My original 68 Cota had a straight rectangle outlet pipe.
I modded mine to match the above picture and there was a slight improvement even though I kept the IRZ carb.
What I can't remember is if the tapered baffle tube remained in the centre of the silencer or was set off to the offside rear!
Or remained central in the box leaving the tail pipe off set and the gasses to collect in the rear portion (curved) to creat a bit of back pressure before exiting out the tail pipe.
Nostalgia is great when I can remember!
If you know the answer please tell, as I am about the cut and repack.
My original had an rectagular tube tail pie with the outlet biased to the of side of the silencer so that it missed the rear mudguard and fitted neatly between the shock mount and mudguard.
The one I currently have has a round tubular outlet that requires the mudguard to be trimmed to get through the gap!
It appears original, but to me seems strange as i cannot understand why the factory would produce it in this way.
Are there any pictures that show the layout for 21M1800 model thet was made in April 70.
Hope you guys can help, and yes I know the frame should be white!.
Yours is certainly an early model. I bought mine in October 68, built it for the Perce Simon and then had it laid up for about 5 weeks as the initial batch on gearboxs were faulty. The dogs from first to second would not engage. Eventually Montala Motors of Dartford (the importers) gave me a complete new box and I gave the bike to Triss Sharp to rebuild the engine. It was then trouble free until I sold it in 1970.
Best trials bike I ever had!!!
Will try to get it ready for Star farm and give the Sherpa a rest.
It runs well but is not quite put together as I want it.
Just various small things like borrowing the wife's 5 1/2" saucepan to make a sheild for the air filter, new snail cams, footrests, moving the condenser up under the tank, exhaust gasket and Handlebars to suit my height.
Unfortunately it has the small front hub (mine had the large diameter original hubs)but all the numbers stack up and it has a V5 showing 2 previous owners.
When I saw it I just could not let it go as it brought back so many happy memories from 1968 to 71 when I got one of the first ones in the country from Westbury Motorcycles RHU71G. I actually sold it to SM at New Milton in exchange for a Pathfinder!!!!!!
Please any pointers with shots, sites showing original configurations will be appreciated.
I believe that the frame should be white, and the original exhaust finished by the offside rear shock.
I will still ride the Sherpa this year in the SM Champs but will fettle the Cota and get it out on a trial as soon as poss.
Look forward to any comments you guys may have as it is now 41 years since I last had one close up.
Solution = Halfords cheapest bike speedo. Mount the magnet on one of the front wheel nearside spokes and using cable ties strap the sender to the inner face on the near side slider. Run the cable up the fork leg tie near the top of the slider and at a point just above the bottom yoke allow (enough lenght)for full extention. Then route up to the display mounted on the handlebars.
Apart from a change of battery it has been trouble free and given good service for 30 months, all for an outlay of
Betors may be cheaper but you will not get better than the Magical shocks and fork springs.
I rode for a season on Betors and std fork springs.
I studied the market and looked at what the Spanish use and took the plunge.
Woody described the feel as plush and boy is he right, transformed the handling. No bottoming out of the forks and rear suspension just settles and grips before rebounding.
So why buy cheap(funds aside)only to replace with the dogs at a later date!
In November 1966 I complained to the Greeves rep(Mike Jackson)that my new Anglian tank appeared to be disintegrating as I could see the white fibres.
He told me not to worry and he was right!
My understanding of building up the fibre laminate is that you have a smooth gel coat on the outside and leave the unfinished (fibres visible) on the inside.
Simply put i believe there are people out there that make tanks without specifying to their suppliers to what use the materials (resins) are to be put.
Then crying foul!!!
Leaving punters to pick up the tab.
Bit like "Fools and Petrol Tanks".
I have spoken to Shedworks during a round of the SM Champs and believe they know what is required.
Sorry if this is a bit blunt but at the moment I believe the fault is with the supplier not the customer.
Seal behind clutch basket should be slightly proud, not flush. This is pictured in the bultaco manual. I can only assume that when flush it is too near the end of the sealing surface.
Regarding the exhaust plate, I had the same problem and just sqeezed it flat in the vice. It distorts because people are too heavy handed when tightening. Just get a new gasket and a bit of (not a lot) exhaust sealant and make sure that the sealant is between to flange on the pipe the the clamping plate recess then a smear on each face of the gasket and you have a good seal.
But do not force it tight, gently tighten each M6 nut in turn to make sure you have an equal gap. Oh, leave the rear bracket loose at this stage and then tighten after everything is lined up.
Front pipe is in position, used a BultacoUK Model 80 pattern front pipe but cut the exhaust flange off and grafted a 198a flange in it,s place. Then welded a servicable middle box on the end.
Next job, sort out the tail pipe and powder coat both silencers leaving the front chrome..
You should have a long split spacer which fits into the near side slider.
When you set your forks up make sure this is free to slide, tighten the spindle, compress the legs a few times, this allows the fork legs to fine their natural position.
Then tighten the clamp on the near side first and then the off side.
Richard(Sammy Millar products) told me today that the decals lift of after a while. Perhaps the Spanish supplier is still using the old spec polymer or polyprop.
So I think the best bet is to talk / ask on this site if any one can advise which make the resin sealer is best.
I cannot get an answer till Wednesday.
However if you can afford it Sammy Miller Products do a very nice fibre glass tank. Give Richard a call.
There were various problems with the old style plastic/poly tanks back in the late 70s early 80s.
This was caused by the type of poly used which, as we know allowed the fumes to migrate through the plastic wall.
Modern materials have overcome this as is demonstrated by plastic petrol containers.
If you look at the thread above you will see how I have overcome this problem.
Basically the tank has been lined with a fuel resistant epoxy prior to the outer surfaces being primed, top coated, decals applied and the whole surface sealed with a clear (fuel resistant)laquer. Expensive but the results are worth it.
However I have a new poly tank for my next project and will not seal it internally just apply the decals and then laquer over the decals to stop the spilt fuel seeping under the decal and dissolving their adhesive.
I suspect (but cannot yet prove)that it is spilt fuel not fumes evaporating through a modern poly tank that lifts the decals.
The lacquers used are fuel resistant type that are developed for plastic bumpers.
Just remember these bike are at least 30 years old and who can say what has been fettled or played with.
So be patient, check that all the other bits are in A1 condition:- compression, crank seals, no air leaks, carb is in a good state of repair, air filter clean and that you are using the High Octane unleaded fuel with around 40-1 semi synthetic oil (bear in mind synthetic oils were not around when Bultaco's were made).
Then you at least know everything is correct when you set the timing.
It really is worth the effort, as my model 80 engined Sherpa is more fun to ride than my GAS GAS.
I set it up in the central position and all was fine.
However over time I have advanced it 3 graduations (rotated it clockwise) and that suits my riding and pulls very slowly and smoothly from low revs with bags of top end.
But my engine has been ported, so I am unable to confirm if my settings will suit your engine.
But good luck, I know it is a nuisance but really just play around with it until you are happy and the power suits your riding.
For you perfectionists SORRY, this is my bike and i have painted in to suit my taste.
Never liked the blue allover look so: white frame; specially painted poly prop (sealed with resin)tank, wheels brake drums sleeved, then built with stainless spokes and new rims, every bearing replaced, KTM fork seals, yolkes bored and sleeved parallel to sharpen steering (saves butchering the frame!).
Nearly a brand new sherpa, just need to sort the exhaust (easy).
I have the same problem with my plastic tank on the 198a.
I'm getting it resprayed but before it is prepared for painting the inside is being lined with a two pack flexible resin that will seal the internal surface of the plastic.
This will stop the vapour bleeding through the plastic and either lifting or fading the top coat.
One of my suppliers whose business is rota moulding (the process used to make tha tanks) told me that the early plastic allowed the petroleum vapour the bleed through. Current formulation stops this(as is obvious the green and red petrol cans).
When finished I will keep the painted tank for display and will use the pattern tank purchased from Bultaco UK.
Whilst on the subject of the replacement tank it is wider than the original by about just over 25mm, this is more obvious when in situ as the frame has much more clearance than the factory tank.
247 Evolution
in Montesa
Posted
Hi Chris
Picture is a great help.
My original 68 Cota had a straight rectangle outlet pipe.
I modded mine to match the above picture and there was a slight improvement even though I kept the IRZ carb.
What I can't remember is if the tapered baffle tube remained in the centre of the silencer or was set off to the offside rear!
Or remained central in the box leaving the tail pipe off set and the gasses to collect in the rear portion (curved) to creat a bit of back pressure before exiting out the tail pipe.
Nostalgia is great when I can remember!
If you know the answer please tell, as I am about the cut and repack.
Regards
Martin