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Check crankcase breather is not kinked or fouled inside. PCV (positive crankcase valve) may be sticking. Either way it could explain idle dropping as fumes in crankcase build up making it harder for piston to travel down cylinder bore at low rpms. This problem would show up more as the breather passed less and less fumes. You’ll probably say that the engine oil is fresh but the breather(s) can be troublesome. The other possible cause is a fuel supply issue where delivery slows down and starves the engine, start with tank breather and fuel filter etc. As jonnyc21 mentioned, tight...ish valve clearances will affect engine performance, but you would notice a drop in engine pull if this was the case. Hope you get to the cause and sort it.

Agree entirely. Except some breakers take apart already running bikes as that’s a more lucrative way to make money!??

That’s exactly it except the street was lined with parked cars and they weren’t stranded either!

Cor you ad shorts, why ey I only had me Y fronts held up with string. Don’t ferget the salt, that’s what kept me going, all that nutrishous lovely salt chucked on t’ road to free up the gravel for thems that could afford it. Ah think it was called dinner money bah ah kanna remember, ‘‘tis the salt ya sees it plays wee yer mind”. And now someone can bemown the fact that I was lucky enough to have string!!

Certainly hope all cars had wheels and tyres, not so sure about everyone having snow chains. Agree we’ve gone soft, slightest whiff of a temperature drop and everyone’s clearing the supermarket shelves. Bread and milk first...why? America just seems to accept that it’s snowed and get on with it. UK gets 0.5mm and complete standstill, elf an safety get in on the act and close schools, don’t want the little darlings falling on the ice so they stay home and go sledging down the steepest hill they can find along with mum and dad who have had to cancel work to look after said sproggs.....great innit!

http://www.betamotor.com/en/trial/bikes Try this link and look for downloads. At some stage sooner or later you will need to get at the carb and other associated engine components so now would be a good time. When the carb is off work very carefully, remove the float bowl and inspect for dirt and debris. The float height must be checked as this can the cause of many issues over proper fuelling. Hope you get on ?

These may sound daft, but due to the running backwards, is the flywheel hub fixed to the flywheel, ie riveted. Has the crankshaft half spun in the crankshaft web. Not sure here if the crankshaft is an interference/ splined fit to the crank web or machined as one? Or was Merlin the magician annoyed at the noise and put a spell on the fiendish machine.??

Mr Allen is not known for selling duff parts.

Maybe so but how can you know who else picked up on the mod. There are probably lots of standard bikes that have not received the ‘mod’??

Ee when I were a lad t’double decker bus would be going sideways down t’ high street!! Ah ad t’ wade through snow t’walk from bus stop to school!! An yer got in t’ big trouble if yer were late!! (Apologies for t’ language)?

Questions the supplying dealer may ask you are, “ have you broken the engines in?” Have you shared the same fuel? As all are misfiring it could be stale fuel. Are the bikes misfiring or are you revving them too high and the limiters operating.

There is a mod that might be needed to the hot start pull mechanism. Involves removing carb, hot start pull and slide, opening out hole. Check it out on the manufacturers web site. Basically the holes too small and needs to be widened. Hope the pics help??

What I said earlier.

Learning to ride again won’t take long, certainly not 37 years!?

Looks good despite the exhaust. Someone was trying to do a reasonable job, you can finish it now. Those ally guards aren’t cheap so bonus there. What does it run and ride like.??

Hey we’ve already communicated, got to your DZ too soon!

I bet your selling dealer left a small amount of oil in the gearbox and did not fully drain down. 400cc is the correct amount.?

Oil level should be in the middle of the window?

Will a flat slide carb give more low down torque. I thought they were better for top end ?

Yep the newer they are the less you get and the more they cost!

Hello wilson c, joining Trials Central gives you something else to do while the snows about⛷??

Is this bike new or just new to you? Adjust everything that affects the way you ride. Handlebars in a line with forks viewed from the side of bike should be a starting point, but we are all different and what’s good for one isn’t always good for somebody else. Controls, levers and throttle need to be easily worked when standing more so than when seated (if you can call it that). Gear lever needs to be positioned to give you a positive push, lift if you feel you selected wrong gear for section ridden. Don’t run gearbox with excess oil as you will force oil out of the seals and or breather. Have you drained all the old oil out completely, including clutch housing? Did you have bike upright when checking level, got to ask that! Gearbox sight glass is good for checking if waters got in.

Haven’t done this mod, but the Bultaco fork internals are supposed to fit inside the BSA C15 forks? I’m sure there will be someone that has the knowledge on this along shortly to advise. I’m assuming by your avatar that BSA might be the preferred option. Cost might be high though. You could always go with DR forks and slide them up or down to achieve your favoured riding stance and then if they prove problematical look for some that measure up to your final settings. My M80 forks have the flat bottom triple clamp, forgot to mention that on previous post.

Go for that one it’s a no brainer. You can get bikes couriered (man in a van) for between £120 and £150 from anywhere in the country, least the one I use does. Oh and for 2K the Trials bike sales market is your oyster! ?

Here you go, full extension 735mm and fully compressed (no spring) 535mm. These forks have the knuckling for the lower clamp to grip on. Hope this is helpful? That should read as knurling and NOT knuckling. The process where a crisscross pattern is rolled into the fork leg to improve grip when being clamped.