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Littering And...........
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Discussion Starter · #1 ·
I have found a WC Gsxr 1100 finally. Completely stock except hindle full exhaust. Anyway the guy that has it is throwing in a set of FCR 41's for $400. Fits the Gsxr and already have the attachments to run some uni socks.

The question is about the carbs themselves. Are they hard to rebuild? I know these have the accelerator pump and what not. I'm new to the FCR type though. Never had a set. So any advice/help on the subject would be great. Hell if anyone has good reading material they can point me too would be great too.

I'm about to hop on google to see what I can find but just wondering what you fellas have had experience with.
 

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sickboy
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3,544 Posts
They are as easy as any other carb, usually you dont even have to replace the AP, they dont usually tear that easy but even if they did its just a diaphragm and a spring/rod and thats it.
 

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sickboy
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3,544 Posts
Couple random tips off the top of my head...
Look at this pic, see right ABOVE the "motorcycle race use only" where it looks like gasket goop is coming out. Thats because the carb does come apart there but its not really supposed to unless ABSOLUTELY necessary. You can not order that gasket from anywhere so if you do take the carb apart there you are going to be dicking around with goop and rvt and god knows what else trying to get it to seal because you cant get a gasket for it.


Another thing... The vacuum release plate (The thing on the right side of the pic below) attaches to the slide but 2 things... 1. It is just a light press fit via the oring seal on it so if its loose on the slide, that oring needs to be replaced. and 2. The plate WILL FIT JUST FINE IF ITS PUT IN UPSIDE DOWN SO DONT DO THAT!! The bike will not idle and run like shit if that plate is put on upside down, so make sure you put it on the direction you take it off. It does not go on the way you would think it does, the arrow pointed part of the slide does not match with the arrow pointed side of the plate, the arrow of the plate points UP towards the top of the slide. That make sense lol?
 

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Littering And...........
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1,073 Posts
Discussion Starter · #5 ·
Yeah it does make sense. Now as far as running fcrs for street use how are they? From what I've gathered they're hard to tune for street, and generally are more trouble than they're worth for general everyday use. Also I've heard that they just don't run as good around 1k-3k? Any truth in that?
 

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old fart
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3,740 Posts
Yeah it does make sense. Now as far as running fcrs for street use how are they? From what I've gathered they're hard to tune for street, and generally are more trouble than they're worth for general everyday use. Also I've heard that they just don't run as good around 1k-3k? Any truth in that?
got a set of 35FCR's running open stacks on my street hornet, runs fuckin sweet, not had any low end fueling problems.
didnt have any setting up problems, but i did ask Allens performance (Kehine UK importer) for base settings before attempting any Dyno runs.
only thing to watch is when running at lowish revs is DONT suddenly W.O.T!, it will just bog down with all the extra fuel that the pump fires into the cylinders:shockerknucks:
smooth opening is where its at.
 

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sickboy
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3,544 Posts
Hahaha okay. I thought that was what the accelerator pump was for? Meh I think I may still pick them up. For $400 I'd be stupid not too.
That is what the AP is for, anyone who would tell you to just avoid stabbing the throttle open just doesnt know how to set the carb up properly.
A lot of the FCR carbs will cause a bog when you open the throttle suddenly but this is because the AP timing is not set correctly. If you open the AP link cover and hold the throttle wide open you will see that the link arm separates from the set screw (this is what causes the bogging), this is because of 1 or 2 things. Either the timing is just off and you need to hold the throttle at WOT then move the set screw out to the link arm and safety wire the two together OR the rivet on the diaphragm itself is to long and needs to be shaved to allow more motion of the AP. If this is the case the AP circuit will now be a little longer as its squirting fuel at the same rate the throttle is twisted. This being the case you will now have to thin out the squirt by installing a larger leak jet.
Its really not as complicated as it sounds and with a little tweaking and testing you can get those suckers dialed in and the bike will run like its got EFI.
 

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old fart
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3,740 Posts
That is what the AP is for, anyone who would tell you to just avoid stabbing the throttle open just doesnt know how to set the carb up properly.
A lot of the FCR carbs will cause a bog when you open the throttle suddenly but this is because the AP timing is not set correctly. If you open the AP link cover and hold the throttle wide open you will see that the link arm separates from the set screw (this is what causes the bogging), this is because of 1 or 2 things. Either the timing is just off and you need to hold the throttle at WOT then move the set screw out to the link arm and safety wire the two together OR the rivet on the diaphragm itself is to long and needs to be shaved to allow more motion of the AP. If this is the case the AP circuit will now be a little longer as its squirting fuel at the same rate the throttle is twisted. This being the case you will now have to thin out the squirt by installing a larger leak jet.
Its really not as complicated as it sounds and with a little tweaking and testing you can get those suckers dialed in and the bike will run like its got EFI.
Thanks for your advice (even if slightly condescending to start with!)
I didnt say that i was an expert on the FCR's! i just said that at LOWISH revs not to suddenly WOT, mine work fine all through the rest of the rev range just not at low revs.
but when i had them fitted to my track bike i didnt ever use low revs, so wasnt a need to try and dial them in for something they didnt need to do.
but i will look into the "adjustments" you mention to see if it will make any difference to mine.
 
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