Spark Arrestors

[Quixote]

Can someone clue me in on exactly when spark arrestors are needed? Specifically can you tell me if a BMW R1150GS with stock exhaust would ever need one or if it already has one?

I am currently negotiating for one and have high hopes of exploring some Forest roads around here. My thinking is that anything that is a public road is ok, such as a forest service road, but what about if I wanted to do some OHV riding? Jim's post on Hollister hills looks interesting and I might like to try some of the easy trails some day.

[DaveG]

A spark arrestor can be summed up by asking-is the muffler straight through? So standing behind the bike, can you stick a long probe into the exhaust pipe and does it hit something or can you stick a 12" probe (coat hanger, screwdriver, wooden dowel) all the way in? If you can shove something all the way in, then it probably doesn't have a spark arrestor. If your probe hits something and won't go all the way in, it may qualify as a spark arrestor....basically. Don't want to get too techical.

[2on2off]

All street bikes come with spark arrestors built into the mufflers. All "Green Sticker" off-road enduro motorcycles come from the factory with spark arrestors.

The only motorcycles that generally do not have spark arrestors are "motocross bikes" like the Yamaha YZ's, Honda CRF's, Suzuki RM's and Kawasaki KX models.

The only way a street legal motorcycle would not have a spark arrestor is if an owner took the stock muffler off and put on an aftermarket muffler without a spark arrestor. This is typical of many Harley Davidson after market exhausts but almost every other street legal motorcycle with an after market exhaust will have a spark arrestor on it.

I have never seen a BMW GS without a spark arrestor. Now that I think about it, the only motorcycles I have ever seen without spark arrestors are Harley Davidson's and motocross bikes used for racing. My friends that ride motocross bikes for trail riding always put spark arrestors on them.

Without a spark arrestor, flames will shoot out of the exhaust and that is why the forest service wants you to have a spark arrestor so you won't start a forest fire when riding off road.

[Quixote]

Thanks for the replies. I figured it was something simple. Just wanted to check and make sure. What threw me off is the KLR650 specs that I have seen list a spark arrestor, and none of the other bikes I was looking at specifically listed spark arrestor in the specs. It got me to thinking and wondering.