serious help needed

[CrazyChris]

Good day Gentleman. I have a bit of a dilema I hope you guys can help me with. Busy putting my ZX400G together (build thread) and the past week I have been struggling with a fuel leak out of the carbs. Got that sorted with Pratley steel but she does not want to fire up. Get lights, petrol pump is working and I'm getting spark. Any ideas what I should be looking for? Don't know for how long the bike stood before I bought it but there was a lot of surface rust everywhere. I also do not have dowl pins between the head and the crankcase

Any help will be appreciated

[Animammel]

Make sure clutch is pulled in and maybe get it off the kickstand (that button it presses). Safety issues.

Turn it over as per norm and quickly remove a spark plug and see if its wet or dry.

[CrazyChris]

I already bypassed the side stand switch. The motor turns over fine but it doesn't start up at all. So I don't know if the clutch stupid switch is the culprit.

[RedexRobB]

Is the battery well charged? the ZXR is prety bad ata starting without a battery in tip top condition. Maybe worth trying to startoff a car battery?

[CrazyChris]

That was my first thought so I charhed the battery. Standing at a healthy 13.5 volts. Didn't think about hooking a car battery up. Gonna do that tonight.

[CrazyChris]

Hey guys. So I connected a Willys Jeep to the bike. Still no luck. It back fired ones through the exhaust (think it might be fuel build up in tbe exhaust cause it only does that after a long time turning the engine) and it back fired through the carb once as well.I sawpetrol fumes coming out of the carb while turning the motor. Its like instead of sucking the fuel into the cylinders its blowing it out. Now my question. How accurate is the cam timing instructions in the manual? When I did the cam timing I put the rotor on TDC but didn't check the piston. Must I use the two marks on the other side of the rotor or not?

[banner001]

how are your valve clearances?

are they set tight, or loose on the ignition side?

when mine were tight (i.e. the valve is open for longer) i would sometimes get the impression that something similar was happening to yours when i had the airbox off, i could see small amounts of petrol vapour coming from the top of the carb...now that mine are set to the loose end (i.e. biggest possible gap) its a lot better, starts better too as im guessing that the piston is "sealed" earlier as the valves open and close later.

[CrazyChris]

And here I thought that I covered all the bases. Thanks Banner. Gonna pull an all nighter tonight and check that before I go on to timing.

[banner001]

check the timing first, once the timing is correct, then check the valve clearances.

timing is easy, at TDC the marks on the cam sprockets should be pointing 180degrees away from each other, and there should be 30 gaps in the chain between the timing marks.

then check valve clearances between the cam lobe and the rocker arm, mine have tightened over time and were all in the 3.00 - 3.15mm range for reference (so at the larger end of what you can buy), shims are all 7.48mm diameter.

put it this way, if you have compression then you will also have air, if you have fuel in the float bowls then you have fuel, and if you have sparks you have all 4 things you need...

things to check, needles and jet sizes in the carb, check that the pickup coil is good, maybe get another IC ignitor as your ignition timing might be off?

when everything is good, if it still wont fire up, i would think its mixture or ignition timing.

[Animammel]

Are the spark plugs wet or dry?

[CrazyChris]

Right, spent the whole night last night working on the bike. Slept a total of 3 hours. . Checked the timing and checked the valve clearances and all is good. Spark plugs are dry. Did notice something though. Seeing as I do not have a compression checker I made a little plan with a rubber hose just to see if there might be any difference between all the cylinders. Number 2 (I think, its the second one from the left side of the bike) has considerably less "sucking" and "pushing" power than the rest. I did put a new head gasket in when I started to put the motor together.Rings looked fine as well. Now correct me if I am wrong but can't the fact that I do not have dowl pins on my head have anything to do with that? One piston being down on compression might cause the bike not to start right?

[CrazyChris]

Right. Spent the whole day working on the bike again. Figured out that I wired the coils wrong. Its so close to start its not funny. Chargin the battery overnight and trying tomorrow

[banner001]

good good, i did say ignition timing

so what did you do, wire #2 and #3 cylinder to #1 and #4 coil?

[CrazyChris]

Yes I did. Also realised the coild must not be earthed to the frame (had to drill holes in the frame cause the rubbers that you screw the coils to were missing) so I made a plan. I think now my cam timing is a wee bit out cause its on the point where the motor turns faster so busy woking on that.

[banner001]

the coils earth to the bike through the spark plug...its the only path for the electricity to go, so it "earths" to the bike head and back to the battery that way.

unless you have adjustable sprockets your cam timing will either be right or wrong, there isnt any adjustment possible. piston TDC on T timing mark, sprocket marks facing away from each other, chain should have 30 "gaps for teeth" between sprocket marks.

then do the valve clearances, balance carbs at fast idle (~3k rpm) and you should be good to go!