Re-Installing Camshafts Problem

Thanks Ron and Skyman! I'll give it a go again. At least the valve clearances are correct after changing the shims! :lol:

I agree with RonKZ650 and Skyman. With my 750, I install the exhaust and then the intake cam. I have to check and double check that the timing marks are still where I left them previous to installing the cams. I have had them move while working on the bike. I also install the auto tenisioner and give the cams a spin with the cover off to ensure that everything lines up before buttoning everything up.

Its all done guys, thanks so much for the help!

Here is the Intake:



Here is the Exhaust:



And here they are together:

I have timed my engine just like the photos above. When I try to start the engine it backfires through the carbs alittle and and makes loud pops in the exhaust system. Any idea what I may be doing wrong! I'm like about to give up.

There could be other problems as to why the bike won't start.

Please indicate the bike in your signature as well as the other work done to the bike. It helps us to make recommendations in regards to trouble shooting.

Post edited by: cafekz750, at: 2008/03/04 13:37

Post edited by: cafekz750, at: 2008/03/04 14:01

Did you have these problems before taking the bike apart? Could it be caused by something other than the timing? I'm just thinking out loud here...

cafekz750 wrote:

The bike could be 180 degrees out of time.

I didn't know bikes could be 180 out, since they spark at both TDC strokes. On mine, it makes no difference which TDC you set the cams to.

my cam timing wasnt exactly on according to the manual but my bike still runs like it did before i tore it down. Waht i mean is that the timing marks on the points didnt exactly line up at the t mark, it was off by about an 1/8 of an inch, but the cam marks still lined up with the top of the head.

Nick

Bountyhunter,
I modified my post. I am thinking about one of my other bikes where this happened to me. Jumped the gun.

cafekz750 wrote:

Bountyhunter,
I modified my post. I am thinking about one of my other bikes where this happened to me. Jumped the gun.

Thats OK, I was remembering because of the dumb thing I did: first time I had to take the head off my 750 twin for a valve job, I reinstalled my camshafts making very sure to get them JUST RIGHT on the marks..... and just before I was going to put the valve cover back on I double checked them by rotating to TDC and found they were 180 degrees off! I could not figure out how I missed by that much. I was scared I had banged a valve, but I immediately unbolted the cams and set them "right" ....

Some time later I realized that they were right either way, because the camshaft rotates only once for every two turns of the crank so I could always find the "180 out" spot for the cams by rotating to the next TDC.... on a twin, both pistons are at the top on either TDC. Live and learn.

I do believe on the four cylinder bikes you have to make sure and get the TDC for the correct set of pistons (I believe it's #1 and #4?) or the cams will be wrong.

Post edited by: bountyhunter, at: 2008/03/04 16:24

duplicate post

Post edited by: bountyhunter, at: 2008/03/04 16:21

triplicate post.... never saw that before

Post edited by: bountyhunter, at: 2008/03/04 16:21