peterb

Hi Jon and Spencer, I have found that when the clutch plates swell (usually with coolant getting into the gearbox oil), the small increase in pack height is sufficient to create a problem with the clutch operation, where the actuation is heavy, seemingly insufficient throw of the clutch lever and a dragging clutch when disengaged. The small increase in the clutch pack causes the 10 operating fingers to move to a position beyond a decent mechanical advantage, and therefore requiring more movement from the slave piston, as Jon said, the significant measurement is the finger height, best around 17mm. An inexpensive fix, is to carefully ease off the fibre plate thickness using emery paper on top of a sheet of thick (flat) glass and get the pack down to about 9.75mm. Bye, PeterB.

Hi Spencer, This is a called a Trial 300 Professional, released ex Italy 1983, 6 speed, DellOrto PHBH 26BS carb. I have oil quantity, jet sizes and other info if you need this. Don't know about spares, try Bill Pye up in Great Ayton in Cleveland, used to have heaps. Bye, PeterB.

Hi ALT, I also don't think you can achieve single finger clutch operation on the Bult. I use the longer front brake lever arm for the clutch actuation on my Bultaco. In the past, I have used the shorter aluminium lever, cut it in two and made up an extension to re-join the two parts, from a piece of 3/8 sst tubing, suitably shaped with a hammer to match the profile of the lever arm. I last used a Bing carb in 1986 and don't remember if it was ever a problem, had my Bult running very well with a 26mm DellOrto, set up for a PRO except for fitting a 95 main jet and a D34 needle. Since then I made up a reed valve block from a PRO to fit and run the bike with a 28mm Keihin flat slide, there is some power/response improvement but really not significant enough to warrant the hours spent making the reed block housing. If your carburation is fine with the Bing, then I would leave as is. Bye, PeterB.

Hi Pixie, I used to run an 8E with a four speed box when I were a lad, which was made for that era motor, not a 9E, it stuck out a lot farther than the 3 speed but can't remember what the difference in ratios was. (Well I was pretty young then). Can't help with any mods, only to take some time lapping the flywheel onto the crankshaft to help stop the timing from slipping. Bye, PeterB.

Hi there, I have not tried this conversion but this imay be worth considering. The clutch, in auto mode, works with increasing rpm by flinging out the 8 x 8mm ball bearings on the back plate to allow or force the clutch plates to move together to each other. The plates are held apart by either the 2 small return springs, or the larger central spring - not sure as I haven't pulled one apart. Looking at the parts drawing, you would either need to remove the two smaller springs or, the larger central spring to allow the plates to be compressed together without the motor going. Hope this makes sense. Incidentally, the 2mm thick plain plate can be fitted in lieu of one 1.5mm plate to the trials TXT50 motor to allow the clutch to take up at lower rpm. (Thanks to Jim Snell for that one) Bye, PeterB.

Hi Stu, Usually there is an adjusting screw where you mention on this shock. I have seen one of these snap off before but have never tried a repair on one. I imagine they would operate a device to restrict the flow of damping oil, parhaps a needle and cone valve arrangement. If so, then what you can see left over may be something completely different - sure it is not half of the adjusting screw? Does the damping action work? If the shock is working ok I would leave it alone, at worst replace with a new one. Same thing for the spring freelength, if it's working fine then no need to worry. Bye, PeterB.

Hi scoobystu, If the bike is a bit of a hand full, you can fit a slow action throttle (black tube) and a Hebo flywheel weight. Jon, thanks for the starter jet drilling out info, they are usually a number 60 and drilling to 0.8mm is a good idea. Bye, PeterB.

Have you been checking the piston ring gaps down the bore before fitting? Is the piston being fitted correctly? (Arrow to the front) Have you recently had a rebore and haven't had the ports gone over with a riffler file to take off the sharp edges? Have the ports got sharp edges anyway? What is the piston/bore clearance measured at the piston inlet skirt mid way down the bore. Look for approx 1.5 thou here. Thats about all I can think of for now. Bye, PeterB.

Hola Javier, ?como estas? That James is in stunning condition, looks like a Suzuki RL250 tank. Well done. Just out of interest, I have fitted a total loss ignition system to my B40 using a re-chargable gel cell battery that easily lasts a full day trial. This method utilises the original points for timing, and drives the spark through a Lucas (Prince of Darkness) HT coil. I have removed the alternator. You would be able to adapt such a system to the Villiers quite easily. Let me know if you need more info. Bye, PeterB.

Hi scoobystu, I set up the 04 PRO 300's with a D34 needle, the standard D36 is leaner and a bit too quick on pick up at low rpm. Set the pilot (fuel) screw 3.5 turns out from fully in and adjust from there. Needle clip position 2nd from the bottom. Plug gap usually 0.9mm. From cold, tip the bike right over to the left as this floods the carb and makes it easier to start. Bye, PeterB.

Woops! Just proof read the message, it should read Keihin carb and Kokusan ign. A senior moment! Ta ta, PeterB.

I have a 2006 Raga 300, with Kokusan and Keihin ign. On the sunny setting, the two wires to the electronic unit are shorted and bring in another ign map with a more agressive advance. I do notice the difference on this bike, it is faster to respond off the idle and carburation feels leaner. It is much more easier to ride on the rain setting (wires not shorted together). Bye, PeterB.

Hello tdp, I have a B40, clutch is a bit heavy. You can try lengthening the clutch arm atop of the gearbox case, it looks like you can get an extra 25mm there before the clutch cable starts to foul the casing, (where the cable exits the casing). Make sure the cable has no tight bends and is well oiled. Bye, PeterB.

Hi Gaz, I also used to ride trials at Woodhouse Farm (Great Ayton) back in the 70's up against Rob Edwards and Jack Galloway. Used to be a derelict house that always had a section running through it, and I remember the hill as I took up a Honda 50 step thru in my earlier years. Was pretty steep. Carlton Bank used to be a good spot till the landowner started chasing riders for money - doesn't go down well with trials riders. Was a bit of a story there with some sinister goings on....don't think I'm allowed to print it. Chop Gate was my first trial, in those years we used to ride our Bultacos to the trials with a gallon can of petrol on our backs as the petrol stations were closed on Sunday's. Still riding now but in sunny (sometimes) NZ - lot's of fun here. Ta ta, PeterB.

To stop this from happening again, remove the woodruff key and lap the flywheel and crankshaft tapers together with some very fine grinding paste, can even mix it with Brasso for a finer mix. Bye, PeterB.

Let me know if you can't get hold of one. I have most of a new one at home, needs the aluminium lever to complete but then I am in NZ. Bye, PeterB.

Yeah, but you only split those motors when you landed heavily on 3 foot rock steps!!!! Twice a year? Couldn't resist it. Time for a practice Tim, come on out and help set up the next trial. Ta ta, PeterB.

Hi Dave, Not too many responses! I don't have the actual TDC figures for the bike, but as a starting point you could try 2.8mm before TDC. Bye, PeterB.

Hi Chris, I'm in NZ, will have to research sizes to relate 9 and 10 gauge spokes to metric. I am pretty sure that Bultaco had metric rolled threads, 4mm I think, I have stocks of these at home so can check spoke diameters for you. Hunter Valley, North Syndey?? famous for wine? Bye, PeterB.

Not 100% sure on the compatability between all models, I think the later PRO fan units run at a higher speed than previous Gas Gas models. The physical mounting should be more or less the same. I have repaired the odd motor, it is a lengthy process, prising open the casings. Usually, vibration and shock from riding trials causes a winding or two to fracture where they are wound over the armature at a very tight angle. You can scrape away the shellac (insulation) and solder up the broken pieces, but, pretty tricky. I would sooner replace the motor these days. Bye, PeterB.

The PRO clutch rattle is caused by the clutch basket gear being a straight cut design and being quite narrow. This set up is prone to be noisey. Previous models had a far wider helical cut gear that runs quiet. It is more expensive to machine helical cut cears, the tolerances are tight and usually the gears are sold as matched pairs; basket gear with crank drive gear. Bye, PeterB.

Hi Zippy, I did the same thing to my 1978 Sherpa. The tubeless would not bead out so I left it as is. Runs a bit wobbly between sections but has stacks of grip. Bye, PeterB.

Hi Max, I just had the same thing on a friend's SY250. In this case it was the slave cylinder adjustment being out too far, allowing the slave piston to end up fouling against the circlip at the end of the slave cylinder. At the same time, we cleaned out the end of the slave cylinder with brake clean, then lubed with hydraulic oil and now the clutch action is a lot easier and smoother. Bye, PeterB.

Hi Andy, The rose (spherical) bearing for the shocks are a special size, std bearing suppliers do not have this size in their stocks. Bye, PeterB.

Hi Andy, Usually, if the rose joint is a bit seized up, then it is usually stuffed. After prising out the two shouldered washers, you can get grease onto the ball and work this in by rotating the ball in its socket using the bolt through the ball to rotate it. The rose joint, has an external housing, it is this that you can match up to a socket of the same outside diameter (OD) and use a bigger socket as described before to allow you to squeeze the old rose joint out, as a complete unit, it doesn't fall apart once removed. These spherical bearings are a bit pricey. Always grease up a new one with water proof grease. At the same time, check out the 50mm long sleeve bearing in the s/arm linkage area, its at the end of the link arms. On older bikes, these could sometimes break up. Bye, PeterB.