Hi, I have just brought myself a 1973 rd250 which is currently fitted with a ds7 bottom end and 250 top. I will be rebuilding the original motor with a 350 top end soon before stripping the rest of the bike for a frame respray.
Looking forward to getting it on the road and scrounging this forum for information, ideas and parts.
New to the two stroke world.
Re: New to the two stroke world.
Welcome Danny.
One thing, and I will say I know nothing about the air cooled bikes, but with the later bikes we always remind people upgrading from 250 to 350 that they need to find the correct 350 oil pump if nothing else, ie 250 carbs and pipes will strangle a 350 at high revs but an oil pump can kill your motor stone dead.
Anyway, put up some pics, lets see what youre working with
One thing, and I will say I know nothing about the air cooled bikes, but with the later bikes we always remind people upgrading from 250 to 350 that they need to find the correct 350 oil pump if nothing else, ie 250 carbs and pipes will strangle a 350 at high revs but an oil pump can kill your motor stone dead.
Anyway, put up some pics, lets see what youre working with
Re: New to the two stroke world.
Welcome Danny!
Good advice from Jon.
Lots of knowledgeable people on here, and none of the interpersonal bullshit of other forums, it's pretty civilised here.
Good advice from Jon.
Lots of knowledgeable people on here, and none of the interpersonal bullshit of other forums, it's pretty civilised here.
Ex UK, now in Adelaide. LC250/350. DT175. Shed full of sh1t in the vague form of dismantled rusty RD’s and RZ’s.
Re: New to the two stroke world.
She is a bit rough. Once I get the frame cleaned up I will be building up to be more of a period racer style of bike with fairings.
I am sure the aircooled cranks are the same as the liquid cooled but what are the differences between those and the rz350 cranks? Or is the rz and rd350lc the same thing?
Currently considering a new crank from Murray West as rebuilding one of mine will likely end up more expensive.
Re: New to the two stroke world.
no all those cranks are all different, subtly. The RZ and LC are not the same thing at all in many many ways... maybe im just an aficionado lol
Do a bunch of research with anything like your crank, why not send the one you have to Link who is on here?
MWR... not my first pick, but some like him.
Do a bunch of research with anything like your crank, why not send the one you have to Link who is on here?
MWR... not my first pick, but some like him.
Re: New to the two stroke world.
There doesn't seem to be much around that I have been able to find so far that still specialises in two strokes but mwr came up pretty often. Weighing up the costs for the moment as my crank with new rods and bearings is looking to be around 600-700+ (300 in labour) compared to say 600 for a new crank.
I guess it depends where you get the parts from. If I had access to a press I would just do it myself.
I guess it depends where you get the parts from. If I had access to a press I would just do it myself.
Re: New to the two stroke world.
How proficient are you with mechanicals?
Easier to get a crank done by others surely.
I don’t know aircooled very well but the later 250 and 400 bikes are different stroke as well as bore, limited interchangeability I’d think.
Splined cranks in aircooled motors? Later bikes aren’t splined so I’d think more fiddly to true-up.
Main difference between LC and YPVS cranks is 1mm wider big ends in YPVS. Can be made to fit in an LC, but requires a little engineering which can be approached in different ways, bigger subject than viable here.
Aircooled 350 cranks I know nothing about.
I have heard of aircooled cranks being modded into later bikes, something to do with perceived/real benefit of splines.
Hang about on here and I’m sure someone with practical experience will chime in with useful info!
Easier to get a crank done by others surely.
I don’t know aircooled very well but the later 250 and 400 bikes are different stroke as well as bore, limited interchangeability I’d think.
Splined cranks in aircooled motors? Later bikes aren’t splined so I’d think more fiddly to true-up.
Main difference between LC and YPVS cranks is 1mm wider big ends in YPVS. Can be made to fit in an LC, but requires a little engineering which can be approached in different ways, bigger subject than viable here.
Aircooled 350 cranks I know nothing about.
I have heard of aircooled cranks being modded into later bikes, something to do with perceived/real benefit of splines.
Hang about on here and I’m sure someone with practical experience will chime in with useful info!
Ex UK, now in Adelaide. LC250/350. DT175. Shed full of sh1t in the vague form of dismantled rusty RD’s and RZ’s.
Re: New to the two stroke world.
Still trying to get my head around some of the newet models and the race models.
I just rebuilt the engine in my Sr400 which is now 427cc which was a lot of work with clearancing the piston and combustion chamber. I believe I should be able to tackle the simple two stroke mechanically but learning how to tune the ports will take me a bit.
There is a UK company that sells new 350lc cranks as well as the webs etc separate which I think uses a different flywheel and has electronic ignition but it would be nice to know that it will fit by someone who has done it.
I just rebuilt the engine in my Sr400 which is now 427cc which was a lot of work with clearancing the piston and combustion chamber. I believe I should be able to tackle the simple two stroke mechanically but learning how to tune the ports will take me a bit.
There is a UK company that sells new 350lc cranks as well as the webs etc separate which I think uses a different flywheel and has electronic ignition but it would be nice to know that it will fit by someone who has done it.
Re: New to the two stroke world.
Call Link and talk to him about your crank, hes done a bunch of cranks for me and my mates and is very helpful.
I have an XT500, so know what youve been up to, and the RDs are quite different to work on, but you'll get there for sure. Im not sure what you mean about tuning ports, thats not something these days we do, experts get you much better results than using a dremel and some files at home.
I dont know the parts you might need for your crank, but I just bought a Japanese made rebuild kit for an RZ for about $150.
I have an XT500, so know what youve been up to, and the RDs are quite different to work on, but you'll get there for sure. Im not sure what you mean about tuning ports, thats not something these days we do, experts get you much better results than using a dremel and some files at home.
I dont know the parts you might need for your crank, but I just bought a Japanese made rebuild kit for an RZ for about $150.
Re: New to the two stroke world.
Let us know how you get on with that kit Jon
Ex UK, now in Adelaide. LC250/350. DT175. Shed full of sh1t in the vague form of dismantled rusty RD’s and RZ’s.
Re: New to the two stroke world.
Its in, Link did it for me. Wont be run until some later build but looked good in the packet and Link didnt complain it was badly built. I recently had some awful Mitaka pistons recently, made in Taiwan, reminded me that if it doesnt say Made in Japan on the box then you can be right to be worried.
Re: New to the two stroke world.
I have just ordered the parts from PJME in the UK, was the most reasonable prices I could find for bearings and rod kits. I may contact link when it all arrives as the local guy has quoted $300 to assemble the crank which I think is a touch high.
Nice work on that banshee/ypvs motor Jon, got me thinking about doing something similar in the future, likely not with this bike tho as I don't think it would look right water cooled.
Nice work on that banshee/ypvs motor Jon, got me thinking about doing something similar in the future, likely not with this bike tho as I don't think it would look right water cooled.
Re: New to the two stroke world.
Do contact Link, hes one of us, that always helps in my view.
Thanks mate, I actually have that engine ready to go back into a freshly repainted and uprated LC frame, now with uprated oil pump from Arrow fitted and a bunch of other upgrades. Will run EGTs too in that bikes next iteration, all fun n games.
Thanks mate, I actually have that engine ready to go back into a freshly repainted and uprated LC frame, now with uprated oil pump from Arrow fitted and a bunch of other upgrades. Will run EGTs too in that bikes next iteration, all fun n games.