still trying

Hey Gas Gas; Why isn't the battery mounted across the top of the gearbox/motor, with the controller up out of possible wet stuff range. Besides which is heavier? A low C of G is kind a good to have. And while they are at it, make the battery easily removable / swappable, so one can be on charge while using the other. Be the first and get ahead of the crowd.

floydbassman is correct, the best system "operational cost wise" is probably a heat pump (read reversible air con). They are typically 300% plus efficient. By that I mean for every unit of energy it uses it moves 3 units of energy (read heat). And as stated dries out your space and is fume free. A warning with burning propane or similar gas, the space needs to be well vented if there is no fume vent to outside, they produce CO2. There have been deaths with portable units for this reason.

For me the only reason to not be riding the grade I used to is fitness, practice, and if I break me, the repair time is too long, (can't get the parts anymore). Here's the hard part, solving the problem for each rider to maximise enjoyment 3 variables are; Terrain, same for everyone,( within grade = constant ) Bike, its ability with respect to terrain ( moderate variation between them, each being fairly constant over time of event ) Rider, their ability to cope with terrain ( widely variable, both between individuals and individual over time of event ) The section markers are trying to alter the constant to suit the variable, (different lines / grades). From a process point of view, completely wrong and destined to fail. Normally you would try to get control of the variables.(Never gonna happen). I guess what I'm saying is; See how impossible it is for the section setters (don't hassell them, help them... nicely) and Sort yourselves out for yourselves. pick a grade that suits. and will take as many points as you think is appropriate (Hope like hell the variables setting it out aren't too different from the last trial). Forget about what other riders are scoring (they have a different expectation). Sorry got off topic, but it was a fun little rant, have a good Christmas all, good luck with next year.

Nothing like a good bun fight, but back to the issue in hand. my ratings of importance go something like this; 1 Safety 2 Comfort. not comfortable will rapidly affect concentration, and enjoyment of the ride. 3 Weight, every gram you don't carry around is more energy to use riding. And the effect can be quite significant on the last lap. A tired neck can subtly affect concentration. note; this is not a piece of equipment that helps you ride better, (it can help you keep riding in he future however).

I like one each way, you can only be half wrong.

Years ago I had a similar problem on a (believe it on not) TY 175. it would start easily and run for about a minute,(enough time to get to the first gate) plug dead. 5 plugs later, (slow learner, and all available plugs stuffed). I went and got a platinum plug and instantly no more problem. As to why, Sorry no idea, but I'm guessing that maybe combustion created a deposit that shorted the plug, and the platinum one ran hotter/colder and prevented this happening. These days I would go for an iridium plug.

It may be because the slide type is more compact, (look at how far a roller hangs below the chain) and lighter. Also no moving parts means less maintenance. Cheaper to make.and lighter,(weight being very important in this sport).

I detuned a gas gas JT95 contact (327cc) by making a head gasket. Easy to do if you have a mill (with rotary table) and lathe. Made mine out of aluminium. Used the lathe to turn face and O ring grooves, then bored cylinder hole, and carefully parted off at 3mm. Note keep tip clear to get a good finish. Next, on the rotary table and do the porting. This could be done with care on a drill press and file to make the slots, just more time needed. The 3.5mm made the bike way more tractable when pulling from low revs, (much smoother, heaps more grip) and really didn't notice much drop in top end. Also I don't have to use 98+ octane anymore as it no longer knocks. I ride in a grade that can see up to 1m high rocks,banks,logs fairly often, just to give a sense of previous statement. I also used to have a 280 climber, great bike for tight trail rides, loved the power.

Thanks for trying, even the little you found out, and eagle8 added helps. Much appreciated, Cheers.

The angles were only to illestrate the point. If the NOS shoes were a smaller dia then clamping force would be greater possibly giving the improved breaking. Making results difficult to compare. However, The good news is that Prelit has done the hard yards and got a solution. Prelit, Could you please find out the name/grade for this break material, as I would like to follow your lead. I'm in NZ and will use a local to reline the shoes. Like you I'll do the machining. The front break on my project KT is not the best, (one of many setup areas yet to sort out).

Just a thought If you consider the cam as it rotates from horizontal (parallel to the shoes), say 10 degrees, the edge travels a larger distance vertically, than when the start point is say 60 degrees. This means that the mechanical advantage (or clamping force) is significantly greater when starting at 60 deg by almost a factor of 10 (if my maths is still functioning). That would mean that the clamp force would be 10 times greater, = better breaking. With the factory shoes thinned to match the drum, is this the cause of the increase in breaking effect? As mentioned above the sand blasting could be making the surface "slippery" as blasting can produce rounded indentations rather than sharp vee like indentations, depending on media and material being blasted. I'm guessing that the surface has worn from all your testing etc, and the blasting is no longer having an effect. If it is still there, then maybe it needs looking at. Thanks for all your testing as I will be heading down that road soon to. Let us know how it goes, cheers

When does something become a "classic" To me its a combination of technological or style change, and time. Which means some things become "classic" before others, e.g. a Ferrari Vs a Fiat. One makes it by rarity and style, the other by surviving (definite simplification here). The time component is for us to forget all the bad bits, and remember the good. The sooner the period becomes "classic" the better it truly was. This probable doesn't help, sorry

To be honest the motor I used was the one doing nothing at the back of the garage a KT250. My "ultimate Twinshock bike" is in projects called KT250r. Really enjoying the build, next challenge is setting it up.

I've always mixed 75ml to 5lt petrol for all my bikes. Ty175 being the first, then Fantics (150,200,201,241,KT250, Aprillia climber, Gas Gas 320), and have had no problems even in 30 deg heat and no wind. Basically my rule has always been use the best oil you can get (don't be cheap it doesn't work long term). For trials mineral or semi synthetic was recomended to me considering the motors can run hot but aren't heavily loaded for long at any time. Also the synthetics have a greater ability to accumulate at low speeds and cause rough running. I would tend to go with the oil manufacturers recomendation over the motor manufacturer for an old (80's, 70's etc) motor as oil technology has moved on several light years since then. Good luck!

The higher the octane number the slower the fuel burns (explodes). raw petrol would burn too fast and make a knocking / pinking sound (called detonation). This destroys motors (basically the petrol is exploding before the piston has got to the top and tries to push it back the wrong way, while momentum is moving it forward, over loading bearings, conrods etc). Higher octane fuels burn slower thus the spark lights the fire before top dead center ( modern engine designs) and the piston is over the top and starting to descend when the explosion starts pushing its hardest. Also the explosion of the higher octane fuel will take longer, pushing on the piston all the way through the power stroke. Higher octane is needed for higher compression ratios. By squeezing the gasses together more they react more violently (bigger bang) creating more push on the piston (more power). With low octane fuel this compression can cause "dieseling" (compression ignition like a diesel engine, very bad, difficult to stop, kill switch wont work on motors doing this, use high gear and stand on the back break HARD). If your motors made a loud sharp knocking noise when hot and under load this might be ocuring, if so use a higher octane fuel. The other alternative is to lower the compression by adding an extra base gasket. Also note that riding around at low engine speeds and loads, can on two strokes carbon them up and then under load conditions make them detonate. To stop this without lifting a spanner, when you have a long hill go flat out in a mid to high gear, make the motor work hard and it will burn this buildup out.Note; It will smoke a Lot if there is buildup, sometimes even when you turn it off! It can make some not nice noises if buildup is bad during this as it blows the crap out. Have a cool down ride after. Your bike will run smoother after, I doubt your motors need octane booster. Compression ratios above 10:1 will need 98 or higher octane if pushed hard. Hope this helps

Best motors I've had to ride would be; the Fantic 200, (light, reasonably narrow, reliable). An Aprillia climber rotax, beautiful power, pull from nothing in any gear, (water cooled so probably not eligble for twin shock class). And my Gas Gas JT35, (super reliable, and heaps of grunt) My advise is to figure out your riding style and what sort of power delivery best suits I like motors that pick up immediately when I open the throttle, so massive flywheels and slow acceleration I don't like, preferring to use the clutch and rate of throttle opening to control things. Especially when 2 foot away from a big step, (big for me that is) accelerate NOW dammit!! And as mentioned above good handling etc allows you more chance of being in control so you can get on the power and make the most of it. After all grip (for a given surface) is a function of weight distribution, suspension geometry, and power delivery. Not forgetting tyre condition. Building a bike check out "Trials Australia" website, - Forums, (new posts), - Twinshock, & classic,- Steer clear. Very good info for setting up a bike. Hope this helps

Hi I'm just about to paint my ali tank. Went to the local paint shop for recomendations for paint that is reasonably fuel proof. They have recomended" Liechler" two pot etch primer, (I've used this on my cars sub frame and it is still brilliant 5 years on). this stuff can be made in various colours and sprays easily. They also recomended a two pack clear coat, saying, that that is what people that do road bike tanks use.. They also have just stocked a spray can that can do two pot paints!! It has a second cannister inside with the hardener. (that's mixing and cleaning sorted) Once you break and shake the can you have to use all of it, There is no reuse at a later date, The left over stuff will go off no matter what. Here (NZ) it's heaps cheaper than 1 liter of two pot and thinners to clean the gun. (A can holds about 200ml). I'll use the gun for the primer and try a can for the clear, as I have further use for the primer.

A small machining hint; I use either a plastic coke bottle with a small hole in it, or an old cleaner spray bottle and squirt water on the cutter/lining to keep dust down, as the particles can hang in the air for long periods. Still use a mask as well.

Hi, before you change your steering head angle check out "Trials Australia" website, go into twinshock & classic trials, scroll down to "Steer clear". It's all about steering geometry and the various things that affect it. As for welding molly steel, Brazing, gas welding, TIG, & MIG are all fine. Its the cooling that is critical. Slow is good. If the metal is less than 3mm thick then it doesn't need to be stress relieved. (Very important fact for the guys making roll cages in race cars). There is a lot of discussion in "weld or Braze" in classic trials on this site. Hope this helps

Hi, I haven't worked on an amal carb, but this reminds me of a friends sons 50cc yamaha. Cleaned the carb checked the float, looked for air leaks, all the usual stuff. Eventually found a blockage in the fuel feed to the secondary, or intermedeate jet port. This feeds fuel into the carb just under or after the trailing edge of the slide (its usually a tiny little hole) to stop leaning the mixture just as the slide opens and manifold pressure drops. If the carb has this jet and it is blocked then just as you accelerate the motor will have a dead spot or stop completely. Hopefully one of us has been helpful, good luck. P.S. breakclean,or carb cleaner in a can is quite useful, and. nylon fishing line to poke through without scratching those small galleries.

Hi, From memory steering head angles on twin shock trials bikes are around 26 deg +/- a few, dependent on make. For geometry info checkout "Trials Australia twinshock forum, article "steer clear" https://trials.com.au/forum/viewforum.php?f=16 I would recomend getting hold of an old bike and converting it, that way you get suspension (nicer on the bum), Anyway good luck, very interesting project. Let us know how it goes.