Jump to content
Sign in to follow this  

Question about cam, timing TDC...

Recommended Posts

So the other day I had new valves put in. The head was obviously off the bike. I get the head back and it looks great. Put it all back together and it took maybe 20 kicks to fire it up. (I also put in a new piston/rings. The sleeve had a nice coat of oil before assembly). Anyway, it fired put and runs like normal BUT it has backfired a few times on start up while I was riding it around the yard.

My question involves the possibility the TDC mark on the crank shaft may have not been 100% lined up to the mark on the case when I put the cam sprocket on. Because Im thinking -yes- it would matter having the timing off, would it be running if the alignment was off in this situation?

I thought about it at work yesterday and the more I think about it the more I wonder if the dang marks were lined up perfectly...

Share this post


Link to post
Share on other sites

To be clear on the backfires, this happens when kicking the bike. I cant recall this happening before... ( Batteries dont seem to like this bike so I quit putting them in it this summer.)

Share this post


Link to post
Share on other sites
To be clear on the backfires, this happens when kicking the bike. I cant recall this happening before... ( Batteries dont seem to like this bike so I quit putting them in it this summer.)

Your bike should start fine, using the starter! If not then you have something else wrong... Possibly the jetting? As far as Timing goes, were the marks lined up when you put it back together? Both the left side (stator) and right side (crank) lined up with the cam gear marks and the carrier. Remove the cover plugs and the Head cover and check! They should all be lined up, and make sure that when looking at the stator side, you line up the second mark!

Share this post


Link to post
Share on other sites

Backfiring through the carb is either a sign of timing being off (radically) or the intake valves not sealing correctly. Did you have the head done professionally or did you just swap them out yourself?

Share this post


Link to post
Share on other sites

I had it done professionally. And about the marks, the red and white Honda manual said nothing about the ignitions side marks but I saw them on a youtube clip. Putting the head back on by myself I had a difficult time keeping the marks lined up. The marks kept wanting to go past the lined up position.

The back fire is out the exhaust to clarify.

At this point the bike starts like normal, second kick. Have not had it do anything funny today (backfire, etc.)

Thanks for input!

Share this post


Link to post
Share on other sites

If the bike starts on the second kick then the timing is most likely on. Being one tooth off makes them hard starting.

Backfiring is always "back" through the intake and carb.

The condition you describe is known as popping.

Glad to hear it's cleared up.

Share this post


Link to post
Share on other sites

A little bit of info I would have liked to have- look straight (level) across the head THEN line up the marking on the cam sprocket-

Im 6'5''. I work on my bike while its on a MX crate. Looking at the markings from a different level got the job done...I had the sprocket one tooth off. That was the popping noise...

Share this post


Link to post
Share on other sites
A little bit of info I would have liked to have- look straight (level) across the head THEN line up the marking on the cam sprocket-

Im 6'5''. I work on my bike while its on a MX crate. Looking at the markings from a different level got the job done...I had the sprocket one tooth off. That was the popping noise...

That's called "Parallax Error" and it used to be a big deal back in the day of all Analog measuring equipment.

Share this post


Link to post
Share on other sites
That's called "Parallax Error" and it used to be a big deal back in the day of all Analog measuring equipment.

It happens to the best of us! ... And myself! Runs great now. :smashpc:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...