1987 GPz305 "Goldie"

I did a test run this evening with my sewing machine, taking some uneven strips of marine vinyl, and sewing them together. I had a few problems with the machine jamming, but adjusting the tension seemed to solve the issue. I'm going to buy some vinyl of the same thickness, in a chocolate brown, and start sewing the real seat cover.
 

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Well, it's been "at least 30 days" since I've posted, according to the warning at the top of the page. In that time, I have made some serious progress and learned a SHIT LOAD about motorcycles. Still, I barely know anything....

First of all, I solved the valve cover issue. I couldn't pull the valve cover off, because the bike was not at TDC for the left hand cylinder, so there was something in the way, preventing me from fully taking the cover off. (I kind of thought that this forum would have been able to solve that problem, when I posted up about it, but I got like, zero replies....)

Anyway, the second weird thing about this bike is that there is no cover on the right side of the bike for the crank. In order to turn the motor over by hand I had to either shift the bike into 5th and turn the back wheel (this presented it's own issue, as the bike refused to shift from first into second without oil pressure), or remove the magneto cover to access the crank from the left side, but also drain a bunch of oil out of the bike.
 

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So, I ended up taking the magneto cover off. Turning the crank with a socket feels a lot more precise than it does to spin the back wheel in 5th gear. We leaned the bike over to the right, in order to minimize oil spillage, but there was still quite a bit that came out.

I sealed up the top valve cover with a liquid gasket and bolted everything down again. I removed the valve cover hole plug things (no idea what they are called, but they are the large, circular plastic pieces that screw into the valve cover with a 27mm wrench. I checked the valve clearances, and they were awfully tight! Good thing I got on this when I did. Satisfied that I was complete on that job, I moved on to the next major issue...

After I cleaned out the carbs and added slightly larger main jets (#100 instead of the factory #95), and cut the rusty tips off my exhaust, the motor was only firing on one cylinder. I had compression and spark on both sides. Felt both the pipes. The right one was burning hot. The left one felt cold. Plus, the bike was screaming, and the only thing that would calm it down was to fully choke it.

I pulled the carbs and double checked everything. Turns out my secondary air jet on both sides was pretty clogged. I just hung sprayed all the carb cleaner in the world into both holes, let them sit for a while, repeated the process until the were flowing more freely, then put the carbs back together.

Another issue I noticed immediately is that the carbs weren't seated properly in the engine intake manifold. So, MASSIVE air leak. Once I got them seated properly, things started to sound a lot better. I hired a guy who used to work at the Kawi dealership in town to come by with his carb synch tool. It was really cool, he had a fuel IV, which just makes so much sense ( I need to build one of these). And his carb synch tool was super old school with a bunch of mercury in a vaccuum. This guy is a wizard. He showed up in a '71 Land Cruiser that he built from the ground up, and converted to hydrogen. After 5 minutes of fidling, the bike started to purr like a kitten!

There are still major issues and I am nowhere near having a bike that's been properly jetted to run pods, but I am a LOT closer. I think that the main jets I put in might actually be too big. Right now, I am experiencing no pull in the mid-range, so I am going to have to mess with those a little bit. Fortunately, a friend of mine who works on natural gas compression engines and tunes snowmobiles for run sent me a book called Olav Aaen's Carb Tuning Handbook. It is specifically for Mikuni carbs, but he has used to successfully as a reference for the Keihin carbs on his sled and a few Honda CB's that he restored. I am going to be digging into that book to see what I can find.

So, what's next? Well, other than jetting the bike, I'm looking at getting a bracket welded on the back of the frame to hold my plate, tail light, and turn signals. After that, I need to add an instrument panel (I'm thinking digital), a headlight, and front turn signals.

Then I need to paint, sand, paint, blah blah blah.... None of that matters to me anymore. I just can't wait to get her on the road!
 

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Time to ruthlessly gut my previous checklist....

Workshop Manual
  • Buy it[/li]

Oil
  • Change Oil
  • Inspect Oil Pump Drive Sprocket - I'm probably not going to do this right away. My sense of urgency around this had completely faded. Will that come back to blow up in my face? Maybe.
  • Inspect and clean Oil Strainer - Same with this.

Intake
  • Check for air leaks
  • Disassemble and clean carbs
  • Replace carb boots
  • Remove air box
  • Install pods
  • Rejet carbs
  • Rejet carbs - might as well put this here again, and again, and again. This is why people tell you not to remove your airbox, kids. My advice: Don't listen to them. Make your own mistakes. Learn from them. Move on.
  • Rejet carbs
  • Rejet carbs
  • Rejet carbs
  • Rejet carbs
  • Rejet carbs
  • Rejet carbs

Paint

This whole part of the project matters a lot less to me now. I'm not going to be on the cover of Iron and Air. I'm not even going to sand and paint my frame. I am going to build a motorcycle that looks cool, to me, and is fun to ride. Hey! Priorities! I have some now.

  • Remove front fender, gas tank, and cowl
  • Sand
  • Choose color
  • Buy DupliColor spray paint
  • Sand
  • Paint
  • Sand
  • Paint
  • Sand
  • Paint

Seat

My seat is probably fine. I am going to consider making one, still. I'm also going to think about buying an OEM replacement. They are cheap, they work, and they look pretty good.
  • Get some samples of marine vinyl from upholstery shop
  • Buy foam - this may no longer be necessary
  • Shape foam - ditto
  • Repair sewing machine
  • Sew seat cover
  • Upholster the seat
  • (optional: Order new seat in case I ruin everything)
  • (optional: Skateboard seat pan)

Engine Covers
What? Did I really want to do this? What happens when I ride through a puddle? Fuck that. I'm not cleaning this shit.
  • Clean or sand these down (currently covered in dirt and gunk)
  • Replace gaskets, if I can find them

Header
Mehhhhh
  • Order DEI Titanium heat wrap
  • Wrap headers

Exhaust
  • Check exhaust exchange for rattle Yup, still rattling
  • Cut exhaust pipes and remove some of the baffling - Doing that this weekend!
  • T'is been cut. Probably should grind off the sharp edges. Maybe add some paint?

Tail light
  • Order a new tail light with integrated turn signals
  • Install tail light

Gauges
  • Go to bent bike and find a new Speedo/Tach - FAIL
  • Replace instrument panel with new shit - I had no idea this shit was so expensive.
  • OR - build a new housing for the existing instruments - TOO HARD
  • Find LEDs for neutral and turn signal indicators - MAYBE
  • Find a cool housing for the fuel gauge - NOPE

Bars

I'm just going to delete this whole section. Bars and instruments are great.

Dat Gap
  • Cut Fender
  • Move battery
  • Move stater - Unnecessary
  • Move regulator rectifier - Unnecessary
  • Remove belt guard
  • Remove center stand

Frame
  • Chop the back - Hopefully this weekend?
  • Weld on a loop
  • Cut off all the excess crap
  • Grind down rough parts
  • Sand and Paint
 
Glad to see you making progress.

Two things I wouldn't put off are checking the oil pump drive and cleaning the
screen on the oil pickup. While you're doing that, flush out the bottom of the
engine and trans. There is always a lot of gunk laying on the bottom. Your
engine will appreciate it. :)

Remember your manual is your friend, everything you need is in there, although
sometimes it's not always easy to find.

I haven't touched my 305 in months, just hibernating.
 
Thanks for the reply! I appreciate the encouragement. I think it's a wise decision to add that back on my list of things to do :)
 
Yeah, the oil system to the cam & head is marginal and you see a lot of 305s' with
scored cams & heads. You need to give it every advantage you can.

One of the main things to remember on any bike and especially on the 305 is make sure
you warm the engine up before you ride.

Keep smilin' ;D
 
Well, I'm not into the phase of tuning my carb and getting those pod filters to work. I have Keihin CV32 carbs on my bike. Right now, I've gotten the bike to the point where it idles smoothly, but when I turn the throttle to 1/3 or more, the bike just dies. I swapped out the #95 main jets for #100s and it felt like the bike was worse. I swapped out the #100s for #102s. Definitely worse. I know it's counter-intuitive, but I am going to try smaller than factory main jets and see if there are any improvements.
 
any updates on this? i just signed up to this forum, just for this thread! as i was reading i was thinking you should try that 98 jet you got along with the 100. running too rich, while usually a safer bet, can wreak havoc. (chasing down problems, trying to tune, etc.)
anyway, just hoping that you're keeping up the good work for those of us that have the same bike, without the knowledge/balls to do some drastic modifications, like you.
cheers
 
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