NooB needs some Float Level checking advice ...

Mean Green Z28 wrote: Well I tried starting her up and it only started up using the choke and I was able to rude it up/down the street on choke only. Still can't run without the choke, so took them off again. Thought I had the float levels wrong and read somewhere here they need to be set at about 18-19 mm dry; that made the level too high and the carbs leaked out the bore haha. Set them back to 22mm.

Also had a issue with cyl 4 not really working. Swapped plugs with #1 and even swapped the wires due to same coil and still nothing ... bought new plugs just cos they are old. Spraying some ether on that pod filter seemed to liven it up.

Compression test showed 70/55/58/70 ... double checked the carb and set the pilot screws to 1-1/2 ... fingers crossed and will try again tomorrow.

^^ Timeline is everywhere haha, but they're sitting on the bench right now awaiting reinstall and start up

Woah. I'm surprised it starts at all with compression that low. Have you adjusted the valve clearances? With compression that low you may have burnt valves or holed pistons... Forget about the carbs until you've got the compression up to at least 110PSI.

I think you need to re-check the compression numbers. You have to have over 90+ psi to run an internal combustion engine. Either your compression measuring technique is faulty or your gauge is wrong. While the carbs are off and you have a fully charged battery run the numbers again.

When running compression tests do the following with a screw in tester. The ones with a rubber cone shaped end are next to worthless.
1. make sure battery is fully charged
2. Hold throttle wide open
3, Spin the starter until ;the compression tester will read no higher. May take 5 to 8 or more complete "thumps" to stop rising.

while the carbs are off the bike is the best time to check compression as there is no carb or throttle in the intake path and each cylinder can suck as much air as possible.


As for only running with choke on you still have plugged idle jets/circuits. Sometimes they can be a bear to clean. The holes involved are tiny but when clean you can see a hole in the jet while holding it up to a light. As for the idle circuit you can wrap electrical tape on the carbs cleaner straw to make it fatter and seal better into the idle/slow speed circuit with the jets removed. Should see a good stream come out on the engine side of the carb body past the throttle butterfly.

Please don't be discouraged. I have done dozens of carb racks and still sometimes have to pull carbs again and finish up what I missed. Most people have to pull the carbs 3 or 4 or 5 times before we get it right.

The bright spot is you get good at removing and replacing a carb rack on your bike :laugh:

It sounds like the compression was not properly tested.

Engine should be warmed up to normal operating temperature.
Remove all spark plugs.
Have fully charged battery.
Open throttle wide open.
Crank the starter until the compression reading will not rise any further.

Ed

I did mine the other day and they all read around 180psi.

Well looks like I may need a rebuild. Warm numbers 90-70-67-90 ... fml
Also, looks like #2 is also not really joining the party.

Mean Green Z28 wrote: Well looks like I may need a rebuild. Warm numbers 90-70-67-90 ... fml
Also, looks like #2 is also not really joining the party.

Do the valve clearances first! If the clearances are too tight, you'll have low compression like this. If the compression isn't above 110PSI (cold) on all cylinders after getting the valves in spec. Then try adding a tablespoon of oil to each cylinder and try again. If the compression goes up, then your rings/cylinders are worn. If it doesn't, then you're left with burnt valves or holed pistons as possibilities. When you take the head off, you'll know which it is just by looking.

The compression will always jump if you add oil to the cylinder because it reduces the volume of air in the cylinder. Take a look at the link below for specifics. Ed

www.kzrider.com/forum/2-engine/598886-19...2-compression#680429

A small amount of oil won't make it jump that much. I haven't heard if the valves were checked yet.
Steve

Would Consider performing a leak-down test.

A leak-down test injects air pressure through the spark plug hole to pressurize the combustion chamber.

Can perform a poor-man's leak-down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air. Or just use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).

Good Fortune!

But, how much is a "small amount?"

One tablespoon equals 14cc. That will definitely have a huge effect on the compression ratio. If 14cc of oil is added to a 250cc combustion chamber that originally had a compression ratio of 10:1 it would drive the compression ratio up to 21.5:1.

Here's why:
- With no oil added the uncompressed volume would be 250cc and the compressed volume would be 25cc. 250 / 25 = 10.0 compression ratio.
- With 1 tablespoon (14cc) of oil added the uncompressed volume would reduce from 250cc to 236ccc and the compressed volume would reduce from 25cc to 11cc. 236 / 11 = 21.5 compression ratio. Ed

Took the head cover off ... need to get feeler gauges tomorrow. Yeah I know the whole dry/wet compression test and leak down test bit ... don't have a leak down tester but will be able to use the quick disconnect part of the compression tester. Didn't have much time this evening to do anything and I can't start up the compressor in the night and wake up the baby haha

I'm having a sinking feeling it's the rings as I sort of remember feeling a lot of blowby coming out of the top vents on the valve cover and the lower vent on the crank case when I first started her up a while ago ... can't belive I didn't think of that till someone suggested the leak down test