I assume you are referring to Falcon Classic steel bodied trials shocks.
The aluminium cover you see that looks like a seal holder is a push fit in the body. It is actually a dust scraper holder. Tap it off carefully with a punch.
Inside you will see the shock seal carrier held in with a snap ring.
Depressurise the shock and then you will be safely able to remove this snap ring with internal contracting pointed nose snap ring pliers.
From there it is obvious.
PS if the shaft and seal is still OK and you just want to change the oil, you can do it through the hole that the gas valve screws into.
Grandma sucking eggs refers to the process of emptying chicken eggs via two small holes, one in each end, to preserve the shell in one piece. It is quite a skill to be able to empty the egg without breaking the shell....hence the saying.
Assuming you are making a heat shield to reduce the heat transfer from the pipe to the carburettor, you should use stainless steel as it is the worst conductor of heat of the materials you mentioned.
Titanium and aluminium alloys are very good conductors of heat so when bare they make poor heat shields. If it was possible to fit insulation to the heat shield, these materials would also be OK.
Steel has higher conductivity than stainless steel yet is no lighter so is not as good as stainless steel as a heat shield.
You are turning the fuel off at the tap when you stop the engine.
Your carby float bowl overflow hose is routed downwards.
Your carby float bowl overflow line is not blocked or kinked.
If you have a problem with the float needle not sealing off and the excess fuel can't get out the float bowl overflow line, it will flow into the crankcases, flooding the engine. I have seen the crankcase so full due to this problem on one of my bikes, it was dripping out the exhaust pipe joint.
Note there is also the possibility of the fuel tap allowing fuel past even when it is shut (easy to test).
If you are using fuel with ethanol or another alcohol in it, all sorts of corrosion problems can occur with metal components exposed to the fuel.
Warm greetings from a warm part of Australia in midsummer (phew not much riding going on at present)
If you want to continue to ride the Scorpa Easy in your warm Israeli rain, I suggest you try a different fuel. The worst fuel for you to use would be a petrol/ethanol blend because the ethanol part increases the refrigeration effect compared with straight petrol.
Insulating the carby would make it worse because in high humidity conditions, carbies need a heat source to keep them above the dewpoint inside. In the case of your Scorpa the heat comes as radiation and convection from the exhaust system and the engine. If you insulate the carby, it will get even colder inside.
Sorry I can't recommend a fuel for you because they vary so much around the world in their properties and composition.
We generally use unleaded car fuel of about 94RON containing no ethanol in our trials bike premix. Some of the modern trials bikes which are a bit sensitive to poor fuel benefit from using ELF unleaded racing fuel because the petrol bought from car petrol stations is variable in quality.
The water you found on your throttle slide is probably condensed from the air. The slide can become cooler than the "dew-point" of the air in high humidity conditions due to the cooling effect of evaporating fuel from liquid to vapour as it enters the airstream at the throttle slide. It is the relative humidity of the air that is important, not the temperature.
The humidity of the air you are riding through will be the determining factor for a given bike and fuel combination. You may have formed ice from the water which jammed the slide if it got cold enough but I doubt this happened. It is more likely that the water/fuel/oil mixture was gooey enough to stick the slide even without the water freezing.
Petrol fuelled cars with carburettors usually have inlet heating systems using the engine coolant to prevent this effect causing problems in high humidity conditions.
If you bike runs well in sections but then pings and carries on when you make the motor work in a sustained manner like riding at speed or up a long hill, it is possible that the fuel supply route to the float bowl is restrictive, causing the fuel level in the bowl to go low during sustained strong fuel demand.
If it is this case, the restriction is usually in the fuel filter, fuel tap or tank breather.
I think you should consider the broader motorcycling market before thinking that the Spanish makes folded because of Fantic. Sure enough the Fantic was a more modern design than the Bultacos of the same year but the seeds of what happened to the Spanish makes were planted 10 years before the Fantic 200 came out.
As popular as trials was and still is in Europe, trials bikes were and still are only a small part of the motorcycle market worldwide. Think about the big sellers ie Road bikes, Trail bikes and Motocross bikes. During the 1970s the Japanese makers took over most of the world market in these fields which had been previously dominated by European brands.
With reduced sales, product development was limited and so the Spanish bikes fell behind others in the race for technological improvement.
There were also significant political changes happening in Spain at the time which led to increased labour disputation issues in the Spanish workforce.
To answer the question about riding it with oil leaking, if it goes bang (noise and jarring felt through the grips) on landing, you are doing damage to the fork internals. Also if it is low on oil it will probably also go bang as the front comes off the ground.
If you don't get a bang, you have not lost enough oil to make a difference yet.
Thanks for the great photos of you and your fine M49. I had a bit of trouble reading your web page (we Aussies only get a small amount of schooling in other languages). Did you say the restoration cost 4500 Swiss Francs?
Mine is also an early M49(M4900100).
You may weep if you saw how unusual mine looked when I bought it so I won't send you any photos until it looks more like a M49. It had been fitted with a road bike dual seat, huge front and rear road-bike type footpegs mounted on heavy steel frames, the rear frame loop had been bent down to allow the double seat to fit better and the tank and side covers had been painted pale blue with a white flash to resemble a 1978 Pursang. The good part is that the bike is generally in quite good undamaged condition and runs well. It still has an old chevron pattern trials front tyre and the original aluminium front mudguard and mounting stays. I was able to buy a correct seat with a good base and a spare tank and set of sidecovers and am still deciding which tank to use. It is very good to see such clear photos of a bike such as yours for when I paint the tank and sidecovers. Yours is the first I have seen with "BULTACO" on the sides of the fuel tank. Was that standard on yours?
I can't quite see what footpegs you have used on yours. Where I ride the safety rules require folding pegs so I will probably make up a set to fit the standard mounting locations for Post Classic competition events.
Thanks twinnshock, I hadn't seen the trialclasico.com site before. There was a good closeup photo of their replica muffler for the M49 so if I want to make one it will be easy to get it looking right. They certainly are expensive to buy. I agree that they are not the most practical type muffler to use but the old Bultacos look a bit strange with cylindrical mufflers.
If you want a good practical cylindrical end muffler for old two stroke trials bikes, I suggest that a Suzuki RGV250 end muffler from a wrecker is a good starting point. They are light, cheap and look quite good.
My Sherpa M49 came without the (top-in bottom-out) triangular box end muffler. I have not seen them for sale anywhere so am guessing will need to make one. I don't have any decent close-up photos of an original muffler to help with this. Maybe the replica triangular muffler (bottom-in top-out) as sold by Sammy Miller can be easily modified. Can anyone help me with this issue?
1 The vertical rotating shaft tends to develop a rounded pit where the end of the pushrod bears on it. This increases the surface area in contact with the end of the rod which increases the friction. It can be restored by welding and refinishing or they are available from Yamaha. Make sure that the point where the pushrod bears on the flat surface of the vertical rotating shaft is well lubricated with a grease containing a high pressure additive such as molybdenum disulphide to resist galling.
2 The action of the TY175 clutch mechanism is affected when the flat face of the rotating shaft that pushes on the pushrod is not at 90 degrees to the pushrod in the middle of its movement. If yours is not at 90 degrees, you will need to make changes to the clutch components to get it there to optimise the action. Things that affect this angle are: Incorrect adjustment of the rotating shaft height, clutch plate wear, pitting of the flat surface of the rotating shaft, wear of the end of the pushrod and wear of the ball. If the angle is significantly less or more than 90 degrees, the end of the pushrod will be getting pushed sideways which will greatly increase friction and wear in the mechanism.
This problem never happened under acceleration hard or gentle. It was when the throttle was being closed and this is what BATRIAL seemed to be saying also. Yes a larger pilot jet will halp with pinging under acceleration but I don't think that is the problem here.
My 2003 REV3 200 used to make the same noise at the same time as what you described; just as the throttle is snapped shut. I tried different fuels, different jetting ie needle position, needle shape, pilot jet size, main jet size, float height, spark plug temperature rating and oil/fuel mix ratio. When I advanced the ignition timing a bit, the noise you described disappeared.
The place where my bike runs so nicely is with the stator screws in the middle of the adjusting slots.
In case there is confusion about what is advancing the ignition, it means to cause the spark to occur earlier ie to rotate the stator in the opposite direction to the direction the rotation of the rotor.
If the red frame is original colour I would be guessing it a 1984 or 1985 model which would be called a TY250N here. I see the wheel rims are different colours. I suspect the rear wheel with gold rim is original and the non-standard front wheel has been fitted as part of the disc brake conversion. I don't know what bike the fuel tank is from.
Someone is sending me a ceramic header pipe for a Mont so we can test that.
Also a mate of mine has his truck header pipes coated localy and claims they drop the temp of the pipe over 110 deg, we will see, if it works I will get my header pipe coated, if it only means saving melting my wellies
Apart from reduced risk of melting ones wellies, can someone explain why reducing the temperature of the outside of the exhaust pipe on a 4 stroke is important?
I would have thought that cooling the exhaust gas as quickly as possible to reduce its volume (by dissipating heat through the wall of the exhaust pipe) would mean the exhaust system could be made smaller diameter than if the exhaust gases were kept hot by coating the header with an insulator.
Advocates of ceramic coated headers on trials bikes please share the reasons for doing it.
By the way I'm not asking about turbocharged diesel truck headers because they are coated to keep as much heat (energy) in the exhaust gas as possible between the head and the turbo.
What is the ideal sprocket combination for Yamaha TY 175, just removed a 60 rear fitted a 51. I have just got a 13 front 51 rear from Talon, so I left the old 13 front on for now. Is the 13x51 the most common combination?
The 51T rear will be fine but I suggest using a 12T front. Using 51/13 means that second is a bit too fast for most competition sections and first is a bit too fast for extremely tight stuff but OK for most sections.
Using 51/12 is better for competition because it allows the choice of using first or second gears in sections and makes first nice and slow. The penalty is that a TY175 with 51/12 gearing will only do about 50-60km/h flat out so might be a little slow if you do much trail riding.
A point on the motor, half an inch below the cylinder head gasket was the point used to record the temp on all bikes, and the thermometer has an error range of + or - 2 deg either way.
The outside temperature of an air cooled (4 stroke) motor is generally hotter than the outside of many water cooled (2 and 4 stroke) motors
The water cooled motors had narrower operating temperature ranges than the air cooled motor (ie their thermostatic control systems were working)
Both are totally expected results
I would also expect that:
If you tested an air cooled 2 stroke motor under the same conditions you would get a result similar to the Scorpa 125.
If the ambient conditions of the test were very cold or very hot instead of the 30 degrees C, the benefits of water cooling would be even more apparent ie the water cooled bikes would have the same operating temperature range as for 30 degrees but the air cooled bikes would be correspondingly hotter in hotter weather and colder in colder conditions and would continue to see a wide temperature range at any given ambient conditions.
BTW I'm assuming you did the testing in conditions considered hot in most of the trials riding world. In most of Australia the normal summertime day temperature is well above 30 degrees C. Where I live it is usually 33 in summer and 27 in winter. Further North and away from the coast summer days are normally around 43 degrees. This why I am an advocate of thermostatically controlled water cooled trials bikes be they 2 or 4 stroke.
Have just brought home a 1974 alpina 350 (i am fairly sure , as it has a head that looks too small for the barrell) , what niche would this bike have filled ? got it started (BLOODY HELL !! the man said it hadn,t done much work he wasn,t lying , it,s got as much compression as my ty350) but haven,t ridden it yet so am not knowing what gearing is like , would it have been like a long distance trials bike perhaps? and i need one fork slider , one is perfect , one is cactus , thanks steve batkines bundaberg
Steve, is that Bundaberg, Queensland, Australia? Yes you are on the right track about the kicking it over compression. I have a M138 (350) Alpina which certainly warms you up kicking it over. If you are from this Bundy, there are well stocked Bultaco parts suppliers much closer than the UK ie Don and Marie Newell in Brisbane and Peter Schoene in Melbourne. Please reply if you want phone numbers.
Sorry if you are from a non-OZ Bundaberg.
From David Lahey, Gladstone (just up the road from the Bundaberg famous for Bundy Rum).
If you are doing the wheelie on the flat, rest your backside up against the rear guard high enough to get your toe low enough to touch the brake pedal.
If you are doing it uphill you can do without the rear brake.
When you are ready, maintain mid RPM and feed out the clutch to get the front up. Starting speed can be almost stopped. The slower the better for starting as you will accelerate as you bring the front wheel up under power.
As the front comes up, move you shoulders and head to one side so you can see where you are going, looking past the front wheel.
The lower you sit, the more vertical the balance point will be.
While the front wheel is still spinning you can get a strong steering effect by turning the bars opposite to the way you want the bike to turn.
Old twinshock bikes with a higher centre of gravity are the best to learn on because they are less vertical at the balance point and have higher seats. This makes them easier to steer during the wheelie.
Keep your torso and legs as still as possible.
Some people prefer to hold the inner section of the bars or the top of the left fork leg with their left hand once the bike is up to get their arm out of their field of view.
Falcon Shocks
in Twinshock
Posted · Edited by feetupfun
I assume you are referring to Falcon Classic steel bodied trials shocks.
The aluminium cover you see that looks like a seal holder is a push fit in the body. It is actually a dust scraper holder. Tap it off carefully with a punch.
Inside you will see the shock seal carrier held in with a snap ring.
Depressurise the shock and then you will be safely able to remove this snap ring with internal contracting pointed nose snap ring pliers.
From there it is obvious.
PS if the shaft and seal is still OK and you just want to change the oil, you can do it through the hole that the gas valve screws into.