Idle

Repost:
Thanks to everyone, I can get the bike kick started The electric starter wouldn't start the bike at all. I wonder if maybe the starter clutch was slipping just enough that the engine couldn't build enough vacuum to start. Now I just need to fix the idle. I think that I may have to rip the carbs apart again. I have the idle set screw backed all the way out but it still idles at 5000 rpm. I think something is stuck in the carb, but I wonder there too. It only goes up to 5000 rpm when the bike starts to warm up but not for the first couple of minutes.

OK I jut removed the carbs and everything looks fine. The butterfly valves are shut and the diaphragms look good. No clues here, can anyone suggest anything?




Steve

KZ750M1 CSR

Sorry, haven't read your other post.

Have you checked for any cracks or leaks in the manifolds? On either side of the carbs, before and aft. Spraying carb cleaner or WD40 around the manifolds while the bike is running, and seeing if there's a change in RPM would indicate a leak in the manifolds.

Why would a leak only come into play when the bike warms up? When it is cold it idles fine.

Go back over your cables to make sure they are not holding the carbs open might loosen the adjustments on the cables to be sure . Also check that all your vaccumn lines are hooked up right .. , Then check for Vaccunm leaks using a can of spray carb cleaner ,, spraying around the carb holders see if the engine changes speed when sprayed

Ag3NT wrote:

Why would a leak only come into play when the bike warms up? When it is cold it idles fine.

everything expands with heat. the leak would show up when hot but not when cold...

Ditto to Arobsum. You prob is probably in the area of heat. Check your carb holders. On my 650 I took mine off then put some liguid gasket silicone to seal up a leak I thought was there, but it so turns out I had a broken hose on one of my hoses that hook up the carb holder to that emissions system thing I have on my bike.

All right the bike ran fine all weekend. Monday moring no love at all. I puled the carbs out again and cleaned them. I had to switch to reserve while riding and looks like I had some crud in the tank. After putting it all back together still nothing. I am stumped, I have spark, and gas is getting into the cylinders. My wife is to the point of wanting me to get rid of the bike. I really need some help here.


Steve

Am wondering whether an ample supply of clean fuel is going into the carbs.

Crud inside the tank may hover suspended in the fuel. When running, the suspended crud may be drawn toward and collect on and obstruct the petcock fuel intake parts fitting up inside the tank. The sensation when riding feels like running out of gas. In this situation, switching to reserve sometimes adds a little more flow from inside the tank via the petcock reserve intake and then on through the petcock outlet and fuel line to the carbs.

Would suggest the following to avoid re-contaminating the carbs (despite repeated efforts, they don't stay clean):

Remove petcock from the tank and clean the area that fits up inside the tank.

Disassemble and clean petcock mechanicals.

Drain fuel tank and flush out with fresh gas to remove existing loose crud, grit, etc. Add fresh gas and physically shake the tank and rapidly drain it out the gas cap filler hole. Repeat several times until only clean fuel comes out.

Attach petcock to fuel tank.

Test flow of fuel through the petcock.

Use new fuel line or use existing line only after cleaning and blowing the line clear with compressed air.

Install a new in-line fuel filter.

The above steps should assure an ample supply of clean fuel going into the carbs. And until so assured, other testing and adjustments are problematical.

Realize this has been an exasperating ongoing problem for quite some time, and hoping to help get your bike back in business.

I'll try cleaning out the petcock/tank this week. Other people have mentioned maybe weak spark or timing since I can smell gas. How would I check and fix that? Would new points and condensers help anything at all? Wiling to try anything at this point.


Steve

Ag3NT wrote:

I'll try cleaning out the petcock/tank this week. Other people have mentioned maybe weak spark or timing since I can smell gas. How would I check and fix that? Would new points and condensers help anything at all? Wiling to try anything at this point.

Could be an ignition issue also, but because "the bike ran fine all weekend," am guessing ignition is okay for now, even if marginal. Having a workable idle speed helps in diagnosing the ignition. Also valve clearances might be an issue (or other compression factors). Will want to assure all non-carb matters being within specs insofar as possible before final carb tuning and adjustments.

Remember the in-line fuel filter.

sounds like a combination of adjustable details.

---

Spark-Fuel-Compression---thats it
1. setting points is an art that requires practice
2. float levels need to be within a millimeter of spec.
3.complete fuel system needs to be clean!!tank to float drain
4.fix/check the plug wire ends and caps and get extra NEW spark plugs
5.valve lash and carb sync after that
6.wiring/battery
7. uhhhhh lets have a beeer
8. sell it to me (no I'm kidding)

I took my bike to the garage today. The mech told me that the problem is lack of compression. He said that it is barely 20lbs and should be at about 80lbs. not sure if it is a holed piston or worn rings. If it is rings/pistons does anyone know of a good source for parts????


Steve