Sign in to follow this  

bridgestone mkII rs200 project

Recommended Posts

 7 years  ago i bought and rebuilt a mini buffalo

which turned out to have a bridgestone 60cc engine fitted (rotary valve 2 stroke single)

wtf  bridgestone as in the tyres guys??? yep.  duning the 60's and 70's they made and competed very sucessfully with motorbikes

read the history and demise of the bike division here


anyway its taken me 8 years to find another bridgeston.

ive now moved to scotland and managed to find a mkII rs  that had been imported from the states along with a bunch of rd350's  the guy who bought it over had no interest in it so sold it to me,


it was produced in december 1968. (1 of 7800 built) mk11 rs200

dual rotary valve induction, twin cylinder 2 stroke,








so the good bits are its pretty much complete,
its only done 2900 miles.  
paint is ok and has a cool patina
frame is in excellent condition

bad bits are, its been sitting for 40 odd years
its seized solid,
all the rubber bits are perished or missing front brake lever is busted,

my plan is to get it running, by doing as much of a rebuild that is necessary,
i wont be touching the paint,  as i dont want a show bike,
replace any missing bits, get it registered over here in scotland and ride it.

im guessing im going to need:
rings for both cylinders
top and bottom bearings,
new conrods, and new crank pins,
piston pins,
all new internal bearings
new chain and sprockets,
rubber carb boots (carb to airbox)
tanks rubber knee pads,
new tyres,
and probably a rebore/re-chome depending on barrel type

i'll post photos as things happen  (which may be a while, in the midst of moving house at the moment)

  • Like 6

Share this post

Link to post
Share on other sites

Wow, that is cool and rare. Parts might be an issue though?

Are they 100% Bridgestone or did they fleece someone else's engine to use in their frame? (like villiers 2 smokes being used in almost every British brand bike)

  • Like 1

Share this post

Link to post
Share on other sites

100% their own design. chrome bores were well ahead of the time, and having a rotary valve was pretty much revolutionary for the time,

kawasaki stole that design for its a1r race bike.


bridgestone took on lilacs engineers (another jap bike company)  when it went under, but they produced 4 strokes,  mostly v twins guzzi style.

Share this post

Link to post
Share on other sites

right, update time.
basically moved house so now have a garage and a place to work on the bike,  :D          
has been a bit of a mission getting settled in, but been worth it,

the garage

first off had to remove the carbs etc from the side of the engine,

all the wiring, hoses, foot rests seat tank etc, so i could unbolt the engine and pull it from the frame,

not a too hard of a job,

 the chain was stuck pretty solid to the front sprocket

next up was to pull the heads which was super easy,

next was barrels.

 not so easy. managed to pull the right hand one no bother, the rings and piston were in pretty good nick, and if it was cast iron bores i'd have been happy with the barrel as well,

the left hand cylinder wasn't going anywhere, so left it for a time until i could get to the nut on the crankshaft and try and brute force it out.

pull the clutch side case,  a combo of black sludge and water came out to reval the mess that is the clutch,
all new friction and steel plates are going to be needed

pulled the basket and all the associated cogs etc, a bit of rust on some, but easily save-able.  then into the rotary valve,

everything is nicely marked so you can't really cock up the timing if you pay a wee bit of attention

rinse and repeat on the oil pump side.
you probably noticed the alternator is out,  that fucker is also seized solid and will also need new bearings.

yep much the same

so that pretty much it. i did get the other piston out.  piston is pretty much done for, and rings are poked, but i sort of thought it was always going to be the case.

crank is feeling really good, so hopefully i dont have to spend $800 usd on a new crankshaft,  its probably going to cost me around that for all the bearings, pistons, rings, seals, gaskets, etc etc

tomorrow night hopefully split the cases....
may be

  • Like 3

Share this post

Link to post
Share on other sites

rotary valve reminds me of wankel spec, can you bridgeport?  :-)


I have been reading up on rotary valve, they sound ideal but limiting with engine size due to carb location.


Awesome progress. Carry on. 

Share this post

Link to post
Share on other sites

yeah, pretty good idea, my vespa has a similar idea, but instead of using a disk it uses a notch cut out of the crank itself,

which obviously is a bit more of an issue to change,


you could possiby use a down draft carb and do a little sweeping curve to feed the port. 

obviously these days if you were going to make a 2 stroke you'd just fuel inject it.

  • Like 1

Share this post

Link to post
Share on other sites

well all tell and no show for this post.
pics in the next post.....

anyway, split the crank cases,  and the news is pretty damn good.
all 3 crank bearings are in good nick with no play, the conrods and bottom end bearings are good,  all the gearbox and bearings are good.
only the selector forks and the selector barrel are stuck at the moment.

even the center seal is good, (was my secret dread, all good bearings but fucked seal, which would have meant spliting the crank.)

so thankfully that'll all save me around £500-600
ill still have to spend around 250quid a side on barrel re-plating, pistons, rings and top end bearings, plus another 100 on intake rubbers
plus another 100 on clutch parts. and atleast another 100 on gaskets seals and other random bits,   

get a vintage 2 stroke they said, cheap fun ... aha :D

  • Like 1

Share this post

Link to post
Share on other sites

Well Suzuki are the cheapest I have discovered of Suzuki, Yamaha and Kawasaki. I'm getting new intake rubbers outta Japan for my GT185 and they $15 nz each. You did pick one of the rarest.

  • Like 1

Share this post

Link to post
Share on other sites

right where was i.
so cases got split,


 crank got pulled,

and onto the gearbox,



the selector dogs had partially welded themselves to the selector shaft and i couldn't free it to pull the shaft free,
but with a combo of blow torch and almost a can of penetrating spray and a few dozen taps from a hammer i managed to get all the dogs moving.
so the shaft came out,
and with a bit of wet and dry and oil i cleaned up the shaft to a nice smoothish and more importantly re-useable condition.

i found this bit of metal in the bottom of the gearbox...

oh so it looks like i have to buy a dog, not to worry, first broken thing ive found,

gearbox bearing are a bit notchy so i'll replace them, and have decide to replace to 2 outer crank bearings as well,  just because.

cases are off to a mate to get sonic cleaned, and get rid of the 40 year old shite on them.

next up, carbs and alternator, then to spend a stupid amount of money on almost impossible to find parts


Share this post

Link to post
Share on other sites

Well Suzuki are the cheapest I have discovered of Suzuki, Yamaha and Kawasaki. I'm getting new intake rubbers outta Japan for my GT185 and they $15 nz each. You did pick one of the rarest.


yep. no mew old stock available, thakfully richard from bridgestone motorcycles in the states got reproduction ones made a full set for both sides

crank case rubber and airbox/filter to crankcase is  $160 usd  so not bloody cheap.  but available non the less

Share this post

Link to post
Share on other sites

ok finally got a decent internet conncetion in the new house so i can upload some photos and what not


carbs was next

 40years of petrol turns into this....  yum






so those and the crankcases went along to my mate with a new ultra sonic cleaner..

most of the stuff is done being unltra sonicly cleaned,
i think im going to have to buy one, bloody awesome.

crank cases.

and carbs.

the floats need a bit of work, as they were floating  :lol:  and couldnt be done properly.
not sure why my mate dint just weigh them down, but im not going to look a gift horse in the mouth.

now its really time for the moths to hop out of my wallet,  and start ordering shit :D  :cry:

Share this post

Link to post
Share on other sites

ordered all the seals and bearings tonight.
im having trouble finding a shifter fork to replace the broken one,
i was hoping for a second hand part, but looks like im going to have to "fork" out for n.o.s. .... bugger,

so my list of bits to get are

* clutch basket /  steels and fibre plates  (£60-100)
* pistons, rings, pins and clips, (2 sets)  (£200)
* barrels, replated or replaced  (£130 per barrel to replate) (£160 for new barrel)
* tank rubber knee pads (£75)
* intake rubbers (£110)
* gasket set (£90)
* brake lever (£15)
* brake shoes (£ unobtainable!! )
* gear change dog (£unknown )
* carb rebuild kit (£ unknown)
* alternator (£100)

so atleast £1k to spend :(

first up will be to get the engine internals. as they will hold up any sort of progress,  and i'd like to get the bottom end back together, whilst i still remember where shit goes

Share this post

Link to post
Share on other sites

most parts have been ordered, it pretty great expense out of the states
the mrs even noticed the drop in the bank account, which she doesnt normally notice.  bugger.  but she just got a new car so i didnt really get in trouble ;) just a stern look :D

ive decided im going to have to rebuild the alternator, after finding out the price on a replacement item, (more than the price i paid for the bike) ive managed to get the cam that opens the points,  so i'll have to free the old ones off, and replace the bearings,

barrels were sent off to to get ceramic plated.

here is the left hand barrel,  it had the rings stuck to the bore,
and required a stupid amount of effort to free them from the piston.
you can see the chrome chipping off at the top, and faintly see the mark just above the transfer?? port where the rings were stuck

next up is the right hand cylinder, which is actually in pretty good shape, and if the left had been like this i wouldnt have sent them off to get ceramic plated.

so thats the befores,  ill update on the afters

Share this post

Link to post
Share on other sites

right been a while.
lots of waiting when parts have to come from the other side of the world,

any way first to arrive was my new shift drum and selector dogs.
i had to buy a whole set to get one dog.  but thats the way it goes
sitting nicely in their new home

next up was cleaning the gear box, removing and replacing all the bearings,
thankfully simply bearings in the uk had every thing i needed in stock,

most of the bits i need arrived from richards relics in the U.S,
the new intake to airbox rubbers and chrome joiner

the new pistons, rings, pins, small end bearings, and circlips


gasket set

and brake shoes

and a funky little key ring ;)

also a new cam lobe for the points inside the alternator/generator

still waiting on to return my barrels,
they were remarkably quick to take my money, but refuse to return an email,  i guess ill have to suck it and see

but the good news is i can atleast rebuild the bottom end back up.


  • Like 4

Share this post

Link to post
Share on other sites

i had to shoot to new zealand for my grandads funeral
had his last ride in his faithful 55 morris
(had it since new)


when i got back my barrels were waiting,



even champhered the ports for me, which was nice

they are like brand new, pretty impressed, with the results... not so much with the service though.

also the new clutch metals and fibres had turned up,

along with new points and condensers.

and a cool little tool box cover lid which i was missing. they fall into the unobtainium category of rare metals,  but managed to find a brand new one in the correct colour :D

so thats where i stand now,
i pretty much have everything i need now to finish the engine,
just a couple of carb kits, and a couple of bearings for the generator to fit,

and a few days she should be back together,  time permitting


Share this post

Link to post
Share on other sites


and a few days she should be back together,  time permitting



ah ha,  well that didnt work out to plan,  almost a year since touching the bike.


to be fair, ive had 4 different bikes stolen,  done 2 top end rebuilds on my own bikes,  done a full rebuild to a tdm 850, and another to a ktm990 (dont ever buy one of them, bastards to work on :D )

fitted double glazing to the house, cut down a dozen trees on the property,

helped convert a bus to a motorhome, started a new job,  missioned about france and belgium in the campervan,

rebuilt my old 1970s swiss made revox amplifier,

plasterboarded all of the upstairs and painted, re-wired most of the house, 


yeah i know, excuses excuses :D

anyway house is looking ok, untill a building warrant comes through for the extension down stairs, so i have some time on my hands.



so i was back to bolting the 2 parts of the bottom end back together,  but thought id go over it all just in case i missed something a year ago, 


just as well as id missed a spring that activates the "highway gear" selector  (basically lets it go from 4th back into neural, or allows it to shift into 5th and stops it going into neutral)    pretty cool idea,




and also forgot 2 split pins on the selector forks, that keep the pins in place and keep it located on the selector drum,


of course like a retard, i didnt have a single split pin any where,  so that made short work of my evenings work on the bike,


hopefully work on this will pick up, and ill have it finished before,...  before sometime :D

  • Like 1

Share this post

Link to post
Share on other sites

after fitting the spring and split pins, refitted all the bits and bobs, you know cogs and all that manly shit



 then got the 2 halves of the crankcase together,

pretty painless,  



then went about popping the right side rotary valve and cover,

and what no in prep of the clutch going on,


made a very advanced clutch plate soaking device,

made fully from recycled materials,  im upto date and very green in my ways.

i give you mince tray clutch plate soaker




the name could do with some work, but you must admit its very effective.


och the joys of cork clutch plates.


put the clutch together, lined up the crank sprocket,

was quite pleased with myself until i noticed another gear....



bugger it,



wont go on unless i remove the clutch and what not,

of course i can't undo the clutch because it just spins, and i dare not use the 4mm clutch bolts to make a holder in case i brake something,


so, have to bring the rattle gun home from work tommow,





  • Like 2

Share this post

Link to post
Share on other sites

ok clutch off ,

idler bearings replaced,

and fitted all back together



next hiccup was i was missing a pin that the left hand side rotary valve needed to turn



old number 2 screwdriver to the rescue



the steel shaft on that screwdriver is bloody hard, ended up wrecking a new hacksaw blade cutting it




time for pistons and what not to be fitted


love the new old stock 60's era bearings,



barrel posts fitted


and barrels




i have to wait on 2 bearings and a seal turning up so i can finish the generator,

also went to fit the new points and condensers,  fucken points were the worng size,  but i managed to fit the new condensers,

and cleaned up the old points which turned out pretty good any way.


the generator is going to be the bit that holds me up,  along with random carb parts that are coming out of the states.


plenty of other shit to be doing i suppose,

  • Like 1

Share this post

Link to post
Share on other sites

right ive gone as far as i can on the motor until the seals and bearings arrive for the generator,

ill also have to wait until the bits from the states turn up to finish the carbs.



was looking for a new set of tyres,  and couldnt find any to fit made by bridgestone :D  funny shit.

  • Like 4

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this