rob w

Here it is from 2008, http://www.trialscentral.com/forums/topic/20843-suspension-set-up/page__hl__%2Bsuspension+%2Bsetup with a link to a very good article. The basics are still exactly the same.

Taff D is right, the big red nut adjusts the preload on the fork spring, hence the amount of sag. The small screw slot adjusts the rate of rebound. The other fork has an adjustment for the rate of compression. I remember a good description of suspension setup on this forum a few years ago. I'll search.

Deon, I took delivery of a new 2012 Ossa last Friday. Before starting for the first time we (my sons and I) stripped it and re-greased the wheel bearings, swingarm, linkage bushes and headset bearings. We checked all the fixing torque settings, bled the hydraulics and adjusted clutch and brakes. We changed the gear oil, and flushed the cooling system. This is something we always do with a new bike for our own peace of mind. With respect to this thread - we found coolant similar to what you described - a clearish liquid with a suspension of greyish matter (it looks like dilute anti-seize paste???) and some alloy flakes. Remember that we had not started the bike at this stage, so it is unused factory fluid. I have seen a similar thing with two other brands. Could it be something to do with the radiator manufacture???. Anyway, we simply flush it out and replace with some trusted green fluid mixed to manufacturers specs. We have never had any more alloy flakes appear, nor had any cooling system problems.

Any chance you can send me some more details Martin? Was it actually for sale? Thanks Rob

Hi Jeremy and every one else. Hey this technical forum is good - I've never made it down the page past the twinshocks. Jeremy I came looking for your post on the clutch removal and found this one too. Here is my two cents. Beta Rev50 for my seven year old has the stock clutch perch, lever and no mods to the clutch itself. Yet the clutch is as light and accesible as any seven year old could need. How? First I moved the perch all the way down the bars to near the bend. This put the end of the lever just in front of his pointer and index fingers, but too far out. (This also has the advantage that when he lays the bike over the bars usually hit the ground first.) Then I made an insert or wedge that fits between the clutch and perch to bring the lever in towards the bars so he could reach it. See the picture. I used urethane because thats is what I do, but you could use just about anything that has a little flex. The wedge has a split to fit it over the cable, a hole at the end of the split for the cable to run through, and is held in place by a cable tie through another hole. Honestly this took less than 2 minutes to make and setup. I trimmed the wedge until we got the lever spaced just right. Then a litle adjustment of the cable adjustors to get the break/engage point right. Because we used the stock lever, last year when he had a big crash at an event he bought another lever from the dealers tent by himself (please put this on Dad's account), and fitted it with his brothers help. All they had to do was unscrew one bolt. All the adjustments stayed the same for him and he finished the event before I knew what had happened. Too easy

Hi J There are a few mods you can do to stop the silencer oiling so much. Here's what we did with our 2005 Go hotter in the spark plug. We used a NGK B8ES mostly but sometimes went with a 7 in cooler weather. Open up the airbox lid so it breathes a bit better - pic below. Leaned the needle position. Clip was in position two from the top. Play with the mixture screw once you've changed the needle and opened the airbox lid. I ran the idle a little higher to help stop stalls. I don't want to start a fuel oil debate, but as soon as I stopped using Motul 800 oil (first in Shell optimax and then in BP Ultimate 98) I found less jetting hassles and much less oiling issues. We now use BP Ultimate with BelRay H1R at about 80:1 (62ml per 5 litres) The 50 ran cleanly and with a near perfect plug with the above settings (slightly sooty on one side sometimes) and I had to replace the silencer packing much less after that. Even so, every so often I gave it to the older boy who gave it two or three laps around the MX track at higher revs. Oh I ended up squeezing on a second o-ring to seal the silencer to the pipe, sometimes with a smear of that blue silicon. Got our 2006 model Rev 50 yesterday. It seems to idle much more smoothly and is much more responsive at low revs. I did the aibox mod but everything else is stock. We are running-in at 70:1 with the above fuel/oil. It runs very smokey. Hope this helps

Hi Ben, WARNING - BLATANT ADVERTISEMENT FOLLOWING If you can't find a NOS or even a good used one to replace yours then I can reproduce one for you. If it is a simle rubber tube then it is relatively easy and cheap. If it has a metal plate bonded in then it gets a lot more expensive, but I can still do it. I would need you to send me the part you have so I can restore it and take a mould from it. My webpage is undergoing a change of provider at the moment so there is not much point looking there, but here are some pics of pieces I have done. Cheers Rob 4.RoBs (Robs Replica and Reproduction Rubber for Old Bikes)

Thanks guys - this is a wonderful place. I thought about dimensions but then thought that it was a fairly unique piece and someone would know what it was. Hey Roy, if I manage to replicate it, remind me that I owe you one. Thanks. Does anyone know if they can be had NOS anywhere?

Does anyone recognise this airboot? My guess is that it is the same or similar to one from a Montesa twinshock. A customer asked me if I could replicate it. But it is split around the folds and will be very fidly (= expensive) to remake. I suspect that there would be a bettter one around if we can work out what it is. Someone might have even already have replica made. Thanks for you help

Whilst we are talking about weird one-offs, this one appreared on the ozVMX forum a few weeks ago. Details at - http://www.ozvmx.com/forum/viewtopic.php?t=465

I use a silver engine enamel on the boys bikes. I just spray the high wear areas after every couple of rides. A sheet of card as a mask stops everything else ending up silver. I don't think powder coating will stop the problem, just slow it down. I have worn through the coating on my old KTM which I restored three years ago. It looks terrible if I spray over it, and to fix it and all the stone chips, I have to get the whole frame sandblasted and redone. So next time I am going to use engine enamel on it too.

Dab Dab, were you going to say something??

No. Thanks Martin. Where is it from and can you email me a hi-res copy? It has 1978 colours and stickers. Looks like he has been mucking with the magneto cover??? Keep 'em coming guys. Thanks

pierced right through the heart

Thank you Martin, let me know. Obviously I would like to rebuild it true to type - so if anyone else out there has a 350 frame or basket case????????

I have no idea??? All I have seen is picture in the back of Bernie Schreiber's Book (did I spell that correctly?) with Walter riding. I am still waiting on a copy of the KTM history book to arrive, which is written in Austrian. Apparently there is a picture of the trials bike in it, but I willhave to get it translated before I can establish if there is anything in the text about it. Big John I would love to know how Walter went about making his KTM trials, or if he knows anything about factory efforts. Despite the lynching threats from my vmx compatriates I still think it would be fun to replicate one. Don't go to too much trouble, but if he is amenable then I would appreciate it. Thanks

Um. OK. So anybody got a spare 320 frame? Martin does all the other running gear fit? Does the nice alloy swingarm bolt on. Whats the geometry like? I have been thinking about the Jumbos exhaust system. How do you clean it, and does the silencer have packing in it ( I will get around to working this out for myself, but for now...??) There has got to be kilos to be saved there (and torque to be gained) by fabricating an alloy sytem and smoothing out the kinks?? Anyone played with this. Sorry. Too many questions - I'll go now.

Thanks David. You know I was more excited about getting the Jumbo than I was about getting the O5 Beta. Oh I love the seat. Sure the Beta was nice, but I can get one of them any old time. Twinshock is much better because I can have two (or three.....or ten) . re the KTM....nope, never, still dedicated to the cause. In fact I remain hopeful in the face of clear hopelessness. Apparently KTM only made two specials for Walter luft to ride. Which means I have two chances I even considered cutting up an MXer frame and fabricating the rest, but the ozKTM crowd threatened to lynch me . Anyway, see you at the twinshock masters on a real bike.

Another view of that slider...

I bought this 1983 Jumbo last weekend. I plan on using it for twinshock competition next year. The fellow I bought it from has two other Jumbos, which I believe, are the only other ones in Australia. One is in bits and is missing the frame. Everything else is there, including plastics, swingarm and bolts, just no frame. Apparently it became a backyard monoshock project and then vanished into the never never. Does anyone have one they can spare - I would love to buy it from you. I would like to fit wider footpegs, but the kickstarter will not clear them. I believe that an Aprilia Climber kickstarter will fit and will clear my wider pegs. Any one know if this is true? I plan to ride in a trial in a few weeks then strip it down and pretty it up. It is generally in excellent condition, but could use a fresh coat of paint and a polish. Apparently Martin Mathews is having the rear guard reproduced - I can't wait. Anyone know anything I should watch out for? I have reproduced the front upper chain slider (the one with the SWM logo) in bright yellow urethane. It realy stands out. I don't know if these fit other models but if any one would like one let me know. Thanks

Hello superhondaman, I have been looking for one for a while now. I think it would be great to an early model of a great line of bikes. As far as I have been able to find out, none ever came to Australia. So unless I use a ktmduke approach (hi there)I think I have buckleys. But any info appreciated. I beleive there was a BetaTR50 advertised here (TC) about 3 months ago. Are you looking to get one?

Good question? I would budget on doing it simply because the manual says too. These beasts use very flat, short skirted pistons so there is likely to be a bit more piston wear after one year than with the squarer type pistons used in older four strokes. Having said that I have seen Honda TL's and Yamaha TY's running on the original pistons 30 years later. But I have also seen Honda CRF 250's (similar bottom ends to 4RTs) lunch a piston and top end after 3 months. (I suspect poor maintenance being the most likely cause, along with high revs.) It surely depends on how hard and how often you ride the bike. And the maunual doesn't state how many hours of riding can be had from a piston. It would be far cheaper to replace the piston yearly than to have to rebuild an engine in the event of a piston failure. And better to wear out pistons than the cylinder bore. But if you are an occaisional rider this period could reasonably be extended. By the way - I am NOT a trained mechanic, but I have built my share of race car and bike engines. So consider what I say but make your own descisions. Cheers

Hi alan.p Servicing the 4RT is not as hard as your mates mechanic suggests. You certainly don't have to remove the flywheel to get to the oil filter. My thoughts can be found at Trials Australia forum. http://www.trials.com.au/BB2/viewtopic.php?t=1035

Hey r2wtrials could you please email me about this - I have some VMX interest and questions Thank you

Potentially a controversial topic as everyone I've ever discussed "running in" with has their own opinion. Also we don't know your engines history. Ie was it running fine before the rebuild, or have you sourced a different carb from somewhere?? In a nutshell - this works for me: Use your usual oil and oil mix - maybe a bit more oil if you are one of these folks who run miniscule amounts (say about 70:1 for a trials motor ridden in a trials fashion. If you ride it like a motorcrosser then 35:1) If the engine was running fine before, then leave the carb settings. You could consider going one step richer on both main and pilot jets in your carb, but this is not vital. Start the bike, warm it up gently then ride it. DO use lots of different throttle positions and different gears. DONT hold it wide open or make it labour in to high a gear. LISTEN for any knocking noises, especially under acceleration or deceleration. These may indicate lean air/fuel mixtures which are potentially damaging. If you hear these stop and change carbie jets. Keep riding until the engine is at running temperature and then ride for as long or short as you like. When you stop riding, let the engine cool to room/ambient temperature (ie. completely cold). Do this four or five times and your engine should be fine for normal use. Off course there are always exceptions and I have seen motors run in on the start line. As for carburetor settings..... Probably just leave them as they were before your rebuild. But a good clean inside and out never hurts. Otherwise, it is a bit complicated to explain here. I suggest searching the web for a site that explains technical operation and reading it carefully. Then we can help you with the specifics like jetting and mixture screw settings. Good luck Rob W