feetupfun

I too am finding the MOTOGP generally a bit boring compared to when it first went to 4 stroke, but I still watch the races in the hope that there will be some racing happen. I'm hoping Bautista gets some podiums on the Suzuki. He seems to be going batter than should reasonably be expected lately. Despite Ducati going so poorly, at least the soap opera aspect of it is entertaining. I find the 125GP races are easily the best to watch and hope the MOTO3 4 strokes replacing them are as much fun.

Maybe Scorpa tanks are made from a different plastic to other plastic motorbike tanks? My understanding is that most plastic motorcycle and car fuel tanks and portable fuel containers are made from high density polyethelene (HDPE) which is used for its mechanical properties and chemical resistance. Are we talking Rotax motor Scorpa fuel tank or Yamaha motor Scorpa fuel tank?

No 30 looked like Stefan Merriman to me

About the 348 clutch springs, the 348 clutch as standard is not far off slipping in the top two gears so the answer is no to less springs with standard plates. I found out a few years ago that there are other plates available that will fit that are the more modern type with friction material, which in theory should allow for less force from the springs for the same torque transmission. I bought some of those plates (Honda CB125 from memory)with the intention of trying them but have not gotten around to trying them yet. There are a couple of potential drawbacks with this approach though: The CB125 plates are quite a bit thicker than the steel 348 plates, so for the plate pack to end up the same overall thickness, there will be fewer plates, which may mean no overall benefit in torque capability relative to pressure plate force due to the reduced effective surface area. The CB125 plates have only half the number of drive tabs that the 348 plates have, and are made of aluminium, so the edges of the CB125 plates may get deformed against the thin steel basket fingers of the 348 clutch or might even shear off. back on the rough engagement, try heavier oil, it worked on mine. I started with a light gearbox oil (castrol VMX80) and it sometimes did protest noisily just as the clutch engaged. I then tried car diff oil (non-extreme pressure additive type) (80-140 I think) and it has been terrific since then. I agree with belldane that if everything is working well the clutch action is very smooth and I find it does not drag when disengaged. The only reason I am interested in trying the CB125 plates is to reduce the lever pressure which at my age I find a bit tiring in tight sections.

Possible sheared magneto flywheel key

Chris unless someone has modified your bike it should not have a condenser or points. It should have a Motoplat CDI. Something to check that is a weakness in the MAR design is that the LT ignition cables come out of the magneto housing underneath and can easily be damaged by the bashplate pinching them against the underside of the motor. Mine had been damaged in that way, but despite the wires being squashed and having conductors exposed, the motor still ran fine. If you search for OSSA on the Trials Central forums or the trials.com.au forums you should find a photo sequence of how I repaired and re-routed the ignition cables on mine out the front of the magneto housing, after a suggestion from Woody. Your ignition may be getting affected by this problem. Other things to check for are loose motor mounts,loose stator screws and a killswitch cable possibly shorting to earth.

They both look like M199 to me. One has earlier model sidecovers and the other has left side braking - both are common mods to M199 and M198. Neither is M199A because they are both missing the swingarm gusseting of the 199A and both have frame tubes under the motor.

I wonder if the seller of the Cota 348 has seen this forum string?

The runaway revving thing as the fuel level in the float bowl goes low can be due to the lean mixture causing detonation instead of the controlled burning that normally happens. It can also be due to the idle mixture being too rich, then becoming correct mixture as the fuel level goes low. No it can't be due to a vacuum leak, because it would do it all the time that the motor was at normal operating temperature, not just when it was running out of fuel.

Scorpa was bought out by Sherco and since then Scorpas don't have Yamaha motors any more The current Scorpas are quite different to the Scorpas that had the Yamaha motors

You can expect more things will come loose and fall off if you don't inspect and maintain the bike.

Bullylover, I could only find 2008 and 2010 photos of your Bultaco. Both taken at Conondale. I'm currently trying to get the photos to show up in this posting I have given up trying to embed the photos for now. Here are links to them http://img220.imageshack.us/img220/6226/pa310053.jpg http://imageshack.us/photo/my-images/689/pb090010.jpg/

I just found a photo of you and the bike at the queue for machinery at the Twinshock Masters in late 2010 and will post it up this weekend

Hi bullylover and welcome. It's easy to know who you are after that description of your ride bike. I might have a photo from when it still had the disc brakes. I'll have a look. Regards David

No not OK to use a rattle gun. Tighten it by hand. It is way too easy to overtighten things using a rattle gun. If you need a new nut and want to use lockwire, buy the nut and drill a hole in it. Maybe you are asking about using a single hex (six flats) socket vs a double hex (standard) socket because the nut hex is damaged???? I would use a single hex socket and tighten by hand using a socket bar. If in doubt about the torque, use a torque wrench instead of a socket bar. If you are having problems stopping the crank turning, wait till you have the motor in the bike and with the drive chain in place, shift it to 5th gear and hold the rear brake on while you tighten the nut. If you want to tighten the nut up with the motor out of the bike, there is a tool available from Bultaco UK to hold the clutch basket still.

The cover has a vent for a reason too. If you seal the space completely the pressure goes very low when the gas inside the cover goes from hot to cold suddenly. With a fully sealed space, I would be worried about sucking oil out of the crankcase or popping out the crank seal in those circumstances.

I use 3mm hole in the bottom and choose a place away from where mud might cover the outside of the hole

My memory of running lights on my Bultaco in the mid 1970s is that the 6V headlight bulb glowed dull red at idle, bright red at mid RPM and pale yellow at maximum RPM. If you brought the brake light on, the headlight went much dimmer. I'm sure that you can get your lights to work very well with modern technology. There is a place in South Australia that specialises in setting up all sorts of dirt bikes for racing right through the night and they have been doing it since I was a kid in the 1970s. I would not expect that the standard lighting on your Bultaco will work much better than what you have found already.

The cylindrical silencer on TY175 models B and C is the same as on TY250ABCD but the inlet pipes are different lengths and shapes (the TY175 pipe is longer). I don't know what a Ty175D silencer looks like but if it is the cylindrical type it will probably be the same. The bulbous TY175 muffler as fitted to the TY175 JC and JE will also work well on the TY250A but again the inlet pipe will need to be shortened.

If you are going to pull it apart, if you can get the cylinder off without separating the head from the cylinder, you will save the substantial cost of a new head gasket.

Ok what do you mean by "allso the thiner off the to goses on the bottom is this right"

Different pistons have different design rings. It's very hard to tell what you have there from your description but maybe one ring is shaped like an "L" in cross section? and the other is not? If the rings are different then the grooves in the piston should be different too - more info needed here

Buckles can usually be cured when respoking but it is pretty hard to say for sure without seeing the buckle you are talking about No need to reline the brake drum if the chrome is good. If you learn how to assemble a wheel and use anti-sieze on the spoke threads you can pull it apart and reassemble it yourself to get the drum relined if you ever need to. I don't understand the question about the compatibility of stainless steel spokes and a new rim. There is no problem with material compatibility/dissimilar metal corrosion. The rim holes would need to be the right diameter, the right number of them, and the holes aligned correctly for the Bultaco hub. A standard pre-drilled off-the shelf rim may have the wrong hole angles for your wheel. Wheel builders can drill a rim to suit your wheel.

The voltage on a basic system like that will depend on the RPM of the motor. What RPM are you measuring the voltage at?

Lengthening the wheelbase and steepening the steering head angle are the two biggies for the TY175. I modified a TY175 to match the wheelbase and steering head angle of my Godden Majesty and fitted TY250 forks. It is a dream to ride now.