jon v8

Sorry if this is a bit off topic... I'm in the middle of a build,not really even a trials bike,its an ex Army B40 frame with a B44 round barrel motor. I'm using four bolt forks and a 6" conical BSA/Triumph front hub.All shiny and smart, except brake shoes are rocking horse poo. Mark Cook of CCM Britain or PES apparently made some new billet ones which I'd like to buy.Been calling on the phone,leaving messages and have emailed as well.No response... Any suggestions, the parts are stacking up and it's close to me needing to nail it all together.The idea is a trail bike or long distance trials nail.

Domino on my bikes,not cheap but so comfy to use...

Those tank seat units were sold by Sammy Miller products. They were very good until Ethanol was added to petrol,completely wrecked mine. a shame because it was signed by Mick Andrews.

I don't know anyone in Oz that does that kind of stuff, but here in the UK its easy. I needed a set of yokes for my BSA a couple of years back and got them made to exactly my specs by Gerry Minshall who also runs the Kia Twinshock series here. http://www.twinshockchampionship.org.uk/

Model 80 makes a good point,I recently bought a piston off Ebay from a seller in Texas, I had to pay £66 to Parcelfarce for handling and customs costs. Same deal when I buy parts from the US for my Chevy pickup, it can almost double the cost of the parts...

If the main thing is reliability, I'd suggest a 68 year old rigid 350 AJS. Not touched mine since the Talmag in Jan, filled it up with Aspen and oiled the chain - Rode the Cotswold Cups on Sunday,an all day thrash.Never missed a beat. Going to oil the chain and refill with fuel then ride the March Hare on April 8th. Thing is I've done a few trials on it since the Arbuthnot last September when I actually gave it a proper service,I spend the whole week with spanners,last thing I want is a bike that needs lots of maintenance.

Buy the spokes and nipples and do it yourself. Very satisfying thing to learn.

Thank you Tony, really glad you enjoyed it - That was the intention ! Also, we raised £515 for the Macmillan appeal,a tidy sum, we are really chuffed with it. Looking forward to getting the next one organised.

Our first charity trial is this Sunday at Star farm near Marshfield. It will be signposted off the A420 from the A46/A420 roundabout. All Pre65 classes and twinshock only. No mono's. The trial is in aid of the Macmillan appeal,11am start. There will be a burger van onsite, 4 laps of 10 sections with A,B and Gentlemens routes. Half the sections will be in a stream,the rest on the hillside next to it. Enter on the day,postcode for satnav is SN14 8LH. Please come and join us,its an excellent venue plenty of scope. look here for more detail; https://joncvsv8.wixsite.com/ashwicke

Your post really is a "How long is a piece of string" type question. Firstly what shape is the C15 in ? If its a tidy and running bike then it would be a shame to break it up into trials bike as you will end up not using most of it. There are plenty of C15 and B40's parts around, it would probably be better to build a bike from bits. It depends what level you want it end up at,there are some lovely ones around that ride very well and some that are heavy,horrible and don't steer,stop or go very well. The main bit is the engine,I think its generally accepted that the later roller bearing big end type engine is better. Mine has just been rebuilt by Rupert Ratio himself,(You need his books for any unit BSA) with a Triumph 5ta piston.(About 260cc now) It has Electrex World ignition and WD B40 gears. Thats it,all the rest of the engine is standard, it is lovely to use,as soft as could be,chuffing down to nothing and picking up crisply.A good spread of the first 3 gears and a jump to top as a road gear. You would struggle to find a nicer engine to use for a Pre65 trials bike. With the frame,you could use a Drayton or Otter, and there are others,all an improvement on the original.Forks again, plenty of choice,mine are the 4 bolt BSA/Triumph ones, not particularly good but better than the original setup. With the wheels I'd straight away go for a pair of Gerry Minshall hubs or Alan Whitton. Lighter and brakes that actually work. I guess its all about how much you want to spend or not. They can be very nice bikes.

I think it would help if you could post up some pictures of the bore and piston,along with measurements of ring gaps and piston to bore clearance etc. My old banger was built up with components from several boxes and just new rings and crank seals.The piston certainly didn't live with the barrel its in now from its past life. Rattles quite a bit, but goes VERY well,me and my kids thrash it around the woods with little care.But all the measurements were in the parish to start with. So all I'm saying is don't assume its worn out because it rattles a bit,from memory even Mick Andrews dismissed the noise from my TY at a training day my son used it for.

They are quite fetching,a bit tight when I first tried them,but have stretched a bit and are working well now.

25thou is not going to hurt. I think that was what the secondhand plug was gapped to on the engine I built out of boxes of junk a couple of years ago. It still starts second kick from cold after being left for a month,pulls like a train and screams its head off if you you need it.Its still on secondhand points,but does all I ask of it.I can't think that electronic ignition is going to need anything much different in terms of a plug gap.

No new works machinery or E bikes - Sounds good to me... It needs more rusty frames and old cr-p to get back to what it should be. Just my opinion of course.

I'd want to start off with a roller bearing big end to build a C15 engine with more output than standard. As B40 RT says the Rupert Ratio book is a bit of a must for any unit single owner. The author,(Dave Smith) is a top bloke and has loads of spares. You can contact him through his website; http://www.bsawdb40.com/Ratio-Rebuilds

Really? So you add your "Tuppence" and muddy the waters even more. The whole point of forums like this is to get individuals to relate their own experiences. There is no single correct answer, for instance you suggest using good fuel and oil - so what do you suggest IS good fuel and oil ? Maybe I'm missing something here ?

There is alot wrong with basic petrol now including the fact there is so much cr-p in it. For a long time I refused to believe that enthanol in petrol was having an effect.Then after a while I found the fuel cap on my old Yam was getting hard to unscrew, then the pilot jet was always blocking up. Next was the throttle sticking,followed closely by blistering of the fibreglass tank.Shame as is was signed by Mick Andrews... Small bits of the tank were breaking away inside and causing the problems,the tank is now an ornament. I've also had to repair Stihl chainsaws and strimmers where carb mount rubbers and fuel hoses have literally fallen apart when fuel was left in them over winter. Some bulk at the price of Aspen fuel,but for how much a trials bike uses I can't be bothered to worry about it.The plastic cans it comes in are completely clean inside,so once your bikes tank is clean there is no need to do any carb maintenance - more time to ride ! The fumes are much less toxic too,ask Network rail - H and S will let them use Wacker plates in tunnels when run on it.

Or you could use Aspen fuel which has a 5 year shelf life. No need to clean carb or drain at all then.

You need to get the Rupert Ratio books.

As Woody says a £160 rechrome from Philpotts is very good value,they did my AJS forks - very pleased with them. From what I understand people who have tried mono forks on a TY twinshock have often gone back to the originals. Magical springs have a good reputation,but even as standard they are a good fork.

Nah, you got me wrong, I'm just a mostly happy weirdo that likes old things. Forgot to mention that cobwebs and dust are welcome in my workshop / mancave.

I must be a bit odd then cos it looks bloody awful to me. I think a man cave should have a lathe,milling machine,Mig, Tig and loads of other kit like a large press and Oxy/Acetylene torch. there needs to be a woodburner and somewhere comfy to sit. Music is nice too... And not forgetting the bikes,there needs to be plenty,British,Italian,Spanish and early Jap.

I've been trying to break a TY250 since about 2006, I have to say the bloody things are tough !

DK Off road have an old TY250 tank for sale at £140; https://www.ebay.co.uk/itm/1974-YAMAHA-TY-250-FUEL-PETROL-TANK-MOTOCROSS-TWINSHOCK-TRIALS-CLASS/253270709570?hash=item3af81c5542:g:t00AAOSwnTdaFEtI Having made aluminium petrol and oil tanks from scratch before,I'd happily pay £140...

Yep, 8mm or 5/16" in proper money.