thedktor

A friend dropped off a TY80 for me to repair, and has since bought another bike for his lad and given me unlimited use of the TY until I can buy it off him. Nice. The bike had hundreds spent on it, including a full engine rebuild, so is in great shape mechanically. But suffers from a gear-change problem

. Lookin at a friend

Some challenges then for you Wayne, keep us posted how you get on. I owe you guys an update on my Mont 349 rebuild, which is going painfully slowly unfortunately! - Steve

Some interesting colour schemes! Nice bikes though, thanks for sharing. Steve

Ridiculous!!

Here's a pic of my 1980 349: Different cable mount position, hence your cable too long.

Interestingly my 349 was completely rattle free before I stripped it down to find the whole engine badly corroded! To be fair the piston looks unworn, but the point to make is that a 349 in "normal" condition should not really rattle should it? Unfortunately taking the barrel off is not as easy as some bikes due to recessed bolts... but there is a post of my experiences (and advice) if you decide to open her up. Steve

Wow great job! Been away from the forum for a while but am about to start reassembling my 349 - it won't be anywhere near as nice as yours as I have no money currently.... but will get it mechanically good. - Steve

Think I posted having problems getting one of the gearbox bearings out, in a blind hole. The bearing is conical, and a small amount of leverage popped out the balls and carrier leaving a conical internal surface and no space behind to get anything substantial in to grip: So I ended up grinding it out (no damage to the case

OK, thanks - that was kinda my thoughts as well. I did indeed make careful notes of the shims, but because I'm fitting the shafts into a different engine some adjustments will be needed I think. Steve

Thanks Stork, points noted! - Steve

Gearbox Shims on a Mont 349

Thanks for the feedback on the gaskets.... Think I will go for the dry option for the centre - I will do some dummy runs anway just to be confident all is ok before clamping it all up properly. Steve

Thanks Stork, and I guess its going to be a try-it-and-see exercise regarding the pin weight, but should be ok on a slow revving trials bike eh. Yes, I have rebuilt a few engines (though not quite to the depth of this one!) and am very careful about preparing sealing surfaces. Question though

Good news! kevinbreedonracing.co.uk couldn

Nice one Steve - I have been following your story with interest as I battle away with my 349 rebuild! (I will of course post progress) - Steve C

Good tip!

Good info thanks Stork. The engineering company who cleaned up my original crank were going to put a sleeve on themselves, after reducing the shaft diameter, and then grind it down to original spec. But they only needed to take a small amount off in the end so left it as is. The new seals sit on there good and tight so I'm happy. Steve

Wow you guys have come up with some great leads, thank you. Er, no, it was sat in the previous owner's (dry) shed for ten years, and I guess the temperature cycling over the years led to condensation build-up. A lesson to be learnt...... -Steve

Is the crank seal area corroded and damaged? Here are a couple of pics from my spare engine (a 349)

. Bore and piston is OK on the 349 but the piston pin has suffered from the same internal corrosion that wrecked many other parts (I already have a rod and big-end kit to fit). I can get a new piston, with a pin, for the oh-so modest sum of

Well, of course I have already removed the infamous primary gear to be able to examine the crank

Wow Ian you are a mine of useful information! A call to Dave Renhams/InMotion (not the engineering company) confirm they sent the wrong ones out

Got loads of parts for the engine rebuild, and have a question about the crank seals. Where the crank bearings sit the shaft diameter is 25mm, and where the seals contact its slightly less, around 24.95mm, presumably to allow the bearing to slide on easier. The seal areas have now been ground down to 24.85mm The original seals were double-lipped (ie two opposite facing lips, with springs), and 25mm internal diameter. The new seals are single lipped and 24mm internal diameter

My Montesa rebuild has been on hold for a while but ready to start again now. I took the crank to a local engineering firm who ground down the crank and all is well again! They only took off .1mm, which according to them is well within tolerance of the seal, and I would have to agree. Well, see my next post, need some opinions on this! Steve