Resurrecting Rusty - My CB400F - Valve Clearances - tools

[SeanFD]

I spent the last 2 days trying to get the airbox onto my carbs and in the end had to take the carbs off again and remove the rubbers from the airbox itself in order to get them on. Now I have the carbs and airbox as one unit and just have to try to fit that! Looking forward to it!!

However before doing that I decided to set the valve clearances. I have no problem with the process, just the tools. As it seems with this project from the start, I am working with a limited set of tools, so I'm struggling.

Can someone please confirm the size of the adjusting screw locknut? I think it is 9mm.

Also what do folk use to turn the adjusting screw itself? I'm using what I think is a bicycle spoke spanner, but it is far from ideal. Is there anything that works better?

Cheers

[Oddjob]

Doubt it would be 9mm, non standard size for Honda. Been many years since I last did the tappets on a 400, I would say 8 or 10mm for the nut, does the adjuster have a slot or is it the odd design of a square type of head like a C50.

If it's the square type there are small screwdriver type tools around that fit those.

[waffey]

9mm flat to flat

[SeanFD]

8mm too small and 10mm too big, hence my guess at 9mm; glad to have it confirmed.

It's a little square headed screw, but there is no slot in it.

Oddjob, can you post a pic or link to one of those tools?

[4wDaz]

I use this


https://www.ebay.co.uk/itm/251957752640?hash=item3aa9da3340:g:OzEAAOSwENVfh7Cm

[SeanFD]

Thanks.

I had a look on EBay and found this:

https://www.ebay.co.uk/itm/253750348091?hash=item3b14b3093b:g:Eh0AAOSwT9FbSPcd

It's cheaper and gives more options it seems. Hope it works too!

[Oddjob]

Can't ever remember it being 9mm but it was a long time ago.

Screwdriver slot, so not the square drive.

That BTW is the top tool in the link you posted.

[4wDaz]

Thanks.

I had a look on EBay and found this:

https://www.ebay.co.uk/itm/253750348091?hash=item3b14b3093b:g:Eh0AAOSwT9FbSPcd

It's cheaper and gives more options it seems. Hope it works too!

I saw them but the 12-pointed socket put me off, I prefer the 6 points as it has less chance of slipping.

[Laverda Dave]

This is the perfect tool you need to adjust the clearance. It fits over the square end of the tappet adjuster. Use a ring spanner over the lock nut and this over the square adjuster that way you can tighten the lock nut whilst holding the adjuster at the correct clearance. Failure to hold the adjuster whilst tightening the lock nut will cause the clearance to close up.

https://www.ebay.co.uk/itm/Genuine-Honda-Wrench-Valve-Tappet-Clearance-Adjustment-Tool-Cub-C90-NEW-/284239888533?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=710-127635-2958-0

[SeanFD]

I thought the same about the 12 points, but then the torque on the nut is not too high.

I looked at the Honda tappet adjusting tool; in the shop manual the part number is 07908-0010000 which is different from the one above - 07708-0030400. Are they the same size?

[Oddjob]

The difference is one is for square adjusting type tappets and one for screwdriver slot style tappets.

If yours has screwdriver slots then it's not the right type.

Incidentally, the yellow one is the same as I have for C50 type tappets.

[Athame57]

I spent the last 2 days trying to get the airbox onto my carbs and in the end had to take the carbs off again and remove the rubbers from the airbox itself in order to get them on. Now I have the carbs and airbox as one unit and just have to try to fit that! Looking forward to it!!

It helps to be slim and fit ourselves for this pain in the *** job, but also it helps if the rubbers themselves are not hardened with age, if so consider new ones. getting the middle two rubbers to fit back onto the carbs can be a real pain especially, I reach into the airbox with a stick and push them onto their fittings that way. I've seen a T shaped homemade tool on here somewhere for doing it. 

[Laverda Dave]

The difference is one is for square adjusting type tappets and one for screwdriver slot style tappets.

If yours has screwdriver slots then it's not the right type.

Incidentally, the yellow one is the same as I have for C50 type tappets.

The 400 has the same type as the C50 Ken so the yellow tool is ideal, had mine for years and its easy to use. I used a pair of thin nose pliers before and it became a pia trying to do the locknut up whilst trying to keep the pliers from turning.

[Oddjob]

Ah, thanks Dave, I wasn't sure it had or not, been well over 30 years since I did the tappets on one.

I have the yellow screwdriver type tool and also a little metal one shaped like a bishops staff which I think is out of a tool kit for a early Honda 50.

Anyone wants the metal one drop me a PM and you can have it.

[SeanFD]

Thanks.

I had a look on EBay and found this:

https://www.ebay.co.uk/itm/253750348091?hash=item3b14b3093b:g:Eh0AAOSwT9FbSPcd

It's cheaper and gives more options it seems. Hope it works too!

Well it didn't work!

The inner part kept falling out which was annoying, but the main issue was the socket wouldn't;t fit properly into the exhaust valve openings - it was too thick.

I sent it back and a little yellow tool is now on its way.