Restricting a 1982 Suzuki GS750t

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

Hello, just wondering if anyone can give me some advice on restricting my suzuki gs750t, as i am low on funds and cannot afford the restriction kit costing £180, would it be possible that a suzuki GSX750 restriction kit would work or is there another way of restricting older bikes? any advice or ideas would be much appreciated Smile

DrSnoosnoo · World Chat Champion Joined: 28 Mar 2012 Karma :

Thottle stop?

Drill a hole and put a screw to give you what, erm up to 60% throttle. I wouldn't know the exact amount but it would definitely limit the amount of power you would get
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Did have: '95 ZZR600 '83 CG125 '97 ZZR1100 '15 Hypermotard 821 SP Do Have: '10 ZX10R

dydey90 · World Chat Champion Joined: 01 Oct 2013 Karma :

I don't know how similar the GSXR engine is, I'm guessing it's ever so slightly nippier. Unfortunately I couldn't find the exact power curve, so this is going to have to be close enough, until somebody with superior googling skills arrives.
Screw in until you can't go past 6000rpm and you're done.

https://www.surfsidemoto.com/images/TRC_Suz_06_GSXR750_SO_Dyno.jpg
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Rogerborg · nimbA Joined: 26 Oct 2010 Karma :

PaddyCert^tm

https://i15.photobucket.com/albums/a376/ms51ves3/Tizrstrictd.jpg

Yes, this is meant to be a serious answer.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

nowhere.elysium · The Pork Lord Joined: 02 Mar 2009 Karma :

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

Okay, so would honda restrictors do the job, im really not sure what bikes use the same carbs, and would it have to be the same year? Thank you for everyone who has replied Smile

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

From memory I think they might have still used slide carbs on the GS750. If so it should be easy enough to fit a tube above the carb slide(s), around the cable and inside the springs to limit throttle travel. Might get away with doing it to only one carb.

nowhere.elysium · The Pork Lord Joined: 02 Mar 2009 Karma :

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

So the best way of restricting is..........? I have no clue on this kinda thing all i know is i can open her up in december Very Happy

but until then im restricted Sad

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

Right, just researched the specs of the carbs: mikuni 6S32SS, 68bhp and some other stuff, anyone know how or what to do to bring it down to 33bhp which is inexpensive
Smile

Rogerborg · nimbA Joined: 26 Oct 2010 Karma :

Mikuni BS32SS. That's a CV carb, so you can put washers in the inlet rubbers.

That means:

#1 Finding out the internal diameter of the inlet rubbers that go between the carbs and the engine inlet.

#2 Finding washers of that diameter.

#3 Drilling appropriately sized holes in each one.

#4 Putting it all back together, which may not be as easy as it sounds if the rubber has hardened, which it will have.

"Appropriately" is where it gets tricky. Without a dyno, you'd just be guessing. Personally I'd guess at 18mm because of reasons.

The other way of doing it is to literally restrict the amount that the throttle can open. The simplest way to do that would be to clamp something like a fishing float or a cylindrical split sleeve cut to the right size onto the throttle cable next to the carbs.

This will stop the cable from withdrawing into the sleeve, or the throttle actuator on the carbs from opening fully.

Ghetto, but what does either method get you anyway? A bike that may or may make over 25kW at the crank, which will itself be a guesstimate based on Dynomaths.

What will be a lot more good to you in 90% of situations is a credible looking piece of paper or some sort of tag or plate on the engine that says "This bike is restricted to 25kW".

You can print that off yourself for the cost of paper and ink. Came with the bike, innit.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

and do you think you could find me the link to the "legitimate" papers Wink

Rogerborg · nimbA Joined: 26 Oct 2010 Karma :

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

HAHA, oh but is it possible that they will contact Fi international? that would be abit awkward :S

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

right I'm really stuck with this now, why does the insurance company require this if its not legally needed, and how many people have actually got away with sending in the "legitimate" certificates from Fi?
i really want to get this oldy on the road but its difficult when you're low on funds Sad

davebike · World Chat Champion Joined: 15 Nov 2013 Karma :

It is a legal requirement!

Some think the risk of being caught is so low they will not bother

Probable why some insurers are now asking for proof you are abiding by the terms of your licence

Driving non restricted bike on restricted licence having told insurance co it is restricted

Un- licensed
invalid insurance Lied on application
Possible criminal record for no/invalid insurance

Dave
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Dave
NC750Xdct + others at work !
davebike1@gmail.com

Rogerborg · nimbA Joined: 26 Oct 2010 Karma :

We're specifically talking about insurers asking for evidence that the bike is restricted. There's no definition in law of what constitutes proof of that. A piece of paper, be it an FI Scamcertificate, a dyno printout, or a self-declaration (including a PaddyCert^tm) is just that: a piece of paper. It says nothing about what state the bike is in at the time it's being ridden.

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

Yeah i have taken out a policy and trying to find a way of restricting this bike, so desperately need a way of a legal restriction that wont cost me close to £200 :/

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

Ahh, i was actually hoping that the restriction kit for the Suzuki gsx 750 (Not the GSXR750) would fit into this carb?

jb329 · Two Stroke Sniffer Joined: 20 Oct 2011 Karma :

You never heard of ebay then??
https://www.ebay.co.uk/itm/Suzuki-GSX-750-F-Restrictor-Kit-33-BHP-certificate-/321308450024?pt=UK_Motorcycle_Parts_13&hash=item4acf79dce8
As for any paper work, our local community copper explained it so.

"If you get pulled for suspected drink driving, you will have to blow in the bag.
If you've got a letter from the pub landlord/your mum/your local JP or anyone else, stating that you only drank coke all night, you'll still have to blow into the bag."

If plod think your bike is not restricted, they'll take it off you and get it tested.
They will not phone FI, or anyone else to ask if they stuck some washers in it sometime in the past because even if they did, you could have taken them out 10 minutes ago and be out seeing how much faster it is now, without the washers.

jb329 · Two Stroke Sniffer Joined: 20 Oct 2011 Karma :

Double post!

DooGie96 · Derestricted Danger Joined: 27 Jan 2014 Karma :

yeah i was asking if the GSX750 restrictors would fit the GS750?

Rogerborg · nimbA Joined: 26 Oct 2010 Karma :

You're vanishingly unlikely to find anyone who knows - it's not a particularly common bike, and as noted, they share an approximate capacity and that's about it.

How about you put the ball in their court. If they say they want "proof", then ask them exactly what they will accept, and where that is spelled out in the contract of insurance.

If they give you any problems, escalate it by writing to their complaints department and head all correspondence with "COMPLAINT".

Whether or how you actually restrict your bike is another issue.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike