May need Cam Timing Help

[magifesq]

Ok, my current project is resurrecting an old 86 ZX900A Ninja. I bought it as a partially dismantled project and looks like it should be able to run.

The Clymer manual shows putting the crank timing mark with the case, put the cam timing marks slightly angled towards the case ends - which I did. I cleaned the carbs and have spark on all 4 plugs. Last night I put gas in the tank and primered the carbs. I put the jumper pack on it, turned the switch, hit the button and I'm getting backfiring but no running .

Does anyone have a factory service manual for one of these old hoop-d's to double check the clymer on?

[ReconRat]

There's 5 copies of the 1999 Haynes ZX900 manual in the Columbus library.

Call number: 629.28775 K224, C775kL

Main Library (SciBusNews) 2 copies

South High 1 copy

Southeast 1 copy

Karl Road 1 copy

None are shown as checked out.

I just reserve them on line and pick them up at the local library.

[serpentracer]

you might have the crank or cams 180 degrees out.

you probably didn't put the crank at the intake stroke, instead you have it at the exhaust stroke. or the cams are on the wrong stroke.

[ReconRat]

The crankshaft mark indicates top dead center of the piston travel. That happens twice for each single turn of the camshaft. Most engines won't care which turn of the two turns of the crankshaft it is on, since it's all the same to the crankshaft. The backfiring is probably a mismatch between the placement of the crankshaft vs the camshaft, when hooking up. Where possible, I try to lash the timing chain tight with the cam chain adjuster, and double or triple check the cam timing marks, before closing up the engine. Do that by turning the engine the correct direction at the crankshaft, till the mark comes back up twice at the crankshaft, and observe the timing mark on the camshaft. It is very easy to get the timing chain/camshaft one or two tooths off at the camshaft. Depending on the direction it's off, the camshaft will be overly advanced or retarded. I once figured my one tooth off at the cam was 17 degrees off timing. Yeah, I've done it. Learned me to double and triple check my work.

Note: some engines must have the belt or chain adjuster tension in use in order to turn the engine. Result can be jumping one or more tooth on the belt or chain.

[serpentracer]

not if he has the #4 piston and #1 piston mixed up. my bet is he has one of several thing going on

1. wrong cam in wrong spot(intake mixed up for the exhaust cam)

2. cams 180 degrees out.

3. #1 and #4 pistons confused.

Edited October 31, 2009 by serpentracer

[ReconRat]

not if he has the #4 piston and #1 piston mixed up. my bet is he has one of several thing going on

1. wrong cam in wrong spot(intake mixed up for the exhaust cam)

2. cams 180 degrees out.

3. #1 and #4 pistons confused.

no kidding. I'm an old fashioned single cam kinda guy. Mixing the cams would be crazy. But basically yes, if there are two sets of TDC marks on the crankshaft, it's possible that the wrong TDC was used. That also assumes that the engine is the "free floating" type. Meaning that the valves won't hit the pistons if the valve timing is way off. Which it probably would if it was 180 degrees out.

But on my bikes, that other set of marks would be the #2 and #3 cylinder TDC. That's Honda. All my #1 and #4 pistons move together (outside pistons).

[ReconRat]

edit: Let's try that again...Mag, you can check the crank timing vs the cam timing by pulling the crank timing cover and the spark plugs, and feeling with your finger or thumb on #1, if the piston is compressing when you rotate the crank to the #1 TDC. It will do that on every other rotation of the crank. (The other rotation is the exhaust rotation.) You should be able to repeat that for each spark plug/piston to check. You'll have to think about the rotations, and the firing order, to determine if one of the cams is 180 degrees out. Meaning that if two of your pistons move together, one will compress while the other exhausts. So when you find one turn that compresses, the next turn will compress the paired cylinder, etc. Same for the other pair.

But if it were me, I'd just start over again. Basically something isn't right. I would make sure the spark plug wires and all are hooked up right first, of course. Won't help any if it was firing wrong.

Edited October 31, 2009 by ReconRat
duh me

[magifesq]

There's 5 copies of the 1999 Haynes ZX900 manual in the Columbus library.

Call number: 629.28775 K224, C775kL

Main Library (SciBusNews) 2 copies

South High 1 copy

Southeast 1 copy

Karl Road 1 copy

None are shown as checked out.

I just reserve them on line and pick them up at the local library.

Is haynes preferable to Clymer?

The Plug wires are labeled lol, I have the corresponding wires / plugs.

I want to rule out fuel starvation, so I ordered the parts to rebuilt the petcock (seriously, who came up with that name for the fuel valve?). Will post progress