February 1, 20179 yr No doubt the Briggs and Stratton design can do a lot more than most people would give them credit. I think if I recall I have heard of custom setups getting around 9K to 9.5K from one. Where a standard configuration runs at maybe 3k to 3.6K it doesn't show its capacity... And just to be clear, I have never said they wouldn't work or are bad motors. In fact I think the design could work quite well, I am just not sure without an update of some kind they would be competitive at the upper levels of trials. When a stock 4RT can go above 8K (don't know the max), most 2T bikes will go over 11000, and if I am remembering correctly the WR250 motor produces max HP at something like 10K and is the same motor used in some of the old Scorpa trials bikes. It's hard to see a flat head design at the world level. I won't clam to be a mechanical engineer. (3 years of diesel and auto tech then going back to school to become a computer database engineer doesn't qualify... ) My 2 cents.
February 1, 20179 yr 12 hours ago, axulsuv said: When was the last time you went to a cart race ? The Tecumseh / Briggs boys , not the honda clone motors .... They get some evil power out of those engines , and with centrifugal Clutch's , Rpm is a big key ... I raced karts from 1976 to 1980 and again 1996 to 2003. In this country I think the classes for industrial engines were dropped around the late 60s. (Honda 4.5hp industrial engines are used for arrive-and-drive commercial circuits.)
February 1, 20179 yr 10 hours ago, jonnyc21 said: And just to be clear, I have never said they wouldn't work or are bad motors. Really I think we're both on the same wavelength. It may work, it may not. It's just that your glass is half-empty and mine is half-full.
February 1, 20179 yr I would agree, I would like to think I am optimistic it would/could work but I admit I am just not there. In a case like this I have to think how fun it would be to have a chance to ride a prototype like this, just so I could have the experience... but I suspect unless I am willing to build my own I suspect that will never happen.
February 10, 20179 yr On 31/01/2017 at 0:05 AM, trapezeartist said: Brilliant piece of lateral thinking. Modern instinct would naturally think of OHC, yet the side-valve is ideal for trials: light valve train, low engine height, low C of G, revability will be adequate, ditto compression ratio. What's not to like? If I had suggested a side valve engine I would have been accused of being a luddite. I reckon side valve would be ideal for 99% of riders but probably could not compete with OHV / OHC at highest level.
February 11, 20179 yr 8 hours ago, dadof2 said: If I had suggested a side valve engine I would have been accused of being a luddite. I reckon side valve would be ideal for 99% of riders but probably could not compete with OHV / OHC at highest level. That may or may not be true, whether you reckon it or not. But as you must realise 99% of riders wouldnt buy it.
February 11, 20179 yr 7 hours ago, nigel dabster said: But as you must realise 99% of riders wouldnt buy it. That may or may not be true. But if Tony Bou won a trial this weekend with a banana stuck in his left ear, we'd all have a banana in our ear next week.
February 12, 20179 yr 16 hours ago, trapezeartist said: That may or may not be true. But if Tony Bou won a trial this weekend with a banana stuck in his left ear, we'd all have a banana in our ear next week. ..maybe in somerset? I doubt the same would be true in Yorkshire. Joking apart if the above were true the 4rt would be the only bike ridden theyve been around ten years now and are still thin on the ground.
February 12, 20179 yr Countyist! Drifting off the subject slightly, but if world-class or even national results could show us the hierarchy of the "best for an expert" trials bikes, I still suspect that the hierarchy of the "best for a clubman" trials bikes might be very different.
February 14, 20179 yr On 12/02/2017 at 10:51 AM, trapezeartist said: Countyist! Drifting off the subject slightly, but if world-class or even national results could show us the hierarchy of the "best for an expert" trials bikes, I still suspect that the hierarchy of the "best for a clubman" trials bikes might be very different. Best for clubman? 250 or less
February 20, 20179 yr Author If a side valve engine would be any good, it would still be used in car, truck or motorcycle engines. Since it's not, it's safe to say it has some serious flaws.
February 20, 20179 yr 2 hours ago, guys said: If a side valve engine would be any good, it would still be used in car, truck or motorcycle engines. Since it's not, it's safe to say it has some serious flaws. Isn't that what the general public say about 2 strokes
February 20, 20179 yr That was my point writing off side valve due to not being in wide spread use is easily extended to writing off 2 strokes for the same reason. Trials engine desirable characteristics are a bit peculiar compared to everything on road. Although having said that desirable characteristics differ quite a bit for different skill levels.
March 3, 20179 yr 2 stoke use on road is in decline due to emissions laws. The side valve engine is not used because it has poor volumetric and scavenging characteristics particularly as revs increase. A side valve engine has very good low speed torque and a linear power curve, Laws in UK restrict car maximum on road speed to 70mph yet nearly every car on the road can exceed this by a large amount. If a manufacturer produced a side valve engined car it could be cheap and have excellent driving characteristics at all legal speeds but it probably would not sell because of the way in which most people perceive vehicles with a low maximum speed. Very frequently people buy what the perceive they need, not necessarily what would be best for their purpose.
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