Author Topic: RD250C rebuild (snakes and ladders )  (Read 57135 times)

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Offline Motty

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Re: RD250C rebuild (porous plastic)
« Reply #255 on: October 05, 2017, 05:25:34 PM »
Graham, you might be interested in post 61 of this thread

http://www.aircooledrdclub.com/smf/index.php?topic=54772.msg441415#msg441415
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Offline Pielight

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Re: RD250C rebuild (porous plastic)
« Reply #256 on: October 05, 2017, 08:04:37 PM »

As a self-employed person I know there's nothing worse than comebacks on jobs you did with good faith so I felt bad about hassling the guy but at least have got a dialogue going with him now which is good as I'd like to get kits made for my 125cc & 200cc bikes. Have asked him if he'd be interested in producing these
I would think he's same seller I bought my kit from - he started to produce RD250/400 kit at my request  - I just gave him exhaust port dimensions (inlets were same as LC for which a kit existed).

Offline Foy(notFox)

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Re: RD250C rebuild (porous plastic)
« Reply #257 on: October 06, 2017, 07:44:19 PM »
Graham, you might be interested in post 61 of this thread

http://www.aircooledrdclub.com/smf/index.php?topic=54772.msg441415#msg441415


That's great Motty. Thanks

Soon everyone will be doing this lol.

Wonder if any UK mechanics back in the 70s ever did leakdown tests. It could've saved a lot of time for dealers trying to diagnose problems
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Offline Foy(notFox)

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Re: RD250C rebuild (porous plastic)
« Reply #258 on: October 06, 2017, 07:45:24 PM »
would think he's same seller I bought my kit from - he started to produce RD250/400 kit at my request  - I just gave him exhaust port dimensions (inlets were same as LC for which a kit existed).

Probably is same guy. He says he's really busy just now but is interested in doing the smaller ones
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Offline Foy(notFox)

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Re: RD250C rebuild (porous plastic)
« Reply #259 on: October 06, 2017, 07:46:27 PM »
If they are 3D printed using the deposition method, which is the normal home hobby type printer, the can easily have voids and paths inside. They could be hollow with honeycomb support inside. The hot plastic is just squirted onto the layer of cold plastic below, and may not stick 100%.

You could probably seal by brushing the surfaces with araldite.

The surfaces are often textured with a linear pattern of fine lines made up by the passes of the print head. These may not seal too well to a flat surface unless gasketed up.

Thanks for the info Martin. I'll give the Araldite a try if the replacements leak too
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Offline Foy(notFox)

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Re: RD250C rebuild (bring on the Araldite!)
« Reply #260 on: October 12, 2017, 11:54:23 PM »
Well I didn't think my last statement (above) would become reality but I got the new plugs (white) today and they are bubbling away, probably worse than the (yellow) originals.

I couldn't find my Araldite so took the plugs back out and smeared the whole reverse with Sika grey sealer and let it dry. No improvement when they went back in.

On the original plugs I used some green Hermitite and it hasn't quite dried yet so still to try that but am starting to think I'm cursed.

Surely trying to get an old bike on the road doesn't have to involve becoming an expert on the porosity of plastic and gasket cements!       
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Offline Pielight

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Re: RD250C rebuild (bring on the Araldite!)
« Reply #261 on: October 13, 2017, 02:37:55 PM »
The ones I got are red...the leak off rate of the engine was just within tolerance but I cant say for certain whether i thought to test the ends of the bungs (though I think I did). I wonder if a hot knife migt seal them - messy though. Supplier needs to come up with something - complete change of material by the sounds of it. Ask him for red ones to try.

Offline Foy(notFox)

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Re: RD250C rebuild (bring on the Araldite!)
« Reply #262 on: October 13, 2017, 09:04:02 PM »
Supplier needs to come up with something - complete change of material by the sounds of it. Ask him for red ones to try.

 ;D cheers Pielight but I did mention the colour thing to him and am not going back a third time. I'm focusing on something more interesting tonight. Don't think I mentioned it (recently) on this thread but did start a thread in the MOT/DVLA/Dating section a while ago.

I imported the bike (correctly) from Jersey CI in 1990 and lost the papers about 2 hours later on train home to Scotland from Poole.

I'll soon need to make the NOVA application and am gonna write to the Jersey vehicle place tonight to see if they have duplicate docs of when I exported it. Going back thru old letters I worked out the weekend I brought it back so they may be able to dig something out the archives   
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Offline Motty

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Re: RD250C rebuild (bring on the Araldite!)
« Reply #263 on: October 13, 2017, 09:40:02 PM »


Supplier needs to come up with something - complete change of material by the sounds of it. Ask him for red ones to try.
I'll soon need to make the NOVA application and am gonna write to the Jersey vehicle place tonight to see if they have duplicate docs of when I exported it. Going back thru old letters I worked out the weekend I brought it back so they may be able to dig something out the archives
That sounds an interesting plan, better than obtaining a Q plate, which needs to be last resort



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Offline Foy(notFox)

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Re: RD250C rebuild (bring on the Araldite!)
« Reply #264 on: October 13, 2017, 10:14:10 PM »


I'll soon need to make the NOVA application and am gonna write to the Jersey vehicle place tonight to see if they have duplicate docs of when I exported it. Going back thru old letters I worked out the weekend I brought it back so they may be able to dig something out the archives
That sounds an interesting plan, better than obtaining a Q plate, which needs to be last resort

I think I could get an age-related plate no matter what as the bike has a frame number (and matching engine number, old tax discs, all parts correct to period etc) but just think with the export confirmation I could fill the NOVA form in honestly. The advice I was getting on the other thread was to say it was a barn find   
CS3B, AS3, RD125, RD250C, Honda SS50ZK1.

Offline Foy(notFox)

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Re: RD250C rebuild (bring on the Araldite!)
« Reply #265 on: October 17, 2017, 06:44:36 PM »
Ok. So the green Hermetite worked no better than the grey Sikaflex sealer so now I have one sealed with Araldite and another with JB Weld.

Did them last night. Will test them tonight and report back...


Hermetite Green - no good



Sikaflex EBT - no good



yellow plug now coated with JB Weld. white plug coated with Araldite
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Offline Foy(notFox)

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Re: RD250C rebuild (JB Weld does the trick)
« Reply #266 on: October 18, 2017, 02:22:46 AM »
So out with the dud plugs and in with the two pictured above. Screw the gauge and pump back on. Pump up to 6psi. Quick squirt of soapy water on the plugs and immediately bubbles come out the white one but not the yellow.


yellow plug is not bubbling from within now unlike white plug so JB Weld > Araldite

So somewhat surprisingly something has worked. I only had a tiny bit of the stuff left so cut the tubes open, mixed it up and applied it to the 3 other plugs (after cleaning off the other substances).

So, tomorrow perhaps, I'll try again.

I spent the rest of the night sifting through soil from a trench down the side of the floor of the barn to find 2 tiny plungers that sprang out of a spare 1A0 oil pump I dismantled ages ago. I'd bought it to fit to my stand-in RHS cranckcase cover so I wouldn't need to disturb the original pump from the original casing which still needs the oil-pump wire thread fixing. Now that I'm (almost) ready to fire the bike up I need to sort out the oil supply.

I didn't find the plungers and am now into a world of which oil pump bits fit which bikes. I didn't realise this was a thing but can see it's came up many times before and ppl have drawn up compatibility charts etc.

Anyway I've got lots of macro photos of 3 pumps to post up and describe. Brace yourselves  :-X 
« Last Edit: October 18, 2017, 02:25:08 AM by Foy(notFox) »
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Offline Foy(notFox)

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Re: RD250C rebuild (oil pump pieces)
« Reply #267 on: October 18, 2017, 11:28:19 AM »
So what have we got here....

pumps:

  • my original pump never removed from the original damaged casing (clutch cover?)
  • a used/damaged pump (1A0 on pulley) that I bought to put on a used casing
  • a NOS pump from an unknown Yamaha

obvious issues:

  • the used 1A0 pump has a damaged pulley wheel and I lost 2 'plungers' from deep inside it when I took it apart for inspection
  • the NOS pump isn't the same as the other two

background:

  • my original casing has no thread in the top where the fitting for the oil-pump cable should thread in. That's because someone fitted a non-Yamaha cable many years ago and it the fitting on that wasn't threaded so they presumably drilled it out to take the other cable
  • I tried to fix it by filling with 'tapable epoxy' JB Weld then tap thread in it (M8 x 0.75 iirc) but it didn't work so it'll need some sort of thread insert
  • I therefore bought a used casing which has a good thread but no pump. I didn't want to disturb my original pump as I feel it's like robbing Peter to pay Paul doing that. EG when I got different bars for the bike I also found a complete 2nd set of cables/controls so that the whole unit can be switched rather than taking bits off one assembly to move to the other
  • used pump seems to be correct one as it has 1A0 on pulley which I assumed is all it needs to be correct
  • NOS pump looks quite different but was very cheap and bought in hope that it would yield 2 tiny plungers as they can't be bought separately afaik
  • leakdown test and ignition timing just about dealt with so decided to address the oil pump issue


what I found out this week:

NOS pump first....


NOS pump. I have swapped the new screws from it onto my used 1A0 unit


has a plastic 'stop' for pulley wheel which you don't get on the RD ones. 10V stamped on it (DT125LC model no. ?)



also has no provision for starter (white nylon thumbwheel)


3J0 pulley on NOS pump (DT175 model no. ?)


washer and shims from NOS pump



NOS pump casing separated



shaft and spring



hmmm. no springs and only one plunger. am sure RD one was different  :-\


washer and toothed-wheel that takes drive from worm shaft. 55T?

So I started to compare the NOS bits against the 1A0 one...


bits from above pulley wheel. only 1 shim on this unit


springs look the same. RHS one is from NOS pump


I found out also that the thread in the top housing of the 1A0 pump where the tiny screw which stops the pulley wheel is damaged but the housing seems to be exactly the same on the NOS pump so could swap them but there is definitely a difference with the plunger. It seems that as the 3J0 pump has no priming wheel they don't need them. when you turn the thumbwheel the plungers recess against the small spring in the shaft allowing the shaft to be turned when the engine is stationary so on a machine that doesn't have this they have dispensed with the springs and only had one longer pin which is permanently engaged. Quite clever really.


NOS pump has one longer pin instead of two short ones as on RD unit

I read on another thread about someone making up new plungers from 2mm dowel but I figure I could possibly make them from the pin in the 3J0 unit.

This meant opening up my original pump to check the size....


original pump with pulley etc removed to have a look at plungers within


you can just see them here. 66T on wheel?


wheel removed to fish-out plungers


looks like one could become two but need to find best way to cut the longer pin

So now that I have disturbed my original pump I don't think I'll get the plungers back in it without removing it from casing anyway so might be easier just to stick it on the slave casing. I also realised that I'll need a worm drive etc for the slave unit. Had a look at that last night and it's not straightforwards either. There are lots on new and used bits on Ebay but there's some confusion over part numbers and interchangability.

For example the 250C parts list shows the nylon wheel inside the casing to be a 280 number which is readily available from the YDS7 but the shaft is a 275 unit which doesn't seem to be the same on YDS7. Also with the shaft there is a huge difference if it has 00 or 01 suffix. The 01 part has no thread at end.

On top of that my bike definitely has a 1A0 nylon wheel so the 280 part must have been superceeded anyway. 1A0 wheels don't seem to be as plentiful as 280 ones. Might actually be cheaper to buy another used casing with pump still attached (from UK). I see one for reasonable price on Ebay but then again might be easier just to usemy original unit or borrow the worm assy from it

 :-\  :-\  :-\     




     



« Last Edit: October 18, 2017, 12:19:25 PM by Foy(notFox) »
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Offline Motty

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RD250C rebuild (oil pump pieces)
« Reply #268 on: October 18, 2017, 06:34:44 PM »
Nowadays the oil pumps seem to be a nightmare! I assume you have found the table Stephen (My Precious) created?
Does your used pump have a dob of paint which will denote the RD model it came from?
The priming wheel was not fitted to the later models
There is also a step by step guide to rebuilding the pumps somewhere on here

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Offline Pielight

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Re: RD250C rebuild (JB Weld does the trick)
« Reply #269 on: October 18, 2017, 09:48:25 PM »
So somewhat surprisingly something has worked. I only had a tiny bit of the stuff left so cut the tubes open, mixed it up and applied it to the 3 other plugs (after cleaning off the other substances).
I'd have put money on the JBweld. Every tool box should contain some!