Honda-SOHC

There's been a lot of post about tyres on this forum and others, but bear with me!

I've been trying to source tyres for my CB400F running what I believe are standard rims (front J18 x 1.6 and rear J18 x 1.85). I am not looking for anything too sporty, just good all-rounders. I have been well and truly around the houses trying to find which size I should get (into double digits of hours researching so far). There are a lot of varied opinions out there  I came to the conclusion that the the most recommended metric equivalent sizes are front with 90/90R18 and rear with 100/90R18. Getting the front tyre is not so much of a problem, it's the rear that is causing me grief.

Many people have recommended Avon Road Riders Mk II. It would seem Avon used to make the rear at 100/90 but not any more. Everyone is out of stock. I've gone through other brands including Metzeler, Bridgestone, Michelin etc but this all led to many dead ends as well as this specific tyres size seems to be much rarer than it was. I can sometimes find the rear tyre size I want but for fitting at the front. I am assuming this is a very bad idea!

However, I can get Avon RoadRiders Mk II for the rear in 110/90R18. I've read that fitting a 110 tyre where a 100 is recommended will "generally slows handling, makes steering feel heavier, and reduces cornering agility".

What would people recommend? Go with a rear 110 width and the tarmac gods will be happy?

Thanks to you both for the replies.

Ash: Do you just use your witches brew for stripping every type of metal, be it high tensile or other? I.e. play it safe and just use your brew?

Also, Do you know if the crankcase bolts are high tensile?

Cheers

Thanks all for you replies!

I asked Ken (Oddjob) (via text) and he's suggested replacing the rose joints completely, so that's what I am going to do. Drill the stud/ball out of the levers and fit new joints.

I've tried picking those dam circlips and although they move, they are very good at holding the joint together fortunately/unfortunately !

I'm in the market for some felt washers for my carb rebuild.

Mine are all pretty perished. I need a full set for both the chokes and the main lifters.

Would anybody want to supply me or know where to get them ?

Thanks
Bill

I could be wrong here but I think it goes brown, black then blue in terms of giving increasing mains clearance. I got this from looking at the shell tables on page 32 of the manual on Ash's link:

(https://www.dropbox.com/s/1n3w5433jkph228/350F%20400F%20_4%20Shop%20Manual.pdf?dl=0)

I think that if have (according to plastigauge) approximately a 0.08mm clearance at the moment with blue shells, if I went down to browns I could knock of 0.02mm bringing it down the clearance to 0.06mm. If that's right then perhaps I could go even further down and go for green main shells as this would bring the clearance down by 0.03mm from the blues to 0.05mm. Although a 0.05mm clearance is above ideal, its much well within the upper service limit of 0.08mm.

Would anyone agree/disagree? If I am going to do this, it might as well be as best as I can get it :-)

So the saga continues... slowly. I fitted and torqued down the <cough> "new" blue main shells with plastigauge. The first plastigauge I used (PL-X) showed a clearance>0.045mm (i.e. off the scale for that plastiguage type).So I then bought plastigauge PL-A and this shows a clearance of more like 0.076mm which means the clearance is at the service limit (0.08mm). So what to do next :-(

Originally I a was trying to source black shells, but I cannot find these for love nor money. I am beginning to wonder if black ones would give quite high clearances. So what would people do next ? Go the other way and get a set of brown main shells ones ? (seeing as the clearance is so large with the blues.)

TIA, Bill.

Hi all,

Thanks for all the previous advice. It's all been very useful.

Well after much hunting I found some 'new' blue main shells. I could not get hold of the black ones for love nor money. So I have had to go up a size, which by all accounts is safe to do, as long as you run it in sensibly. I say 'new' because these shells are not in original Honda packaging but they have been carefully labelled with the correct part code in hand writing. I can also see the blue dot of colour on their sides, so that's very reassuring. So fingers crossed, they are what they have been sold as. I am going to clean up my case and check the shells with plastiguage.

The shell's look 'new', but they have horizontal marks across them i.e. perpendicular to the direction of rotation where you would expect to see marks on shells that have been used. Attached are 3 pictures of just one 'new' shell. Perhaps they have been tested in a crank case, and then found to be not suitable? But I would not expect a new shell to have any blemishes. The blemishes seem light enough to me but just want to check in with the experts :-) N.B. As before, these images greatly exaggerate how they look in real life ! Please bare that in mind when viewing the images. Is it normal for new shells to have these blemishes?

Thanks in advance!