Honda305.com Forum

Teaser update on this long-dormant project: my bike is back together for mock-up purposes.

I built a motorcycle workbench out of a set of old steel shelves, cut down to 36" height, bolted together with storage underneath. It is working out swell so far, and I'm glad to see my pile of parts looking like a complete vehicle again.

I'm really happy about the look of the black anodized wheels, stainless spokes and polished hubs - I think they compliment the bike perfectly.

The engine in the bike now is just a mock-up using an old set of cases, cylinders, and head. Sitting on the bench behind the front wheel is the major modification this old CB77 will be subjected to...

Is that what I think it is ?

Mikeyrx

That depends - what do you think it is?

;-)

could it be a.............(small turbo ?)
Mike

Correct - a very, very small turbo. Probably the smallest available (or soon to be available) in the US. It just happens to be a perfect match, in terms of flow range, for a 305cc engine that can rev to 9-10krpm.

I'm currently looking at how to oil this little guy; there are several options I am considering at the moment:

1. Add an external or secondary pump that can meet the oiling requirements for the turbo, which should need 25 psi at peak torque engine speed & 10 psi at idle.

2. Modify a standard pump to increase output - I talked to Les Barker of the Vintage Advantage, and he can double up the stock pumps for twice the flow, but he only makes them in batches and he's not sure when he could do another. I need something by October.

3. Do nothing - just plumb the turbo into the stock oiling system and see if it gets sufficient oil flow for about 7 psi boost pressure, which is right around 200,000 rpm turbo speed. This is way less stressed than its original application, the India-only Tata Nano Diesel 800cc twin. If the bearing fails I can get a replacement turbo without much trouble.

Any thoughts? Has anyone here added an external chain or belt driven pump to one of these engines?

Also - if someone already has a Les Barker modified pump they aren't using, let me know if you want to sell.

Back to the garage...

Well it's been another few years of hiatus for this project, but I'm getting motivation again to get the bike finished and running. Not sure how active this forum is anymore but hopefully there are still people building these 305s and enjoying them. Below is a bit of a brain dump of everything I can think of from the past few years.

Since 2012 I finished the engine rebuild - bottom & top end, restored the starter, reinstalled everything into the frame, and fitted the NOS wiring harness I scored many years ago. Brakes are reassembled as well.

My sticking point this time was the cost of bodywork, paint, and especially chrome plating. I had all of the zinc plated fasteners and brackets redone in clear zinc; that was reasonably priced and turned out nice. The chrome parts however are so far gone that it would cost a small fortune in labor to get them restored by a good chrome shop, especially in CA. I'm going to buff out the ones that aren't so bad, and explore alternative finishes for the other parts, along with good replacements for the stuff that will stay chromed.

I need to organize my past few years of photos from the project. For now here are a few mock-up shots from after the turbo manifold was built by my friend Alex Buchka. I realized I never posted these photos in this thread, so these are way old now. The manifold was made from stainless tubing in 2 sections, with small v-band flanges at the joint between sections and at the turbine inlet of the turbo itself.










The GT0632 turbo uses a 32mm compressor exducer (major) diameter. It's tiny.




My plan now is to get the bike running NA with stock carbs and exhaust to get everything broken in and sorted out. Then I'll finish the turbo installation, with carb swap, fuel pump, and likely an external oil pump. For the carbs I found that the only OE blow-through turbo carbureted bike setup would work - the Yamaha Seca 650 turbo was a 4-cylinder, but two of the Mikunis from that bike should be just about perfect for my bored-out 305. These carbs are sealed and have foam-filled floats so they can take boost.


Just scored a nice finished fuel tank and headlight bucket that have already been restored and painted, which should save a ton vs. reworking the sad parts I have now. Getting excited to get this thing on the road finally.

Wow. Speechless! Nice work...