GS(X)-250E Motarding.

[mike-s]

I've seen people cafe up bikes like the gsx quite often, and as nifty as that looks, it just doesn't feel like my cuppa tea. Ever since i saw that someone on a sportsbike forum i am also on went and successfully went and converted a ZX-10R to a absolutely mental motorcross bike, i have always had a little voice inside my head telling me i should consider doing that to a road bike as well. Although I must admit i wouldn't start with anything even remotely as crazy as a sportsbike when doing this.

Now it seems that the GSX-250 is working reliably, i want to take the lines from something like this (this is my actual bike):

to something half resembling this:

It's something i've wanted to do for a long time, and the way I am going about it, if it turns out to be a bad modification, i can just swap the parts straight back, no harm, no foul. I have already gotten a pair of shocks that are 3.5cm or so (1 & 1/3 inch-ish) longer and have a lot longer travel than the stock ones. I've also gotten hold of a pair of forks for a TS-185 as well as a pair of stock forks for my gsx-250. I plan on using the longer fork inners & valving from the TS-185 along with the fork outers from the GSX so i can retain the front brake and other hardware (the ts-185 has a drum front . I'm initially going to keep road tires on her until either 1) i wear them out or 2) i've taken her dirt-squirting and i like the way she behaves and figure i should go the whole hog and add knobbly tires as well as fabricate myself a bash plate to protect the engine and exhaust.

There are a couple of other things i wish to do as well, namely relocate the choke operation from directly on the carbs, up to the choke gizmo that was on the switchblocks i replaced the gs250 ones with (from a gs500), as well as sand back and repaint a spare set of plastics i happen to have for the bike. Though i admit the last bit is going to be a log and slow process as i find the time to do it all. Aside from that, hopefully this won't take too long as i've got most of the hardware sitting & ready to go.

For those whom wish to follow this, thus far I have already swapped the stock 2-1-2 exhaust for a single sided one.

 

[mike-s]

Well i had a fun time in the garage this afternoon. Took the crashguard off as well as all the screws holding the sprocket cover on and got a bit of measuring happening.

Here is a pic of the proposed new rear shock, for those wondering it's on the second highest preload of about 5-6 steps, I'll probably be backing it off one or so as it's a moderately stronger (it's the front shock from a quad bike) and it's 3-3.5cm longer at this preload setting.

Chain has 2.5cm clearance at the moment

Here's my guestimate of the rear geometry with this new shock.

I am going to likely have to put one of those nylon chain guards there as it appears according to my half educated/hopefully accurate drawing that i'll have 15-16mm or so space between the swingarm and chain with the new shock. [edit] yes i am aware i may have naffed the accuracy of the rear sprocket/chain slightly, but still the measurement of clearance after i ammended it (not shown) is still within .5mm of what i wrote earlier, now it's about 14.5-15.5mm of clearance instead.[/edit]

After i got that far with the shocks i figured i should make a start on the forks and see what i could make of them and if i spent my money well or badly. The "broken" gsx fork was an peice of cake to take apart compared to the headaches i've had in the past. The ts-185 forks were a right bastard, with the spacer tube having corroded solidly in place, taking a lot of "penetrene" as well as coercing with a mallet and a screwdriver. I have the spring of one out, but for the life of me i CANNOT get the valve to seperate from the bolt at the bottom of the tube. I have used a vice attached to a workbench to grip the outer tube and put a scissor jack underneath and pushed up and had a go at it with a hex key, but it just spins.

I then sprayed in a bunch of penetrene inside the tube to loosen any corrosion between the valve and the bolt, reassembled it up tight and then tried using trailer tie down straps with the hooks attached to the top of the fork tube in a removal recess, looped down and around bolts firmly screwed into the side of the tube and ratcheted it as tight as i could to put as much pressure against the valve as possible, no dice.

Now i'm leaving the bastard to soak for a few hours and may attack it again tomorrow. I'm also going to go in search of an 8mm socket attachment that can fit my rattle gun in order to try and persuade that sonofabitch to come out.

Any other methods i could try? I've done searches on google for specifics or quirks relating to this particilar model, but it seems a "plain old fork" from what little i can find on the net about these things.


What's the bet once i get this one apart the other one is going to come apart as-smooth-as-can be

 

[spyug]

Interesting idea. I'll be following along on this one. I have seen something similar but I'll be danged if i remember exactly where. What got my attention was that it was a GSX-R 750 with big knobby tires and studs.....talk about an ice racing monster!

Good luck with it.

Cheers,
Spyug

 

[Flaming Chainsaws]

Subscribed! Can't wait to see what happens .

 

[Guest]

Show us what you got Mike! I considered longer forks and shocks for my scrambler in the back of my mind but dismissed it because it'll be road only, so very keen to see what you do...

 

[Charlie G]

Hey Mike, I'm along for the ride here as well. Cheers!

Charlie G

 

[mike-s]

Got the Metric hex socket set in my lunchbreak today (Kingchrome Part # K5023) as well as a 3/8 to 1/2 adapter as i haven't a clue where my one has walked to. Am happy getting the Kingchroke set as it is about as good as sidchrome from my experience and others value it just as highly, but it cost me 1/2 as much as a generic set from an autoshop and 1/4 that of a genuine sidchrome set, I just got lucky that it was dirt cheap.

Will hopefully tonight take pics of the disassembled GSX forks as well as the (hopefully taken apart) TS forks, at the very least i'll take a pic of the setup i'm using to compress the springs to provide tension against the valve

 

[mike-s]

Using the rattle gun was a brilliant move, it's out and including putting on the strap it took 15 minutes, tops.

Here is how i pre-loaded the fork springs so that the valve would stay put when i tried to remove the bolt.

Using the hex socket and my electric rattle gun just like so

It's out!

The TS-185 fork taken apart.

Here is the GSX fork next to the TS fork. In each component, the GSX gear is on the left. I find it interesting that the GSX spring is longer than the TS spring despite the TS fork being longer. But then again the GSX is about 30kg heavier than the TS.

I'll be doing an experimental reassembly shortly with the inner fork and valve from the TS and the rest from the GSX.

 

[Guest]

Definitely getting interesting.

So, just in case I'm confused... you're using the lowers to retain the same brake setup of the GSX but using the sliders from the TS to get some extra ride height? Neat stuff

Only thing I can really say is don't forget to extend your side stand and centre stand if you're retaining it

 

[mike-s]

I may have to put in an extra couple cm of pre-load and increase the fork oil by about 20cc or so to compensate for the extra weight on both the compression and damping but that extension is exactly what i'm planning on doing.

Retaining the brakes, wheel and mudguard both improves on the frankly crap braking ability that a TS has, which would be made worse by the increased bike weight. As well as reducing the cost and complexity significantly, as i won't have to worry about the cost of a new axle, rim or triple tree.

As to the sidestand, that was something i've already been thinking about. As it is the sidestand on this bike is exceptionally short and cants the bike right over. However the centre-stand has a fair bit of height to it and with the front wheel on the ground the rear wheel sits about 4 and a bit cm off the ground. If i go about this the right way i may be able to easily make do with the centre-stand for a while until i get the side stand suitably modified. Failing that i could just keep a block of wood handy in my backpack and use that under the sidestand until it's tweaked.

 

[Flyboy]

Interesting, I will be watching for sure.
I think the easiest would be to turf the center stand off all togerther, never saw an off road with one anyway, and build a suitable spacer to bolt in between the side stand and the frame, and use longer bolts to secure the side stand.
If the bike is leaning excessivly the side stand is probably bent, it happens with age.
Check where the side stand itself bolts onto its bracket, you will find that the two sides either side of the stand have opened up, leaving the stand itself with a lot of side to side movement, this is what creates the excess lean.
Easy enough to fix with a bit of heat and a big hammer, just hammer them closed again so the stand itself fits nice ad snug with just enough clearance to operate without binding.
You will also find the pivot bolt holding the two parts together is worn, allowing the movement, replace/bush whatever, but remove the play there to.
Hope that helps a bit.

 

[Guest]

I'm guessing it's also possible a sidestand off a dual sport of some sort may bolt on and should be longer than the OEM...

 

[Flaming Chainsaws]

I'm guessing it's also possible a sidestand off a dual sport of some sort may bolt on and should be longer than the OEM...

Or just put a wood block under the sidestand .

 

[mike-s]

A little progress made today, both good and bad. Unfortunately i didn't get to spend more than a couple hours in the garage today.
Some basic cleaning up of parts was done, I've determined that the fork retaining bolts are different sizes,with the TS having a 14~ish mm head and a 9.5mm thread, the GS has plenty of meat in the fork lower and i'll be able to size up the holes without a problem.

Further cleaning up of bits got me deciding to try and take the fork seals out, which confirmed something i've been worrying about, The fork oil seal in the GSX fork, at least the left one, is rusted in there SOLID. I bent a small cold chisel just trying to lever/hammer the old seal out. Have soaked it with pentrene and will do the same again tomorrow morning and evening, etc. And yes i took the fork seal retaining spring out.

But i don't fancy my chances of being able to make this a swappable mod, not unless i decide to go and buy another pair of GSX forks, which i may not even need. Then again i could continue and use the current mangled bottom end as a practice run and decide how hard it is to do, and get the conversion process right and then go ahead with the existing forks. THEN if i don't like the conversion, I can go and buy an unmolested pair of forks.

And no pictures of the rusted solid fork seal, i've already done some pretty decent mangling and it isn't a pretty sight.

 

[hillsy]

What about using the GSX damper rods? That way you don't have to mill out the fork lowers to accept the larger TS damper bolt.

 

[mike-s]

That's a fair question, and aside from the fact that i'm pretty sure the valving is a slightly different diameter on the gsx compared to the tx, the question has to be asked about the advantages gained from using the valving from the road bike and only the TS's fork inners. Not a lot to be gained apart from an extra 4cm of ride-height due to the longer tubes as I am going to be limiting the stroke by using roadbike valving. Just having extra ride height isn't a big help as I've got longer stroke shocks to fit on the rear.

 

[Woodsy]

When i take my bike off road the centre stand bangs away on the frame with every small bump, i'm tempted to take mine off because of it, might be something to consider.

 

[mike-s]

Well as you can see in the top picture the centre stand JUST touches the exhaust when fully down, so that's another reason to think about not using it, though i'd happily take to the centre stand with a round file and cut a slight insert out. Or just not use it unless i really needed to.

Popped into the garage this morning on my way home from nightshift and wanting to only do minimal work as i was quite tired i just took a couple of photos to help figure out how hard it would be to mount a bash-plate under there. From what i can see it will be quite easy to do aside from the big fat exhaust sitting under there. But i should be able to get something put together easily enough. I'll do it after all the other modifications like sorting the suspension are completed, but it looks simple enough.

I can get some cardboard and make a mockup to get the dimensions right and then to get a 50x50cm 4-5mm sheet of aluminium and i should be well underway. That is once i clean up all the oil and crap that has accumulated under there.

 

[Guest]

Hmmm... bash plate... that may not be such a bad addition to my scrambler!

If I can get my exhaust made up like I want it, I'll have no exhaust clearance issues either... have you considered a different exhaust more inline with a motard style?

I'm gonna guess that you've already realised it will restrict access to the oil filter and maybe the sump plug depending on how long you make it...

 

[mike-s]

I'm very much aware of the whole "access" issue, and something like this, this or this answers that issue. The one thing that is very important is to NOT excessively restrict airflow as from what i remember around 1/3 the cooling is done via the sump, hence a lot of finning down there.

I'm going to certainly be making a few calls around and see what i can do/get. The guys at http://www.obrien-aluminium.com.au/ are starting to sound an attractive prospect and if i can give then a basic design to prefab, including pre drilled cooling holes along the front, along with minimal bends i should get it at a minimal cost. However i shouldn't get ahead of myself and just get a few ideas together for a bit further down the road, excuse the pun. However if the prefab work costs a bit of money i might just stick with getting the base sheet off them and going at it myself.

I like the idea of 5083 alloy, but a high magnesium alloy (about 4-5%) like that can start to cost a bit and i might be better sticking with 5mm 5005 with it's sub 1% magnesium as it's a lot cheaper. I'm going to do my best to avoid using diamond plate unless it is substantially cheaper than other options.