Author Topic: ST70 Re-Commission The Fun Begins  (Read 439 times)

xbally

  • Full Member
  • ***
  • Posts: 998
ST70 Re-Commission The Fun Begins
« on: June 14, 2024, 08:39:36 AM »
OK, so I've changed the oil, squirted some 2T oil down the plug hole, put some 2T in the fuel, checked for a spark but.......the kickstart while partially turning the engine over under compression (with the plug in) doesn't appear to be fully turning the engine over . I don't think it's slipping at the kickstart shaft and will easily turn the engine over with the plug out.

I'm guessing the clutch maybe slipping? I don't know anything about these automatic clutches or how to adjust them and wondered if anyone can point me in the right direction.

I'm armed with a can of Easy Start but that won't work unless I can get the engine properly spinning.

In the old days when I was a lot younger I would have tried bump starting but I don't even know if this is possible with a semi automatic transmission. The sight of a 60 something pushing his nearly as old small motor bike is not something I'm too keen on.
HONDA CB250RSA HONDA ST70

themoudie

  • Full Member
  • ***
  • Posts: 4678
Re: ST70 Re-Commission The Fun Begins
« Reply #1 on: June 14, 2024, 09:00:12 AM »
Morning Martin,

Please send me your email via a PM and I will send you a workshop manual for the ST50-70's 1969-1982, via WeTransfer that'll save you cloggy up your email account.

Good health, Bill

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #2 on: June 14, 2024, 09:06:07 AM »
Morning Bill.

PM sent.

Many thanks.

Martin
HONDA CB250RSA HONDA ST70

themoudie

  • Full Member
  • ***
  • Posts: 4678
Re: ST70 Re-Commission The Fun Begins
« Reply #3 on: June 14, 2024, 08:30:10 PM »
Aye Martin, two to you.

Bill

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #4 on: June 15, 2024, 11:52:46 AM »
Thanks for your help Bill.  ;D

Pushed it up and down the drive in top with the plug out and bike now turns over more readily on the kick start with plug in.

Still not firing though even with Easy Start.

Looks like a carb strip and clean and maybe ultrasonic bath and rebuild might be called for.

Got the wheels off and am going to local bike shop for new tyres and tubes and a battery. Some parts ordered from UK based online store to brighten up corroded items.

It's cleaning up pretty well though. Will post more pics when it's back on its wheels - hopefully next week.
HONDA CB250RSA HONDA ST70

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #5 on: June 17, 2024, 06:18:22 AM »
Reading through my back issues of Classic Motorcycle Mechanics I see Mark Haycock is restoring an ST70 , the same model as mine, and he had exactly the same problems with the clutch / kickstart. I'm hoping I won't have to strip my engine but his articles are very helpful should I need to do so.
I'm now waiting to get the tyres and tubes back from QB Motorcycles which is my local shop where I  try to frequent as much as I can as I think we would be the poorer for it without the choice of a local shop.
They've offered me a discount on Michelins and free fitment which will save me the hassle of struggling to fit the tyres and tubes. I'm given to understand the split rims make tyre fitting easier but am wary of corrosion and associated problems you can get with these older bikes.
Having removed the wheels and looked into a few other potential jobs I'm encouraged to find whoever has been in there before has lubricated parts before fitting them back together.
I had to re-make the battery wiring connectors yesterday and the horn now works but so far none of the lights do. Got to check the bulbs aren't all blown as I seem to recall this can happen with these basic 6 volt systems.
When I re-fit the wheels I can resume my efforts to try to get the engine running which may involve stripping the carb and more kick / bump starting.
Bill has very helpfully emailed me the HOnda workshop manual so I have this to consider as well :)
HONDA CB250RSA HONDA ST70

Moto63

  • Full Member
  • ***
  • Posts: 3858
Re: ST70 Re-Commission The Fun Begins
« Reply #6 on: June 17, 2024, 08:45:17 PM »
All sounds promising Martin on the whole. I’m starting to get a little excited for you 🤞👍
Cheers, Michael

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #7 on: June 19, 2024, 04:49:07 PM »
Thanks Michael. I've got the rear wheel back with a new Michelin but the front was punctured so I'm waiting for a new tube
HONDA CB250RSA HONDA ST70

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #8 on: June 29, 2024, 08:48:38 AM »
Got the wheels and new tyres fitted.
Am now turning my attention to getting it running.
The clutch plates are stuck and will need stripping and probably replacing so I'll need to order some parts and a special toll to undo the clutch nut.
In the meantime here are a few more pics...
HONDA CB250RSA HONDA ST70

Moto63

  • Full Member
  • ***
  • Posts: 3858
Re: ST70 Re-Commission The Fun Begins
« Reply #9 on: June 29, 2024, 10:28:52 AM »
That looks as cool 😎 as you like doesn’t it, scrubbed up really well Martin. Bet you can’t wait to give it a spin eh👍

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #10 on: July 01, 2024, 12:14:31 PM »
Thanks Michael.

Got to sort out a leaking carb / fuel tap next. It appears to be cheaper to buy a new re-pro carb form a reputable source rather than try to cure the ills of the OE equipment so that's the latest track I'm currently going down.
HONDA CB250RSA HONDA ST70

iansoady

  • Full Member
  • ***
  • Posts: 1725
Re: ST70 Re-Commission The Fun Begins
« Reply #11 on: July 01, 2024, 03:37:35 PM »
I bought a cheap (£15 or so) Chinese copy of a Keihin that I fitted to the sadly departed Tri-Greeves. It seemed to work quite well although I had to modify the mounting flange as the carb bore wasn't in line with the mounting stud holes.

Ian.
1964 Norton Electra
1969 BSA-Suzuki
1992 Yamaha SRV250

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #12 on: July 01, 2024, 08:16:18 PM »
Yes thanks for posting that up Ian. From enquiries I've made the copy of the OE Keihin has proved to be a cheap but useable replacement. The supplier reckons to have sold over 200 of them .I am a bit irritated though as I spent £25 on a Keyster rebuild kit which does not contain some of the spares I need to repair the original carb. Had I done more investigation beforehand I would have discovered the Honda carb repair kit contains everything I think I would have needed to repair the original. I'll keep the original carb and Keyster kit as I'm sure if I am going to keep the bike they will be needed sooner or later.
HONDA CB250RSA HONDA ST70

xbally

  • Full Member
  • ***
  • Posts: 998
Re: ST70 Re-Commission The Fun Begins
« Reply #13 on: July 04, 2024, 07:29:50 PM »
Ok so the repro carb arrived today and I bolted it on, ran the bike up and down the drive in gear with the plug out and manged to free off the clutch so I could kick the bike over with the plug in and....the engine started ,ticks over and sounds quiet....result :D
HONDA CB250RSA HONDA ST70

kevberlin

  • Jr. Member
  • **
  • Posts: 94
Re: ST70 Re-Commission The Fun Begins
« Reply #14 on: July 04, 2024, 08:44:17 PM »
Nice one Martin
1983 Honda CB250RS
2023 BMW G310GS