If you want to invest in something really better working in terms of mixing air and fuel try a SmartCarb especially for MX or Enduro bikes. The manufacturer will adjust the carb to your Bultaco and then you never have to adjust the carb again.
A Dellorto might be OK, I have a VST mounted to my KTM 500, it is a flat slide and I would suggest something similar but it will be a long and costly journey to get the carb proper adjusted.
3rd Idea is a Mikuni or Keihin here I would ask the Bultaco MX riders in the US as there most of them uses these carbs or SmartCarb on their Pursangs.
To the AMAL carb Carl Ekblom is pretty right about the jets and nozzles. IF you think you have a carb problem you might replace the jets against new one, too the needle and in case of AMAL please look up the status of the slide and the inner cylinder inside the carb body. AMAL had sadly a soft carb body and a soft slide too, this resulted in quick wear and likewise worn out slides and inner bore (cylinder).
I personal like the AMAL not and have replaced them against something contemporary else.
I had a Puch with a Bing carb fitted with a tickler.
You should press the tickler down until the gas runs out fron the hole for the tickler rod, that ensures that the engine has got enough gas to start in my experience.
Nope they can be very different there are the standard ones in bare alumiuim, the racing versions are in black or in red these have often different idle jets instaed using nozzles.
To the PHBH inbetween there where even standard ones in bare aluminium made with idle nozzles instaed of jets, then there can be many different types of needle nozzels mountet, from type AS to type T there are 12 different versions!
(AS, AV, BC, BN, CF, CU, DG, DN , EF, M, P, and type T).
Ask the seller about the mounted jets and nozzles (Standard are 5mm idle jets and 6mm main jets and AV needle nozzles).
Also the float set up can be different too, but with not big effect to the air - fuel mixture.
I have read some literature about the boost bottle and the main reason for mounting one is to collect the deflected air gas flow from the piston inside the crank.
With mounted reeds this effect is much lowered thus the boost bottle will not have a big effect, but try it out and go ahead.
If there is some effect please let me know.
More effect would be installing a newer carb and newer reeds if you ask me.
Mostly the gear selector mechanism in the extra casing is the problem, a bit delicate if the lever got hit it can cause a slight warping of the inner lever and cause trouble in setting gears.
My suggestion is too inspect the parts (shaft for the gear lever and the drum lever) if they are still straight. I once had a blocked 6th gear just because the extra side case was mounted in first hurry not pefect aligned to to the shaft.
Be aware that the TXR have a later Dell'Orto PHBH 26, of type SD which is a Mikuni clone and fitted with an air screw.
The factory adjustment for the 240 and 276cc model are:
main jet: 88,
idle jet: 58,
nozzle jet: BN 266,
clip: 2nd from above,
slide: 45°,
air screw: 1/4 out,
float: 8.3 gramm,
needle: I have to look up, if of interest
gas valve: 200
When I upgraded my SWM with original spare parts there where no problems, prices where low and most stuff was available.
Now supply has come to an natural end.
I ordered many tiny parts twice back then to have a spare, did so too with the enhanced clutch engage system. These where sold a bit over ten years by Dagaracing in Italy for just a couple of Euros...
No one needed that stuff beside a group of riders on weird bikes... that changed much and now the part party is over, likewise to TXR covers...
Had a discussion with a number of Bultaco experts some time ago about possible shades of Bultaco blue. It ended "there is only one known Bultaco blue from factory". Different shades of blue seen on old colour photos is possibly due to agening photos. This is good for me unless someone has different and more correct information.
Bultaco used many German standards but produced their bikes due to the Spanish tax regulations,
Like the strength of their bolts, the Bing carbs build by them and as told I painted two bikes in RAL 5015 and where told both times that is the right color, still it shades a bit depending the brand.
I think it worked out very good. First photo of the pair is original, the second is rebuild a rebuild.
First 2:
175 Sherpa in summer 82 and in summer 83 refurbished.
Second 2:
2x 340 Sherpa when pulled out of a garage in 2009 and later refurbished:
Very nice, I would love to come to the Alpes for riding again, it is a couple of years ago I was there last time for motoalpinismo.
And I believe the sections have got a bit more casual too compared with trials event of the former years,
which is in my opinion a good move towards the old material and riders on old bikes at least.
I thougt it should have a frame from that era too, likewise other parts should be (not must be) in general match with the era the bike comes from if still possible?
Posted
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Edited by pschrauber spelling issues as usual ...
In doubt I would dump the Amal and mount a DellOrto.
I did so with my Bultaco and too with the Montesa.
You can take the standard DellOrto of your SWM and mount it once to the Armstrong to figure out how well that type will work compared to the original Amal.
Most old Amal carbs have the issue of a worn out cylinder for the slide as back in the 80's the material of the body and the slide where of the same material. Thus lead to much friction and worn out both components.
in very short the answer is the older bikes make trials riding more complex as you need more physical and mental power to do the same things with a twinshock compared to a modern bike, thus you learn common trials riding with them better and faster if you want to improve!
That was the failure of all the posters before that they did not bite the bullet and tried harder, instead anted better results with less effort.
Still you can't ride modern riding style and sections as well with a twinshock then with a modern bike.
Then you have to think about where you do will find yourself in the way you improve.
With 53 you don't will be the next world champion and also not the national master so you will stay in modern riding in the advanced rider class, as modern trials is a bit acrobatic which you should have learned when you where younger, now you are sadly too old to learn that as easy as other much younger trials rider that start with as little knowledge and skills as you. That you can not improve as easy and as good as younger riders will get you embarrassed, if you like to punish yourself go one with it, if this is enough for you and what you want then get a 200cc modern Beta and all is fine.
With 53 riding twinshocks or pre 65 you can improve further to the expert class with challenging sections for twinshocks to me that sounds a little bit more interesting, but too needs more effort in the beginning, then a Fantic 200 or 240 is a good choice.
Or get a aircooled mono if these bikes have an own class where you live and here the Beta TR34 would be a bike just in between the modern and the old twinshock world.
I personal ride classic trials on Twinshocks and Pre65 and do long track trials in the mountains with aircooled monos, the modern stuff is cool but with 57 I don't see a long future in that department.
I would suggest you design them by yourself and let them print by a print shop on sticker material that is used to wrap car bodies.
That foil can be heated up and streched to the needs of the surface geometry.
The standard foil can -as woody- mentioned be a problem when mounted on rounded surfaces.
I made myself register sticker plates to my bike and these where printed on car body foil which was easy to apply
if you follow the instruction using soapy water, a hot air gun and a squeegee.
I use now one oil to fit all my bikes and that is ELF HTX 740 works very well for gearbox and clutch.
Before I have used Putoline SP GEAR OIL and standard gear oil too with good effect. But the ELF oil provides best clutch action in my personal experience.
At a guess none. Exactly the same figure as from ethanol additive petrol.
Nope as You and all other gasoline customers where informed in the advance that E5 and E10 ist not suitable for some vehicles and with E10 the effects are even more visible.
To ether, this chemical is the additional indigence that has replaced lead in the fuel in terms of rising the octane, (not the lubrication of valve shafts). You find ether especially in these fuel products:
- Startgas cans,
- DME: Di - Metyl - Ether is cleaning the diesel engine inside, *
- MTBE: Methyl - Tert - Butyl - Ether is the ether that is rising the octane level for petrol engines,
- ETBE: Ethyl - Tert - Butyl - Ether is the ether that is rising the octane level too for petrol engines,
* That is why you get better fuel consumption with Ultimate diesel fuels, as ether has more energy stored.
** That is why you get a little bit of power increase with Ultimate fuels and much higher octane as these have more energy stored
and rise the octane level.
Although there may be less with the water absorption.
Nope, as this is gasoline is sold to all kind of cars all around Europe and these use... guess what... a lot of that rubber parts too and then please read what is written about the material and the harmfullness.
In the chart of your link a 4 is doubtful which means it can in doubt harm that's all it is not an F!
How many claims are there from thousands of car and motorcycle customers that are using this fuel?
If there would have bern or is an issue with ESSO or ARAL premium gasoline we would have known that for years .... .... You are looking something up that is in fraction harmful but in practice not important or as we say you are nearby to count pees.
Gasoline and alcohol in general are solvents and thus are dissolving part of the rubber and the effect is that the rubber gets faster old and cracks, likewise does UV radiation and hot / cold cycles.
What solvents do to rubber is that they dissolve the chemicals responsible too keep the rubber or plastic smooth and flexible as mentioned that is happening anyway, but so little there is no difference.
It is a good idea to use fuel without ethanol, because ethanol is shortening the storage time, especially in cold seasons. I have had some experience with desintegrated fuel when stored in harsh winter climate with under - 20°.
Thus I avoid that fuel now completely.
And as other stated it is in my opinion very good to use premium fuels, especially when they are ethanol free and come with cleaning chemical elements.
Here I would recommend ESSO Ultra or ARAL Ultimate. ESSO bought ARAL and thus theur Ultimate petrol and diesel fuels which are ethanol free and have engine cleaning components included too have high octane and produce less carbon.
- higher octane will avoid pinging and you can too set up your trials bike to a leaner carburation which is uselfull as we ride a lot with very low rpm.
- without ethanol there is no storage problem anymore.
- instead of ethanol ARAL / ESSO uses ether wich gives an extra boost.
- the ether works too as a cleaning components and will wash away the carbon build up inside the engine.
I run Ultimate in my TY, SWM, Montesa, Bultaco bikes with good result.
For long term storage and very low temperatures I use Aspen racing as last fill up before the bike goes in a longer hibernation but I don't think you need to go as long.
Frontera 181 Carb
in Bultaco
Posted
If you want to invest in something really better working in terms of mixing air and fuel try a SmartCarb especially for MX or Enduro bikes. The manufacturer will adjust the carb to your Bultaco and then you never have to adjust the carb again.
A Dellorto might be OK, I have a VST mounted to my KTM 500, it is a flat slide and I would suggest something similar but it will be a long and costly journey to get the carb proper adjusted.
3rd Idea is a Mikuni or Keihin here I would ask the Bultaco MX riders in the US as there most of them uses these carbs or SmartCarb on their Pursangs.