Hi Guys,
I have a Suzuki GS500FU BK4221 K4 bike. /25Kw/
My question first is how can I de-restrict it?
The 2nd. question is, is there anybody this bike with 15L/about 4Gal/ capacity fuel tank?
Thanks,
De-restrict it? Intake, exhaust, and jets. It's not like it has a governor on it, it's a ~40 hp bike lol.
He's got a European restricted bike. About 34 hp.
Quote from: redhenracing2 on November 17, 2010, 11:15:03 AM
De-restrict it? Intake, exhaust, and jets. It's not like it has a governor on it, it's a ~40 hp bike lol.
Maybe in the intake and exhaust hasn't difference. The differences are in the carburetors only.
What is your opinion?
(http://lh4.ggpht.com/_3HpGoAsF7vc/TOQqCyF4mkI/AAAAAAAABWo/R_jDTZVxHzo/s800/GS500FK4_carb.JPG)
Quote from: Paulcet on November 17, 2010, 12:08:10 PM
He's got a European restricted bike. About 34 hp.
Yes it's true, by the factory really 34Hp.
I interested in what modifications are necessary to enhance the performance to 48Hp?
I would recommend pulling the carbs and taking a look at the jets. There's LOTS of information on the forum and wiki about changing the jets. I also think that there must be some type of intake restriction as well, like a restrictor plate or something.
The carburettors are the same, just a small change in jet size. There must be some other modification, maybe exhaust or camshaft timing. Or there may be a restrictor in the inlets, between the carburettor and the cylinder head. :dunno_black:
Sledge! Where are you oh guru of European GSs? :bowdown:
Quote from: the mole on November 17, 2010, 12:47:06 PM
The carburettors are the same, just a small change in jet size. There must be some other modification, maybe exhaust or camshaft timing. Or there may be a restrictor in the inlets, between the carburettor and the cylinder head. :dunno_black:
Sledge! Where are you oh guru of European GSs? :bowdown:
Is there in this forum anybody who successfully de-restricted a GS500FU ?
Quote from: Paulcet on November 17, 2010, 12:08:10 PM
He's got a European restricted bike. About 34 hp.
I stand corrected. I have no idea what the difference is between them.
I suspect its a stop in the slide. You can open the throttle but not get it over the 3/4 for slide opening. A plastic rod inside the slide spring would do it.
Not jets, that would cause it to knock before it would cut down the power output.
Cool.
Buddha.
Pull the carb slides out, you will find 3 holes in the bottom of the slide.
The center hole is for the needle jet, so leave it alone...the outer two holes need to be sealed in order to allow the slide to raise fully.
It's usually done by drilling and tapping the holes, then sealing with a grub screw or some sort of bung....just make sure that you loctite it firmly into place, you don't want loose stuff floating about insider the carb.
I don't think that is right.
Quote from: Miraz on November 17, 2010, 03:36:53 PM
Pull the carb slides out, you will find 3 holes in the bottom of the slide.
The center hole is for the needle jet, so leave it alone...the outer two holes need to be sealed in order to allow the slide to raise fully.
It's usually done by drilling and tapping the holes, then sealing with a grub screw or some sort of bung....just make sure that you loctite it firmly into place, you don't want loose stuff floating about insider the carb.
yeah, I don't think that's right either. It's definitely some type of physical stop, either the rod in the return spring for the carb slides like Buddha suggested, or some type of plate on the intake side of the carbs, or in the airbox itself.
The additional holes limit the vacuum draw against the spring, so the slide never opens fully....plug the holes and it works properly.
There are 3rd party restrictor kits that fit between the carb and head, but the original Suzuki restriction was a different carb slide.
So, If I plug both holes in my slides I'll get more power?? :woohoo:
(I'm being sarcastic. According to the manual, if you plug both holes, you will have NO vacuum to raise the slides.)
Where's Buddha? The question about the extra holes in the carbs came up before. It seems that three holes are normal, at least on American models.
Quote from: The Buddha on October 28, 2010, 09:13:40 AM
Stock Slides have holes, 3 of them. DJ makes you block 1.5 of those. The third is the center one for the needle.
You dril lit, then tap it, then plug it. :cookoo:
Cool.
Buddha.
http://gstwins.com/gsboard/index.php?topic=54326.msg612577#msg612577
Quote from: Miraz on November 17, 2010, 06:52:20 PM
The additional holes limit the vacuum draw against the spring, so the slide never opens fully....plug the holes and it works properly.
There are 3rd party restrictor kits that fit between the carb and head, but the original Suzuki restriction was a different carb slide.
Before 2004 the carburetor can be de-restrict easily, here is some image on this page:
http://akmt.hu/sufnituning/25kw35.html (http://akmt.hu/sufnituning/25kw35.html) translated version from Hungary to English: http://translate.google.hu/translate?js=n&prev=_t&hl=hu&ie=UTF-8&layout=2&eotf=1&sl=hu&tl=en&u=http%3A%2F%2Fakmt.hu%2Fsufnituning%2F25kw35.html (http://translate.google.hu/translate?js=n&prev=_t&hl=hu&ie=UTF-8&layout=2&eotf=1&sl=hu&tl=en&u=http%3A%2F%2Fakmt.hu%2Fsufnituning%2F25kw35.html)
But 2004 and after installed carburetors has more part then older.
I interested in how can I de-restrict this (http://akmt.hu/sufnituning/13.jpg) carburetor.
Ah, according to those pictures, there's a hole on the FRONT of the slide. Definitely don't have holes there on the American version.
(http://akmt.hu/sufnituning/3.jpg)
The FU`s were low powered versions built in the factory to comply with the various learner laws that are in place in certain European countries, they are not full power versions with restricter kits fitted......they are just low power versions that have never seen more than 30 or so hp.
The carbs differ in the way of jetting and slide design, the exhausts are more restrictive and the ignition timing is slightly different so I would guess if you replace your carbs, exhaust system and the ignition advancer from a full fat GS500 you might see some gains :thumb:
The FU was never sold in the UK or the USA, Germany was/is the biggest market for the FU`s , perhaps you might get more info you need in one of their forums.
Ah, finally an authoritative answer! Thank you Sledge!
What did I say. :thumb:
Sledge, you're the man! :bowdown:
What does Suzuki mean by the FU suffix? :icon_lol:
Quote from: noworries on November 19, 2010, 03:01:49 AM
What does Suzuki mean by the FU suffix? :icon_lol:
As I know:
F it means full fairing
U it means restricted model,
In the engine is same as in the unrestricted models, but the carburetors differ between the jets from K4 and newer by the supplemental manual.
By the difference the overall performance is 25Kw 34Hp.
I wouldnt term it as a restricted model, more like a lower power model.
Restricted suggests its a full power model with non OEM mods to reduce its power.............. but the U`s never had full power to start with :thumb:
Quote from: sledge on November 20, 2010, 11:28:48 AM
I wouldnt term it as a restricted model, more like a lower power model.
Restricted suggests its a full power model with non OEM mods to reduce its power.............. but the U`s never had full power to start with :thumb:
So, does that mean it's a different engine? What exactly are the design changes that reduced the power?
I think the question here is if there is a simple mod that can turn an FU in to an F. If the engine is the same, I can't imagine it being that difficult.
Quote from: 007brendan on November 20, 2010, 08:06:34 PM
Quote from: sledge on November 20, 2010, 11:28:48 AM
I wouldnt term it as a restricted model, more like a lower power model.
Restricted suggests its a full power model with non OEM mods to reduce its power.............. but the U`s never had full power to start with :thumb:
So, does that mean it's a different engine? What exactly are the design changes that reduced the power?
I think the question here is if there is a simple mod that can turn an FU in to an F. If the engine is the same, I can't imagine it being that difficult.
To quote Sledge's post at the bottom of page one...
Quote from: sledge on November 18, 2010, 06:15:45 AM
The FU`s were low powered versions built in the factory to comply with the various learner laws that are in place in certain European countries, they are not full power versions with restricter kits fitted......they are just low power versions that have never seen more than 30 or so hp.
The carbs differ in the way of jetting and slide design, the exhausts are more restrictive and the ignition timing is slightly different so I would guess if you replace your carbs, exhaust system and the ignition advancer from a full fat GS500 you might see some gains :thumb:
The FU was never sold in the UK or the USA, Germany was/is the biggest market for the FU`s , perhaps you might get more info you need in one of their forums.
Michael