DR650 mini-backfires - normal?
 

Hey there,

I've got a 2012 DR650SE that makes small backfiring type sounds (pop pop pop) when engine braking, or after closing the throttle when riding downhill (leaving the bike to coast in gear).

My 2007 KL250H (Super Sherpa) does the same but it doesn't stress me out as much because it's older and has much higher mileage. Oddly, my first bike - an abused 2001 KLR250 - hardly ever made such sounds.

Is this normal on a relatively new DR (only c. 5,000kms on the clock)?

Or, have I or the previous owner done something wrong?

Many thanks,
Scott

yep perfectly normal, the DR650 engine runs lean on the overrun and pops.

Do you know what modifications (if any) have been done to the bike ?

There's more carb info here:

http://www.horizonsunlimited.com/hub...altitude-73533

check out the links to MXRobs website and the BST40 Bible

Yep, totally normal.
It can become a bit irritating if you are running a louder aftermarket pipe, like an FMF or YOSH. But with the stock muffler it's more like a soft "putter putter putter" sound. I hardly notice it ... but I ALWAYS wear ear plugs. :thumbup1:

You can reduce (not eliminate) some of this decel popping by richening up the idle circuit (pilot fuel screw) a bit and raising up the idle a few hundred RPM. But doing this costs fuel economy ... not worth it IMHO.

Adding an adjustable, extended Pilot fuel screw is a good idea on the DR650 for other reasons too and gives you some control over this issue.

To reduce popping, going a bit richer (turn screw OUT one revolution or so) can help a bit.

bier

Many thanks folks - I'll sleep easier now I know there's no big problem with my investment. :thumbup1:

I can agree with the comment re: ear plugs - I've had this bike for a while now but only taken it on long rides on the weekend, with ear plugs. It has only really been recently when riding around town without plugs that I've noticed the popping.

Your comments also make sense in relation to my Sherpa, and my old KLR. The previous owner of the Sherpa did a [misguided - I think] re-jetting job that makes the bike run very lean. The KLR had no choke lever (it was an ex-army bike with a few strange quirks) so I had turned the idle up higher to help compensate for the lack of choke.

Thanks again for helping me learn! I'll be sure to check out MXRob's site too.

Cheers,
Scott

Yeah.. Just the overrun. It's more noticeable with a race exhaust. The stock muffler with dampen it and you won't hear it. Even though it's still there.

If it pop's and rasps when you're open throttle, it would sound like you're running too lean and need to up jet.

Like said, you could richen your pilot circuit a little which also helps for easier cold starting but you can risk making your bike bog down or even stall when you close the throttle.

Carb tuning is a balancing act.. Trial and error.