Will poorly adjusted valves make a motor quit?

[ReticulatingSplines]

I have a CB350 that had a fresh top end job before I got it. The mechanic set the timing, the valves, the carbs and charging system up to spec and all was working well


I ran the bike for ~100 +/- miles and checked the torque on head bolts, a little loose but I torqued them to spec. The mech told me to do this.


The mechanic also told me to check the valve clearances, which I forgot to do until maybe 150 miles after rebuild... I had a couple of other "little kinks" I have been working out. I assumed I would be working dealing with small things here and there, but the bike started to die at traffic lights unless I revved the motor. This made me worry, and reminded to to check the valve clearances.


Valves were checked and set to spec, and checked again. Bike idled great so I went for a short jaunt, maybe 2-3 miles, and the bike would not stay running when I came to an idle.


I will be redoing the valves bc I believe the motor is running a bit hot, mostly concerned as to why its quitting out after warming up.


QUESTIONS:
Will poorly adjusted or seated valves cause a motor to cease running?
will poorly adjusted valves cause it to heat up above normal (im assuming yes, if it is not allowing all gasses out of chamber)


Thanks! This is my first question on this forum, hoping I get it figured out soon because I need this bike for transportation!!!!!

 

[Von Braun]

yes and no. if the valves are poorly seating or burnt it will run horribly. not just at idle but all over the rpm range. if your valve clerance is off that bad,as in make it run bad, you normally hear ticking in the top end. if it wont idle but runs if your in higher rpm i would check your idle jet. probly clogged with debris. the higher temps are probly from running it in higher rpm while sitting. if you can do a compression check and/or leak down. that will let you know if you have any valve issues. hope this helps.

 

[VonYinzer]

+1 to the above, and make sure you check your timing as well. The timing is known to wander a bit on the 350 if everything isnt set just right.

 

[woolsac]

Hey splines, this was an old post, but was wondering if you made any headway in regards to not having your engine quit at idle. I'm experiencing the same issues and would like to hear if you fixed it. Mine starts up great cold. Runs strong at high rpms. After engine is hot, and come to stop lit, can hear sputtering then dead. Restarts just fine but then need to rev it to keep from stalling. I'm hopping its just clogged idle jet.....
Thanks for your help

 

[NortonGuy]

Will poorly adjusted or seated valves cause a motor to cease running?
will poorly adjusted valves cause it to heat up above normal (im assuming yes, if it is not allowing all gasses out of chamber)

I can make an engine quit running by poorly adjusting any adjustment it has.

You forgot to put a question mark after your second question. What is your first language?

An engine will run hot if the valve lash is too tight because when the valves can not seat then they can not get rid of the heat, not to mention the burning fuel jetting past them into places it is probably not supposed to be.

 

[Tim]

Hey splines, this was an old post, but was wondering if you made any headway in regards to not having your engine quit at idle. I'm experiencing the same issues and would like to hear if you fixed it. Mine starts up great cold. Runs strong at high rpms. After engine is hot, and come to stop lit, can hear sputtering then dead. Restarts just fine but then need to rev it to keep from stalling. I'm hopping its just clogged idle jet.....
Thanks for your help

Best bet would be to shoot him an email or PM. This thread is pretty old. Clean your jets, tune the bike up (valve adjustment, timing, sync carbs) and see what happens.

 

[woolsac]

Best bet would be to shoot him an email or PM. This thread is pretty old. Clean your jets, tune the bike up (valve adjustment, timing, sync carbs) and see what happens.

True. Thanks Tim. I'll let ya know how it turns out when I get all in place.