Building a GT185 for GP200 AHRMA.

[wadarush]

Hello Hello!

Haven't posted here in a quite a while, mainly just been lurking in the shadows and living vicariously through all your guys great looking bike builds....

Possibly a good ten years ago now I bought my first motorcycle:
1973 GT185


Wayyyy too much money later and more labors hours than I'd care to add up she ended up looking like this:


I got some good use out of her for quite a few years, sadly ended up selling her off, and went on to a few other various "newer age" motorcycles. During the rebuild I searched the internet high and low to replace a missing air box and only returned results that would have cost me more money than what I had paid for the bike in the beginning. Luckily enough I came across a guy selling a complete GT185 on ebay that was most certainly a sight for sore eyes but it came with an air box! I ended up winning the auction for the bike for $50.... jackpot!!!

Anyway... long story short. I've held onto this parts bike for longer than a decade. Hid it at my parents house for a while, then storage facilities, then tucked it away in some awkward shelving at an apartment complex for a few years, and finally I now have a decent house and garage to facilitate building up this parts bike into a GP200 racer.

I've tore the engine down recently and began the rebuild. I've got the cases pretty much all cleaned up and the transmission bits looking well enough. The crank on the other hand had some melted seals and notchy feeling bearings so made some progress on the rebuild of that tonight.

I had a horribly hard time locating all the factory crank bearings for this bike this time around. I ended up just getting quality brand bearings without the locating pins installed and had a buddy at a machine shop work his magic and put a hole in my new bearings. Also luckily came across a supplier of 0.100" spring pins.

I FREAKING love my harbor freight press... hahah.... 20 tons of pressure makes a crank press apart and together like butter.

Nice and shiny looking...

Haven't got to the hard part yet of the crank reassembly. Going to wait until I can grab a few V-Blocks and a qualified flat surface from work before I start pressing it all together and hopefully achieving that 0.002" tolerance of runout if I'm reading right.


More to come....

P.S. If this post makes no sense at all I apologize. Some Wild Turkey 101 snuck it's way into my glass a few times tonight...

[Alan H]

Welcome to the asylum.
The 185 is a nice bike - a good mate has one and I was very surprised at the performance when I had a go.
Good luck with the crankshaft.

[wadarush]

Made some more progress on the crankshaft...



Got it mostly assembled while adjusting the alignments along the way as best as possible. Best alignment I could muster out of the first half of the crank was 0.001" which got me worried since I was already half way to the Suzuki established tolerance of 0.002" total run-out. After assembling the crank to the point in the picture i only had 0.002" of total runout. I was only measuring the run-out at either end of the crank and adding it together which is what most of my internet research has told me to do.... I've definitely lost faith in majority of the internet postings about aligning a two stroke crank because majority of them tell you to only measure run-out at the ends of the shaft. This is B.S. because it's possible to have an extreme case of run-out inboard of the ends while maintaining a reasonable run-out at the end of the shaft...
This is exactly the case. At the moment I have 0.002" of run-out at the ends of the shaft but if I look inboard at the inner journals it's all over the place... possibly more than 0.02"...

Not sure at the moment how I'm going to tackle this but it probably involves tearing it apart again and starting fresh. Possibly going to have to use my work related connections and look into piecing together some kind of a jig to press this puppy together straight.

I've got another crank laying around that I believe hasn't been taken apart before. Might have to use this one as a template...

[wadarush]

Might give up on the crankshaft alignment for the weekend and concentrate on getting the frame in order...

Pieced together a make-shift sandblasting booth yesterday.


Going to have my way with the frame, swing-arm, and who knows what else...
Sandblasting is fun

[wadarush]

Made a bit more progress on the crank but then discovered the next downfall that will need to be adjusted.
I now have all the run-out taken out. Only 0.0015" total run-out.

But now I've discovered that I'm 10 degrees off cylinder to cylinder.
So now I need to think up some kind of way to clamp one cylinder's portion of the crank in a vice and some how rigging up something to hold the other half sturdy enough that I can whack it around with a brass hammer.

Slowly but surely... she'll get there...