At first you need the right springs that matches the bike weight and your weight with gear to your rear shocks and the fork.
You can determine the right springs if these deliver the right sag for trials riding static and dynamic.
static = standing bike without weight of the rider,
dynamic = standing bike with the weight of the rider while standing on the bike (with full gear).
If so everything is OK and any personal adjustments then can be made by changing compression, rebound or damping. The main effort is to get the right springs according to your and the bikes weight
I had similar problems with frequently fouled plugs. Also the engine dis not run well
There where two issues.
Issue #01:
It turned out that the engine did not got enough air due to a hole plate mounted inside the air box provided to little air flow. I replaced it against a much less restrictive (in terms of air flow) plate which is more like a mesh and the engine worked much better
The second issue was the carb and the float valve it worked good while the engine was.off and the bike stood on even ground. But once the engine was started and the bike stood just a bit up or downhill the carb flooded itself and the cylinder causing a much to rich air gas mixture. The issue was a float valve (brand new) that was about 1mm shorter then the old one.
Anyway I would check the air filter if it's not clogged and too the level of the floats also if the seals to the carb are still working here the seals to the:
- choke lever (bottom),
- choke jet, o-ring,
- float valve, rubber cone,
- idle and mixture screw the little o-rings inside.
Letting the engine run while waiting in front of a section has been less and less an issue.
I think the mind sets in earlier nowadays, not at all, there are exceptions to the rule, to them a short friendly reference and the engine is mostly shut down too.
You really need that gear, there is one teeth missing...
Sent me the picture and surplus which gear it is in the horizontal and vertical section drawing (see attachment)
and I think I can get you one. You know my eMail
Again I would leave everything as it is reassemble and in the meantime save some money for a complete rebuild of cylinder, custom made piston and con-rod with new upper and lower pins bearings and if in need thrust washers. That done by one company so no one could blame any other and the next 10 years of happy riding are ahead.
There is a saying:
The cheap pays twice.
And as the part situation isn't the beat anymore and you sometimes need as mentioned here special sizes that than again only fit to NOS cylinders without wear and to replicate just the same coating ... too many incidents, too many conflicts and left over questions.
Well it looks used but still not too bad not to ne used again. The plating looks OK with little wear. The piston is used.
To the measurements You made a piston is different in size depending where You measure. The piston should ne a but wider at the bottom compared to the top and also in comparison between the axis in drive direction towards the axis of the piston pin, because the exhaust side is often hotter then the port /intake side.
I personal would clean everything up very well polish the piston top and the head Inside, then rebuild all again and ride the bike until you get the feeling the engine has lost power or statt rattling more. Then I would so a complete rebuild including con-rod and crank pin.
UK or not when I look at your prices for labor +10%, for parts +20%, for postage +20% and +1% for VAT.
I once ordered a custom ignition rotor with added weight for a Swedish SEM ignition to an Austrian bike in the US and was very pleased by the outcome and too about the price so a win / win for all.
But on the other hand that's me and you are you...
Most important plated cylinder and piston has to match.
Some air cooled Monos are known for their bad running behavior. The 250TY and sometimes -not all- batches of Fantics and also Beta TR's with just super noisy engines.
If you need both a new cylinder coating and a new piston with rings, pin bearings and circlip, even decide to spend some money in a new con rod and lower pin with bearings.
You might ask Woessnerkolben in Germany they do al three things at once, custom build a piston that will fit your cylinder after the old one and plating the cylinder too, then all parts you need too surplus a con-rod with all parts if you are in need. Maybe some extra money spend by a non brainer to me as you get every bit from one supplier and with I the guarantee that it works now and in future. All other combination will be of separated guarantee (if any) a lot of time will pass until everyone knows to which diameter the piston or the cylinder has to be made and so one ... As spread mentioned in my personal experience I can highly recommend their work and craftsmanship.
You might exchange the older rear silencer against a newer one from the Jumbo model. But it's not worth all the hassle.
Bed improvement over all would be to give our outtake a good internal clean up I recommend mild blasting.
Then cut up your mid box get everything cleaned up very well, (and now the trick), do media blast the hole tube so much that the holes get their original diameter back. If the hole tube is too much corroded buy a new one with some hole pattern and hole diameter out of stainless steal and place it inside. Then get fire proof medium hard rock wool that is sustainable to temperatures above 1000 deg. Celsius and carve out two halves that than can be placed then around the holetube. Rebuild everything and done.
For riding use 2stroke oil with very low burning point so it get's burned away instead of thrown out of the muffler and good gasoline ethanol free from 95 to 100ROZ and you engine will stay together with a .NGK BP 4E and a mixture between 1:66,7 and 1:75 very clean inside.
You don't need them if the carb has an extra filter like AMAL, Bing and DellOrto. For the other carbs without an extra filter nigh be a good thing to have as the small plastic mesh tube attached to the petcock sometimes changes place or better said doesn't perform as thought
I use Ariete greenish transparent plastic tubes that are available in all sizes and just cost 1 - 2 € the meter depending the size. I would in any case switch to a transparent fuel line much easier to see if gas is running or not.
Mmmh ... probable it will not be eaten as hot as it is cooked now.
With our licences you get a full insurance, our trials has to be insured too when comparing the costs for a trials event in the UK there is no big differences instead our trials seems to be mostly cheaper.
To the licenses they are paid ... much more expensive as I believe but there are different licenses too. Anyway you get with an insurance a complete bundle of insurances you are even insusred for reparation.
It depends on how much you use your bike, in which terrain and weather conditions you have ridden. Even which chain you use.
In my experience MX chains do last extremely well and worth their money DID ERT2.
I replace the chain when the chain has got signs of wear being to long or having too much side play or if the chain has been damaged partly by a rock for example.
When I change the chain I change both sprockets too. Worn sprockets will ruin new chains as worn chains can will ruin new sprockets, this is mandatory.
I have some bikes.
I get several seasons with one chain and sprocket set up when using MX chains. With standard light Regina chains less.
So if everything is sorted, like carb, intake rubbers (both of them), air filter, engine wise too as I understand, the pressure of the compression we might call OK too. Even timing and a CDI mounted. Then how good is the magnetism of the rotor, the engine is old and with the time the rotor can loose magnetic power if so the spark won' t be as good as it should you might compare with your 320 TL.NW.
This can happen by age but too through an hard impact!
That would simply produce less electric energy and thus a less good spark, my advice go to the next Bosch service and let them test the rotor you can take the 320 with you for comparison. 20€ well spend.
So did a test run and ... Mmmmh ... yes it's running ... but could run crisper, needs more idle and runs a tad rich in my personal opinion, adjusting the mounted carb did not change much beside idle rev. So I took off the carb and took a deep look inside.
Well the carb need's an overhaul, the slide is pretty much worn out, never have seen so much wear !
The jets / all screws where assembled with maximum force, on screw that attaches the flange to the rear manifold towards the airbox was sheared, .
I would love to get this carb in decent condition back, what type is it as AMAL has some types of the MKII, is it a 2000, 2600, 2900 or a smoothbore I have no idea?
Printed carb- number at the top: 625 720 403
Printed carb- number at the side: L25 27 and below 418
So can someone please get me in the right direction which AMAL type carb I have here?
Below some pic's of the mess:
Anyway I think I get additional a DellOrto for the bike,
the same typo like the TXR have with following set up:
In general found a topic about the carb swap at the old ToDo trials form from 2009 the use of the DellOrto was heavily discussed and many settings where posted as too both possible carbs PHBH and PHBL.
Without getting a favorit beside the Italian gas air mixer was in favor towards the Spanish Amal. Their jetting set up was quite wide in the range. To make things worse Todo Trials sells now a "ready to race" Mikuni variant too which makes the decision even more difficult.
I personal now thinking about the Mikuni clone form DellOrto with air screw and idle jet nozzle or instead the DellOrto VHST which uses the same specs as the PHBH wich a square slide.
But still their might be an owner of an 242 which had already done the carb swap and may be can share about his experiences?
I' am looking for an alternative carb for a Montesa Cota 242, the OEM fitted Amal is good but shows some wear especially the slide and cylinder area of the carb body , surplus the bike came from a high mountain area and I live at 50m above sea level so I have to readjust the carb of bike quite a bit.
As the bikes I have in the garage are fitted with Dell'Ortos, I would like to keep the inventory of spare parts jets, needles gaskets and so on low .
So do anyone have tried to swap the Amal through a Dell'Orto and can even provide their choice of jetting's needle and slide? would be great and !
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, surplus the bike came from a high mountain area and I live at 50m above sea level so I have to readjust the carb of bike quite a bit.
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Rear Suspension Theory
in General Trials Talk
Posted
At first you need the right springs that matches the bike weight and your weight with gear to your rear shocks and the fork.
You can determine the right springs if these deliver the right sag for trials riding static and dynamic.
static = standing bike without weight of the rider,
dynamic = standing bike with the weight of the rider while standing on the bike (with full gear).
If so everything is OK and any personal adjustments then can be made by changing compression, rebound or damping. The main effort is to get the right springs according to your and the bikes weight