March 9, 200719 yr after some investigation it seems that not all Jumbo's have a Reed Valve engine, rather than the 280 Disc Valve. However it seems that there is a No-Reed Valve version also. The Reed Valve Block was only fitted on bikes with engine serial number upto 178597, after that you got a blanking plate. Recent performance comparison's with my 280TL (currently in Gavin's tuning shop, ie my neighbours workshop) have got me lusting after a Reed Block, which are now not available from Rotax. It pulls well without, but is missing some of the 'rush' I'd expect and can be quite slow to get on the power (this is also probably due to the slooow action throttle). I need to do some further analysis, probably with the acquisition of a Reed Block....from somewhere. Also, have realised that I now live in one of the few places on the map that has as many SWMs as there are houses....
March 9, 200719 yr I saw at Malvern some of the twinshock scramblers were fitted with reed conversions, where they did not have them back in the day. May be your best route. PS Malc I have lusted afer some things in my time, but never a reed block. Edited March 9, 200719 yr by bo drinker
March 10, 200719 yr i normaly ride a 280 but my buddy has a 83 350 jumbo.that thing has almost as much power as my 290 sherco.it pulls hills in 3rd that my 280 only pulls in 2nd.guess what?no reeds in that motor...johnnyb
March 10, 200719 yr Hi Malcra I have a factory released document somewhwere which shows this reed removal modification being carried out - suposed to make em go better - will have a look thru my old suitcase over the weekend and see if I can send you a scan.. jumbostu
March 10, 200719 yr Author the parts manual seems to indicate that this was a factory mod, with only the early engines with the reed block in place. the bike does pull like a tractor, though it is not as 'snappy' as the 280. Some work on the carb and timing needed but will see how it runs tomorrow...
March 12, 200719 yr the parts manual seems to indicate that this was a factory mod, with only the early engines with the reed block in place. the bike does pull like a tractor, though it is not as 'snappy' as the 280. Some work on the carb and timing needed but will see how it runs tomorrow... Think it might make it unrideable Malc, I definitely have a new set of reeds if you want to try them....will need to check for the block though. Martin
March 13, 200719 yr I have a reed fitted on my Jumbo. Still not impressed by the power. Way less than I expected. I have an old article where it states that the blanked off reed was to reduce the throttle response. Modern tyres grip and we are used to case reed engines so it is not much of an issue. I would like to fit an electronic ignition to mine to reduce the flywheel weight. Martin do you know of one off a motocross or enduro bike that fits??
March 13, 200719 yr I have a reed fitted on my Jumbo. Still not impressed by the power. Way less than I expected.I have an old article where it states that the blanked off reed was to reduce the throttle response. Modern tyres grip and we are used to case reed engines so it is not much of an issue. I would like to fit an electronic ignition to mine to reduce the flywheel weight. Martin do you know of one off a motocross or enduro bike that fits?? Matt The electronic ignitions fitted to the Enduro & MX SWM's are tiny in comparison to the trials units. They also work "inside out"...with the coils mounted on the inside of the flywheel case. Using one would make it run like a motocrosser. I think the later TXR Aprilias used an electronic ignition....perhaps Mr Seales may be able to confirm this .....however, you would need to check on the crank taper, as they do vary beteween models. Cheers Martin
March 15, 200719 yr Didn't they used the 175 Enduro piston for the conversion ? Think I recognise the section in the middle photo Motosinge.........is that Brokeback Mountain ???? Martin
March 15, 200719 yr Hey Motosinge - I may well have it?!?!? Bought a Plastic tanked 200 SWM from a lad in Keighley a couple of years ago - will have to have a closer look at it. I also bought a "200" from a Paul Waugh back in 1982/3 tho at the time was told it was 175cc. Had a sound all of its own - pretty much like the one I have now. Any idea what size the upgraded carbs were?? jumbostu Edited March 15, 200719 yr by jumbostu
March 15, 200719 yr This unidentified rider was a regular but only went as far as no socks and slippers..? Preferred factory wear to sunscreen.. Motosinge83. Ah....those would be the "works" r2w trials slipper.....manufactured by Alpinestars, extensively tested in East Sussex, before being banned by both the ACU and FIM. There was an upside to the tale, and the Alpinestar "Brindleys" are now common place in the Bolshoi ballet Sorry Motosinge, cant make Brokeback this Sunday.....Mothers Day Ciao Martin
March 16, 200719 yr The lovely Lisa on the SSDT 200 SWM. Motosinge...........I'm told by friends in low places, that you knew Lisa "quite well" Cheers Martin
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