Double Trouble

[John H]

Was sidetracked trying to get the cranks ready for the grinder so made time to clean the sludge traps. It's centrifical for that slings the particles away from the rod bearings. Pretty crude but these older engines had no oil filter at all. After years of this buildup sludge turns to a hard dry crust and stops oil from flowing to the bearings.
First the indexing bolt is removed then the end plug that keeps the tube sealed in place. Both parts were loctited in place at the factory so it takes heat to soften this before trying to remove either one. This is the easy part.
To get the sludge trap out I first drilled the crud out then threaded a 5/8-11 tap into the tube. A nut is threaded onto the tap to make a puller. It took more heat and two attempts before it finally came out.
Now on to the second crankshaft.

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[John H]

I'm stalled on the exhaust pipe dent remover tool for now. My original plan didn't work.
Spent some time laying out the fuel and oil tanks. How many ports and the location comes next.
Each fuel tank requires filler neck, an outlet, a bypass inlet and a vent. The oil tank gets a outlet, a return inlet and a vent. Each vent must go to a safety catch can with a breather.

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[John H]

Made the final cuts on the fuel tanks and welded the front beveled ends in place. The rear ends will get tapped for both the fuel outlet and return lines. A pipe inside the tank connected to the return port takes the bypassed fuel to the front of the tank. This is to keep air bubbles from being sucked back into the fuel pump causing a lean condition which melts pistons.

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[John H]

Finished the bracket for the fuel filter but when I tried mounting it to the backbone tube I found heavy rust inside so now it will require a sleeve welded in place so there goes the beautiful powder coating.

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[John H]

I finally opened up engine number 1 to determine which crankshaft it had. It has the light flywheel. I have two cranks on the bench. One has a heavy flywheel and one has a light flywheel. I need to switch these since the rod journal on the light one is damaged. To exchange them I need to use heat as they are shrunk in place.

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The difficult job here is lining up the three bolts that keep these flywheels from shifting. Once the flywheel is changed the completed crank has to be rebalanced. Remember this engine is now 800cc instead of 650cc so balancing will be critical.

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[John H]

Bad news and more bad news.. The crank I wanted to use has a damaged rod journal that would require welding up and regrinding. That along with magniflux and balancing makes for an expensive piece. I'll start searching for another one.

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Other bad news is on removing cylinder #1 I found a rusted / pitted circle in the cylinder wall where the compression rings has been for several years. These cylinders weren't designed to rebore for oversize pistons. So out of three cylinders I have one good one. I will research a low temp brazing material and attempt filling the pitted area and then hopefully hone the bore back to size. Nothing gambled nothing gained.

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[John H]

Back to cams for a moment. The Norris cams used in these engines are a special grind. I found an old Norris catalog I hope will have some information that will help identify them. Meanwhile I will plot the lift, duration, lobe separation angle and overlap. Can't really get all the data until I determine if flat bottom or radius bottom lifters are required. Hard to explain here but with nitro, the exhaust cam usually has more duration than with gas.

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[Lotus54]

Thanks for the updates. I like seeing how you are coming on the machines.

I have a DomiRacer degree wheel too. I think I got it mid-70s

[John H]

Yeh, these degree wheels are classic now. I like being able to write the numbers down on the wheel then later put them in my notes.
How is the Benelli progressing?

[Lotus54]

I have the Benelli parts, but I’ve been trying to finish up a few other projects before diving into the engine.
I also have been looking for one last part to be able to put a primary chain tensioner on it (from a 650 Honda 4, SOHC).

Sold two bikes, new one ordered (more to come on that).
I have been taking some more things off the frame too- getting ready to clean and paint.