About a month ago I finished rebuilding my Mojave due to a major chain mishap [img]i/expressions/face-icon-small-shocked.gif[/img]. Its alot of work replacing the shift drum after the chain takes of the external stud. Anyhow, it was running excellent [img]i/expressions/face-icon-small-happy.gif[/img]. Then after 2 weeks of all out destruction it decides to burn oil. The compression was at 70psi (the minimum operating level). So I had the cylinder bored and honed 20 over and all the valve seals replaced (they were shot). Now it is once again back together. However, now when my Mojave is running (starts first try by HAND! and has excellent power) there is a loud "tick" sound coming from the top end. I have spent hours looking for the problem but have had no luck [img]i/expressions/face-icon-small-mad.gif[/img]. Spark plug is not being damaged and the cam chain is tight. Any suggestions?????? [img]i/expressions/face-icon-small-confused.gif[/img]

 

is it when you are on the gas or always
sounds like a weak valve spring it may be slappin closed

 

Yeah, its always tickin. When I raise the RPMs it becomes more rapid. (Thanks for the quick response..)

 

i am not shure get mor openions but i think it would be somthing with the way the valves are closing

 

valve adjustment. One of your valves is either sticking or out of adjustment.

If they need adjusted, adjust them. If the tick is still there, run it down the street and check them again, make sure the valves are staying in adjustment.

Do a leak down test. This can coinside with a compression test. To do a leak test put the piston at TDC of the compression stroke, put 7 psi's in the cylinder and see if it holds for 10 minutes.

Compression is a good way of judging the health of a cylinder, but low compression isn't always the rings. The valves can be a culpret as well. The easiest way to find out if it's the rings or the valves is to put about a half ounce of oil in the spark plug hole, if the compression comes back up, it's the rings, if not it's the valves.

The ticking is the valve train thow, adjusting and seeing how many hours between adjusting you need to re-adjust tell you alot about how the valve to seat relationship is going. Also after dissasembly of a head the valve to rocker relationship is different and adjustments are more freaquent for the first 50 hours or so.

Always, always, adjust your valves and do compression test while the motor is cold. Doing it in the morning before you ever start it is the best way, most common *******mistake********* Doing it after it has been started that day!!!!!

 

Thanks for the help. I'll give it a shot...
For a little more info when I had the cylinder bored 20 over I also had the top-end inspected and valve seals replaced (I dont own a valve spring compressor, so it went to the shop). The dealer also replaced the intake valves. When I picked the cylinder and top-end up there was a tag attached telling me to adjust the intake and exhaust valves from 0.005 to 0.008 (I did 0.007 which is 0.178mm). The service manual I use calls for 0.20mm to 0.24mm originally. Has anyone else had to lower their "stock" valve clearance?

Or had the "ticking"?

 

I suggest you stick with the manuals reccomendations. The clearence is there so when the heat expands the components the clearence will be correct at that time. Other wise you most likely will accellerate the ware of the rocker/valve and have tight valves as well. Kinda hurts the performance.

 

Check the timing chain and adjuster. My lakota did the same thing, and it ended up being the timing chain adjuster was stuck and was not putting the correct tension on the timing chain.

 

I agree with everyone about the valve adjustment.I set mine to stock specs(.008-.010).Another possibility could be the compression reliese "thing" on the exhause valve is damaged or missing a spring and flopping around.

 

mojaves have a compression release does it just open one exauhst valve