I just got a savage on the road... yesterday. I have never owned a bike before and what fun it is. Now I have driven a dirtbike before and do know how to shift gears, but am by no means an experienced rider. All that being said, this is what's happening.

When I shift down to slow down or brake to slow down, I often get a backfire. I was out for maybe an hour and it must have happened 20 times. It's a bit on the disconcerting side and sure makes everyone look...

My bike is an 87 frame with a 2002 engine from a crashed bike.

Any ideas what might be causing the backfire's and is this to be expected?

don't overtighten the header bolts  - can be really easy to strip them I've heard! hopefully someone who can find their manual (don't even ask!   ) can post on here the correct tightness for you. also as I'm sure you know, check them when the engine  is dead cold.

Thanks, I'll check that and let you know.

I just got a 2007 S40.  It would backfire everytime I rolled the throtle to idle while driving.  I pulled the brass plug from the idle mixture screw.  The screw should be about 2 1/2 turns from fully seated.  The one on my bike was barely 1/4 open.  I opened it to 2 3/4 turns open then re-set the idle speed.  The engine was more responsive but still backfired a little (mostly when ridden agressively).  I increased the idle speed a little and now the backfire problem is just about non existent.  I can still get a pop when riding agressively, usually at throttle roll back before entering a turn.  The backfire is less violent, and my wife can not make it happen when she rides it.

If it feels like it's chopping its way down and popping, try setting your idle higher.  I just discovered that this was causing a lot of the "problems" I was having.

courtem wrote on 12/31/69 at 16:00:05:


Turning the idle speed/rpm up a bit can help with the backfire issue, but keep in mind that doing so is sort of like a "cheater step" in the tuning process.  If you need to do that ( increase idle rpm), it is a substitute for the low speed range (pilot system) being a bit on the lean side and and not getting the pilot system dialed in just right.  When the pilot system is properly jetted and tuned there will be no backfiring and the idle can be set at the standard 1000-1200 rpm.

Slight, or even moderate, popping and crackling is perfectly fine on a well tuned engine.  It is very common on race bikes, and not unusual with modified street bikes.
I consider it to be the sound of a successfully well tuned modified big single street bike. .. oh yea !