How To Swap Large Fuel Tank In Place Of The Small Fuel Tank-Update 6-14-11

[ben2go]

No smoking or open flames on this project.

New model GS500 larger tank swapped to an older model GS500 with the smaller tank.

Now is a good time to swap out the old petcock for a 2004-07 Honda CRF250X petcock.See this thread. http://gstwins.com/gsboard/index.php?topic=56352.0

I have a seat that I am in the process of redoing to fit the new style fuel tank.I will post a write up on that when I have time to finish it.Please make note that there is enough variance in Suzuki's tolerances during the manufacturing of these motorcycles, that make it difficult to modify a seat without having the bike in front of me.SO, I am very hesitant to modify someones seat to fit my bike and then send it to them.If you are in the area,I can cut down the front of the seat to match the fuel tank and adjust the cover.


Tools

Hack Saw
Mill Bastard File
Hand Drill
9/16 and 9/32 Drill Bits
Flat Head Screw Driver-Long
#2 Phillips Screw Driver
Metric 3/8ths Socket Set
Metric Allen Wrench Set-optional if you use allen head bolts listed below
8 inch Adjustable Wrench-This is used to help bend the brackets.
Sharpie marker or a pointed tip marker

Supplies

New Style Tank
New Petcock-If you are planning for a new one.
New Fuel Lines-I use 1/4 inch or 7mm ID for a push on fit.5/16 inch or 8mm will work but some require hose clamps.
Two Bolts-You will need two bolts that are 1/8 inch longer than the original tank bracket to frame bolts.I used allen head type bolts for clearance around the bolt, and less chance of a tool slipping and scratching the tank.Zinc plated/coated grade 5 bolts are fine.Ace True Value is where I got mine.
1 Inch Wide By 1/8th Inch Thick Steel/Aluminum flat stock-12 inches long-Aluminum of the same dimensions will work.It will be easier to bend.Purchase from any hardware or home improvement store.Also,check with scrapers,machine shops,welding shops,or body shops.They may have freebie off cuts.
1 sheet of 320 sand paper-Doesn't have to be 320 grit.220 to 600 grit will work.Just want paint to stick.
Paint for the brackets.-freedom of choice here.


Only neded if the tank rubs the frame.
Two Bolts-1/8th inch longer that the factory bracket to tank bolts
Four Fender washers that fit bolts
I get all my hardware from Ace True Value hardware store.



First off,let me clear up some false statements made on this forum.

1)Yes, you can use the old style tank petcock.I do not know if the California models are different.

2)Yes, you can use the old style seat with the new style tank without modifying it.My pics prove it.

3)Yes, you can use the new style seat, but it stands way up off the frame, and looks really out of place.I will try to get a pic of the 04 seat I have, with it on my bike.

4)Yes, you can use your original fuel cap from the older tank.

5)Yes, you can get away without using the brackets to hold the front of the plastics on.They will crack over time without them.These things are to scarce, and expensive, to take a chance on skipping a half hours worth of work.

6)No, the tail plastic do not need to be modified in any way.NONE!

7)No, your seat latch does not need to be modified in any way.NONE!

My bike will be different than some, as mine came to me already modified with the 04 tank.I had to redo it all.The tank was buzzing against the frame like crazy.It also damaged the paint on top of the frame.I touched it up.The original tank would have done the same thing.

If you are going to be doing this swap yourself,I am going to go out on a limb,and assume(@ss-u-me) that you know how to remove the fuel tank.If not,I suggest getting a Clymer Manual for the GS500.

NOTE, before I get into this.If your bike has been dropped or wrecked,be prepared to tweak the bracket.Mine is twisted in away that makes it hard to bolt the tank on.

THIS IS BEST DONE WITH AN EMPTY TANK AND A HELPER THAT IS CAPABLE OF HOLDING THE TANK WHILE YOU MAKE ADJUSTMENTS AND/OR TURN ON/OFF THE TANK PETCOCK.

First thing to do is completely remove the tail plastics and put them away in a safe place.DO NOT LEAVE THEM HANGING ON THE BIKE WHILE YOU WORK!THEY WILL GET SCRATCHED!Remove the tank and be sure to shut off the tank petcock to prevent leaking fuel every where.Horizontal is the off position on the tank petcock.Remove the tank bracket,bushings,washers,petcock, and fuel cap.While you are there might as well clean and lube the fuel cap.The tank vents through the fuel cap,on older bikes and non California bikes.Here is the link to my "How To" on disassembling and cleaning a fuel cap. http://gstwins.com/gsboard/index.php?topic=41061.0

Check and clean the tank petcock.A new strainer is available from Suzuki if yours is plugged or broken.They are a tight push on fit.Now reinstall the bracket,bushings,washers,fuel cap, and petcock on the new fuel tank.

Now is a good time to install a new frame petcock, or do the 2004-07 Honda CRF250X petcock up grade.How to link is above.Well worth it to eliminate fuel starvation caused by the crappy factory vacuum petcock.It may also eliminate some running issues caused by an internal fuel leak, allowing the vacuum line to suck to much fuel into the carbs.

Temporarily install the new tank.Make sure that you have a minimum of 1/8th inch between the tank and frame.3/16th of an inch is even better.Then lets move on to making the brackets for the tail plastics.

If your tank needs more frame clearance then keep reading.If not,skip to making brackets.

Suzuki had very loose tolerances on their lower end bikes which vary greatly from bike to bike.The 02+ got a little better and the seat was more form fitted to the fuel tank.The older bikes had very loose tolerances which causes the body panels,seat,and tank to not mate up perfectly.This is why I can not do a seat for someone's bike and use mine for the mock up.I have to have the bike in front of me.My bike has been dropped a few times before I got it and the tank bracket is bent enough that the tank rubbed the frame.

If you need more clearance between the tank and frame,add the four fender washers and longer bolts I mentioned in the supplies list.The fender washers go between the bushing and the tank.The longer bolts compensates for the increased height.Just make sure they do not protrude enough to touch the gas tank.If they touch,they will rub a hole in the bottom of the tank.


MAKING BRACKETS

This isn't precise fabrication work.If you make a mistake it shouldn't cost anything, but time to make another bracket and some spare metal.12 inches should be enough for 4 to 6 brackets.

First drill a hole in one end of the metal for the bolt.1/2 inch in from the end of the metal to the center of the soon to be new hole should be fine.I used a 9/32 drill bit.5/16 may work,but the bolt will need a fender washer.Next bolt the metal to the tank, and keep it even with the bottom of the tank.It may be necessary to bend the metal out slightly to clear the frame.Once it's tight and even with the bottom of the tank,bend the metal out and then back in,making an offset.Now temporarily place the side plastic back on.Make sure to snug the bolt up that holds it on.Bend and adjust the metal so that the little plastic stud is in the center of the metal.Make sure that the metal is square and parallel to the flat spot at the base of the plastic stud.If everything looks good,mark the location of the plastic stud on the metal.Remove the side plastic and metal from the bike.Last thing to do is drill the hole in the bracket for the rubber grommet where you made your mark on the metal.I used a 9/16 drill bit.A 5/8 drill bit would work, but the grommet will be really loose.Once the hole is drilled for the grommet,measure and make a mark 1/2 inch from the edge of the hole.This is where the excess metal needs to be cut off.I used a hack saw.A dremel or angle grinder works also.Repeat on the other side.Finish up by sanding and painting the brackets.

I don't have pics of the brackets being made,but you should get the idea from looking at them.

Here are the pics of the old style tank bracket mounted on the new style tank.Please over look the gray spacers.My bike came with only the two top bushings and a bent bracket.I made the gray spacers.I have the proper repair parts.I am just to lazy to install them.





Here are my brackets.Remember what I mentioned about dropped bikes causing bracket problems.My tank sets to one side more than the other so my brackets compensate for that so my side plastics line up.I have a new tank bracket waiting to be installed.I may have to remake my tail plastic brackets.





Here is how the brackets line up when installed.Note the Honda CRF250X petcock bling.





Side plastics installed.Make sure you have a 1/8th inch gap between the tank edge and side plastics.They will rub and crack.






Here is my original 89 seat on my 89 GS with an 04 fuel tank.







There are a couple more pic in this album. http://s205.photobucket.com/albums/bb17/ben_2_go/Motorcycle%20Stuff/Tank%20Swap/
I'll post a pic of an 04 seat on my bike as soon as the weather clears up and I can get back outside.

[Tombstones81]

^^ The man!

If I end up having to replace my tank, this helps TREMENDOUSLY!
As everyone knows, GOOD LUCK finding an older style tank in good condition not needing a paint job that isnt almost as much as the ppl paid for their bikes, vs the sweet conditions of the newer style ones for decent prices.

Bookmarked for future reference.

[ben2go]

04 seat on my 89 to show how bad it fits.There is no support under the rear of the seat.A rear passenger could bend and break the seat pan or latch.

There are more pics in my album.
http://s205.photobucket.com/albums/bb17/ben_2_go/Motorcycle%20Stuff/Tank%20Swap/

[The Buddha]

Ben2go: You can weld these ears to the tank carrier bracket. That way they wont swivel.
Cool.
Buddha.

[ben2go]

Ben2go: You can weld these ears to the tank carrier bracket. That way they wont swivel.
Cool.
Buddha.

Yes, but few that do this swap have access to a welder like us.

[jeffdodge]

About the seat... You can shave the bottom of the latch and it will work better. Did it to mine.

[ben2go]

I have been waiting for parts for my bike since I did this write up.As soon as I get my bike up and running again,I will do the seat mods and do a write up.

[codajastal]

This info is invaluable to me right now. It should also be stickied.
Ben2go did you ever do the seat mod for this bike?

[ben2go]

This info is invaluable to me right now. It should also be stickied.
Ben2go did you ever do the seat mod for this bike?

I did but I sold the seat soon after modifying it.It's pretty easy and all I used was a staple gun and 3M contact adhesive.I pulled the seat cover back to where the front of the seat pan turns and goes back.Then I folded the foam and cover back and held them in place with shipping tape while I marked the plastic seat pan and cut it.Then I used some 120 grit sand paper (any grit will do) to smooth out the cut.Then I used a good heavy pair of upholstery scissors to trim the foam back.I left just enough to fold over the edge of the seat pan.Next,I used the spray glue on the bottom of the seat cover and seat pan where the staples go in.A little over spray on the pan won't hurt.It usually dries hard so no sticky crap will be there.I started stapling at the bend of the seat cover making sure to pull the seat cover tight but not so tight that it stretches the cover.If it's pulled to tight,it will split over time.Once the seat cover is stapled down,I let it set for a couple hours for the glue to dry.Then I cut the excess cover off making sure to leave .25 inch between the staples and the cut line.I need to do another one.I may do a write up on it.I'll see if I can get it in the next couple weeks.It took me about 1.5 hours to do including the hour dry time for the glue.

[codajastal]

Cool, I would love for you to do another and post pics before I attempt it.
Cheers


Sent from my iPad

[Calpantera]

I wish I had seen this before I got that 99 tank for my 93, I would have gone with a bigger/cleaner tank.
Great thread!!

[mustangGT90210]

I must have been lucky, my 04 tank and seat bolted right up no problems. I've got some blocks of wood as temporary spacers for the rear seat supports. Also no tail plastics but that's just personal preference. I'll add some pictures if anyone is interested!

[ben2go]

I must have been lucky, my 04 tank and seat bolted right up no problems. I've got some blocks of wood as temporary spacers for the rear seat supports. Also no tail plastics but that's just personal preference. I'll add some pictures if anyone is interested!

All 89-00 GS have the body line issue when running the new style seat.Some people have modified their rear frame to lower the seat to follow the body line of their bikes.Most people don't have access to a welder to make those changes.You aren't running body panels so no big deal.Make up some spacers out of PVC or what ever is laying around as you suggest.

[Philipp]

Hi Ben2Go

Absolutely invaluable in fact I got the same 05 tank just now as you have, my question is what are the dimensions of your tabs for the plastics?

Thank you
Philipp

[ben2go]

You're welcome and thanks.I wasn't the one who came up with the mod.I just put it in pics as the way I did it.

I don't have measurements on the tabs.All 6 of my GS are different just enough that it won't swap around.I just eyeballed everything  and drilled the holes.Use steel.Aluminum will fatigue crack over time.Suzuki has never been keen on tight tolerances on their low end bikes.

[Philipp]

Awesome thanks you gave me massive help with this

[ben2go]

Awesome thanks you gave me massive help with this

You're welcome.