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Mexican Hard Shell Taco
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OK, I have a Katana 750, CA model. The thing has 105 main jets, and I don't know what kind of pilot jets it may have (the numbers on them are unreadable).

Here is what it does:

a) Hard to start when cold, have to let it warm up real good or it will run like isht!

b) In traffic, if I stop, lets say a stoplight, when I try to take off it will run like crap, if I give her gas it will sputter and seem to run on 2 cylinders. I have to give her full throttle or rev it up before letting the clutch go. Sometimes, if it is reall hot and the stoplight was long, I will have to rev it a few times before it is able to run right.

c) Doesn't like low RPMs. When hot, cold is way worse, I can't try to accelerate at 3K rpms, I have to downshift or give it very little gas, or it will sputter and run on 2 cylinders until it gets to 5-6k rpms.

d) Sometimes when I'm cruising around 5K rpms, if I give her a little bit more gas it will sputter and do the same as above, I have to downshift or give her more gas.

Top end of the RPM band seems to be fine, pulls hard, but I can't really tell if it is as hard as it should.

Plugs look really lean, the "white" part of the plug is "too white", no brown/tan as it should be. Also, the exhausts have no carbon deposits, if you stick your finger in there it is just dirt/rust or a yellow-ish dust, that I think may be sulfur (our gasoline is high in sulfur), but not any black carbon as it should be.

That and the fact that the exhausts are drilled and the bike has pod filters, makes me think the bike is running extremely lean.

Note:

I'm not as dumb as to drill the exhausts, I think the PO is extremely dumb to do that to the bike, but well, what can I do now? Also, why the pod filters? Well, the PO was so dumb that took it to a very bad mechanic, who never bothered to correclty install the airbox, so all the tubes connecting the airbox to the carbs are deformed and wont fit anymore.

I must admit, the bike looked way better than how it really was. Had to replace the battery, one fork seal, tires, adjust the valves, change the oil/filter, those problems with the airbox, new sparkplug wires, etc.

I'm starting to regret about it, it is being more expensive than what I can comfortably afford...

Anyway, my idea was to buy a junker and fix it up, but I decided to start with the nicest junker I could find, guess this junker was just a looker, not a runner.
 

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Before you go and try to rejet it, spend a few dollars and just replace the plugs with quality ones. I bought a bike I was going to flip (resale) and it ran like crap. I got a great deal on it because the owner thought it was messed up. It had noname plugs in it. All I did was replace th eplugs and it was like a new bike.

You might also need to sync the carbs/throttle boddies. That will make a bike run like $#%@ if they are out of sync. A very simple fix that costs you no money if done yourself.

I love trying to fix bikes as it is normally something simple that the previous owner thought was a major problem.

Keith
 

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Carb synching will only smooth out a rough idle and cruising behaviour.

I would check the spark plugs to make sure they are the right temperature and type for the bike. I would replace them and then take the carbs off and see what exactly has been done to them. It sounds like your running extremely lean which will damage the engine if left to long. You probably need to richen up the mid range at least. If the previous owner put only an aftermarket pipe on the bike your ok without jetting, but if they put pod filters on it you had better jet it properly or the bike will run dangerously lean.

Check out factory pro's tuning guide to diagnose your condition and see what parts of the rev range you need to richen up:
http://factorypro.com/tech/carbtune,CV,high_rpm_engines.html
 

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Mexican Hard Shell Taco
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5,894 Posts
Discussion Starter #4
Sparkplugs are new NGKs, the specs recommended by Suzuki for the bike, also sparkplug wires are new NGKs.


The bike idles smoothly, doesn't misfire, maybe rmps go up and down 100rpms, but thats it.


Now, the fact that the plugs are WHITE, there is no "soot" on the exhausts, the extremely hot engine point into a lean running engine. I've already went through valve adjust, carb cleaning, new airfilter, oil change, new sparkplugs, new sparkplug wires, etc.
 

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It sounds like you are lean, most likely due to the pod air filters. The air/fuel mixture screw will help with idle. Do you know if the bike has an aftermarket jet kit in it? If it does not and you would like to keep the individual filters, I would purchase one. If you go with a dynojet kit, make sure it is the stage 3 kit.

If you don't want to spend the extra money, call dynojet for the air fuel mixture screw setting, main and pilot jet sizes for your bike using the individual filters. Just say you lost the instruction sheet.
 
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