metisse Posted November 24, 2014 Report Share Posted November 24, 2014 This subject was raised some some three years ago and to be fair opinions shared. Given the time frame I wondered if these we still valid. I have a red and white Guanaco with the mazocchi set up. Whilst its alright, they do tend to be very soft even after changing and playing with the springs. I have a nice pair of late betors including yokes / tete de fourche and my French guru is trying to convince me to go down this route. Some mentioned on the previous thread that all the works bikes had married the Mazocchi yokes to betor forks and I have since seen this recently on a very nicely prepared Belgium bike of Michel Gossiaux, again his name was mentioned in the previous posts. I understand there will be some machining to do, so the question really is, will the amount of work involved really merit any improvement. Thanks Quote Link to comment Share on other sites More sharing options...
b40rt Posted November 24, 2014 Report Share Posted November 24, 2014 Machining what, thought they were a straight swap ? You also need the mudguard brace, a new mudguard, and possible brake tie. Check the length, as Patrik pointed out, betors vary. Having said all that, I would also consider the various inserts you can get from HFS suspension etc. Quote Link to comment Share on other sites More sharing options...
metisse Posted November 24, 2014 Author Report Share Posted November 24, 2014 The betors are larger in diameter, so to use with existing yoke will require inlarging. I believe they came of a jumbo. I managed to secure the mudguard stay, spindle and brake arm, so hopefully that is the easy bit. Cheers Quote Link to comment Share on other sites More sharing options...
b40rt Posted November 24, 2014 Report Share Posted November 24, 2014 Not legal then in most trials as far as I'm aware. 38mm are only allowed if originally fitted, otherwise 35mm. Quote Link to comment Share on other sites More sharing options...
woody Posted November 24, 2014 Report Share Posted November 24, 2014 It's all subjective Hamish, I know, but I've always thought of Marzocchis as having a better action than the Betors. I've ridden SWMs, Fantics, Armstrongs and always thought the front forks better than my Bultacos, not a huge difference but noticeable. Maybe one thing to check on the Marzocchis is the fibre seal around the piston at the top of the damper rod. These can wear and / or go hard over time and they don't seal as they should. It's possible this may have happened in yours which allows the oil to flow outside of the piston rather than through the damper rod and this can reduce damping, making the forks soft. If you take the forks apart, then insert just the damper rod into the tube, there should be some resistance to pushing the rod assembly up the tube. On some I've had, if I put the rod into the tube and then turn the tube upside down the rod just slides down with no resistance. When I've replaced the fibre seal (I make my own out of PTFE card) the rod needs to be pushed due to the resistance of the new seal, it no longer just free-falls down the tube - this is all my theory of course but it must help the damping by reducing the amount of oil that can bypass the piston If I was having the yokes bored to take the 38mm forks, I'd want to be sure that it wouldn't affect the angle of the forks to the steering stem. As far as I know, the angle is built into the stanchion clamps, not the stem - ie: the stem is set at 90 degrees to the yokes but the stanchion clamps have (for argument's sake) say 2 degrees rake built in. If the clamps are just machined out to 38mm and are machined 'straight', you may lose the built in angle of the yokes and end up with parallel forks which would affect the steering. I'm assuming your engineer mate will know this (Stuart?) but worth considering Personal opinion again, but I think I'd persevere with the Marzocchis and see if there is a damping issue before going to the trouble of fitting the Betors. Incidentally, the 38mm forks were fitted to the last 240 SWMs as well as the 350 2 Quote Link to comment Share on other sites More sharing options...
woody Posted November 24, 2014 Report Share Posted November 24, 2014 Not legal then in most trials as far as I'm aware. 38mm are only allowed if originally fitted, otherwise 35mm. Don't forget Ross, Hamish is in France Incidentally, the 35mm measurement allows the use of upside down forks as they use 35mm stanchions....... Quote Link to comment Share on other sites More sharing options...
metisse Posted November 24, 2014 Author Report Share Posted November 24, 2014 Thanks guys it would certainly make sense to stick with the original set up, if we could get them to work better. In all honesty I don t know the ruling here on forks , but as they are more than happy to let Rtl,s and mono yams run with the twin shocks I doubt the changing of forks will raise any eyebrows. The man who has done this on his Gunaco is with us this weekend in Spain, so I will pick his brains as well. If I learn anything of interest I will share next week. Thanks again Quote Link to comment Share on other sites More sharing options...
pschrauber Posted November 24, 2014 Report Share Posted November 24, 2014 Mmmh, there is now big advantage in fork action between the Marzocchie and the 35mm Betor. My bike had Marzocchis mounted and they worked pretty well, still felt a little bet more spongy and have more stiction then the Betors when they were sealed with one oil seal on each leg. The main advantage is that the Betors are shorter then the Marzocchies so this will let to a steeper steering angle and shorter overrun. The effect is better turning and less pushing out of the curve, ( if they are mounted to the Marzocchi yokes ). This will not happen if you mount the Betor yokes as I measured out there attachment points to the fork are lower thus compensating the less long Betor legs. Otherwise as Woody stated as long as the guiding bushes of the Marzocchie are not worn out not much difference, I personal believe the Marzocchies mounted to my TL.NW are a tiny little bit less good in damping (forks are rebuild and proper oil was used) then the Betors. I think if you use the yokes of the newer SWM with the 38mm fokes there will be not much change. You can check out the difference by lowering the clamps fastening of the Mazocchies around 20mm, if you then feel an advantage go for it if not you might let it as it is. Quote Link to comment Share on other sites More sharing options...
b40rt Posted November 24, 2014 Report Share Posted November 24, 2014 (edited) Get a pair of Piaoli's, still 35mm and better than betor or marzocci, in my opinion. See your entered in the Pre80 next weekend, would you still be able to do that ? Edited November 24, 2014 by b40rt Quote Link to comment Share on other sites More sharing options...
pschrauber Posted November 24, 2014 Report Share Posted November 24, 2014 Piaoli's work great and as B40RT stated are legal, the 38mm would be unacceptable for our classic trials if grandfathering isn't involved. Quote Link to comment Share on other sites More sharing options...
metisse Posted November 24, 2014 Author Report Share Posted November 24, 2014 I am riding with the bike as is at the moment, in all honesty its fine, I have never been that good at developement. Some people jump on a bike and straight away the foot pegs are too high too low, the suspension is too hard too soft.. I just ride whats under me.... excuse the pun....thats not to say that I also like the bike to be as good as possible hence the post... Changing the subject there are 300 odd riders next weekend at Sant Feliu, nearly sixty pre 65's, its getting to be 'the' Spanish trial to do ... The site is exceptional with the last sections on the beach on the breakwaters, one wrong turn or a dodgy dab and your five metres into the Med...I have my techy man as a minder so I will try and post some pictures next week. Thanks for all your help. Quote Link to comment Share on other sites More sharing options...
iconic558 Posted November 24, 2014 Report Share Posted November 24, 2014 As an aside is it possible to get parts for these old zokes and betors such as bushings etc? Quote Link to comment Share on other sites More sharing options...
woody Posted November 26, 2014 Report Share Posted November 26, 2014 I wouldn't even know where to start looking for those. The pistons / bush have a fibre sealing ring around them and after 30 - 40 years they can be worn out so they don't seal as effectively any more. Early 70s Betors don't even have the fibre ring, just a plain piston / bush. You can make new ones from PTFE card which is on ebay. Use the old fibre ring as a pattern and to get the thickness of card required, then cut new strips with a blade. I'm no engineer but I've done it ok, just a bit fiddly Quote Link to comment Share on other sites More sharing options...
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