750 Katana Resurrection

[nvr2old]

I've had to walk away more times then I want to admit. It's all you can do until it dries thoroughly. As Steve mentioned, way better then hitting the floor, although not much solace, I'm sure. Your repair looks good, and I like the red Suzuki letters. They go better with your stripe design imo. That bike is gonna be really nice when it's done.

 

[KiwiAlfa156]

Thanks fellas, I was fine after an hour or two of self-flagellation, burning regret, a beer, and a good night's sleep. Looking forward to finishing the painting so I can start on completely stripping down the engine. Although more paint will be involved.

 

[Nessism]

I had almost the exact same thing happen when painting a 1000S tank; during the very last clear stage, the tank slid off the support and flopped upside down on the ground. It was horrifying. I baked the paint overnight then sanded out the debris and reshot the clear the next day. $hit happens. It's how we bounce back that matters!

IMG_1348 by nessism, on Flickr

 

[KiwiAlfa156]

​​​​​Cut and polished the last piece of body work this morning. Colour sanded with 1500 and then 2000 grit to remove (most) of the orange peel. Then cut and polished by hand with a corse then a fine compound. Assembled the fairing and loosely fitted everything on the chassis and took it out into the sun for a look.

It's not perfect, but overall I'm pleased with the results. It's been a learning experience with a couple of stuff-ups along the way.

 

[KiwiAlfa156]

Started the engine work at long last. I took the head and barrels off earlier and as you may recall that was a horror story of stretched and snapped cylinder studs from a literal "tighten her up until she strips and back of a quarter turn" engine reassembly. To be generous, a lot of ambition, unfortunately not matched with the required knowledge/skill.

Plan of work is to do a full strip down of the bottom end to check for damage or missassembly; clean the cases and paint them satin black; reassemble assuming no repair is required. I'll take the head a barrels to my automotive engineer to skim true the face of the head, and to plane 0.15mm off the barrels to give me a squish/quench clearance of 0.85mm. This hopefully will be the only part of the resurrection that will require work outside my garage. I'll give the ports a bit of a clean up, lap in the valves (the seats look OK) and hone the cylinders myself.

So I stripped the head of the valve gear and found a few issues. After cleaning the valves, it became obvious that the stems of the exhaust valves had suffered some corrosion

Priced replacing all 8 valves and it's more than what I paid for the entire bike! But this is more a function of the low price paid for the bike than the price of the valves. You could probably refit them and just cruise around. But I don't 'cruise' and revving it out would cause dropped valve anxiety. No fun.

Also the RH exhaust camshaft bearing pillows seem to have been repaired by welding and machining back. This is the "B" cam cap side. The oil ways are uneven as is the wear pattern.

I decided to check the clearance using Plastigage. I started with blue to check whether the clearance was over the 0.15mm stated in the manual. It wasn't

So then I used green to get an accurate read and it measured up at 0.1mm which seem about right.

Three out of the four threads on the 4-bolt "B" cap were stripped so carefully drilled, tapped and helicoiled

 

[KiwiAlfa156]

Oh dear........

 

[KiwiAlfa156]

Removed the broken and the stretched stud by welding a nut on to each of the damaged parts. Yes, that is a splatter shield made out of a cardboard beer box. And yes, it did at one stage catch fire. But it did work.

​​​​​​Sludge and a few silicone worms in the pan

 

[Guest]

How many hours do you estimate you have put into this project?

 

[KiwiAlfa156]

How many hours do you estimate you have put into this project?

To be honest, I have no idea. It's mindfulness time. It's therapy. I can't tell you how many hours I've spent fishing over the years either

 

[KiwiAlfa156]

Degreasing In the parts washer followed by a wire brushing and P80 to clean off the crusties. 340 grit to surface. Masked up and grease and wax remover, Duplicolor engine primer and the Duplicolor satin black engine enamel paint.

 

[Guest]

To be honest, I have no idea. It's mindfulness time. It's therapy. I can't tell you how many hours I've spent fishing over the years either

Understood, I was just curious. Keep up the great work!

 

[KiwiAlfa156]

Parts back from the machine shop. Barrels planed 0.15 mm (0.006") to close up squish.

Head refaced 0.07 mm (0.003").

 

[KiwiAlfa156]

More paint, primer then enamel.

 

[KiwiAlfa156]

Had a good look at the ports and found various flaws and steps and undercuts where the inlet port joins the valve seat. Which is the most important part of the port - the throat.

Basically the turbulence created by the casting flaws at this point has is extremely detrimental to flow past the valve.

I will carefully cut back imperfection and blend this section of the port back into the bowl. What is important is to maintain the valve to throat percentage which I measured at 82% stock. The throat acts like a venturi so I don't want to disturb this area at all. Work on the port above the throat has to be carefully done but isn't as critical.

I've started on one of the less problematic ports.

 

[KiwiAlfa156]

Did some work on the worst of the inlets

Comparison.

A mark is still visible, but it feels smooth and a dentists pick doesn't catch in it.

 

[Forden]

this build thread is a real education in itself, thanks for sharing your work in such detail--you say it's therapy, well, I thank you for sharing your time on the professor's couch.

I could never quantify the time I have spent fishing, either... probably best not to think about it too hard.

 

[KiwiAlfa156]

Thanks Forden, that's very flattering. Just sharing the journey and posting what I think is interesting. Hopefully others, such a yourself, find it interesting too.

 

[KiwiAlfa156]

Pretty much finished the inlet ports. Got some valves coming to replace some that need to be swapped out.

Tried to take minimal material out as I'd like to maintain as much port velocity as possible. Also left the throat area as undisturbed as possible apart from cutting out the casting flaws on the long side and blending a gentle radius back into the bowl. On the short side I radiused it as best as possible, removing the sharp step which is ringed in red below. Again removing minimal metal.

Cleaned up the casting core flashings in the turn of the ports and blended then into the throat area. The bottom pic above is one done, and one to be done. Surface finished in 80 grit.

Fitted new roller bearing on the clutch release shaft. Never regretted buying a hydraulic press..

 

[KiwiAlfa156]

Exhaust ports cleaned up. A couple of the inlet valves are badly cupped on the sealing face. It looks like the valves have been heavily lapped on using an electric drill. Replacements on the way. A serviceable inlet is shown for comparison.

I'm using a marker pen as a substitute for engineers blue to reveal and measure the seat contact width. The inlets appear to be over the 1.1mm limit. As do the exhausts.

 

[KiwiAlfa156]

Ugh: These days someone has always been there before you.

Ain't that the truth