Looks like M-80, upright center post (air box srews to top), one peice swing arm (not like 199 etc) slimline tank/seat unit etc, just seems like its made from "decent tubing" and had no frame number on head stock or footrest mounts,
Hi, I am just wondering what material the M-80 frame is made from. Mine has no frame number and is very light although extremely hard.( could not stamp number on footrest mounting area but can pick up frame with little finger) some areas have been stripped to bare metal for several months and show no signs of even the slightest surface rust. I know later frames were chrome moly which is lighter but were there any after market or factory frames made around 1970-72 when the slimline was built?
Hi, I am about to put engine back together and was wondering, are the two alloy spacer washers needed between piston and con rod and if so, what do they do?
I got a new spindle from Billetparts, (site sponsors) not expensive and good quality. may be a good place to start. They are very helpfull. Maybe a post from someone there may help.
Cheers for that. I have contacts in several CNC companies that could skim or re sleeve for me. How do you secure sleeve to prevent slippage and what material would you recommend?
I believe correct ID is 140mm is that about right?
Thanks everyone, its definitely an M-80 and there does seem to be some signs of rust developing whilst it has been standing. I will try to post decent photo for clarification,
Hi, I have the rear wheel out of th bike and I have some questions about the brake hub. What is the correct internal Dia (Mine has a slight lip then is a chamfer to main braking surface, it measures 140mm on lip but I cannot get measurement beyond this as I only have a vernier not an internal Micrometer) Next what should the surface look like and is it a replacable liner or an integral part of the hub. If necessary can it be relined easily? Finally what thickness is the brake shoe when new so I can judge wether replacement is due?
I am rebuilding M-80 and before I stripped it down I rebuilt the Mk1 concentric and it started 1st or 2nd kick from cold. This was with a knackered piston and worn bore no air filter and an old plug. Something must be causing problem like poor jetting,blocked idle jet pulling air at cranks poor spark or timing. worth doing search on this forum for poor cold starting and see what comes up. Mine would only start after a 50 yard push before carb rebuild!
Cheers, Looks like a gasket and seal set from Bultaco UK, I may still use Hylomar as it is non setting and can be seperated and rejoined and retain its seal,
Hi, I am continuing with rebuild of M-80 engine and would like to know types, quantities and sizes of seals required when replacing both outer casings. There is also a fibre washer to fit behind clutch arm stem on casing (missing when stripped down) is it a standard size? When I reassemble is Blue Hylomar ok instead of paper gaskets?
Hi, continuing with top end rebuild of M-80, can any one help with info on head gasket. Haynes manual (original 1970's version) states NO head gasket fitted. However I remember fitting them many years ago. If they need a gasket what material and thickness is best suited?
Hi, Just had a look at the underside of the crank cases and I am not sure if they are 100% ok. On the gearbox drain plug side there is a ridge (crack?) that apears perfectly straight for about 1"then turns perfect 90 degrees and runs for another 1". In the center of cases ( where the casting has a hole running back up into it on about a 45 deg angle) there is a similar ride. Could they be casting marks or has something gone a bit wrong at some time. Photos of some in good condition would be appreciated,
Thanks guys, No specific problem but have chance of a haynes manual 1972 onwards and I was wondering how relevant info would be for my M-80 engine etc. also had offer of some engine spares so now I know what to watch out for
Hi, I checked clearance on sides of con rod to crank an they are 11-12 thou so presume it is within spec. I am now looking to order new piston/smallend kit from Bultaco UK so I can get engine back together. Any thing else that should be done before re assembly?
M-80 Frame
in Bultaco
Posted
Looks like M-80, upright center post (air box srews to top), one peice swing arm (not like 199 etc) slimline tank/seat unit etc, just seems like its made from "decent tubing" and had no frame number on head stock or footrest mounts,
Cheers,
myson