Need Kawasaki KV 75 help....

#1
I have a late 70s Kawasaki KV 75.
It had a dirty carbureter and the float had a pin hole in it. I cleaned the carburetor and installed a new float and needle and seat. I adjusted the float height as per my instructions. Roughly 21 mm measuring without the bowl gasket in place. I even checked the fuel height which is around 5 mm below the gasket surface. Fresh fuel mixed at 40:1. Oil injection not hooked up. New spark plug and air filter in place during testing.
My issue is.... it starts right up but bogs out. I have had the carb off more times then I want to mention and always the same. Starts but won't take throtle without bogging. If I turn the fuel valve off and let it start to run out of fuel..... it will then Rev out. So to me that says I am getting way to much fuel ???? I am very mechanically inclined but this bike is makin me feel pretty stupid. LOl. Any help you can give me would be greatly appreciated .

Mark23
 

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#2
Does it run better or worse when choked? Does it start easy or do you have to wind it up by kicking rapidly? Do the rpms change when spraying WD40 or carb cleaner around the carb or crank seals? Check the jet sizes. Quite often the pilot jet is overlooked and will determine how it runs. It's usually down in a port next to the main jet and is sometimes hard to see. If you cleaned them with drill bits, you may have opened them up too far. The numbers on the jets represent that percentage of a millimeter. Like a number 100 jet measures .03937 of one inch and you can choose the correct bit to run through it. All of these are clues to how the engine runs. Other forum members will have more ideas and info.
 
#3
Does it run better or worse when choked?...
That's where I usually start, too. If it won't run with the choke off the pilot jet is likely to be plugged. Remove the pilot jet from the carb body for inspection. You should be able to see daylight through the tiny hole. I've never used drill bits to clean these. I haven't had one yet that I couldn't fix by just stabbing at it with a sewing needle. Soaking in carb cleaner helps also. While the jet out of the carb body, blow compressed air through the passage. Air should come out of little hole in the carb throat. My experience with crank seals is that the dry side (ignition) that will usually fail first, before the side with the primary gears and clutch which are bathed in oil. When the crank seal fails the bike will rev too high at idle. Nice looking bike, BTW, and welcome to the forum.
 
#4
Does it run better or worse when choked? Does it start easy or do you have to wind it up by kicking rapidly? Do the rpms change when spraying WD40 or carb cleaner around the carb or crank seals? Check the jet sizes. Quite often the pilot jet is overlooked and will determine how it runs. It's usually down in a port next to the main jet and is sometimes hard to see. If you cleaned them with drill bits, you may have opened them up too far. The numbers on the jets represent that percentage of a millimeter. Like a number 100 jet measures .03937 of one inch and you can choose the correct bit to run through it. All of these are clues to how the engine runs. Other forum members will have more ideas and info.
Does it run better or worse when choked? Does it start easy or do you have to wind it up by kicking rapidly? Do the rpms change when spraying WD40 or carb cleaner around the carb or crank seals? Check the jet sizes. Quite often the pilot jet is overlooked and will determine how it runs. It's usually down in a port next to the main jet and is sometimes hard to see. If you cleaned them with drill bits, you may have opened them up too far. The numbers on the jets represent that percentage of a millimeter. Like a number 100 jet measures .03937 of one inch and you can choose the correct bit to run through it. All of these are clues to how the engine runs. Other forum members will have more ideas and info.
Thanks for your reply.
It starts very early. Fires right up. Then about 5 seconds in. Doesn't take throtle. Juse wants to bog. I never did try putting the choke on when it bogged. I did shut the fuel off to lean it out. I will try the choke later today and see what it does. The bike was running in the summer. The carb and jets were all removed and soaked. I can blow air through every orifice and see light through all the jets. I can try some brake clean around the flywheel area and carb and see what happens. This bike has me puzzled.
 
#5
Thanks for your reply.
It starts very easy. Fires right up. Then about 5 seconds in. Doesn't take throtle. Juse wants to bog. I never did try putting the choke on when it bogged. I did shut the fuel off to lean it out. I will try the choke later today and see what it does. The bike was running in the summer. The carb and jets were all removed and soaked. I can blow air through every orifice and see light through all the jets. I can try some brake clean around the flywheel area and carb and see what happens. This bike has me puzzled.
 
#6
That's where I usually start, too. If it won't run with the choke off the pilot jet is likely to be plugged. Remove the pilot jet from the carb body for inspection. You should be able to see daylight through the tiny hole. I've never used drill bits to clean these. I haven't had one yet that I couldn't fix by just stabbing at it with a sewing needle. Soaking in carb cleaner helps also. While the jet out of the carb body, blow compressed air through the passage. Air should come out of little hole in the carb throat. My experience with crank seals is that the dry side (ignition) that will usually fail first, before the side with the primary gears and clutch which are bathed in oil. When the crank seal fails the bike will rev too high at idle. Nice looking bike, BTW, and welcome to the forum.
I had the carb off too many times that last few days. Lol
I know the jets are clear and the passages are clear. Seem to all start with the new float and need and seat. I set the float as per the instructions and I even went as far as reinstalling the old needle and seat. Still has the same issue.
 
#7
You didn't mention trying different float levels. It may not be closing soon enough. Instructions are usually good, but it may be worth a try. I attached a vent hose to the fuel tank once by mistake and needless to say it flooded profusely. Very embarrassing. I went dirt bike riding years ago on an old Kawasaki F6 (my first off road experience) and a piece of silicone sealer got into my carb and held the float down, flooding my engine. No tools and miles from camp in the Mojave desert. The only thing I did right that day was not to go out alone. My riding buddy (a mechanic) suggested I close the fuel valve until it kept running. It worked well enough to putt back to camp. You can check for flooding by using the fuel tank valve to meter the fuel. When you shut it off and it starts to rev, open the valve slightly and see if you can keep it running that way. Very simple test, may be worth a try.
 
#8
You didn't mention trying different float levels. It may not be closing soon enough. Instructions are usually good, but it may be worth a try. I attached a vent hose to the fuel tank once by mistake and needless to say it flooded profusely. Very embarrassing. I went dirt bike riding years ago on an old Kawasaki F6 (my first off road experience) and a piece of silicone sealer got into my carb and held the float down, flooding my engine. No tools and miles from camp in the Mojave desert. The only thing I did right that day was not to go out alone. My riding buddy (a mechanic) suggested I close the fuel valve until it kept running. It worked well enough to putt back to camp. You can check for flooding by using the fuel tank valve to meter the fuel. When you shut it off and it starts to rev, open the valve slightly and see if you can keep it running that way. Very simple test, may be worth a try.
I just had it fired up. Runs great for about 5 seconds upon fire up..... then bogs. Putting the choke on makes it worse. Sprayed brake clean around the flywheel and the carburetor and the inlet. No change. Gave the air filter a quick spray..... she didn't like that. Drowned out the engine. I have tryed the engine with the fuel valve off. When it starts to run low on fuel it revs nice like a 2 stroke should. It's getting toooooo much fuel in my opinion. May have to keep trying to lower the fuel level with the float. I am actually a bike mechanic by trade and this lil bike is getting the best of me I am sad to say.
 

Gatecrasher

Well-Known Member
#13
One thing to check is to remove (unscrew) the main jet & needle jet from the carburetor body. Separate the two and clean them both making sure to poke the tiny holes in the sides of the main jet. They can be clogged and sometimes it doesn't really look like it.

I'd probably totally disassemble the carb and soak everything and re-clean it. Your symptoms definitely point to something being clogged.

These carbs are super=easy to tune when they are functioning properly. You wouldn't be having the problems you are if it was.

Most of these carbs have been run with no filter or even the factory screen on the petcock for years and then parked for a few decades. Lots of dirt, debris, varnish, all kinds of crud gets in there that can be difficult to remove without a poker and some scrubbing along with some high pressure air.
 

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Gatecrasher

Well-Known Member
#14
I just looked at your picture and noticed that you are using an aftermarket air cleaner. When you switch to a less-restrictive air cleaner you need to richen the mixture some by moving the "C" clip down a notch or two on the jet needle. Without the adjustment you will usually get a lean bog when opening the throttle.
 
#16
I tryed moving the needle up and down with the clip. No real change.
This all started with the new float and needle snd seat. Old float had a hole in it and was filling with fuel. I have a new float now but I am guessing it's my float level that is playing tricks on me. Do u know the proper float height measurement. There was measurements with the new float but they didn't seem to work very well. Hence the bogg.
I have had the carb off a few times today trying to get it dialed in. The best I had it was with the float at 30mm from the carb surface. It ran lean and when I put the choke on it ran pretty well. Changed the float to 27 mm and right back to the bogg. Choke made it worse. This bike is getting the better of me. this bike is making me feel pretty stupid I have to say. Appreciate any help u can give me.
Thanks
Mark
 
#17
I tryed moving the needle up and down with the clip. No real change.
This all started with the new float and needle snd seat. Old float had a hole in it and was filling with fuel. I have a new float now but I am guessing it's my float level that is playing tricks on me. Do u know the proper float height measurement. There was measurements with the new float but they didn't seem to work very well. Hence the bogg.
I have had the carb off a few times today trying to get it dialed in. The best I had it was with the float at 30mm from the carb surface. It ran lean and when I put the choke on it ran pretty well. Changed the float to 27 mm and right back to the bogg. Choke made it worse. This bike is getting the better of me. this bike is making me feel pretty stupid I have to say. Appreciate any help u can give me.
Thanks
Mark
check the seal on the bottom of the choke plunger.if it leaks there it will run rich.
 

Gatecrasher

Well-Known Member
#18
Not to sound like a broken record but these carbs are super-easy to tune so if you are still having a problem you still have something clogged or wrong with the carb.

There's not a whole lot to them and they are very forgiving. No "magic" settings or tuning involved. I'd completely disassemble the carb and clean it immaculately making sure all the tiny holes in the jets are clean. I've seen it many times before with these carbs.

Worse case you can send it to me for a complete rebuild including full tune-up on a running bike so all you will need to do is bolt it on and go.
 
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