Finally, running like a top!!!

After putting some miles on the bike (about 75 or so), and after trying to get the idle right (tweaking it a bit each ride), I came out to the garage one morning to find a strong odor of gas.  I didn’t fully trust that old vacuum style petcock (even though I completely rebuilt it).  Sure enough, the cylinders were full of gas, and gas was dripping out of the exhaust pipes.

I stopped by Sport Wheels in Jordan, MN – looking for a possible replacement.  They had plenty, but the employee I talked with indicated that most of the used petcocks probably suffered the same issues.  Even after a rebuild, he said, the pot metal matting surfaces are often pitted with age.  He said (with a laugh) if I had the tooling from Suzuki, I could clean up the surfaces; other than that I could either put in-line fuel shut offs or get an aftermarket petcock.

Given I had spent 7 months on the frame up rebuild, I wasn’t about to hack around with some shut off valves.

I ended up getting a very nice Pingel petcock manufactured in Wisconsin – (part number 3311-D-AH if anyone is interested).

In addition, I replaced the pilot jets, the idle (pilot) screws, the needle jets, and the float bowl valve assemblies.

The GT250 is now idling like it came off the line in Japan!

(if you’re having problems viewing this, you can see the video on YouTube)


Polishing, sandblasting, and washing parts

As parts came off the GT250, I quickly realized I’d need to learn how to polish all the various bits of aluminum (40 years of corrosion); something I’ve never done before.

I checked out a number of how-to guides on-line.  Some folks were doing it by hand, using all sorts of household chemicals, etc.  That just wasn’t going to cut it for me (as my Dad says, “work smarter, not harder”).

Ends up it’s very simple to polish aluminum – here’s a nice video of the technique (he’s using a big electric polisher, but the idea’s the same).

I ran over to Northern Tool and grabbed a cheap 1/4″ die grinder and some buffing wheels and polishing compounds (the compounds will indicate what metals they can be used with).  The link for the buffing wheels/compounds isn’t exactly the ones I got though.  They also sell a package with two 3″ wheels and compound for like $4-$5 dollars (their site doesn’t have it listed).  Wheels bigger than 3″ really slows down the air polisher as well (probably want to avoid them).  Be sure to squirt some WD-40 or similar into the air inlet of the grinder/polisher every day you use it – else the tool really slows down.


Some of the aluminum parts on the bike have a clear-coat finish on it (usually yellowed at this age).  The polisher will remove that as well (which is fine and necessary).  They did this to prevent corrosion from forming.  You can leave the aluminum naked (but you’ll find it picks up fingerprints very easily).  Others have reapplied clear-coat to the polished aluminum.  I decided to try ShineSeal – it supposedly gives you the best of both worlds (a nice polished look and prevents corrosion)…we’ll see how it works.

I also used a sandblaster cabinet with glass beads (don’t get media that’s more abrasive or you’ll pit the aluminum).  A sandblaster cabinet can be had for ~$100 new, and a better one if you get it used.  This was used when the aluminum was really in bad shape.  You could eventually polish through it, but the glass beads made quicker work of it – after blasting it you can polish it easier.

Finally, as you polish you’ll want a rag of some sort to clean off the buffing wheel (you can see the guy in the video above doing that from time to time).  It helps from transferring the stuff you polished off to the new areas you’re working on.  One last tip, the spent polish will get into crevices and smaller details on the aluminum (like lettering).  I found it wasn’t easy to clean off until I squirted some brake cleaner on it…then it melted right off.

Here’s a before/after look at the aluminum (they are different parts, but both looked the same when I started), click on the photos to zoom in:




The tear down (part 2)

I figured it would be best to do the engine rebuild before the chassis rebuild (as there wouldn’t be so many parts floating around).  Plus – engines are a bit more fun in my mind.

Given the age of the bike (and because it was running a bit wonky when I purchased it…the left cylinder wouldn’t fire unless I had my hand over the carb), I decided to completely tear the engine down.  I was concerned that those old two-stroke crank seals were the likely culprit.

After receiving the crank seals and lower rod bearings, I brought the crankshaft and cylinders up to Bill Bune enterprises in Anoka MN to be rebuilt (the cylinders were just re-honed, as I installed new rings on the pistons…at 3500 miles, there wouldn’t be a need to bore the cylinders).

Here are a number of pictures of the whole process.  This engine is fairly simple – and thus I had no “gotcha” moments (other than a stuck stator rotor):

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My makeshift bench to hold the engine parts (used the cardboard trick below to know how the bolts go back into the right place):


The stuck rotor…it finally came off after some WD-40 soaked the shaft for a few hours:

WP_20150321_008The case in half – time to bring the crank to the shop:

WP_20150322_008Engine block cleaned and the halves back together:

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And…the pistons reinstalled (with the new rings), cylinders back on, and clutch cover back on (after polishing)…the air ram system still needs to be cleaned up:WP_20150517_004Now, on to the chassis!

Afternoon at the junk yard – and dealing with the gauges

There’s a great resource near me, Sport Wheels in Jordan MN.  It’s a motorcycle salvage yard that has acres of bikes and parts (pictures taken on a nice day February – thus the snow).

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I headed down there to see if they had any parts (or parts bikes) for the GT250.  I wasn’t looking for anything in particular; I just wanted to check out what they had, so I could take mental note of it in case that part was needed later on.  That and, well, it’s just a cool place to shop (kind of like women shopping for shoes…but actually fun…and not shoes…and I’m a guy…so, never mind).

Unfortunately, I didn’t find much.  All the GT250 parts bikes had been purchased and shipped to the U.K.  According to an employee, the Suzuki GT series has a big following over there.

I did run into an older gentleman looking at a couple of GT750 parts bikes – he’s been rebuilding various water buffalos (the nickname for the 750) for years.  We got to talking about how it’s becoming more difficult to locate some key parts for the GT’s (then again, that’s part of the fun).  He mentioned a part he was in search of (I don’t recall what it was exactly), but he claimed, “it’s rarer than unicorn teeth.”  Needless to say, that phrase was quickly added to my vernacular. 🙂

The GT series bikes have sealed gauges (the plastic lens are glued in place).  As you can see, the bike I purchased had cracked and yellowed lens.


Because I wanted to keep the original mileage, I decide to forgo looking for used gauges.  I saw on some forums that others have had success using a Dremel to remove the plastic lens.

So I started with the tach, as if I screwed that up at least I could get a used gauge – as there’s no odometer on it.  Although it took an hour or so per gauge, it went surprisingly well.  The most time consuming part is learning how close you can get to main body of the gauge (where the lens ends).

Here’s a representation of how the lens sits in the gauge (cut-away view):


 The lens doesn’t actually go into that little channel above, but rather sits on the base below it.  I believe the channel is for the glue that holds the lens in.  Therefore, once you work up the nerve to cut ever so closer to the edge of the gauge body, you’ll discover that the glue ends and/or peels off from the lens and body:

dremel bit

After the lens were removed, I contacted APT instruments in Bloomington MN.  They are a small shop near me that specializes in gauge restoration.  They aren’t too keen on dealing with these plastic gauges though (as, understandably, there’s just too much liability if they muck up a part that can’t be replaced).  But they agreed to fire some gauge glass for me now that I had the plastic lenses out.

There are a few errant Dremel marks on the tach – but the housing covers that up nicely:

gauge glass

I sparingly used some white silicone caulk to secure the glass lens to the gauge housing.

The tear down (part 1)

The very first thing I learned with a Suzuki GT250 is to loosen the exhaust support bracket (by the footpeg) before attempting to loosen the headpipe.

Sure, it looks like you can just use a big screwdriver and hammer on those nifty exhaust pipe slots to remove the pipe from the exhaust port (as I did with the Yamaha Trial 80); but after 10 minutes of hammering and spinning the exhaust pipe collar, it wasn’t coming off (all with a few choice words).  After loosening the support bracket, the pipe came off really easy!  I ended up having to have the crank shop re-thread the exhaust port on the left cylinder.

exhaustSo, after the first gotcha, the first part of the bike came apart quite nicely…



Engine out…

engine out

first frame

Be sure to take pictures of every nut/bolt/part before you move on – you will thank yourself on reassembly.  Also, put each parts section in a disposable cup(s) labeled with a permanent marker with what exactly the parts are for…at the time, you will think, “oh, I’ll remember where this goes,” but you won’t after 50 more nuts/bolts/parts come off.

The Purchase

I wasn’t looking for anything in particular, other than the requirement that it was a two-stroke.  See, I was born in the ’70’s, so I never experienced a two-stroke bike that was street legal.

At the age of four or five, my dad owned a Honda CL350, and he gave me a ride or two on it (I still remember the exhilarating ride with him – in front, holding onto the handlebars).  Sure, it wasn’t a two-stroke, but still, I was sold.

cl350  In February of 2015, fishing around eBay, I found the perfect restore candidate (probably because it was February in MN with nothing else to do).  A couple of photos from the ad:

gt250-1gt250-2In hindsight, every eBay photo looks pretty good.  The bike had about 3500 miles on it – but when you peel back the layers, you quickly realize that 40 years of “old” really adds up.

None the less, I was the highest bidder (at a fair price), and my wife and I headed down to pick it up.

On return, I built a make-shift motorcycle stand to support my ambitious plan to have it up-and-running by June 1 (a soft date, but still something to shoot for).

gt250 on standIn the meantime, I found a Haynes repair manual on eBay.  Compared to other Haynes manuals, the one for the GT250 isn’t quite as detailed and a bit harder to understand – but generally will get you pointed in the right direction.


A bit of history

I grew up on two-strokes

From the age of 7, I rode the wheels off a 1974 Yamaha Trial 80 (thanks Dad).  My parents had a nice little cabin on a lake (still do), and the adjoining pasture land was owned by my grandparents (now owned by my parents).  This is when my passion for motorcycles began.

trial 80

Back then, you could ride the highway ditches and play in the county-owned gravel pit without looking over your shoulder for a superfluous helicopter parent or a bored county sheriff…parents would only REALLY worry if you didn’t get back before dark.

It’s kind of like the documentary On Any Sunday if you haven’t seen the movie, you are doing doing a disservice to yourself.

After an engine rebuild, I still find time to ride the Trial from time-to-time (along with my family). My wife says I look like a big silver-back gorilla riding it.

I graduated to a 1986 Yamaha YZ80 after out-growing the Trial (thanks again Dad).  This is when I fell in love with two-strokes – I had no idea that a pipe with a real expansion chamber could produce a permanent smile as the RPM’s went up.  My dad took one ride on it, got off (shaking his head), then muttered something about me ending up in the morgue as he walked away.  It was the last time he rode it.  At that point, I knew I had a winner!



Later I owned a couple four-stroke four-wheelers…I raced the local district 23 hare-scrambles on a mildly built 400ex (bored, high-compression piston, etc) with some sweet Elka shocks; and although it was great fun in the woods, I missed the two-stroke light-switch power in the open.

So, I was drawn to a grandfathered in two-stroke street bike, I found it last February on eBay – in Iowa no less (a three hour drive to pick it up).