Topic: PharmD's 78 750 Cafe Build

[pharmd750]

So I have been procrastinating getting a build thread posted but decided now that I am finally in the rebuilding stage that I will get one going.

I purchased a 78 750k last fall that the PO could not get running.  I got it for a pretty good price and after 30 minutes of looking the bike over when I had gotten it home I was able to get it running just by changing out the old gas with new gas.  Lucky me I guess. haha  I rode it for a month or two until it was too cold and decided to tear it down and build something custom.

The build is taking me a bit longer than I expected because I am in pharmacy school in the Chicago area and I keep the bike back home in Wisconsin.  So I am only able to work on it about one weekend every month.  But its coming along nicely.

So I started doing some general searches and came up with a general idea of what I wanted.  It was to be a café styled bike with gsxr forks, ducati 900ss monoshock, and a lengthened swingarm.  I began by cutting the unnecessary tabs off the frame and welding a 5 1/2 inch piece to the end of the frame to lengthen it a bit.  I also lengthened the swingarm by 6 inches and added a loop to mount the shock to.  I then got the frame and swingarm powder coated medium gloss black.

While I was working on the frame I had a local shop rebuild the motor.  I used cycle X 849cc pistons and a bigger cam.  I can get the exact numbers on the cam if anyone wants them.  Tomorrow I will hopefully be getting the motor put in and running it for the first time.

I bought a set of black 2006 GSXR forks and calipers off of ebay and should be getting those put on in the next week or so once I order up the parts I need from cognitomoto.

I still have a long ways to go but will hopefully have a finished bike by mid summer.  Any suggestions will be greatly appreciated.

Anyways here are the pictures everyone would rather want than to read the jibberish above.

[calj737]

Some fairly extreme extensions to the seat and swing arm. I can't tell from the pictures, but when you extended the swing arm, you put a flat gusset across the top and bottom. Your secondary hoop for the mono shock bears on the gusset. Is there a piece of tubing in the trailing end of that gusset to handle the shock load? Or are you welding straight to a flat gusset with the shock mount?

Is that question clear? I'd be very concerned about the strength of a flat piece of steel supporting the shock mount alone, unless it were reinforced with a piece of tubing (1/8" wall min.) closing the gusset and handling that stress.

[Retro Rocket]

Why on earth would you lengthen the swingarm then monoshock it, most people go the monoshock route to improve handling, lengthening the swingarm detracts from that, I never understand these type of contradictory mods.... The gsxr triple clamps will also add trail, slowing down front end response, same with your rear mods, so basically you started out with a bike that liked corners and ended up with one that prefers to go in a straight line. lengthening a rear arm is used by drag racers for 2 reasons, straight line stability and to slow down wheelies so the power can be put down better....Just saying....

[pharmd750]

The swingarm has 3 thick pieces of tubing welded inside of the two ends of the swingarm and then it is boxed in with thick steel plate.  I'm not worried about its strength.

RR I knew that issue would come up.  I'm not racing this bike and nor do I plan taking corners at dangerous speeds.  I go on rides for fun and don't expect that these mods will affect my riding that much.  If they do, well then I will buy another swingarm for 50 bucks.  This is what I had in mind and wanted to try it out.

[Retro Rocket]

The swingarm has 3 thick pieces of tubing welded inside of the two ends of the swingarm and then it is boxed in with thick steel plate.  I'm not worried about its strength.

RR I knew that issue would come up.  I'm not racing this bike and nor do I plan taking corners at dangerous speeds.  I go on rides for fun and don't expect that these mods will affect my riding that much.  If they do, well then I will buy another swingarm for 50 bucks.  This is what I had in mind and wanted to try it out.

Just so we are clear, i never said anything about dangerous speeds, i was talking about handling generally. It may just be the way i think but before doing chassis or suspension mods on anything i do lots of research so i can do it properly and not detract from the original bike..... Yours will be harder to ride round corners any way you ride it, as long as you know that,  its fine, wasn't trying to talk you out of it, just informing....

[pharmd750]

Yeah I understand RR.  I did some research on it as well and understand the pros and cons to it.  It's just the look I wanted to go with.  If it affects it to the point that I feel unsafe, or just plain disappointed with the performance then I will change it back.

[calj737]

Will you be running an offset sprocket? The angle of the pictures on the left side don't show clearly the alignment of the swing arm.

You may also want to take advantage of member 754's frame kit. It allows service of the engine upper end while in the frame, and makes engine installation/removal much easier!

[SOHC4 Cafe Racer Fan]

At least he's not compounding the handling geometry issues with Firestone tires!

[Jerry Rxman Griffin aka MuthaF'er]

Good luck with finals 

[pharmd750]

yeah I was thinking about that frame kit but decided against it.  I am having an experienced shop do the install.  They only deal with older bikes and work with the Hondas a lot.  The swingarm is aligned just as it was stock when it was welded together.  Would that change the alignment? 

[pharmd750]

Good luck with finals 

haha thanks!  Its a struggle trying to study when the only thing on my mind is getting this bike finished.

[calj737]

I was more curious about potential conflict with the secondary hoop obstructing your chain. Without the motor in the cage, it can sometimes be hard to know if your weld meant has the hoop in the way.

Not harping, but re-think the frame kit. It's for "later" after you've put the motor in, spent all the money, and assembled a fully dressed frame, motor, and accessories, then have to pull the head for some reason. It will save you heaps of time (yours) or time and money (shop rates). Haven't heard a single member ever express regret at installing one, only NOT installing one.

[pharmd750]

I was more curious about potential conflict with the secondary hoop obstructing your chain. Without the motor in the cage, it can sometimes be hard to know if your weld meant has the hoop in the way.

Yeah that's a good point.  When I had the rear tire in the swingarm I ran a square against the rear sprocket and it seemed to be ok.  I guess tomorrow I will know for sure, but from what I remember there should be enough room.  Its hard to remember the details of everything since I get to work on it once a month.  Spend most of my time double checking things that I did the time before. haha

[SOHC4 Cafe Racer Fan]

I was more curious about potential conflict with the secondary hoop obstructing your chain. Without the motor in the cage, it can sometimes be hard to know if your weld meant has the hoop in the way.

Not harping, but re-think the frame kit. It's for "later" after you've put the motor in, spent all the money, and assembled a fully dressed frame, motor, and accessories, then have to pull the head for some reason. It will save you heaps of time (yours) or time and money (shop rates). Haven't heard a single member ever express regret at installing one, only NOT installing one.

You will thank yourself later if you do this now.

[Jerry Rxman Griffin aka MuthaF'er]

Good luck with finals 

haha thanks!  Its a struggle trying to study when the only thing on my mind is getting this bike finished.

At least you don't have to do CE. What do they call you with a 2.0 when you pass the NABPLEX? The bike is more important 

[pharmd750]

Good luck with finals 

haha thanks!  Its a struggle trying to study when the only thing on my mind is getting this bike finished.

At least you don't have to do CE. What do they call you with a 2.0 when you pass the NABPLEX? The bike is more important 

C's get PharmD's