Day 35 - Oil Pressure Investigation

So time to investigate why I might be getting low oil pressure. After pulling the sump I notice a few metal shavings in the oil strainer, and I also notice that the O ring on the pressure relief valve needs replacing as the rubber is very worn. It's a good thing I can do this stuff with the engine still in the frame....


Oil pressure gauge still hooked up - that'll be the first sign I will used to determine if I've fixed the problem or need to pull the engine again...


Clutch and oil pump parts laid out on the garage floor. It'll stay this way until I get new parts.


So this I think is the problem. I took apart the oil pump and noticed that the oil pump gears are very much pitted and scored. I've read this can definitely cause low oil pressure. So at the moment things are looking hopeful that I don't have to pull the engine and it's recoverable. A new oil pump is on the way along with the new O rings for the oil strainer and oil pressure relief valve as I never replaced these. Also it's worth noting that I never overhauled the oil pump when I was rebuilding the engine and made the false assumption it was all fine. How wrong I was!


Oil pump laid out...


So as for right now, not much I can do until new parts arrive which will probably be some time next week.

Day 34 - Tail Light and Oil Pressure woes

So I got this low cost LED tail light, which I initially thought stopped working but in fact stopped working when I hooked it up to the bike because I wanted to see how it compared to the old bulb tail light. However I realised that the tail light positive terminal was being grounded by the presence of an old style bulb.

New LED looks ok, and is fairly bright when on the tail light, and brake light seems sufficient, I'll have to sort out that rather large gap around the edges of the light.


So now onto the next issue. I took a 70 mile ride from London, and when I got to my destination I noticed the oil light was flickering slightly only at idle. I then went ahead and measured the actual oil pressure using a pressure gauge and the oil pressure was in fact quite low. The manual says that the pressure should be around 71psi at 6000 rpm, but at 6000 rpm I was barely registering 30 psi which is quite low. After some research about what could be causing this, and the main results coming back that it's most likely the main or rod bearings, I've decided to try and eliminate the other potential causes and check out the oil pump, oil strainer and pressure relief valve. So I've pulled the sump and had a look inside the engine and overall it looks pretty clean...


I'm surprised the engine looks quite good inside and the oil sump didn't really have many metal shavings and neither did the oil when I drained it.


Only a small view of the crankshaft here, can't see the bearings but crank bearing caps look ok.


So next task is to pull the oil pump and have a closer look at that. If it's not the bearings then the only thing it could be is the oil pump. I really don't want to have to rebuild the engine again and if I have to do that I'm thinking I'll just go ahead and get another engine.

Day 33 - Exhaust, Clutch, Cosmetics and Oil Pressure

So now after riding the bike to work a couple of time successfully without issue - it's time to focus on the little annoying things. First thing was the stupidly heavy clutch that was on there. Now this could be due to aftermarket stiffer springs in combination with the shorty levers, but instead I had an idea of just extending the clutch arm for more leverage. Whilst being careful to ensure that the clutch still engages fully enough to allow proper gear changes. I wanted something that I could revert to should the need arise so all I had to do for this one was grind off the little rivet holding in place the cable holder and then bolt on a piece of metal which I cut into shape with a couple of extra holes. This proved to make the clutch much lighter.


The next thing was the exhaust. I found the stock exhaust to be way too quite around busy traffic in central London so I've gone for a fuel slash exhaust which gives it a much louder and deeper tone.


The number plate has been reduced in size, and completion of the wheel rim strips. I then decide I'm going to take it for a 70 mile ride from London being it's longest trip yet.


The trip goes well - bike performed great however when I arrived at my destination I noticed that the Oil light was flickering on and off. This would only happen at idle and even if I revved the engine only slightly the flickering would immediately stop.


After some reading and research I've concluded this must be a faulty oil pressure switch. However to be sure I've got an oil pressure gauge on the way so I can make sure the oil pressure is according to specs. A replacement oil pressure switch is also on the way so I can replace that when it arrives. For now I'm going to wait until those bits arrive before I ride it again. It's probably fine to ride as it is but I want to be sure that oil pressure switch is faulty and I'm getting correct oil pressure when tested with the gauge.

I also noticed that on longer rides my backside does tend to get a bit on the sore side and the hornet never really had the most comfortable of seats so I may upgrade the seat and reupholster it with a built in air hawk.

For now though, it's looking and sounding great - a few minor rust spots to sort out and cosmetics to sort out, and I really want to sort out that tail light and replace it with a LED tail light. Those leds I wired up myself turned out to be not so great and not bright enough so I'm gonna find a better solution for that one.

Day 32 - Lack of Power & Cosmetics

I then decide to take the bike for it's first ride to work - a nice ride to central London and back. I notice some serious power problems. Although initially I thought the bike had the power of a 600 - that was only at low throttle. As soon as I gave the bike some large amounts of throttle for more acceleration, the bike would hesitate and stutter and very very slowly accelerate. I concluded that this must be a carb problem and as I hadn't yet overhauled the carbs I decide to go ahead and remove the carbs from the bike, separate them and dismantle them to see if I can spot a problem.


I couldn't really find anything obviously wrong. No obviously clogged jets or anything like that. So I go ahead anyway and do what the manual says and get some carb cleaner and blast each of the holes in the jets and each passageway in the carbs with carb cleaner followed by large amounts of compressed air. I did this in turn to each carb, and put it all back in the bike.

To my surprise this fixed the problem! The bike now felt much MUCH more responsive and much better when giving it large amounts of throttle.

Perhaps my blasting of passageways and jets with carb cleaner must have done something. I then go ahead and replace the spark plugs and air filter element with new parts as these had not been done. I go for some nice iridium plugs.


After this success with the carbs, I focus more on cosmetics and take off the exhaust headers and repaint them with VHT paint.


The wheels also get treated to a reflective strip around the rims...


The one thing thats bothering now is that rear tail light. I'm not a fan of old style bulbs as they don't have the brightness or the responsiveness when hitting the brakes so I decide first to keep the tail light housing and make up a board with leds to replace the bulbs.


I may end up ditching this idea if it looks rubbish, but we'll see what it looks like...

Day 31 - Rectifier and HID

So whilst replacing the rectifier, I decide it's time to sort out some cosmetic things so I go ahead and remove the Ohlins shock thats in there and attempt to remove the spring so I can get rid of that rust and repaint it.


I also go ahead and remove the rear hugger. The carbon looked had faded so badly it looked rubbish. So I sand that down and respray it a nice clean matt black. The chain also needs replacing - there's a link that is totally seized and won't free up.


Due to the rectifier problems I had, I decide and replace the headlight bulb with an 8000k HID bulb. This gives the light output a bluish tint which I sort of like, but more importantly it doesn't take as much power from the bike and should therefore give the rectifier an easier time when charging the battery.

Day 30 - First Ride and Carb Sync

So I've fixed the brake light - it turns out the front brake light switch needed replacing as the internals were very worn and rusted. The rear brake light switch does work fine but the rear pads needed some rebedding into the disc which give the rear brake pedal some extra downward play and making the switch work like it should.

So here's a video of the first ride of the Hornet. I take it for a 20 mile ride which is mostly dual carriage ways and motorway. I keep the headlight on for visibility.

The next problem I had was when I went to start the bike to come back home - the battery was dead already. This led me to check out the rectifier which I subsequently did and found that the ground connection to the frame wasn't great so I cleaned that up.

The rectifier was also proven to be faulty. The manual says to put the headlight on high beam, and then get the bike to 5000 rpm, and the voltage at the battery should be around 13.5 - 15V. I was reading only 12.5 so after testing the stator and making sure that the resistance across the coils was according to specs I went and replaced the rectifier.

When going to sync the carbs, I found that I could only check them and found that they weren't too badly out of sync. The rough idle was in fact due to the fact I had disconnected the pair valve vacuum hose and I hadn't plugged the vacuum hole on the cylinder head. This was causing the rough idle. I only discovered this by accident when I noticed the idle sounded much better with the carb sync gauge hooked up.

Day 29 - Fixing Oil Leak

Now to address this oil leak. Thankfully it's a nice day for diagnosing oil leak problems.

The good news is that the oil leak is not coming from the sump but it's coming from the Oil cooler where the oil exits the engine and goes into the oil coolers and comes back through the filter and back into the engine. Although to fix this I will have to remove the exhaust headers, drain the oil, drain the coolant, remove the oil cooler and replace the O ring seals on the little metal cylinders that connect the oil cooler to the engine block. Thankfully halfords had the right sized O ring seals in stock and I also put some oversized O ring seals to fill in the gap between the oil cooler and engine block for extra good measure.



One thing however, when draining the oil I did notice these little metal shavings come out into the oil. Now I suspect this are from the main bearings and came off during that time I was starting the engine for the first time trying to get it going. I will change the oil again once the bike has done a few hundred miles as I'll have to treat it like a new engine. Thankfully the metal shavings are big so this doesn't worry me too much. I remember reading that even brand new engine will have tiny metal shavings on the first oil change.


However now that the oil leak was fixed I was able to properly fill the cooling system and get all the air out, so I decided to take it for a small spin around the garage just to see if it will ride.

Good news is it rides really well, sounds great and it also feels like it has the power of a 600cc motorbike. Good news. Now to fix other little things as the brake light doesn't work, and the brakes need looking into and I really want to get those carbs synced as the idling sounds a bit on the rough side.

Day 28 - Engine first start

So now all of the engine components have been reinstalled and connected up, its time to hook up a new battery and reinstall the fuel tank and try and fire up the engine. Not forgetting to first fill it up with Engine oil and coolant. 

Here's a video of the whole first start process...

It didn't really go as I had initially hoped but the end result was good. My thoughts on the engine being too tight were correct as initially I had killed the battery just by trying to turn the engine over 3 / 4 times. That was a brand new battery too so I know the engine was way too tight at this point.

After connecting it to the car battery and jump starting it, it took a good number of attempts to get it to fire up, but even though it fired up it didn't want to stay running until a number of attempts later.

I had a couple of theories as to why it took so long to start:

 - The engine was too tight and it took a while for the bearings to loosen themselves up and for the engine oil to start creating a film between the main bearings. The moly grease I used may have also contributed to the tightness of the engine.

- When I first removed the carburettor, I had only drained 1 carb of the fuel and I left 3 of the carbs full of fuel. This may have caused the engine to initially start running on just 3 cylinders until the engine had turned enough times for the 4th carb to refill with fuel - although I may be wrong on this one.

The good news is it eventually started and ran! My attention was immediately drawn to the exhaust leak that was evident from the nasty tapping sound. Thankfully this was nothing serious and was due to the blanking plates I had made up to block off the pair valve holes on the exhaust side - they weren't creating a perfect seal so I used some exhaust putty to properly seal these up.

I also discovered after fixing the exhaust leak I also had an oil leak! It appears initially to be coming from the oil sump! Not good but thankfully not coming from where I had sealed the 2 crankcase halves together - that would have been bad - at least the sump can come off without having to remove the engine. More diagnostics tomorrow...

Day 27 - Carburettor and other components

So with the engine back in the frame the next set of tasks is to reinstall all the other engine components. The next thing to be reinstalled is the Oil cooler along with a nice new oil filter...


The carburettor is next to be reinstalled. I haven't yet performed a full service on the carburettor mainly because I know it was running before with the carbs as they are currently and I just want to see if the engine will run as is. I'm also reconnecting electrics as I go along, and routing them as I put things back in.


After the carburettor the air box is next to go back in, along with the air filter element. There is a K&N air filter element installed so it's probably worth giving that a clean at some point.


Other things have been done like getting the chain back on the engine sprocket, and sorting out more wiring. I've also installed a nice connector for the stator cables as previously this was selotaped together which is big no no...Almost ready to fire this thing up.