AlphaGeek
Member
I believe strongly that sharing failures is *at least* as useful as sharing successes. Here is the first of probably many interesting failures I expect I'll be sharing with the community.
Equipment: GEBE kit with Tanaka 33cc on Giant MTB; at time of this experiment motor was 100% stock and mounted in standard position (lower bracket oriented perpendicular to ground, cylinder axis pointed forward)
Having seen various suggestions regarding a reduction in perceived exhaust noise to be had by mounting a 90-degree redirector tip over the exhaust port, I decided to give it a shot. The metal-joint solutions (i.e. copper elbow joint) I read about here were either too permanent (welded) or failed to stay on (soldered) so I set that option aside for now.
I haven't located a good high-temp silicone elbow joint online for anything approaching reasonable prices. Standard silicone is rated to 350F and can actually tolerate 400-425F, but two-stroke exhaust is considerably hotter than that. Fast forward to me in the local hobby store buying an off-the-shelf Ofna silicone elbow joint, which the clerk assured me (heh) that was suitable as an exhaust coupling.
The joint came with two small white zip-ties, which I set aside in favor of a beefier black zip-tie. Install joint with black zip-tie, take a 1-mile test run... hmm, something smells like melting. Clipped off zip tie, pulled off elbow joint, inspected, reinstalled with galvanized wire twisted on to secure joint in place of zip tie.
The silicone elbow joint melted and fell off around halfway through my commute the next morning. (sigh)
Lesson learned: hobby-shop grade Ofna silicone elbow joints are NOT up to the task of redirecting the exhaust from a Tanaka two-stroke.
I probably won't try any more experiments on the stock exhaust, as I have a performance pack including tuned pipe on order. However, if I were going to try again, I would drill and tap a hole in a 90-degree stainless steel elbow joint from McMaster-Carr and attach it with a set screw and high-temp thread-lock.
Hope this helps someone avoid wasting $5.75 and valuable time repeating this experiment.
-AG
Equipment: GEBE kit with Tanaka 33cc on Giant MTB; at time of this experiment motor was 100% stock and mounted in standard position (lower bracket oriented perpendicular to ground, cylinder axis pointed forward)
Having seen various suggestions regarding a reduction in perceived exhaust noise to be had by mounting a 90-degree redirector tip over the exhaust port, I decided to give it a shot. The metal-joint solutions (i.e. copper elbow joint) I read about here were either too permanent (welded) or failed to stay on (soldered) so I set that option aside for now.
I haven't located a good high-temp silicone elbow joint online for anything approaching reasonable prices. Standard silicone is rated to 350F and can actually tolerate 400-425F, but two-stroke exhaust is considerably hotter than that. Fast forward to me in the local hobby store buying an off-the-shelf Ofna silicone elbow joint, which the clerk assured me (heh) that was suitable as an exhaust coupling.
The joint came with two small white zip-ties, which I set aside in favor of a beefier black zip-tie. Install joint with black zip-tie, take a 1-mile test run... hmm, something smells like melting. Clipped off zip tie, pulled off elbow joint, inspected, reinstalled with galvanized wire twisted on to secure joint in place of zip tie.
The silicone elbow joint melted and fell off around halfway through my commute the next morning. (sigh)
Lesson learned: hobby-shop grade Ofna silicone elbow joints are NOT up to the task of redirecting the exhaust from a Tanaka two-stroke.
I probably won't try any more experiments on the stock exhaust, as I have a performance pack including tuned pipe on order. However, if I were going to try again, I would drill and tap a hole in a 90-degree stainless steel elbow joint from McMaster-Carr and attach it with a set screw and high-temp thread-lock.
Hope this helps someone avoid wasting $5.75 and valuable time repeating this experiment.
-AG