Noisy Trials Bike----help!

It is normal to feel the pulses from 10 to 15 feet away from the back of the bike - these motors run 13:1 compression, so the exhaust is expelled pretty quickly, and if the holes in the baffle are packed then there is a straight path through for the exhaust. Most Betas also make a fairly loud popping noise especially around idle - it also happens on my y2k 200c bike, and is even louder on the 270cc bikes.

I have used the silent sport packing, and found it difficult to get right, especially on the horrible shaped Techno muffler (its much easier on the Rev3 muffler). What I ended up using was a sheet of muffler packing wrapped around the baffle, and then used the silent sport stringy stuff wrapped around that fairly tightly to hold it in place while installing the baffle back into the muffler. Also remember to pack the very end cap of the muffler fairly tightly with packing - otherwise the rest of it will get loose and not muffle properly.

The main reason for the noise is the clogged holes, and if you have cleaned out the end muffler's baffle holes then you are halfway there. I sent you a PM, explaining how to clean out the middle muffler. If you look closely you will see that the middle muffler also has a baffle and packing, and these holes in this baffle can get blocked too. Fortunately the middle muffler uses wire wool as the packing, so you shouldn't need to try and repack it, only clean it out with a solvent.

Good luck

The baffle on the middle silencer is a formed mesh screen not a straight through pip like the rear one, so repacking it would be a major PITA! When I used the solvent trick, I took the whole middle silencer off and duct taped the end of a grease refill cartridge (used to refill my grease gun!) onto one end and this seemed to seal one end off quite well. I then stood the thing on that end in a small empty bucket and poured the solvent in. Apparently some of the other guys over here use petrol rather than turps, so I guess that would work too.

Another way of getting rid of the excess oil is to have a burn off in the exhaust pipe - such as suggested in the Tech Tips forum on www.trials.co.uk. You can do this by giving the bike a major clean out up a hill until the excess oil in the exhaust catches fire. If you have about 10 full throttle runs up a decent sized hill in third gear you will notice a large amount of smoke coming out the exhaust - this means that the unwanted oil in your exhaust has caught fire or is smoldering. Then if you give the bike another blast up the hill every once in a while to keep the temperature up you will eventually burn the excess oil out of the silencers. This might not be such a good idea if you are riding near any forestry, but works pretty well over here on the grass farmland that we seem to be using every other trial.

I guess the bottom line is that the person who had the bike before you either only used very little throttle on the bike when riding it (so it hasn't been thrashed and abused!), or was using far too much premix. The general rule of thumb for trials bikes is to use a ratio of at least 70:1 for the premix, unless you are riding the bike like a MX bike, and 80:1 is even better for a lower level rider like me - the top riders use 100:1, but they probably change the piston and rings quite a bit more often. Obviously if you are using too much oil then it has to go somewhere - usually straight into your exhaust pipe to goo things up.

The thing is that the wet soggy packing won't allow the gas to flow through it, and it will block any gas from flowing forcing it out the end of the exhaust, so you won't get any noise reduction. Thats my understanding anyway :)