Hello SOHC-forum!
After reading hundreds and hundreds of threads while researching my dream bike I thought it was time to build up the confidence to make a thread myself.
Ever since I was a child I've always loved building and fabricating things, no matter the materials or what it is. And with a way older and cool uncle who rode Ducatis on the race track (and had tattoos, and had been in the french legion, and etc etc) I have always found motorcycles fascinating and interesting.
However, I never grew up with a moped or a motorcycle, and have actually close to zero riding experience myself. Today I work with selling motorsport equipment and parts which takes up a load of time, but at the same time I have access to machines, tools and contacts that would be extremely valuable in building my own bikes. So about a year ago I purchased my own bike - a Jawa 350 634 Oilmaster. It had not been run in twenty years, and I had absolutely zero previous experience with bikes. However, I got it up and running (after LOTS and LOTS of hours put in - probably 40+) just to have the needle bearing holding the piston pin fail and destroy the left cylinder and piston. This was when I first rolled it out from the workshop to test ride it.
I managed to find a new set of cylinders and pistons in Ukraine, which obviously got stuck in the customs and I had to wait close to a month for them to let it through due to silly paperwork etc. Ecstatic about finally being able to get it up and running I changed the cylinders and pistons, and for the first time fired it up and got it running. There's a video clip of it here;
https://vid.me/KC1OI've made some pretty astounding things in my life, but I think this was one of the proudest moments I've ever had.
Had it running for about a total of thirty minutes or so while adjusting this and that, before I went on my first ride. About twenty seconds in I hear a metallic noise, and the power fades from the engine. I quickly engage the clutch and the bike slows down the engine dies, and the engine is seized. I've had great luck with this bike. Yay... Rolled it back, and realized that the engine isn't seized (I can turn it back about half a cycle) but it won't go anywhere without force. So I've parked this bike now, and won't touch it for many years.
Jeez, that was quite a long introduction... And not anything about the bike this thread is about. Sorry about that!
Anyway! Since september last year I've been on the hunt for a CB750 SOHC here in Sweden. Checked the equivalent of craigslist about ten times every day, and haven't found anything that suited me. These bikes are fairly rare here in Sweden, recently there has been one put out for sale every week or so, and a fairly shabby but running one sells for about $2500, and a regular one in good condition sells for as much as $5000. This was not the starting point I'd like, so I have been looking all over Europe, but the issue is that the ones that would make for a great project are sold within hours, and the ones that aren't are too expensive to drive for thousands of kilometers to pick up.
During the months since september I've seen three bikes up for sale below $1800. Two of them were sold within hours, and the third one I managed to get. He put the ad out at about 09:20, and I called him twenty minutes later. By then he had already had several calls. The picture in the ad really didn't give me any information, since it was pretty much an engine in the frame and not much more. He said that he had started restoring it, but simply had too many projects going on and needed to get rid of one. It was a K7, he had the papers on it, it had been running when he bought it about a year ago (but you can never trust this) and he had most of the parts for it he said. The listed price was $1850, and I lowballed him for $750. After some back and forth he agreed to sell it to me for about $1000. I knew that he would definitely get closer to $2500 for this bike (since I know the market) so I said that I'd make a transfer for $250 if he'd hold it for me and I'd drive up after work if he needed me to and didn't want to wait until the next day. Since it was an eight hour drive he said he could wait until the day after.
Keeping my fingers crossed I made the transfer and hoped that he'd stay true to his word - after all I had never met this guy and if he took my money he was too far for me to bother about visiting him to get my money back.
Anyway, the next day I took my van and started driving at 10:30 AM. It was 550 kilometers, but my lovely woman agreed to come along to keep me company. When I got there I was greeted by a WAY better bike than I had seen in the photos. The bike was rolling, the seat was great condition, the tank was mounted, and he really had more parts than I thought, including the side covers, speedo, tacho, etc etc.
He said that he had had more than two hundred phonecalls before he decided to turn his phone off, including about twenty different people from all over Europe. I couldn't believe that he held the bike for me, as some of them had offered some serious dough. Turned out he owned A LOT of perfectly restored vintage bikes for several hundred thousand dollars, so I guess the money wasn't an issue.
Anyway, here's a picture at a pit stop on the way home;
Sorry about the horrible picture, but it's pitch dark in there and the only light is from the flash on my cellphone.
When we arrived back home the time was 03:30 AM. We had three stops for gas and two stops for food, and spent about 30 minutes with the sellers for a total time of about 1h30m - meaning we were on the road for 17 hours straight. Wasn't pleasant, but was DEFINITELY worth it.
I had already started gathering some items for my project since a while back which I had started on - for example a front fork off a CBR1000F that I am going to use. I would take a more modern suspension, but from what I've read (and managed to deduce from photos) the frame isn't rigid enough to make use of a modern sportbike front suspension and modern tyres. So I'm going to try with this one and see if I'll be content, otherwise I'll change it.
I've already had the shocks disassembled and replaced the bushings, seals and oil. They were in great shape, I probably wouldn't have had to do it, but it feels good to know that it is done.
Anyway, back to the bike. The next day I went to my parents basement where I temporarily store it to inspect the bike more closely. I didn't actually inspect the bike at all while I was there, for the price and after him neglecting so many bids I would have purchased it no matter which shape it was in. But I was extremely pleasantly surprised.
The engine turned over without any problems. He had drained the oil and replaced the oil filter. The air filter in the stock airbox (which I am going to keep, don't really like pods very much) was new. The brake fluid smelled a bit rancid, but it was definitely fairly fresh and the front brakes locked the wheel but didn't stick which made me happy. I even managed to undo the air bleeding nipple - think it's the first time I've ever managed to not break one off.
But it was when I got to the carbs that I got my greatest surprise. It was completely renovated. This came back to bite me in the arse, but only in a minor way. More on that later!
All in all, this bike was in EXCELLENT conditions, under all the dirt. It looks way worse than it actually is, mainly because the gas tank has been garage rolled black by a few owners back. The only two things that didn't work on it was the horn and the ignition switch. I can live with that!
The PO had even purchased a repair kit for the ignition lock.
When I opened the old one up the only thing I saw (other than fairly worn plates) was a bent spring. Nevertheless, I used the repair kit and after many curses I realized that I was trying to assemble the whole thing backwards, making the springs a true hell to get in place. When I figured that out it took about two minutes, and voilá!
https://vid.me/81MgAnd before anyone thinks I ran the starter engine without oil in the system - don't worry. Filling her up was the first thing I did, before starting on the ignition lock.
She's a beaut! The engine is even fairly clean.
After the electrical was all cleared (for now, obviously I'll redo it since it the original wires) I hooked up the carb. Jesus christ do I have too large hands for this...! I heated the intake boots and revitalized them with some oil, and I managed to get it all in place. I haven't yet leak tested it with some spray while running, that's on my to-do list.
Regarding the throttle wires, do you know what a smart man with NO clue as to how they go would do? He would have figured it out before the put the carbs in place... And I'm not a smart man.
I managed to do it. At last. Probably took me an hour, no exaggeration. Problem now was that one of the wires would hinder the return. I hooked one of them off and realized it was the push-wire. Nothing to argue about, I just ordered new wires. Here's a video showing the non-snap back return. If I want the carbs to fully close of I have to push the throttle back manually.
https://vid.me/U7ODI also mounted the exhausts. He had all the screws and parts needed. Damn, these exhausts are true porn from the front!
Stupid as I am I also mounted the air box without trying to start it. I OBVIOUSLY have to remove it again, this isn't a perfect world. It took me two or three rounds of putting it on and taking it off before someone on this forum said that it's about a gazillion times easier to do if you split the air box.
Well, it is.
I'm stupid.
Anyhow, after the air box was mounted I rigged a temporary fuel system with a bottle and a piece of string hanging it from the roof. Fire proof, obviously.
This is when I realized that carb #1 is leaking, from what I now realize is the overflow. Remember when I said that the renovated carbs would come back to bite me in the ass? Yeah. This is it.
Anyway, I tried firing it up anyway.
https://vid.me/yJ7DIt's aliiiiiiiiiive! Would only run on choke (the green garden string) and would not run very well. Not too weird, figuring that I had cut off the fuel supply from the carbs, and that the #1 had less to begin with (me being stupid about that, not going to tell how!
)
Anyway, I took the carbs off again, and opened the #1 up. Know what the problem was?
Well, it wasn't odd. That's for sure. The float was turned upside-down. Easy fix! I measured it and set it to the same height as the other ones, and it has worked ever since.
One thing that didn't come with the bike was the chain. This is where the next chapter of my build begins. The rear sprocket was completely new and had never touched a chain, so I ordered a new chain from Ebay.
This chain didn't come with a master link.
Well, #$%*.
Let me walk you through the steps this rookie takes to mount a closed chain to a CB750 K7.
Step 1)Remove the swing, keep the wheel on (yeah, didn't really know how I was thinking). P.S. This makes the thing really heavy and will most likely hurt your back. Great!
Step 2)Realize you're #$%*ing stupid and remove the wheel.
Step 3)Be lucky to have the correct chain for the rear sprocket. I was. Never checked if he had the standard sprocket.
Step 4)Remove the transmission cover COMPLETELY in order to remove the chain cover. You don't have to do this. You never tried just losening it.
Step 4B)Destroy pretty much every single screw. #$%* it, this bike deserves allen screws anyway. Order the entire kit.
Step 5)Damage the gasket. Now, since this is an old gasket that doesn't matter too much and I was obviously going to replace it anyway, but I managed to destroy the new one as well. Luckily I bought several.
Step 6)Get the chain on, without checking if the sprockets are level. This is really important, since this means you have to do the entire thing all over again. And please don't think about doing it while aligning the chain, even though you even take a picture before aligning the wheel which should spark the idea.
Step 7)Try to figure out what the hell the previous owner did to this screw.
That's all the steps. Follow every one and you'll get that warm feeling of self hatred when you realize what you've done instead of just purchasing a master link.
Anyway, after this I de-gunked the tank (ice rules), mounted the carbs and air box again, mounted the linkage to the rear brakes (#$%* that spring) and tested the brake light.
Lo and behold, it works! Both with the front and rear switches, amazing.
Anyway, after this I tried firing it up again. It ran WAY better this time, didn't even have to touch the choke. It even idles, which it didn't do before.
https://vid.me/i9NfObviously I need to do a carb sync. I only did a bench sync (which I don't even know if I did correct, I set all slides to the same gap as #2 since you couldn't adjust that one) for this. However, some of you might notice that after I rev it a little it stays at that rev for a slight moment before slowly descending. Am I right if I guess this is thanks to the accelerator pump squirting fuel in? I didn't have the boot clamps tightened here either, since the PO used the kind that loves to cut into rubber since they lack the rounded edge.
However, during this test fireup I was going to engage a gear and see if the gearbox acted the way I hoped, but then the clutch "popped" when I tightened it and stuck engaged. I turned the bike off and took off the clutch cover. If I manually struck the linkage it would move back, but when I tightened the clutch it "hopped" forward and got stuck. I adjusted the clutch ever so slightly (can't remember if I tightened it or loosened it) but after that it worked. I then fired the bike up again and engaged a gear, and slowly let the gear out. However, when it started to drive with the rear wheel in the air the chain really made a lot of noise, and even made a metallic noise which immediately got me to engage the clutch again and turn it off. The front sprocket isn't new, so if I'm going to take everything off again (remember that I didn't measure that the sprockets were aligned? Yeah...) I'm going to get a new front sprocket so that is ordered.
So that is pretty much where I sit right now. Realized this post got A LOOOOOOOOOOT longer than I initially intended, so if anyone actually reads through it... Thanks!
I'm going to post my plan for the build shortly. The short version is this;
1. Get the bike running and driving properly.
2. Change the front end to the CBR1000F, including making a custom triple. Haven't decided on which brakes to use yet, but will probably make it easy for myself and use the CBR1000F early brake system without linked front/back brakes.
3. Make the necessary changes to the rear end to accommodate for the new front end. I would LOVE to use the CBR1000F wheels, but I guess the rear wheel is A LOT too wide. I'll have to look into this. Perhaps it's possible with an offset front sprocket and with changes to the swing arm? Anyway, this is a future issue to figure out.
4. Get the seat on, in order to be able to decide on clipons and rearsets. Problem is I haven't decided on which seat to use, and if I'm going to go with a seat/tank combo or keep the stock tank. I'm probably going to go with a Benjie-seat though.
5. Get clipons and make custom rearsets.
6. Get exhaust, leaning towards Carpy's "Yoshi" 4-1.
7. Redo all the wiring
8. Do all the cosmetic small changes
9. Paint
10. Love my new bike
Anyway, this concludes the start of my first build ever. I'm hoping it will be as much fun as I hope it will be.
Thanks for reading, if anyone actually did. :p
