate it.

I have only a basic idea of what I'm doing here. I'd love to figure this mess out, lol.

I'm not willing to go back to the stock muffler, and I'm not dropping down the subframe to put the box back in.
Then, at the very least, go back to the stock jet and see if that doesn't improve things. If it does, then you will know that the 160 is too rich and you can begin finding the right jet to get the Air/Fuel ratio correct. You should be shooting for a mixture of about 13.5:1. That's a slightly rich mixture that will insure you're running cool and avoiding detonation and all the other evils of a lean condition. You can read the plug to see if you are slightly rich.

I am suggesting that the 160 main jet has got you in the 11:1 range, or even worse, and is the cause of the stumbling, hesitation, lurching, bucking, puking, what have you. There's so much gas there that the engine simply can't create a combustable mixture.

Tom

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“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.
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