Struggling with Cam Timing

[Ricky Gee]

Morning.
I have got the bike all back together after a engine rebuild. Have my valves all within spec. i have good compression 130psi. Leak down checks are good. Try to start the bike and It pops and spits out of the intake and exhaust which leads be to believe my cam timing is off? I've have my dots as the should be and the crank is on the T as the book shows. What am I missing? Been struggling with this for a week now and I'm out of ideas? Do any of you XS Gods have and idea on where to look next??

Thanks
Rick

[Appie]

Hi Ricky Gee

I wish I was an XS god but I’m definitely not! I did however have a Honda doing exactly that after a tear down and I had my ignition leads mixed up. I swopped 1/4 and 2/3 leads in error.

[DEEBS11]

Timing could be off. Check your mechanical advance connections. Check your spark plug wires (coil to cylinder placement-very common problem). Could be air leaks (manifolds). Could be lean mixture due to clogged carbs. Many variable due to the rebuild of the motor and so many parts to re-assemble.

[Ricky Gee]

I marked my wire before I pulled them. I did try moving the timing plate (the whole assembly) around with no change. I read about some sort of tabs on the cam gear has to be in the correct spot. I'm wondering if this is where I went wrong. The gears appear to look the same no matter where the tabs are. But it does have me wondering. The bike was running strong right up to the crankshaft breaking.

[Radioguylogs]

I had a similar problem when I revived my XS1100SG.

Turns out I reversed the wires that send power to the ignition coils. I had each pair of wires connected to the opposite coil. I found it when I measured the timing and found it was out 180 degrees.

[DiverRay]

It does sound like you have the coil wires swapped. It's fairly easy to reverse the wires on the coils, and try again. Also remember one coil feeds the two outside plugs, and the other coil feed the two center plugs. As this is a "wasted spark" engine it fires both plugs at once, but only one is in the fire position when it does.

[Ricky Gee]

Ill double check the plug wires. is there a chart that shows which wire goes to which plug? I havent found one yet..

[DiverRay]

One coil has longer plug wires that the other. Long wires go to 1 & 4, short wires are 2 &3. One coil has an Orange wire, the other has a Grey wire feeding it. They both have Red/White wires as well. You can swap the Orange and Grey wires to see if you are using the proper coil for the plugs.
Again, one coil feeds the two OUTSIDE plugs, long wires, and the other feeds the two INSIDE plugs, short wires.
Hope this helps a little. I don't have the exact wire color/coil/plugs because a lot may have changed on the bike. I know I'm running new coils, as the old coils were failing on my '79.

[Ricky Gee]

That's what I thought. the previous owner custom cut the wires when he installed the Danas. I put them back as they were when I put it back together. ill try swapping those wires that you mentioned and see if that makes any difference. Have you any experience with the tabs that are on the cam gears? I'm wondering if that makes a difference to the cam timing.. I have all the dots and the T lined as the book shows. makes me question the cam timing might be slightly off because of that. I read about that on a another forum. But they didn't go into much detail sadly as to why that was important..

Like I said. It's got me scratching me head on why this ole war horse doesn't want to light off..

[Ricky Gee]

DiverRay
You there winner of this mystery. Swapped the orange and blue wires around and she fired off. Man that makes me a happy man. Now to pop the valve cover back on and figure out my exhaust leak at the header..

All you guys rock!!!!
Thanks for the help. I would have never guessed those wires were crossed. I didn’t touch those when i took the engine out. Only guess there is a difference between the 80 model and the 78-79..

[DiverRay]

We may be old, but most of us here still know the "easy" way to find or fix a problem. Glad you have that done!
Do you have stock exhaust or aftermarket headers? The stock exhaust has a SMALL hole on the underside of the pipes to let water drip out. This is to keep the rust down on the stock pipes.

[Ricky Gee]

I hear you. I’m pushing 67. I’m normally pretty good at figuring stuff out. But this one had me stumped. I have what i hear is a hard to find set of Kirker headers. They are in fairly good shape for being as old as they are. The muffler has some ride rash sadly. But they sound good and have that old school rumble that i love..

[DiverRay]

Kirker built the BEST header for this bike, IMHO. I've had two XS1100's with the Kirkers on them, and loved the sound. On one ride, a fellow rider commented that he knew I wanted to go when he heard the exhaust note change from rumble to a scream. Someone who knows how to weld should be able to fix any holes in the header.

[Ccitis]

I hear you. I’m pushing 67. I’m normally pretty good at figuring stuff out. But this one had me stumped. I have what i hear is a hard to find set of Kirker headers. They are in fairly good shape for being as old as they are. The muffler has some ride rash sadly. But they sound good and have that old school rumble that i love..

I am not even sure my XS would be on the road without the gents in this forum. So many tips and tricks. Honestly one reason to be invested in one of these bikes. Great people and knowledge. Enjoy yours.