I own a 2017 beta evo 125 2 t and now feel it needs more power I would like to know if it’s possible to buy a cylinder and piston from a 250cc or 300cc and put that on the engine or get it bored out and where I can get it bored thank you ...p.s. I live in bury manchester
I'm afraid not. The 125 has a shorter stroke so even if the bigger barrel fitted you'd be looking at a new crankshaft, plus carb and CDI unit, possibly flywheel and exhaust header too.
The message is, if you want a 250 or 300, buy one.
Yes, the Sherco has electronic ignition but since owning that I moved on to a 280 Scorpa, where it's possible to tweak the timing by moving the backplate. I run it a bit retarded for that soft, sloggy feel to suit old fashioned riding style.
I also ride a 247 Cota, the very one I bought new in the 70s. Interestingly the recommended timing figure for that model changed from 4.0 to 2.5 mm btdc at some point in the 1970s, though there were no apparent changes to the bike/motor itself.
I've always liked the adjustability and cheap repair options of points systems.
Advance means the spark occurs earlier, retard means it happens closer to tdc. So advancing the spark in terms of crank rotation means it happens at for example 10 degrees btdc, advancing further the spark could occur at 20 degrees btdc....retard the spark and you move back closer to tbc.
Yes, I know. 3.25 is advanced relative to 2.8. We covered that. My question was how advancing the timing would reduce running backwards, when it's over advance that causes it.
Advance timing for more pep, retard it for softer response, as copemech says.
I’ll mention a famous name... Miller, he told me that setting the timing at 3.25mm btdc would soften the engine performance and reduce any tendency to start up and run backwards...very embarrassing! Having spent a very long time on ‘t’ shop floor on the tools and then ended up teaching others about the suck,squeeze, bang, blow process et al. I have to say that with a two stroke that has no advance or retard map, mechanism, or vacuum device to alter timing as stated should produce a slightly softer engine as opposed to one set at 2.8 mm btdc. I used this setting on my 325 Sherpa and it was indeed softer or docile if you will, compared with another 325 that was very peppy and much easier to loft the front wheel....and it would start and run backwards...usually into a tree, with rider cursing vociferously! Timing on that beast was 2.8mm and I use these examples to help our man with his 250 Ossa Gripper. That timing was easy to remember ‘325’. I dare say our man with the Gripper will go with 2.7mm or there about. This concludes today’s sermon, ???
...but it's over-advance which induces a motor to run backwards, n'est-ce pas? So how come advancing it reduced such occurrences?
Fantics were the most common in catching out their unwary riders in my personal experience. You'd reach the head of a queue, release the clutch and cause mayhem behind.
The underside of the piston on any downward stroke will create a pressure in the crankcase. If this pressure cannot vent or escape it will find or make its own way out, such as blowing oil out of the main bearing seals, forcing oil seals out of their housings etc. So your breather pipe looks as though it was the issue here. Make sure all breathers are correctly routed and fitted to the correct inlet or outlet, check to make sure no breather pipes or connection points are blocked. Excess crankcase pressure can severely restrict engine performance.??
An article by one of my favourite authors on a topic related to your last sentence:
Fraid not, advance means to spark earlier ie 3.00mm btdc as opposed to 2mm btdc and retard spark later...closer to tdc?
I know. Your earlier message suggested the advanced setting (3.25mm. btdc) would give a softer response. It's the retarded setting which would do that. Hence, t'other way round.
Setting at 3mm btdc would not do any harm as a starting point, but the manufacturers specs must be around some where! Not too sure if your Gripper may have electronic ign. Fairly convinced it’ll be on contacts breakers so go with 2.8mm btdc for zappy pick up or 3.25mm btdc for a bit less go and a softer engine????
T'other way round. Advance the timing for more pep.
Cloburn 180 trials are running a Vertigo open day this Saturday. I had assumed this would be one the test days Vertigo set up from time to time but a phone enquiry revealed it's actually to try to move on their second-hand Vertigo stock, which seems to tie in with other comments in this thread.
I recall from personal experience that steering head angle was not exactly crucial on the first Beamishes, at least, as this was self adjusting as the gusset plates at the steering head buckled. As the dealer would say, "they all do that Sir".
Good for you. I was reunited with a 247 Cota which I bought new in the 70s after a gap in ownership of 34 years. Makes me feel as if I'm in my twenties again when I ride it.
The strange thing is that of 15 trials bikes I've owned, that is the only one I've ever seen again. Where do these bikes go? I guess by now almost all of the pre 65 stuff has been pulled out of barns to be sold at huge prices, but there must be hundreds of Bultos, Montesas and Ossas lying around somewhere. There aren't many in twinshock trials.
You could try contacting the Yorksbire Classic club, www.yorkshireclassictrials.co.uk, look through their classifieds, post an ad yourself asking for help or ask around at one of the many trials they run. They'll have loads of members with first hand experience of Greeves and other Villiers engines bikes.
As another option, it shouldn't be too difficult to source a suitable flat sprocket for a different bike, even if you have to re-drill it to match your bolt spacings, or have one made, and use a spacer between that and the hub. This was standard practice with the Ossa MAR which also used a dished sprocket.
I ride a 247 and find it to be fine for twinshock trials. I haven't ridden a 248 or 242 since they were introduced decades ago but don't think one of those would be any better for me. Big difference is that new and used spares are a lot easier to get hold of for the 247.
I remember him from my days of riding in South Yorkshire/East Midlands (late seventies), 348 mounted I think. He seemed old enough to be something of a veteran then, could be around 80 now?
I've ridden a Beta 4t and would recommend it for a beginner from a riding point of view, perhaps less so from the perspective of maintenance as, for example, removing the carb for routine cleaning out is a more complex task, then of course there's valves to keep adjusted. I ended up buying a Beta 125 for the simplicity and easy maintenance of a two stroke.
Suitable modern type footrests for the Cota are made by Raceline. I got mine from Motomerlin, just needed a touch of modification with a grinder to get them sitting horizontally or just above.
Fantic 200 sprocket
in Fantic
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