john b Posted December 7, 2010 Report Share Posted December 7, 2010 (edited) I have a Montesa 172 with Gearbox selection problems. Will go into first, but will not change up ? I've done as much as I can think of to repair (and I'm fairly mechanically minded) to no avail. The bike is in really good condition and a shame just to leave standing. A couple of options I can think of....... 1 - Does anyone know of a business or individual (preferable in the North East of England so I could take the whole bike along) who could repair ?? 2 - Engine swap ? Thought of TY175, or even TL125 (CG 125 etc) - Any opinions (or even any suitable engines anyone has lying about they may want to sell !!) ?? cheers and thanks in advance for any advice cheers John Edited December 7, 2010 by John B Quote Link to comment Share on other sites More sharing options...
woody Posted December 7, 2010 Report Share Posted December 7, 2010 You don't say what you have checked - so have you checked the selector pawls. Assuming it is the same design as other Monts, I've never had a 172, there are two, one for selecting upwards, one for downwards. If the edge is chipped off the pawl that selects upwards it won't engage with the selector drum and you won't be able to change up. It's a fairly normal Montesa problem, usually happens by clattering the gear lever on something like a rock or tree stump, forcing it upwards which breaks the end off the pawl. You can still change down as the other pawl is unaffected. It's easy enough to check and just involves removing the clutch cover. This gives access to the selector mechanism and from memory (I think this is right, as it's been a long time since I used to do this regularly on a MH349...) removing the 4 screws and the cover accesses the pawls. It will be fairly obvious if the end is chipped as it should have a sharp edge shaped like a chisel. Worth a look if you haven't already. Quote Link to comment Share on other sites More sharing options...
belldane Posted December 8, 2010 Report Share Posted December 8, 2010 The 172's did not have the pawl set up as other Montys. The gear lever is connected to a shaft that goes though both cases and from memory there are a set of teeth that obviously engage to another set of teeth to make changing gears possible. I have a 172 motor under my bench and I can have a look if you like but I think your problem may be those teeth not engaging properly or an internal problem and you will need to split the cases. Vintage Cota. What do you reckon ? Hope this helps Manuel Quote Link to comment Share on other sites More sharing options...
vintagecota Posted December 8, 2010 Report Share Posted December 8, 2010 (edited) The 172's did not have the pawl set up as other Montys. The gear lever is connected to a shaft that goes though both cases and from memory there are a set of teeth that obviously engage to another set of teeth to make changing gears possible. I have a 172 motor under my bench and I can have a look if you like but I think your problem may be those teeth not engaging properly or an internal problem and you will need to split the cases. Vintage Cota. What do you reckon ? Hope this helps Manuel They do have the pawl system. The lever comes through to the other side and has a rack pivoting on it, then there's a pinion to turn the shift drum. The pinion comes off, then there's 3 screws holding on a cover over the shift drum. The pawls and spring are under that cover. Edited December 8, 2010 by vintageCota Quote Link to comment Share on other sites More sharing options...
jon v8 Posted December 8, 2010 Report Share Posted December 8, 2010 I have a Montesa 172 with Gearbox selection problems. Will go into first, but will not change up ? I've done as much as I can think of to repair (and I'm fairly mechanically minded) to no avail. The bike is in really good condition and a shame just to leave standing. A couple of options I can think of....... 1 - Does anyone know of a business or individual (preferable in the North East of England so I could take the whole bike along) who could repair ?? 2 - Engine swap ? Thought of TY175, or even TL125 (CG 125 etc) - Any opinions (or even any suitable engines anyone has lying about they may want to sell !!) ?? cheers and thanks in advance for any advice cheers John Why not go to a trial and ask the riders who they use,in our club there are several people who fix others bikes and are well known and respected for it.I'd be suprised if there was no one in you club that does the same. Quote Link to comment Share on other sites More sharing options...
belldane Posted December 8, 2010 Report Share Posted December 8, 2010 Ok Vintage I stand corrected but it has been a while since tinkered around with the 172 motor. Nice bike to ride it was until it was stolen about 7 years ago Manuel Quote Link to comment Share on other sites More sharing options...
john b Posted December 8, 2010 Author Report Share Posted December 8, 2010 Thanks guys I have checked the selector mechanism previously, did seem ok to me but I'll follow through your suggestions. I do trials regularly and there are a few people who are more mechanically minded than others. I haven't really asked yet, but now the Montesa has got to the top of the project pile (after the TL, and the most recent TY80 now ready and sent to Santa for xmas !)I might have to actively ask around, I just hoped from the post that there was the off chance that someone may have been able to help (and earn a bit of pocket money!!). It does seem a shame to junk the engine, it's on standard bore, I put new rings in and it runs sweet - just the gearchange !!!! cheers and thanks again John Quote Link to comment Share on other sites More sharing options...
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