Plastic 33bhp Restrictors

[upanddown22]

Just bought myself a GPZ500 which i'm now desperate to get restricted.

I know the dimensions for the washers and i'll be getting the bike dynoed soon after. I'm considering making some up out of plastic bought from B&Q or such like. Anyone got any opinions on this?

I don't want to get into the whole legal side of it, just want to know if this is a stupid idea!

Opinions/advice or other ideas welcome
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Kawasaki GPZ500S 1995

[chris-red]

Petrol will eat certain types of plastic, also it may melt over time, Why wouldn't you use metal, it is not like plastic is much easier to use.
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Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
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[phonesurgeon]

Legalities?

As long as the dyno reads at less than 33bhp you ok!
I am with chris... use metal if you already know measurement?

[Kickstart]

Hi

Another vote to use metal to avoid potential issues with some plastics.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[upanddown22]

Just easier to work with plastic in a flat! Haven't got space or tools for metal working.

tbh i'll probably just have to be patient and wait until I cant buy some or get them made up. Sucks having the bike sat there just waiting!
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Kawasaki GPZ500S 1995

[That_Hornet]

I had plasitc in my bike, Made them up and stuck them in petrol for 3 days, they didnt dissolve so i stuck them in, 1 1/2 years later they were still there, like new, when i took them out. Fine in my opinion.

[upanddown22]

[Moo.]

Wont repair washers do?
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A2 Passed 18/6/10

[upanddown22]

[Jamie S]

Why risk MAJOR engine dammage just because you can't be arsed to spend some time with a file and a drill ...... ?

[Nexus Icon]

Nylon is very chemical resistant and will give you no problems whatsoever, assuming temperature isn't an issue.
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Greetings from Shitsville!

[Willson]

Personally, I wouldn't use plastic. If anything happened to them and they ended up in the combustion chamber you could be in a world of pain.

Simple solution: Get a piece of metal(steel, ally, whatever) and dependant upon how many discs you need drill that many very narrow holes in it (make sure it's as close to the correct thickness as possible) Mark out the correct size and number of circles with a compass and a scribe tool from the holes you drilled earlier and cut out roughly with a hacksaw/junior hack saw and sand/dremel smooth into a circle. Then, mark out the size of the holes using the same method. Drill to as big a size as you can, then sand/dremel to get them to the right size.

Simples! That's how I'd do it if I didn't have access to any machining tools. Hope that makes sense!

Willson

Edit: a file works well too!
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Riding: '00 Suzuki SV650S. Previous: '99 Kawasaki ER5 - sold, '02 Suzuki GZ125 Marauder - sold

[Moo.]

[stinkwheel]

You could cut them out of a bit of alloy sheet using an appropriate sized hole-saw then take the middle out with a drill in a few minutes.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
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[upanddown22]

Thanks everyone, my main trouble is lack of tools and an area to do the work in.

Anyways went out and bought some sheet steel and a dremmel tonight, taking ages as didn't get enough cutting bits! They don't look great as in the central hole isn't 100% round but i'll get it dynoed and if there are any issues i'll replace with proper ones.

Thanks for all the pointers
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Kawasaki GPZ500S 1995

[Ayrton]

wouldnt it be easier to get a washer and then get the correct drill bit to increase the hole. rather than uses a dremmel and sheet steel?

[upanddown22]

[Moo.]

[upanddown22]

ah cool, couldn't see them after numerous searches, tbh i'm just being impatient. I know a place where I can get them made but it'd be over a week before I could get them. But I want to ride it now!

Need to figure out where to take it to get it dynoed around Guildford as well.
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Kawasaki GPZ500S 1995

[yuri2085]

If you're that desperate then just ride it without them.

Disclaimer: It is theoretically possible to get caught.

Although after you put the restriction in you will hate your bike if during the next week you ever went above 5k rpm.

[hmmmnz]

make a throttle stop, take it in for a dyno, job done,
ive done it to a few bikes, when teaching mates to ride,
(stops ham fisted idiocy)

there is no specific way that you need to restrict the bike, or any proof that it is even restricted.

kiss
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Wiring Diagrams BIDNIP it bitches

[Pete.]

Agreed, or slide restrictors. That way you aren't messing with the airflow more than it would as standard.

By the way, often the holes in the restrictors are not in the middle.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[upanddown22]

It's done now! Took bloomin ages as had to file and hand cut most of it as the dremmel only came with a couple of cutting bits! D'oh.

As you can see they aren't perfect, the centre holes are slightly wonky but figure this won't make a difference, i'm thinking the bike will have lost some power anyway being 16 years old.

Thanks everyone
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Kawasaki GPZ500S 1995