The Hodaka Club Forum

Hello,
I am hoping to ride in the Bad Rock event this June, but my Super Rat exhaust pipe with its J&R spark arrestor is not stamped with the required USFS approved wording. I wasn't able to find a similar J&R arrestor in the USFS approved spark arrestor booklet either, so I assume I will need to put on an additional arrestor, but I can't find one designed for it. Do any of you have any recommendations?
Thank you.

Can you insert a screwdriver or other probe directly into the tail pipe and past the silencer? If so, yours is not a spark arrestor at all, just a straight through muffler. In that case, you would need to remove your silencer and install a spark arrestor in its place. I don't know of any spark arresting device that is intended to retrofit a straight through silencer.

Arizona Shorty wrote:Can you insert a screwdriver or other probe directly into the tail pipe and past the silencer? If so, yours is not a spark arrestor at all, just a straight through muffler. In that case, you would need to remove your silencer and install a spark arrestor in its place. I don't know of any spark arresting device that is intended to retrofit a straight through silencer.

Thanks, Arizona. You are right. It is just a muffler. So I need to cut it off and install an arrestor in its place. Any recommendations on a new arrestor?

Is the stinger 1 1/4" or 1 1/8"? Usually you can find one on the internet auction place used for 50-75.00. Do a search for whichever size you need spark arrestor. You might have to saw a portion of the inlet pipe off and hose clamp it together but the good news is the aftermarket aluminum silencers/spark arrestors usually have really nice mounting tabs to easily attach it to the rear of the frame. An added bonus is that they tend to be pretty quiet as well. Quiet is good.......

Most spark arresters these days are made specifically for existing models of bikes. The basic unit may be the same, but the plumbing varies by model.

FMF makes a universal spark arrester in either 1 1/8" or 1 1/4" and I believe these dimensions are I.D. There are few other out there anymore that are the old generic type we used to find at every bike shop. From the photo, your stinger looks like it may be smaller than 1 1/8". The smaller stingers also used to be quite prevalent. 7/8" used to be very common for MX bikes, some with no muffler at all if used strictly for racing. Back in the days when noise was thought of as a beautiful thing. On the other hand, many of the stock Hodaka pipes that had the built in arrester were 1 3/8" ID. The only thing I found that readily fit that dimension was the old VW Beetle exhaust tip. Slipped right in, glass packed, worked fine. I raced two years on that and still have the exhaust tip in the garage.

If yours is an odd size, you may have to build a stinger by cutting back the rear of the final cone until you get to the dimension you need, and then weld in a new stinger. Keep in mind that modifying stinger length and diameter affects performance, but if you are not building for that last half a horsepower, it should not make a difference in rideability. If I remember right, increasing stinger diameter generally lowers power peaks. Length of stinger can be matched to whatever diameter you are using to balance out the difference in power between two stinger diameters, to some extent.

DG makes generic silencers in standard diameters. Here are two side by side, the one with the small hole in the tip is 1 1/4" ID ( which is also 1 3/8 OD fitting old Hodaka Ace pipes ), the other is 1 1/8" OD, which is also 1" ID.
Here is shown the 1 1/8" OD silencer on a 7/8" ID stinger. The stinger OD is nominally one inch as is the ID of the silencer.
The point here is that there are still a few products out there but you will need to know the inside and outside diameter of your stinger, and verify which dimension a manufacturer is using when they say there's is 1 1/8" for example, so you get something compatible. Otherwise you can pick your product and make a stinger that matches, if you have welding equipment.

Thanks, Charlie and Arizona for your advice. I will measure my stinger and find an appropriate add-on.

If you can find a beat up wombat pipe you could hack the muffler off it and weld it in you super rat pipe and then it would be identical to a 1971 Rat . I dit it a couple times .

Rich

Thanks for the suggestion, Rich.