Newbie from West Sussex

[Otis]

Welcome to the forum Graham.

Something not mentioned yet is the battery, a slow delivery can make even a decent sprag clutch reluctant to bite.

Jump it from a good car supply to assess this aspect. If its successful, a new battery of decent quality may be in your shopping future 

In fairness, I replaced the original wet battery with a new dry battery and keep it on permanent trickle charge but it is to no avail.

[Otis]

Welcome to the forum and welcome back to biking👍.
The 350/4 is a very nice looking bike (and was also Mr Honda's favourite bike so you are in good company.
I think you are going to have to bite the bullet and take the engine out to fix the starter clutch as it is located deep inside the engine. I'm not sure if you can access the starter clutch from below if you take the sump pan off, if you can access will be tight and very awkward.
Having the complete engine on the bench will likely save you time in the long run and will be easier to dismantle.
Make sure all the parts you need are available before you begin (not forgetting you'll need a new sump gasket as well). With the similar 400/4 engine the starter clutch is assembled with the primary drive chain loosely located on the sprocket of the starter clutch before the lower crankcase half is attached to the top crankcase half. The engine clutch driveshaft is then passed through the starter clutch and located in the bearing in the crankcase, this then tensions the primary chain.
I can't remember if the starter clutch can be separated from the primary drive chain and removed from the engine without first taking off the lower crankcase half, someone will hopefully be along soon to advise further.

Thank you.

I always loved the fact that MR HONDA built it because he could, not because there was any desire for it.

I have seen a video that shows a similar problem being dealt with via the sump and clutch cover but I tend to agree that it is a lot of grief. May I ask if anyone knows if there is a definitive test that can confirm whether the engine needs to come out or if there is an alternative fix?

Is the removal of the engine within the skills of a moderate DIY mechanic?

Thank you
Graham

[Bryanj]

It is possible to do the starter clutch on a500/550 through the sump BUT i dont think its possible to do on a 350/400 as you have to remove a circlip and move a bearing to get enough room to get the starter assembly free enough to split the cases.

Removing the engine is well within diy means as long as you are strong enough to lift the engine, to do the starter there is no need to loosen cylinder head or barrells just split the cases after removing side covers and clutch.

Please describe the symptoms you are having that make you think the starter clutch is bad

[Otis]

It is possible to do the starter clutch on a500/550 through the sump BUT i dont think its possible to do on a 350/400 as you have to remove a circlip and move a bearing to get enough room to get the starter assembly free enough to split the cases.

Removing the engine is well within diy means as long as you are strong enough to lift the engine, to do the starter there is no need to loosen cylinder head or barrells just split the cases after removing side covers and clutch.

Please describe the symptoms you are having that make you think the starter clutch is bad

Hi Bryan and thanks for your guidance.

The starter motor just spins up constantly. I can kick start it but it's also not easy. When it eventually fires two of the downpipes are cold but eventually fire. When the bike is running she is an absolute beauty and pulls effortlessly in every gear which suggests to me that the air/fuel mixture is good as is the timing. It's really odd that she just doesn't like starting from cold. After a run, one press of the button fires her up or at worst a single kick. I just can't understand it.

[McCabe-Thiele (Ted)]

There are quite a few "born again bikers" here including myself, welcome to our sohc community.🛵🏍️

[Bryanj]

If you remove the starter motor in the hole it fits into you will see a toothed gear, you need to see if that will spin both ways easily, if so the sprague clutch is gone

[Otis]

Welcome Graham from a slightly chilly Orkney,
I too have a 350 Four but not as nice as yours.

(Attachment Link)

  Are you sure it's the starter clutch - have you had the starter motor out - the easy bit?  As far as reluctance to start when cold goes - did the PO strip the carbs?  Yes, they are a bit of a bugger to remove/refit but worth doing right once.  Nearly everyone on this forum will tell you not to replace the brassware but use originals thoroughly cleaned.  I also had a DOHC 750 - an FA.

Ian

I think you underestimate how lovely your 350 is; great colour. I think I would sacrifice a little bit of shine for a working starter!!

Yes, I had the starter out and swapped it for another to try but it was exactly the same. While it was out I was able to move the clutch and with minimal effort it seemed to act as expected ie. moves in one direction only but perhaps under more torque it slips. I have seen a video where a chap overhauled the clutch from the side and beneath but as you say it is a real fiddly job and I could see much grief coming. My first step will be to drain the oil and remove the sump to see if there are any lurking springs or rollers. Interestingly and dare I say slightly suspiciously I noted from the invoice history that there had been a new sump gasket fitted shortly before I purchased it so it could well be that the PO had already done the same check?
With the help of a friend we fully removed and reset the carburettors but the worst thing we found was that the electronic ignition was way out. After this was corrected the performance of the bike was stunning and runs beautifully when I do get it started.

What a coincidence that you also had a 750F.

Thanks for your guidance Ian and just for your information John from Orkney knows all the buggers I know. What an amazingly small world.

Cheers
Graham

[Rayzerman]

Welcome, Graham.  I'd love one of those Z900's as well, unfortunately many do and I can't find a bargain, lol.

[Athame57]

Hello Graham
Welcome here, nice bike pics! 

[Rayzerman]

I would first run that engine a bit with fresh oil and hopefully it's just gummed up a bit..... otherwise, a big job.  Good news if the starter gear turns only one direction.

From my experience so far, it's a finicky job to get the ignition set up properly.  Do remove the advancer and give it a good clean.  Many have advised getting original point sets, and I did have some crappy aftermarket ones.  Well worth spending the time getting it right.  As for the carbs, same deal, float levels need to be right and bench sync'd..... then onto the bike and check ignition timing... vacuum sync the carbs.  It can be a little cold-blooded to start, but once you get it tweaked in, should be good.

I'd love one of those Z900's.