honda305.com Forum

Hi Sara

Work has a habit of getting in the way of life, doesn't it?

Nice to know that the 'old girl' is close to hand, though.

It's going to rain here on Saturday. Hopefully, that means workshop time....

G

sarals wrote:A 305CC thumper? It qualifies!

Things look to be moving along, Graham!

On my home front, I haven't touched the Old Girl. Life has been so demanding as of late! She sits in my garage under a cover, safe and sound. I ran her up just yesterday, and she pleasantly "tump-tump-tumps" merrily away!

I'm doing a rain dance for you (even though WE could use rain, too)!

Sara

If we get a surplus, I'll send some over.....

G

The rain came and so did some 'workshop time'

My 10mm plug head was nice and clean but there were one or two burrs on the joint faces that I wanted to tidy up. Neither joint face was very flat and both were a little convex as often happens when they have been cleaned up using abrasive paper. The edges tend to be a little lower than the middle. Torquing the head down well would probably straighten things out but I wanted to start with some nice flat faces.

First up for treatment was the top face. It took a few light cuts to get to a flat surface but it all cleaned up nicely within about 0.35mm.



The head was held down using two M6 studs through the outer studs near the spark plug holes.

With that done I had a nice flat surface on which to mount the head to do the bottom face.

I wanted to get rid of this gouge near one of the front stud holes, in order to give the seal an easy ride. The gouge is a little too close to the stud for my liking and while it is too deep to remove completely, getting enough surface for the seal seating is my target.



I put some clamps through the cam bearing holes and took some very light cuts across the head, paying a lot of attention to the harder steel skull. It all went quite niceley but it is always tricky skimming a big part on a small machine. Overlapping cuts have to be made and it is important to avoid any steps, just getting the tool to 'kiss' the already cut surface.



I only had to remove 0.25mm (10 thou) from the surface to get most of the gouge removed and overall everything is now nice and flat.



I may just give the surfaces a quick rub on a flat plate lined with fine abrasive paper when I have done all the other jobs.

G

One of the combustion chambers was pretty badly pitted from corrosion and I had those valve seat inserts to tidy up. Using a combination of the dremel with grinding and sanding heads plus my Neway valve seat cutters, I had a rough clean-up to get both chambers to a similar state.

I even found this NOS genune gasket set that I bought a while back.



It was only when I dropped some valves in that I realised the valve guides were a little past their best.



I tried to convince myself that they would be OK but, in the end, they had to come out. I measured up and made a drift that would sit inside the guide and pass through the valve guide bore, then heated up the head.

The guides were pretty tight but drifted out nicely. This is the first time I have seen those specially-drilled inlet guides which match up with the air bleed holes at the back of the head.



Not much else to be done until the replacement guides arrive, but I was able to clean up the rocker shaft bores and investigate why my tachometer drive was such a tight fit. It turned out that the edge of the cam bearing bore and the tacho drive both need a few burrs tidying up.




G

Looking great

Are you going with the NOS guides or compromise a little a go for the Viton seal type

G

Waveblaster

I've ordered a set of bronze one with the viton seals but I may still go with the Honda ones. I've had to do a fair bit of cleaning up on the head so it is already the least standard part on the bike.

It still looks perfect on the outside and has the 10mm plugs so it's still authentic from that perspective...

G

Waveblaster wrote:Looking great

Are you going with the NOS guides or compromise a little a go for the Viton seal type

G