View Full Version : Running lean, engine damage?

03-21-2016, 8:17 PM
Got my first bike, a 600/shadow vlx,this past fall. I removed the baffles,and have put over a thousand miles during the winter.
After reading about how the bikes are tuned lean from the factory, and how removing the baffles makes it even worse, I'm now paranoid that I have damaged the piston heads like I have read..
It does pop quite a bit during decel, but otherwise seems to run good with no major hesitation or popping while accelerating.

Should I be concerned?

03-21-2016, 8:59 PM
If you've put that many miles on it in its condition with no mechanical failure, then the bike is fine. Run the shit out of it! Haha

03-21-2016, 9:28 PM
If it was gonna die, it would have. A Dynojet kit or other mixture enrichment may make you more power and run cooler as it usually does, but I've not done one of those.

Check Honda forums for whatever the latest greatest mixture recipe may be.

03-22-2016, 8:16 AM
I personally don't understand how dudes are content living with decel popping on their HDs. I see it all the time too.

It's not a healthy engine condition and can be corrected. I don't think engine longevity with regards to bad tuning is a good barometer for overall engine life.

Check your exhaust gaskets for leaks first. I also lifted this from another thread to help explain what's happening:

Why does a lean running engine have a tendency to excessively pop? The exhaust gas temperature of a lean engine is substantially higher than one that is running on the rich side ( an EGT probe will show this). Therefore, the high EGT serves to heat the pipe more and the gases themselves become a much better source of re-ignition. By richening things up, you are cooling down the exhaust temp and therefore reducing potential re-ignition sources.

03-23-2016, 10:07 AM
One safe way to richen the lower end if you don't want to spring for jets or have none handy is to go one number drill SHANK size above what fits through your low speed jet. I've done that to sort out many "lean from the factory" carbed machines. Too many people change main jets when most of the problem is lean low speed jetting.

Hold drill bit in a pair of visegrips. Roll jet back and forth between thumb and forefinger until is slides over the drill. Stop rolling then slide jet back and forth a couple of times to deburr. Blow through jet and ensure you see daylight.

Drill sets are only a few bucks on Ebay and you don't need anything special for brass. Do not use a powered or manual hand drill for these tiny holes in soft metal.

Your ignition timing probably didn't change since it's electronic but it never hurts to check.

http://www.ebay.com/itm/280747113869 works fine. You can also use a micrometer and drill bit SHANKs to measure hole diameters.

Most people use the wrong screwdriver on carb jets. You can buy or grind something like illustration 6 in the linked page below:


Even better for brass is instead of a straight tip with parallel sides, use a fine grinder stone or Dremel to make the tip with )( sides so it grabs the brass instead of smearing it.

This style screwdriver also useful for mixture adjustments after you remove the plug or snip the cast pot metal "wing" off the ancient (long before Honda Shadows) exposed style screws.

Random example mixture screw plug removal: http://www.howmotorcycleswork.com/r6/carb04drillingplug.jpg

03-23-2016, 1:15 PM
Proper screwdrivers are a MUST if you do much carburetor work. :)

03-24-2016, 8:09 PM
I had a Shadow once. VT750. I put straight pipes on it and it hard the worst decel popping I've ever heard. Seriously sounded like firecrackers going off. All I did was was make lollipops and the problem went away completely. Never had a problem after that.67918

03-25-2016, 12:08 PM
Thanks farmall for pointing out those screwdrivers, I just ordered the whole set of drivers, I have messed up more than a few brass jets, not just on bikes, but small engine work too, but no more, plus I'm a tool junkie.

03-25-2016, 12:20 PM
How do your spark plugs look?

Running a little lean isn't bad. But running A LOT lean isn't good.

I don't agree with the notion of "If you haven't experienced a noticeable problem yet then your fine". Damage can occur slowly inside a motorcycle, it's not always going to be immediately apparent or suddenly catastrophic. It can take time, and cost a person dearly in the future.

Ideally, the white insulators on your spark plugs should be tan/brown. If the insulators and electrodes are white, you're running too lean. If the plugs are black, sooty, oily, your running too rich.

But to get a proper read of your plugs you have to start with a new set and ride with them awhile. If you still have the same plugs that were in the bike before you removed the baffles (or made other changes that affect the gas/air mixture) then you won't get an accurate reading.

One of my Honda Shadows is 13 years old, the other is 11 years old. I do all my own maintenance. And both are going strong.

03-25-2016, 1:07 PM
Bikes tend to run a little leaner in the winter/cold weather. I wouldnt worry about it. Your not going to run a little lean and slowly cause an issue. If its lean enough to burn a piston or a valve it would have during the winter