2008 GS500F + full exhaust + K&N + rejetting

[drewbytes]

This weekend I've modded my 2008 GS500F. After reading as much as I could from this forum and the Wiki I decided to do exhaust, K&N filters and re-jet to suit the mods. Other dyno results point to approx 7-10 hp gain at the wheels from these mods which isn't bad considering they dyno at 35-40 hp standard.

First off was an exhaust from Formula 1. For $720 delivered I got a complete exhaust, chromed headers + mid pipe + polished allow muffer. Initially I wanted a Jardine or Vance & Hines exhaust which is what the guys in the USA use, but I couldn't find one for the 2008 model so I decided to buy local.

Removing the standard exhaust was very easy and quick. However I struck a hurdle putting on the new headers. The flange on the original exhaust is very thick and on the new headers very thin, meaning the stock header bolts were too long to be screwed in all the way. A trip to Bunnings to and I bought 4 x 8mm nuts which spaced the bolt out enough to screw in properly.

Started up with the exhaust and I grinned, certainly loud. Took it for a short ride to make sure ok and it's certainly loud - maybe too loud.

Next, remove the fuel tank to get at the carbs. I followed instructions from the "Poor mans rejetting pictorial". Spent a few hours removing all the necessary stuff to get the carbs removed from the bike. It was pretty quick apart from it took me a little while to work out how to get the choke and throttle cables removed. I labelled everything as I went with electrical tape and a small note with a numerical order to make sure I wouldn't forget anything or do out of order.

Next problem was getting the cover off the carbs to get at the jets. For the life of me I couldn't remove the 8 x Philips head screws. I ended up stripping most of them badly. To fix I hacksawed across each bolt head, and used a flat head to remove quite easily.

Replacing the jets was quite easy, just screw out and replace with new jet, except for the main in which the jet is part of a bigger jet and has to be removed from that first.

After putting the carbs back in, I put the twin K&N filters on which means you no longer need the stock airbox and single filter which is apaprently quite restricive.

Going back together was easier than pulling apart. Took 1 hour to put it back together. Went to start the bike and it cranked over but wouldn't start. Bugger, I was thinking I'd have to strip and check everything. After a moments thought I realised I hadn't turned the pet-chicken screw back on under the tank. Fixed that and started first time.

Took it for a decent ride and gave it some stick to test out. Stock the jets from 2004 onwards are 17.5 pilot, 60 mid mains and 130 mains. All the advice points to 22.5, 65, 147.5 was the go with good exhaust and K&N's so that's what I did. Today is another scorcher here (40c) so it's hard to tell how much effect the mods had, and whether it's jetted correctly.

I have a feeling it may be a little rich, possibly need a 145 or maybe even a 142.5 main jet. I'll ride for a few days and see how it goes, then rejet it if necessary. I think I could rejet quite quickly next time, possibly without even removing the carbs from the bike. I'll update the thread with the results after more testing.

If any GS500 owners have any questions about the process I'd be happy to help. I am in no way a mechanic, so if I can perform this myself, then anyone should be able to give it a go.














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[Bluesmudge]

Damn your bike is clean!!!!

[jtolentino637]

Great pics. nice mods

[ohgood]

any year gs500 exhaust will fit on any other (V&H, Jardine, etc) some need a flange, some are full, and don't.

did you really paid $720 for a gs pipe ?

i'm on the wrong business !

nice clean gs you have thar, enjoy the rumble

[drewbytes]

any year gs500 exhaust will fit on any other (V&H, Jardine, etc) some need a flange, some are full, and don't.

did you really paid $720 for a gs pipe ?

That's $720 AUD, which is about the same price of a V&H or Jardine exhaust shipped to Aus. The pics I've seen of those systems is they are just painted like the stock exhaust  - this is full chromed.

I contacted V&H directly and they told me they don't make one for a 2008 GS500. One would think they would know and could of informed me of that - weird.

Edit: Realised didn't have my location in profile hence the confusion. Now updated.

[Bluesmudge]

Yeah, V&H is painted, Jardine is stainless though, very nice.
It doesn't really matter how much it costs if you are happy with it. Looks great, probably sounds great and its unique.

[galahs]

Nice pics!

I found ya 147.5 too rich. I went 20 65 145 and its pretty damn good.

[galahs]

What are you going to do with your cracnk case breather tube?

I made an oil catch bottle for mine
http://gstwins.com/gsboard/index.php?topic=5180.msg428043#msg428043

[drewbytes]

Thanks Galahs. Good idea on the breather. I'm thinking of trying a 145 also to see how that goes. Only problem is buying jets and then if they don't work they're useless.

Do you have any tips on how to tell if it's running rich under power? My gut feeling is that it is, but it would be nice if there was an easy way for me to tell.

[galahs]

Spark Plug Chop is about the only method available if you don't have an oxygen sensor
Basically run it at wide open throttle in 1st gear, hit the kill switch, coast to the side of the road. Pull a spark plug and see how it looks. Blackish = rich Whitish = lean


Jetting carbs is a black art. I found mine by finding what was the lowest jets I could use without loosing power.

[5thAve]

Lovely pipes!  I was hoping to get a set of Laser Deeptone -- but getting them to Canada costs too much $$$. I am going with Vance and Hines this spring.

[Helmet27]

Hey, nice picks mate, i might have to have a look into an exhaust and set up like yours

[fred]

The floats are supposed to be white? Wow, your bike is really really clean. How do you keep it so clean? You must have barely even gotten dirty taking that thing apart. Looking very good. I like the shiny shiny exhaust and those filters are cool!

[drewbytes]

Fred, my bike is just over 5,000 kms (3100 miles) old. I give it a wash every weekend, noting special, but I do wipe down pretty much everything I can reach.

[ohgood]

any year gs500 exhaust will fit on any other (V&H, Jardine, etc) some need a flange, some are full, and don't.

did you really paid $720 for a gs pipe ?

That's $720 AUD, which is about the same price of a V&H or Jardine exhaust shipped to Aus. The pics I've seen of those systems is they are just painted like the stock exhaust  - this is full chromed.

I contacted V&H directly and they told me they don't make one for a 2008 GS500. One would think they would know and could of informed me of that - weird.

Edit: Realised didn't have my location in profile hence the confusion. Now updated.

that's odd. maybe their help desk has a flunkie, cause the gs's exhaust hasn't changed since 1989. you can take any year gs exhaust and stick it on any other year. may need to remove the center stand for some, but it will work just fine. (clarification)

[Helmet27]

Hey drewbytes, or anyone else on this thread, do you know the internal diameter of the pipe that connects to the exhaust??? Or if there is a double pipe in there (coz the diameter of the pipe at the exhaust is larger than at the header junction, cheers

[fred]

Fred, my bike is just over 5,000 kms (3100 miles) old. I give it a wash every weekend, noting special, but I do wipe down pretty much everything I can reach.

Ah, I see, so it isn't old enough for you to loose interest in cleaning it yet... When I first got my car I cleaned it all the time, but 100,000 miles later I pretty much just occasionally scrape the crud off the windows so I can see... Both of my GS500s were already long past this stage by the time I got them, so I've never really cleaned them...

[The Buddha]

Too rich - what throttle position is it acting rich? Idle ? low end ?
20 pilots is supposedly the right one. 22.5 will make it over rich 0-1/8th throttle.
And we dont touch mids, we put a washer under the needle. 147.5 is about right for the mains though.
65 mids can leave you rich in the mid range and 145 mains will of course be right up high with 65 mids in there.
Cool.
Buddha.

[drewbytes]

Thanks Buddha - great info. Idle is rich, don't need choke to start and idle like I used to. But the main spot is at full throttle around 6-9k it feels like it's way rich as sometimes it feels like it's held back from over fuelling. But my gut feel is it's rich everywhere. BTW I am at 450m elevation (1500 feet) if that makes any difference.

Before your reply I was thinking of going back to 20 pilot, 62.5 mids, and 142.5 mains. I had even considered putting the stock 60 mids back in there. I don't really want to do the washer thing as it means pulling more apart that I might stuff up.

[fred]

Thanks Buddha - great info. Idle is rich, don't need choke to start and idle like I used to. But the main spot is at full throttle around 6-9k it feels like it's way rich as sometimes it feels like it's held back from over fuelling. But my gut feel is it's rich everywhere. BTW I am at 450m elevation (1500 feet) if that makes any difference.

Before your reply I was thinking of going back to 20 pilot, 62.5 mids, and 142.5 mains. I had even considered putting the stock 60 mids back in there. I don't really want to do the washer thing as it means pulling more apart that I might stuff up.

Putting washers on is easy. I'd never done it until this past weekend and I had no trouble. I didn't even have instructions in front of me, I just read some forum posts beforehand and was able to retain enough to just do it. It really is easy...