[Jaydawg6528]

I have adjusted the valves 4 times cleaned the carburetor 3 times I’ve set the valves to the tighter side and looser side but I have a loud valve noise and it backfires through intake side. At higher rpms it doesn’t backfire but still really loud valve noise I’m ready to drive it off a cliff. Please help

 

[morphrider]

Welcome to the forum. Are you positive it is from the valves? Take a 3' section of garden hose, one side to your ear and the other in various parts of the motor. Pinpoint the location and report back. They are kind of loud machines anyway.

 

[Jaydawg6528]

Maybe I’m wrong and it’s not the valves. I have a a stethoscope and I listen to each valve cover and it doesn’t seem loud. But I’m getting backfiring through the intake side of the carb it’s idling up and down and I have this loud tapping. I did the valves again for the 4 time now I’m a pretty smart fellow when it come to motors but this one has got me stumped. Is there something else I should be checking any ideas will help

 

[Sixpack577]

Bent valve or air leak

 

[Jaydawg6528]

Maybe I’m wrong and it’s not the valves. I have a a stethoscope and I listen to each valve cover and it doesn’t seem loud. But I’m getting backfiring through the intake side of the carb it’s idling up and down and I have this loud tapping. I did the valves again for the 4 time now I’m a pretty smart fellow when it come to motors but this one has got me stumped. Is there something else I should be checking any ideas will help

Bent valve or air leak

Bent valve or air leak

So got it all back together and it started right up same noise. I decided to take some carb cleaner and spray it around the carb no change in running till I get to the brake side and spray it on the boot were it meets the motor and it starts reving really hi so that is telling me there is a leak in the gasket. I just ordered it will see if that fixes anything

 

[Sixpack577]

That's it, crack in the boot, common problem.

 

[Jaydawg6528]

Nope not it put it on same shit noise and back fire. What do I do next guys!

 

[Jaydawg6528]

So I figured out one issue I had and that was the valve noise I guess I’m not as smart as I thought I was. So I also have a 2004 Suzuki LTZ 400 that I did the valves on once I had to buy a special feeler gauge that had a .05 in a .08 measurement on it it’s one gauge but it has two sides to it I was looking at it and I was looking at the numbers and then I was looking at what I was measuring them out and when it said .06 to .10 I was actually going with a .006 to a .010 What a dumb ass huh. Now there’s no valve noise but I still have the hiccup in backfire through the intake in the idle Is a Radick even though I replaced that gasket between the intake and the cylinder when I spray flew over there it still changes the motor RPM. Any ideas thanks guys

 

[Jaydawg6528]

So I figured out one issue I had and that was the valve noise I guess I’m not as smart as I thought I was. So I also have a 2004 Suzuki LTZ 400 that I did the valves on once I had to buy a special feeler gauge that had a .05 in a .08 measurement on it it’s one gauge but it has two sides to it I was looking at it and I was looking at the numbers and then I was looking at what I was measuring them out and when it said .06 to .10 I was actually going with a .006 to a .010 What a dumb ass huh. Now there’s no valve noise but I still have the hiccup in backfire through the intake in the idle Is a Radick even though I replaced that gasket between the intake and the cylinder when I spray flew over there it still changes the motor RPM. Any ideas thanks guys

Also the header pipe is glowing red

 

[Sixpack577]

You obviously still have a big air leak at the carb boot.
Which is also why the header is glowing, as the air/fuel mix has become very lean from the leak.

 

[Jaydawg6528]

I will try a new boot and see if that fixes it thanks for ur input !

 

[Sixpack577]

I will try a new boot and see if that fixes it thanks for ur input !

The boots dry rot and crack, it is a common problem.

 

[Jaydawg6528]

But that boot is thick as shit and I can’t see any cracks on it. Anyway I just ordered a new one and will pick it up when they open I will have it installed this afternoon. So hopefully that’s it !

 

[Sixpack577]

But that boot is thick as shit and I can’t see any cracks on it. Anyway I just ordered a new one and will pick it up when they open I will have it installed this afternoon. So hopefully that’s it !

If you spray around it, notice a change in idle, if the boot is not split somewhere, then it is not sealing correctly at the carburetor or the cylinder.
Isn't there an o-ring between the boot and the cylinder?

 

[Jaydawg6528]

Just picked up new boot and gasket will install when I get home. Update coming soon cross ur fingers

 

[Sixpack577]

Just picked up new boot and gasket will install when I get home. Update coming soon cross ur fingers

I always put a small amount of vaseoline on o-rings, especially at the boots.
It helps them to stay in the groove for assembly, and helps prevent them from being pinched or cut.
It'll make sure they seal good, and is petroleum based, so harmless to any parts.

 

[Sixpack577]

If there is a flat gasket there(I don't remember if the 350 has a gasket or an o-ring), generally intake gaskets don't get rtv silicone, but, if you have air leak issues, from a possible uneven or damaged sealing surface, a Small amount of rtv spread evenly around the gasket can help.
But try it without rtv first.

 

[DEZPERADO]

Gas will bloat and cause RTV to deteriorate. A non-hardening Permatex or Yamabond is a better choice.

 

[Sixpack577]

Gas will bloat and cause RTV to deteriorate. A non-hardening Permatex or Yamabond is a better choice.

Yep, sorry, I should've been more clear.
Yamabond is good stuff too, as I've never had cases leak after a rebuild on many engines, even years later.

 

[Jaydawg6528]

So I got home and before I put the boot on I wanted to check compression it’s at around 140 150 I also sprayed some carb cleaner in the intake valve hole and it bubbles could the valve not be closing all the way