OK... so my engine build is pretty much done at its current stage, so this thread is mostly for posterity. I'll be focusing mainly on the technical, but I'll be happy to answer any questions on the aesthetic (should they arise).
Goals:
*Repair Cooked Top End
*Increased Power
*Higher Redline
*Hitting "The Ton"
*Fun and Learning
Changes to Engine:
*+2mm bore (356cc to 378cc) done at the local machinist
*Custom Forged Pistons from Arias (Compression from 9.5:1 to 10:1 and 11g lighter than stock despite being +2mm larger in diameter)
*Megacycle cam (duration from 221° to 251° and lift from .341" to .382")
*R-D Valve Springs with Aluminum Caps
*Steel Dragon Velocity Stacks (tuned for 5th wave at 10,000 RPM)
*Custom Copper Head Gasket from Copper Gaskets Unlimited
*Front sprocket upped from 16t to 18t
*Stiffer Clutch Springs from Dennis Kirk
*Stainless Steel Caphead Engine Bolt set from eBay (seller: alloyboltz)
*New Gaskets All Around
*Tachometer Cable Blockoff from our own crazypj
*Hondaman Transistorized Ignition Assist Unit
*Oil galleys from the crank case to the head drilled out slightly (13/64" maybe?)
*Removal of stock 2:1 exhaust and switch to a set of stock CB360 2:2 headers
*Spark Plugs (TBD, but hoping to find a dual electrode set set with the specs I need)
*Jetting (TBD)
Early in October of 2010, I was riding into work when the bike started making some funny noises. I pulled into my parking space and there was some white smoke coming out of the breather. I immediately shut everything off and checked the oil level. The dipstick couldn't find any. At lunch time, I came back out and gave the ol' girl a kick and everything turned over OK so I picked up a quart of oil and added it in. I made it home OK but things were not sounding good™.
I let the bike sit for a couple of weeks without riding it until I made the decision to just tear it apart and restore it from the ground up. This led to my desire to café it and you can follow my full thread here. This thread will focus on the engine.
Here's how things looked straight off of the bike:
As you can see, I had an oil leak coming from the head gasket (which was the probable cause for my oil starvation issue) and a lot of metal dust under the sprocket cover (cause still unsure, but I'm going to attribute it to poor chain lubrication).
After opening the rocker cover, I could immediately see that the rocker arms on the left side had been eaten up. The lack of oil led to too much heat and there was significant scoring on the followers and the cam. Luckily the journals were OK and the coking came off with a bit of 800 grit paper.
The dark black streaks on the cam lobes in this pic and next indicate it's time for a new one:
The combustion chambers look OK, but the darker combustion on the left chamber is a possible indication of running rich. In my case, I had oil leaking from the head gasket and into the cylinder a bit at a time.
Just a quick shot of the inside of the cylinders with the head off:
Engine finally disassembled after a rubber mallet and a blow torch finally loosened the jugs from the upper case:
Inside of the cylinders and the skirt of the pistons all looked good with limited wear. Everything measured in spec but at this point I had already decided to replace the cam with an aftermarket part that would require deeper valve pockets. The piston cost for increased compression and larger bore was negligible and so I decided to go for it.
A couple of more pics of the rocker arm damage:
Now that all of the engine was taken apart and cleaned up, it was time to do the carbs. I disassembled everything and dumped all the parts (excepting the diaphragms) into a gallon of pure lemon juice and then proceeded to boil them for 15 minutes. Man, alive! That is a FUNKY smell. I also had the joy of boiling them over and burning lemon juice onto the top of the stove... The Mrs loved that.
Here's everything after the lemon juice bath. Boiled lemon juice has worked better than anything else I've tried and would definitely do it again.
Next, the carbs went back together again. I used some small caphead screws in the diaphragm cover and bowls to replace the stock JIS ones. While I was there, I fixed the choke (PO had the lever on wrong and the butterfly valves in backwards).
Sometime later, my refurbished cam finally arrived in the mail!!!
Followed shortly by my new pistons:
New springs from R-D came in a bit later:
Followed by velocity stacks from Steel Dragon Performance:
While waiting for parts to arrive, I got some painting done on various engine bits, including the cases. Nothing special here, just some Rustoleum Metallic Enamel which will later be clear-coated with some 2K urethane.
The engine is starting to go back together now. Up first, I reassembled the head with the new valve springs and retainers. As you can see in the pic below, the valve stem now sits a bit above the retainer. I was assured (after double-checking) with the manufacturer that this is by design and all the clearances checked out.
After that, the bottom end started going together. I made sure to use clean towels on the workbench to avoid screwing up the paint any more than necessary. Yes, I am missing one of the gears on the shaft. No, I didn't realize it until I had everything put together.
New piston at TDC:
After getting the bottom end sorted out correctly, it was time to check clearances for the new cam and pistons. A chunk of modeling clay laid across the top of each piston prior to reassembly will let me know all is good:
After assembling the engine and turning it over a few times, I took the head back off to examine the clay. Looks like the valves didn't "cut" all the way through and so we're OK (that tear on the right side was caused by me, bending the clay back. Ignore it.)
Then I had the fun of getting an 18t sprocket to fit in place of the original 16t. The 18t sprocket fit onto the countershaft OK, but it was too wide to secure using the stock clip. Not having access to any milling equipment, I decided to take a bench grinder to it and used a steel straight edge to check my progress. The fine adjustments were made using a die grinder with a 60 grit sanding wheel attached. Final fit is close and I'll have to keep the chain tight to avoid eating up the guard under the sprocket cover.
The engine is now sitting reassembled and (as of this date) still waiting to be fired up:
I've since got the engine into the bike and adjusting the valve lash and timing. I went with spec on the tappet to valve clearances but decided to go with an addition 3° of advance. The reason being is that the cam, having more overlap, may induce some tougher starting if the spark doesn't fire soon enough. I will probably have to/want to retard the advancer an equal amount.
After I get this thing dialed in, I'm (optimistically) expecting a gain of around 10 peak hp; an increase of about 1/3. Most of that comes at the expensive of moving the power band up to the higher RPMs due to increased duration of the camshaft. Under 3,000 RPM I'm expecting to lose about a 1/3 of the power I had before. That, coupled with my gearing changes, may make the bike a bit of a pig at low speed. I'm hoping that first gear is low enough to pull through it though and I'll just keep it above 3,000 RPM the rest of the time. I'll only know for sure once I get her on the road. Provided things don't work out as planned, I can also drop a few teeth on the front sprocket and/or up the teeth on the rear until I get a decent feel.
Estimated top speed is around 115. Maybe 120 after I make some further modifications...
Things I would have done differently (or things I would still do the same, but probably shouldn't):
*Made use of used rocker arms with new cam
*Didn't remember to match up rocker arm pins with the specific arm from which they were originally pairs
*Forgot to measure thickness/warpage specs on the clutch plates before reassembly
*Had the inside (possibly outside, too) of the cases professionally cleaned and/or blasted
*Had the new valve spring strength tested to ensure proper strength
Possible list of future modifications which I am planning (and will update this thread if/when I get around to it):
*Skimming the head and slotting the cam gear for additional compression
*Electronic ignition
*External oil pump + cooler
*Remove casting marks and polish the rockers, conn rods, and crank
*Mill/grind gear edges to cut down on rotational masses
*Fuel Injection?
Goals:
*Repair Cooked Top End
*Increased Power
*Higher Redline
*Hitting "The Ton"
*Fun and Learning
Changes to Engine:
*+2mm bore (356cc to 378cc) done at the local machinist
*Custom Forged Pistons from Arias (Compression from 9.5:1 to 10:1 and 11g lighter than stock despite being +2mm larger in diameter)
*Megacycle cam (duration from 221° to 251° and lift from .341" to .382")
*R-D Valve Springs with Aluminum Caps
*Steel Dragon Velocity Stacks (tuned for 5th wave at 10,000 RPM)
*Custom Copper Head Gasket from Copper Gaskets Unlimited
*Front sprocket upped from 16t to 18t
*Stiffer Clutch Springs from Dennis Kirk
*Stainless Steel Caphead Engine Bolt set from eBay (seller: alloyboltz)
*New Gaskets All Around
*Tachometer Cable Blockoff from our own crazypj
*Hondaman Transistorized Ignition Assist Unit
*Oil galleys from the crank case to the head drilled out slightly (13/64" maybe?)
*Removal of stock 2:1 exhaust and switch to a set of stock CB360 2:2 headers
*Spark Plugs (TBD, but hoping to find a dual electrode set set with the specs I need)
*Jetting (TBD)
Early in October of 2010, I was riding into work when the bike started making some funny noises. I pulled into my parking space and there was some white smoke coming out of the breather. I immediately shut everything off and checked the oil level. The dipstick couldn't find any. At lunch time, I came back out and gave the ol' girl a kick and everything turned over OK so I picked up a quart of oil and added it in. I made it home OK but things were not sounding good™.
I let the bike sit for a couple of weeks without riding it until I made the decision to just tear it apart and restore it from the ground up. This led to my desire to café it and you can follow my full thread here. This thread will focus on the engine.
Here's how things looked straight off of the bike:
As you can see, I had an oil leak coming from the head gasket (which was the probable cause for my oil starvation issue) and a lot of metal dust under the sprocket cover (cause still unsure, but I'm going to attribute it to poor chain lubrication).
After opening the rocker cover, I could immediately see that the rocker arms on the left side had been eaten up. The lack of oil led to too much heat and there was significant scoring on the followers and the cam. Luckily the journals were OK and the coking came off with a bit of 800 grit paper.
The dark black streaks on the cam lobes in this pic and next indicate it's time for a new one:
The combustion chambers look OK, but the darker combustion on the left chamber is a possible indication of running rich. In my case, I had oil leaking from the head gasket and into the cylinder a bit at a time.
Just a quick shot of the inside of the cylinders with the head off:
Engine finally disassembled after a rubber mallet and a blow torch finally loosened the jugs from the upper case:
Inside of the cylinders and the skirt of the pistons all looked good with limited wear. Everything measured in spec but at this point I had already decided to replace the cam with an aftermarket part that would require deeper valve pockets. The piston cost for increased compression and larger bore was negligible and so I decided to go for it.
A couple of more pics of the rocker arm damage:
Now that all of the engine was taken apart and cleaned up, it was time to do the carbs. I disassembled everything and dumped all the parts (excepting the diaphragms) into a gallon of pure lemon juice and then proceeded to boil them for 15 minutes. Man, alive! That is a FUNKY smell. I also had the joy of boiling them over and burning lemon juice onto the top of the stove... The Mrs loved that.
Here's everything after the lemon juice bath. Boiled lemon juice has worked better than anything else I've tried and would definitely do it again.
Next, the carbs went back together again. I used some small caphead screws in the diaphragm cover and bowls to replace the stock JIS ones. While I was there, I fixed the choke (PO had the lever on wrong and the butterfly valves in backwards).
Sometime later, my refurbished cam finally arrived in the mail!!!
Followed shortly by my new pistons:
New springs from R-D came in a bit later:
Followed by velocity stacks from Steel Dragon Performance:
While waiting for parts to arrive, I got some painting done on various engine bits, including the cases. Nothing special here, just some Rustoleum Metallic Enamel which will later be clear-coated with some 2K urethane.
The engine is starting to go back together now. Up first, I reassembled the head with the new valve springs and retainers. As you can see in the pic below, the valve stem now sits a bit above the retainer. I was assured (after double-checking) with the manufacturer that this is by design and all the clearances checked out.
After that, the bottom end started going together. I made sure to use clean towels on the workbench to avoid screwing up the paint any more than necessary. Yes, I am missing one of the gears on the shaft. No, I didn't realize it until I had everything put together.
New piston at TDC:
After getting the bottom end sorted out correctly, it was time to check clearances for the new cam and pistons. A chunk of modeling clay laid across the top of each piston prior to reassembly will let me know all is good:
After assembling the engine and turning it over a few times, I took the head back off to examine the clay. Looks like the valves didn't "cut" all the way through and so we're OK (that tear on the right side was caused by me, bending the clay back. Ignore it.)
Then I had the fun of getting an 18t sprocket to fit in place of the original 16t. The 18t sprocket fit onto the countershaft OK, but it was too wide to secure using the stock clip. Not having access to any milling equipment, I decided to take a bench grinder to it and used a steel straight edge to check my progress. The fine adjustments were made using a die grinder with a 60 grit sanding wheel attached. Final fit is close and I'll have to keep the chain tight to avoid eating up the guard under the sprocket cover.
The engine is now sitting reassembled and (as of this date) still waiting to be fired up:
I've since got the engine into the bike and adjusting the valve lash and timing. I went with spec on the tappet to valve clearances but decided to go with an addition 3° of advance. The reason being is that the cam, having more overlap, may induce some tougher starting if the spark doesn't fire soon enough. I will probably have to/want to retard the advancer an equal amount.
After I get this thing dialed in, I'm (optimistically) expecting a gain of around 10 peak hp; an increase of about 1/3. Most of that comes at the expensive of moving the power band up to the higher RPMs due to increased duration of the camshaft. Under 3,000 RPM I'm expecting to lose about a 1/3 of the power I had before. That, coupled with my gearing changes, may make the bike a bit of a pig at low speed. I'm hoping that first gear is low enough to pull through it though and I'll just keep it above 3,000 RPM the rest of the time. I'll only know for sure once I get her on the road. Provided things don't work out as planned, I can also drop a few teeth on the front sprocket and/or up the teeth on the rear until I get a decent feel.
Estimated top speed is around 115. Maybe 120 after I make some further modifications...
Things I would have done differently (or things I would still do the same, but probably shouldn't):
*Made use of used rocker arms with new cam
*Didn't remember to match up rocker arm pins with the specific arm from which they were originally pairs
*Forgot to measure thickness/warpage specs on the clutch plates before reassembly
*Had the inside (possibly outside, too) of the cases professionally cleaned and/or blasted
*Had the new valve spring strength tested to ensure proper strength
Possible list of future modifications which I am planning (and will update this thread if/when I get around to it):
*Skimming the head and slotting the cam gear for additional compression
*Electronic ignition
*External oil pump + cooler
*Remove casting marks and polish the rockers, conn rods, and crank
*Mill/grind gear edges to cut down on rotational masses
*Fuel Injection?