bultobill

Stay with standard stuff. Just because it sparks doesnt mean its going to spark at the right time through the entire rev range especially if its not off a trials engine. Getting it to run is one thing getting it to run well is something else. That said does the electronic system actually advance the ignition as the revs rise? Maybe someone on here knows? Is getting the original unit(s) repaired not an option?

Looks very original even got the toolbox! Kickstart mechanism was a little fragile if I remember corretly so just check it works as it should.

Not sure from your post are you opening the throttle or not when trying to start from cold with choke on? Seem to remember delorto choke isnt effective if the throttle is open at all. Lift choke and kick it with throttle fully closed till it fires should only take one or two kicks.Never had a sherco but had other bikes with delortos on.

I assume we have a brand new plug in it at this point?

Ok Ben looks good. Would like to point out politely that practicing without boots and helmet is considered "bad form" especially if your photographer is around!

I understand your concerns but I believe them to be a true replica of the bike Doug rode at the time down to the last detail. If this is in fact true you may need to loose a bit of horsepower!

Well said ChrisCH

What jonboy is saying I agree with and that is what happens in reality..... Light mods = good to go. A lot depends on if it was manufactured and sold with an approval cert originally or home built if you want to get really fussy about it. Ever heard of anyone getting pulled on this one? No me neither. Read small trailers section in link for cert requirements and how its meant to work. https://www.nidirect.gov.uk/articles/trailers

Not sure but here is a start for you doesnt look to expensive even if it does need IVA https://www.gov.uk/government/publications/individual-vehicle-approval-iva-for-light-trailers-help-to-get-a-pass/individual-vehicle-approval-iva-for-light-trailers-help-to-get-a-pass

Honest answer is no experience of spun crankshaft, or 250 A, just changed a few crankpin/conrods and thats how I do it as thats how I was shown how to do it. I do know the production racing guys used to weld crank pins as it was a common problem to them but never had to do it myself on a trials bike. Happy to go with Feetupfuns comment an experienced guy would be able to tell if it was still tight enough from experience. A point to note here and I stand to be corrected but the DTI / clock shouldnt go on the weight it should be placed on the bearing journal as that is the bit that needs to be true and by putting it on the weight you are relying on the journal and weight diameters being concentric to each other (which in theory they should be but...) Just another point in passing ,this is why when stripping or rebuilding engines of this design its bad practice to tighten the flywheels by putting a spanner on the nut at the other end of the crank to hold it. Good luck.

Not difficult to do just hold it in the palm of your hand by the weights and hit the appropriate weight with a copper hammer of a normal size. You dont have to hit them that hard to move them. Occasinally they become "stretched" and need springing a little in a vise or similar at the opposite side to the crank pin to get the last little bit in that plane. A little patience goes a long way.

The Jets I cant help with but the little mesh (gauze) thing I can. Its role in life is to hold a little bead of fuel under the hole in the main jet in negative gravity situations with large throttle openings (like jumps etc ) when the fuel in the float bowl moves to the top of the float chamber. Without it on a momentary loss of power can take place as the jet will draw air up instead of fuel, similar role to the large brass washer with the 4 holes in you see on Mikuni,and similar, main jets. I know it sounds a bit made up but its true.

I seem to remember the second "bung" was actually the tap and regulated the flow onto the chain?

So to put a different perspective on it. If you guys had ridden in Scotland you would have to change wheel bearings during the week? Wouldn't expect to (and generally didn't ) fit new bearings in a new bike for at least 12 months if it was ridden every week. Never owned a Honda but was always lead to believe reliability was their thing.

What happens if you try and compress it without the top cap on at all?

Scarborough motor club, Job done, http://scarboroughdmc.co.uk

Easy enough to fit a new sleeve if you can get one just put the barrel in a domestic oven cook for 1/2 hour as high as it goes and old sleeve will fall out, drop new one in and position while still hot.You will need to then get it bored though as they didnt come finished to size.Done a few a long time ago.

I would go with Diggers advice try something like Champion N21(assuming its a long reach plug) or equivalent. If it runs how you want it to now why start changing the carburation and other things?Often on kids bikes they dont get any real hard work to do so the natural cleaning process never takes place then you end up with a black sooty plug that doesnt work.

The basic configuration regarding wheelbase minimum track width and engine position originally comes from the old Austin 7 they are the same size believe it or not.1650cc max must be from a road going car although just about anything goes regarding mods.Greychapel is on the money with the gear box ,to get the reduction, bottom about 25:1 through to around 14:1. Ballast? we will pass on that one! Regarding the "odd" lines its sometimes preferred to go at a slight angle to get the weight on the low wheel so the high wheel can be prevented from spinning with the fiddle brake, one for each of the rear wheels, the foot brake generally only operates the fronts. Trials "riders" generally cross over pretty well. If you fancy a go put the date in your diary 20/10/18 in Oxfordshire. But be warned you may just get hooked! http://btrda.com/championship/sporting-trials/

Its a while since I have done points but the bit your interested in is when the points initially open as thats when the spark occurs remember changing the amount they open will also alter the timing slightly.Sorry cant help with the numbers though.

Stihl (the chainsaw people) make a nice no spill fuel spout that works really well when you press it on top of the tank the fuel flows as soon as you lift off it stops ,might be worth a look?

SP8 (Speight) Engineering) Pocklington done some ally for me and hes into bikes and stuff.

As the saying goes what people need and what people want are often not the same thing if a standard 250 was good enough for James Lampkin in this years scottish ,not forgetting he has been runner up in the past, why wouldnt a 250 be good enough for you? But if you want the pleasure of riding the best bike money can buy regardless go for the factory every time!

Had a few rev 3s one of which bought second hand after it had done SSDT rode it most weekends for about 2 1/2 years never had the barrel off! The trick as with any trials bike is to keep the air filter proper clean. They can suffer from noisy main bearings which you will be able to hear easy enough,check the alloy brackets that support the rear mudguard and air box aren't bent or cracked as they were quite expensive, and the chain can sometimes rub on the rear brake pedal causing it to become thin and the end drop off. Other than that what you see is what you get,in its day probably one of the most robust bikes on the market the Achilles heel being the ignition tended to fail on occasions resulting in a new or repaired stator being required and the water pump housing as you have mentioned. Sorry cant guide you on the price.

Scarborough motor club would be a good place to start , especially living at / near Helmsley I think Hull auto also run conducted trials alongside the main event. Often in the Rosedale area http://www.scarboroughdmc.co.uk/