woody

The tubliss system is designed for tubed type rims, I doubt it would work or even fit properly on a tubeless rim Hasn't your 175 got a tubeless rear wheel?

You are taking this subject much too seriously. There is absolutely no jealousy or intimidation on the part of anyone. Probably because English isn't your first language you have misunderstood the ironic humour in the comments. Irony is a big part of English humour (and I don't mean that as criticism as your English is very good) The works Hondas were developed for Honda in the UK, originally by Sammy Miller. Honda supported quite a few UK riders on the original 305 longstroke bikes and then the 305 and 360 shortstrokes, therefore there is a lot of knowledge here about these bikes from people who were involved with them and rode them. When Honda pulled out of trials in 1977 Honda UK took over and kept the UK team going with development support from Japan. It seems Honda got interested again and continued to develop the bike themselves which was now the 360 only. It was into the 80s before Japan completely ran the team again which was by now just two riders, Lejeune and Hattori Any number of 1970s bikes still survive and there were also replica frames made for the spare engines that had been provided, so there are a number of 'official' replicas with works engines too. In the 1980s and 90s, Honda's policy was to crush works bikes at the end of each season - hence comments on here about help from Honda - irony The shortstroke bikes date from '76. There were many variations on the bikes

If you search the Bultaco forum using the word 'packing' you'll find some previous topics on packing the exhaust with more useful info.

These are the jets on the PHBH 28BS that I have on my 340 and it runs very clean. Pilot 40 Main 98 Needle tube AV264 Needle X2 Slide 4.5 The early 250 and 325 bikes which used a 627 27mm Amal shared the same jetting, so although mine is a 28mm and on a 340, it won't be too far off for the 250 and a good starting point.

Pictures have now been deleted from the mx site

You need to understand the history of these bikes - I don't think Honda will be very helpful...

The frame is that used on the 250 models from 158 - 190. The 175 is essentially a sleeved down 238cc model 190 with the blue colour scheme. They were built primarily for the Spanish holiday resort hire market with big tank, dual seat etc. Some ended up over here in trials trim.

This is your model, although the frame is the wrong colour on this one it has the right mudguards fitted. There is only one blue and this is it http://www.ebay.co.uk/itm/RARE-BULTACO-175-SHERPA-TWIN-SHOCK-TRIAL-1495-ONO-PX-BETA-BSA-TRIUMPH-/200880595933?pt=UK_Motorcycles&hash=item2ec56aa3dd They are readily available on ebay although as someone has already mentioned Bultaco UK (also trade under In Motion) will have all you need. http://www.ebay.co.uk/itm/Trials-Plastic-Blue-Mudguards-Bultaco-Ossa-Montesa-Twinshock-Pre-65-/380547589499?pt=UK_Motorcycle_Parts&hash=item589a67657b

Modern filming style is wonderful isn't it. First pioneered by Top Gear years ago (before the current line-up of clowns) when they zoomed in and out, swapped camera angles, tilted the camera shots so many times that you never actually got a clear or complete view of the car they were "showing" you Sheffield must have been using one of their old camera crew. I found the minder cam so innovative and useful that I hit the off button after about 10 minutes - the bit where they switched from Fuji mid-section to show about 15 seconds of Dabill just sitting on his bike waiting his turn was particularly inspired direction too. Like watching paint dry.

I have a dellorto on my 340, when I next work on it I'll note the jetting and let you know. It should be close enough

At least you tried so the effort for doing that is appreciated Clashes by Nationals with club and centre events is and always has been inevitable and even more likely now with so many additional events on the calendar in comparison to 20 / 30 years ago. Can't be helped. The Greensmith Miller round usually clashes with the Lakes 2 day for example, so I don't get to ride the Greensmith too often. The Nostalgia usually clashed with another Miller round and my own club's 2 day club trial and we now have an excellent modern 2 day road based trial around the same period, so another potential clash. Just one of those things. But hopefully, next year, the national classic events can avoid each other to the benefit of all.

OK, well that's me out of ideas - if the rim hasn't given problems before, the rimlocks are the same as used by others, it can only leave the tyre

ok, just wondering as tubeless don't seat well on the DID.

I remember the diameter discussion but I've no idea how you would accurately measure the ID of a tyre. Is this the first tyre you've fitted to this bike - If the bike is relatively new to you are you sure it hasn't been fitted with a tubeless rim? I'm not implying that the tubed tyre can't slip, just trying to think of other possibilities.

With a tubed or tubeless tyre?

Oversize C15? A C15 is 67mm standard bore, but not sure about pin size, piston height etc. relative to the Cub Triumph 500 and 650 pistons will fit the C15, so maybe the C15 will fit the Cub?

You don't say which Fantic wheel it is. From the 303 model range to the K-Roo they had tubeless rims that looked just like tubes rims - a tubed tyre won't necessarily seat properly on one of those. Any model prior to the 303 range had tubed rims.

Which manual - genuine Bultaco or one of the Haynes / Clymer as the latter don't always necessarily get it right. If it is the wrong jet, maybe someone tried to richen it up to compensate for an air leak at some stage - worn crank seal, worn throttle slide, or maybe they just fitted the wrong jet. As for advantage, if everything on the engine is working as it should then no, there shouldn't be any advantage to fitting a larger than standard jet.

Possibly, many of the early bikes didn't have matching numbers whereas the later ones are more likely to, so yours could have come like that or it could be another engine fitted by someone. As they are so close, it's more likely it came like that. The story is that when the engines were bench tested, the better motors were put aside for the works riders which is why there were mis-matches. No idea if this is true or not but you'd think that from the first time that was done with each new model, none of the subsequent bikes could match unless they omitted a few numbers on the frames to get them back into matching sequence....

I don't, no. Most are holed because of the kickstart stop missing. It's the kickstart that does the damage if it goes all the way round and uses the fragile magnesium casing as a stop. The casing for that engine is hard to come by. It will repair ok with metal bond etc. but make sure you have the stop fitted.

Have fun getting the motor back in the frame..... I did... You may want to try fitting the frame around the motor before fitting any other parts to it. It's awkward because there is only one rear engine mount and the swingarm spindle goes through it. It was a bit of a wrestle as I remember. I use Barnett plates in my Ossa and Bultaco and they work very well. I tried them in the Jumbo but they made no noticeable difference (why I didn't mention them) which is what led me to believe that the main problem was the actuator mechanism rather than the clutch itself

Sorry, mis-read your previous post as the Jumbo you rode had the reed block assembly fitted, not blocked off with the plate. With the reed blocking plate fitted (therefore no reeds, it's either / or) it does flatten the power off a bit at the bottom end, but not much, but it will still pull like hell when opened up. With your engine completely rebuilt and with a reed fitted, I don't think you'll find it too linear. If you do you should have been world champion... As I said, mine had the extra weight and fully retarded timing and a carb that wasn't spot on tune - it still pulled any gear you wanted and I'm 17.5 stones (250lbs over there) Understand what you mean now with matching the cases - no, nothing like that was done, it was just stripped and everything rebuilt - honestly, it doesn't need anything, but if you can do that sort of thing, I guess it won't do any harm. I repacked the exhaust on mine too, middle and tail pipe as this makes a big difference to how smooth they run. And when they are packed properly they have a superb exhaust note. The clutch is heavy, even with the extra arm under the tank. If you try to lighten it by elongating the actuator in the casing I think you have the situation where the clutch doesn't fully disengage as the lengthened arm doesn't throw the plates out far enough. If you adjust it on the centre adjuster to eliminate the drag it will then slip. The clutch action and actual bite of the plates can be juddery as well although this seems to fluctuate from bike to bike (clutch is the same as 240/280 SWM) The actuator runs on 3 ball bearings and there are 3 different sizes, so it may be worth trying other cases with the larger (12mm) diameter balls. I also found that the actuator was rubbing on the casing which didn't help things, so I ground back some of the ribbing so that it didn't catch. It is possible to get them working to your liking, just takes a bit of time and trial and error. I also tried running 2 less springs but the motor has too much power and the clutch will slip if you're trying to fire it off the clutch in 4th gear up big climbs. Best get it working with all springs in. Best twinshock there is in my opinion (but there's another one I have never tried yet, so you never know...)

Hi Scot, a model 92, also 325cc, in good fettle puts out oceans of power, pulls like a train and breathes just fine through that airbox so I can't see any reason it won't work efficiently on your bike. As long as an airbox doesn't stop the engine getting the air it needs it will work. You should see how small a KT250 airbox is but they will rev their nuts off - contradicts all this stuff about large volume being required. It's only my personal opinion, but the flow of air being unrestricted is more important than fitting the largest volume airbox possible

Rob's bike is my old bike, it has a flywheel weight fitted, not weight taken off the flywheel, there is absolutely no point or need to take weight off the flywheel Are you sure it was a Jumbo you rode? As said before, in standard form the Jumbo motor is sharp and will lift the front wheel in 4th from tickover without even trying, they are very powerful. If it was a Jumbo, there was something wrong with it or it had been de-tuned somehow. Even with the flywheel weight and the timing on full retard mine would still pull from tickover in 4th up a steep bank - more than a 340 Sherpa is capable of.

What do you mean by matched the cases? What sort of difference are you looking for? The Jumbo is the most powerful air-cooled trials bike I've ridden. Mine had the reed cage fitted, most didn't. With a flywheel weight and the ignition fully retarded it still pulled like a train and I could easily shut right off and bring the power back on in 4th gear up steep banks. With the timing at normal setting and no flywheel weight, it was very agressive Biggest frustration was the clutch action.