1975 Z1 900B

Okay... I have been building this bike for over two years now (1975 Z1 900b) and I am so close to getting it finalized. But now I have run into a problem with the starter or starting up the bike...

A few ground rules...

I am using or replaced the following parts:
-EarthX battery (ETX18b) Specs are listed below.
-Dyna coils DC1-1 3 ohm
-replaced clutch rollers and springs
-VM29 Smooth Bore Carbs (bench Synced) 2.0 slides instead of 1.5 slides (which are recommended) but I did setup the jets and needles for -that size slide (2.0). Pilot Air screws are turned out one full turn each.
-Mikuni Large Round Main Jets #120 (recommended by Jeff at Z1)
-Pilot Jets VM22/210 #22.5 (recommended by Jeff at Z1)
-Starter Solenoid (Ricks from Z1 Enterprises)
-K&N Pod Air Filters
-Custom 4 into 1 exhaust
-Spark Plug Gap .033

So when I go to start the bike It will start and run for a bit, but then as I go to adjust the idle screw it dies after a bit. When I go to restart it with the electric start, the starter gears just spin and it makes horrible noises. Occasionally it will catch and almost start but then it back fires and nothing happens. I end up having to recharge the battery because it drains it after a bit of trying to start it. I thought It was the rollers and springs in the starter clutch, but that did not help it. I also thought it was maybe the original starter solenoid and that has not helped it. I replaced the positive and negative wires to the battery with brand new ones. Still nothing. The wire is a little bigger gauge. I think OEM is 4 and I am using a 6 gauge. But I could not see that being the issue :blink: . Replaced the Battery, specs are below.

I cannot seem to figure out why the starter is not catching. Or if its the spark. I also checked the spark plugs and they looked pretty wet and black. So I know I am running rich.

Any thoughts on where to start troubleshooting or some thoughts will be greatly appreciated.


Battery specs:
Voltage: 12 V
Ah: 6.2A
Pulse Crank Amps (PCA): 340A
Cold Crank Amps (CCA): 230A
Recommended Charge Amps: 1-8A
Max Charge Amps: 30A
Weight: 2.2 lb (1.0Kg)
Dimensions: 5.3in (L) x 2.6in (W) x 4.1in (H) 135mm(L)x66mm(W)x105mm(H)
Environmental (water resistance): IP 66 (water wash down)
Terminal Polarity: Universal

Starter motor may be bad. What mods have you done to the engine. New coils? Points? Stock engine and 29's?
jetsrus.com/carburetor/carb_mikuni_VM29_...oded_view_parts.html
Specs call for a 1.5 slide. 2.0 is lean. Valves adjusted?
Steve

The Z1 starter clutch is different than that of the KZ650, but on the KZ650 if the boss on the starter clutch gear is worn it can cause the starter clutch to make a horrible noise even with new springs and rollers because the rollers can create ridges on the boss. The image below compares new and old KZ650 starter clutch gears. Ed

The starter clutches on the Z1-KZ big fours are very tough. Never had one fail. The motor would drag if very old. (bad bushings and brushes)
Steve

Ill check the clutch again and see what it looks like. I did check it a while back and it had no flat spots. Ill take a picture of it.

Thanks Steve.

No mods have been done other than what I listed. I talked to Jeff at Z1 and because I don't want to fork out $250 for new 1.5 slides he recommended that the bike would idle higher than usual but with the jet set up I have I should be fine. And now I am here... LOL

Jeff has helped me a ton. I just need to fly him out to work on my bike. LOL

I have not adjusted the valves and will measure them later tonight if I can't find the fix. It ran not too long ago but had issues keeping it running. Then I started having issues with it starting. Now I am a mess.

Yeah, check the valves. Might be over jetted for a 903 engine.
Steve

Okay. so some new info...

I checked the spark plug gap and I am just at .032. however what I did notice, is that when I take the spark plug out and keep it in the boot, I ground it on the engine, I have no spark. I have no idea what the deal is....

I took my multimeter and measured the top two screws on the coils and they read 11, when the battery reads 12.35. But I then checked all 4 spark plugs for spark and I have nothing. WTF...

Pics? Points?
Steve

Ill get some pics here in a minute. Have to get to my pc to upload them. Which pics would help?

Plugs, points THE BIKE. :lol: Screws on the coils? Dyna's?
Steve

Pics: