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My new project bike buildup

11K views 82 replies 21 participants last post by  stnkbg1 
#1 ·
Ok, so this is gonna start off not very sportbikeish but I promise it will get more sporty as it goes.

I guess I was getting bored, or had too much extra fun money sitting around or something, cause one day about a month ago I decided to buy another bike to hack up. I might have had a little too much extra cash around, but certainly not a large enough sum to buy something cool with, so I bought this POS off Craigslist.

It's a '96 Honda Nighthawk 750 that some kid bought, then promptly plowed into the center divider of the street right in front of his house. From what his mother described he made it all of 100 feet. One more example of years and years of dirt riding not translating well to the street. The forks were bent, the tank was junk, and so were the bars, gauges, headlight, etc. It ran beautifully though, and other than the tank it was in great shape from the forks back. Even the front wheel managed to survive with just a minor scrape. I got it cheap, and after a bit of a headache with the paperwork (he never transferred it into his name) I now have it registered in my name.
 

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#2 ·
As I was making the deal on the bike I started searching around for some proper forks. I ended up scoring a sweet deal on a complete front end from a wrecked ZX10R and started taking measurements to see how I could make them fit together.

I also got started on stripping the bike down to the frame so I could figure out what needed to be done to de-cruiser this thing. I happened to have my last project bike in the shop for an oil change and started comparing the different lines of the frames. This is gonna take some work.
 

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#3 · (Edited)
Before getting too deep into the frame mods I decided to tackle the bent up front end. And boy was it bent up. Both fork legs were bent much more than it looked when they were mounted, the axle was bent, and even the steering stem was tweaked. Basically the whole front end was junk. I ended up cutting out the steering stem and using it to make the adapter parts and it's in the bike for mockup right now, but I ordered another lower crown off Ebay to get a straight one from for the final product.

On the last bike I swapped on a complete ZX6 front end, wheel and all then did a bunch of work to make a Ninja 250 rear wheel with the matching spoke pattern fit. On this bike I decided to do it a bit differently. I actually really like the Nighthawk wheels and I think the 18" front will work nicely for the look I'm goin for. The tricky part is making it fit. I had to order different wheel bearings to fit the Ninja's 25mm axle (stock honda was 20mm). The real trick is gonna be centering everything up though. The single rotor is actually the right diameter, but the offset is wrong so currently the wheel is 1/4" offset to the left. Gonna have to fix that one soon.
 

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#4 ·
The new tank finally showed up so that I could start figuring out the rest of the bike. It's from a 1980 KZ750 twin and amazingly the front mounts actually fit, but are just a little bit too low. Pretty easy fix there though. Now I can get to the real work...
 

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#8 ·
The motor runs so nice and smooth I dont think it really needs much. Pod Filters and exhaust of course, but other than that not much.

And yes, I am goin for the cafe style. I fear calling it a cafe racer though because of that one dork that thinks anything that doesn't have the right wheels on it cant possibly be a cafe.
 
#9 · (Edited)
The motor runs so nice and smooth I dont think it really needs much. Pod Filters and exhaust of course, but other than that not much.
true true. i loved that Honda smoothness. and the dang thing always started. didn't care how hot/cold it was (unlike some HD friends.... nothing like trying to get an HD restarted in the Badlands. )

ya know, i should do something like that. they're cheap, get great MPGs, easy to work on, could learn how to do customizing.... hmmm, need to talk to the Financial Advisor after we get settled in once we get back to SD.
 
#10 ·
After cleaning up the frame I started bending up the new seat hoop. Ended up needing to do it in pieces, which were spiced together with some stubs inside to keep everything straight. After welding up the seams I'll smooth it all out so it all looks like one piece.
 

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#12 ·
I currently ride an '03 Nighthawk, mechanically and cosmetically identical to the '96. We have a forum where a lot of people post their attempts to turn Nighthawks of all years into cafes or bobbers. Few are successful, either mechanically or aesthetically. We're looking forward to seeing the rest of your build.

FYI, these motors aren't happy with pods without a bit of tweaking, and they're a bit finicky about exhaust mods, too. Rejetting is often required to get the thing running right.

If you're interested in another forum where you can get some useful technical information, the folks over at nighthawk-forums.com would love to see this thread.
 
#14 ·
Yeah, it'll be staying dual shock. I'm trying to make this thing look like an older bike than it is, and converting to a single shock would kinda defeat the purpose.

I'm also pretty familiar with the need to re-jet. This bike really isn't much different than my other CB750 mechanically. It's not that hard to do really. Dunno about signing up for yet another board though, I'm already on enough as it is. If you wanna post a link to this over there I wont mind though.
 
#15 ·
The diagonal seat stays were a little bit tricky. Not only are they not quite straight, but the original frame tubing is a fair bit thinner than what I'm using, so the sleeve trick I used on the seat frame wouldn't work so well. Instead I ended up chucking pieces of tubing in the lathe and turning the end down to a tight fit inside the original frame tubes. Then I added a little bend and notched the other end.
 

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#17 ·
Spent some time with the TIG welder over the last couple days. Got everything all welded together and got to work on the new shock mounts. Took a couple tries to get the gussets to line up properly and fit the way I wanted them, but I'm very happy with the results.
 

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#18 ·
Next up is to finish the tank mounts, and get the front end swap finished up. Then some wiring, a seat, and paint.
 

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#20 ·
Spent a little time making the rear tank mounts and frame gusset. I thought about modifying the tank and adding a mounting bracket more like the Honda ones, but after thinking about it I decided it'd be better to just use what was already there. The Kawi tank uses a pin on the bottom to locate the tank and another pin/hook thingie to hold it down. I fabbed up a little stand for the locating pin, then drew up the frame gusset with an extra tab to bolt on a removable mount for the hold down. For cushioning I actually used the 2 rubber grommets from the original honda tank that the side panels snapped into. Worked out pretty nice, and holds everything quite securely.
 

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#21 ·
A couple last updates before I head off for vacation. I decided to finally finish up on the front end today after packing for my trip. First up was finalizing the steerer tube. Just like my last bike I pressed out the stock Kawasaki steerer which is a lot b***** than the Honda. I then salvaged the stock Honda piece by grinding the welds off the bottom of the lower crown, then pressing it out. To make the little peg fit the big hole I machined a sleeve with outside dimensions to match the Kawi, and inside diameter to press the honda into. I didn't remember to take a picture of the sleeve, but it's basically just a carefully sized tube with a step in the end so that it cant slide all the way through the lower crown.

After pressing all the pieces together all I had to do was weld the bottom of the honda steerer to the sleeve and assemble. For the top crown I simply machined a little aluminum sleeve to fill the space between the tube and the hole in the crown.
 

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#22 ·
Now that the forks were firmly attached I moved onto the wheel. I think I mentioned before that the rotor didn't line up properly with the caliper, or that the wheel wasn't centered, depending on how you look at it. I needed to move the rotor out 1/4" to get things right, so I made a spacer. In case anyone was wondering how I cut out all these complex parts so accurately....I cheat. CNC makes things a lot easier.
 

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#23 ·
Last on todays list was to make the actual spacers for the front wheel. Not a terribly interesting or difficult process, but a bit tedious to get the dimensions right since It's difficult to get any measuring tools in there. It's done now though.

And now the bike looks just like it did yesterday, except that the front end is actually straight and firmly attached.
 

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#27 ·
I just realized how long it's been since I updated this thread. The whole project had kinda taken a back burner for a while, but I'm back on it now. Just had to renew the registration, and I haven't even ridden it yet!

First thing I did was to finally cut out the seat pan. Simple piece of sheetmetal with some speed holes to add lightness. I then glued a couple layers of foam together and started cutting and shaping til I got it where I wanted it. I then sent it out to get upholstered.
 

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