How would you use your beautiful engineering minds here?

[2tenjoyer]

Trying to fit the airbox here, but seems to be hitting the shock absorber. Modified the mounting points for the airbox, didn’t help, so went back to stock ones.

[Nobby the Bastard]

Three questions.

1) Is this the correct airbox for the bike (though I expect it is)
2) Thats not a standard shock. Do you have a standard shock to try?
3) Usually the visible damper bar would be at the top and not the bottom, and the preload the opposite. Have you put it in upside down?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[2tenjoyer]

[Nobby the Bastard]

Bikes are not lego and you can't just swap things about between models, as Marjay repeated says.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[stinkwheel]

There are airboxes and there are airboxes.

Some of them are designed to reflect pressure waves back into the engine with minutely calclulated baffle placement, volumes and trumpet lengths. Without it, they wont run properly. Early 90's kawasaki sportsbikes being a good example.

Others hold a certain volume of still, clean air ready for the engine to suck in.

Looking at the pictures, yours is probably one of the latter. So the obvious thing would be to make up a new airbox that fits in the space you have. Try to keep the overall volume and inlet/outlet dimensions the same as the original.

I'm presuming this is going on a rorty, fuel injected single? Should be less fussy about pressure wave dynamics over having enough air available to suck in.

If I was going to make a custom airbox, I'd probably sculpt the shape in foam then do a composite layup over the top. If I had better fabricating skills, I'd make it from aluminium plate. If I had better computer skills, I'd 3D print it.
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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.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Nobby the Bastard]

It's an NSR125 and he couldn't work out where to plug in the CDI last week....
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[2tenjoyer]

[2tenjoyer]

[quote="stinkwheel"]There are airboxes and there are airboxes.

Some of them are designed to reflect pressure waves back into the engine with minutely calclulated baffle placement, volumes and trumpet lengths. Without it, they wont run properly. Early 90's kawasaki sportsbikes being a good example.

Others hold a certain volume of still, clean air ready for the engine to suck in.

Looking at the pictures, yours is probably one of the latter. So the obvious thing would be to make up a new airbox that fits in the space you have. Try to keep the overall volume and inlet/outlet dimensions the same as the original.

I'm presuming this is going on a rorty, fuel injected single? Should be less fussy about pressure wave dynamics over having enough air available to suck in.

If I was going to make a custom airbox, I'd probably sculpt the shape in foam then do a composite layup over the top. If I had better fabricating skills, I'd make it from aluminium plate. If I had better computer skills, I'd 3D print it.[/quote

Yes, this is a 2000’s frame. I was originally going to do a layup, but modifying the mounts will be more time efficient. The 3D is definitely the best choice, but I don’t have any 3D scanner laying around and reacreating the same shape is a pain in the ass. About the airflow, well I’m not a specialist in that sphere, but you do make a great point. Although I think that it won’t lack any air whatsover, I think this will come down more to when the bike is running.

[stinkwheel]

[2tenjoyer]

[2tenjoyer]

[MarJay]

[Nobby the Bastard]

Jesus wept. Yet another person who reckons thay can cobble something together that will do the engine justice without melting it who hasn't the beginning of a clue how to start when Honda spent probably in the millions developing it....
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Robby]

It's an engine that makes something in the range of 200bhp/litre without using forced induction. The exhaust and airbox are critical for that, and it still won't last that long.

Just don't go chopping engine mounts to make it fit. This project is never seeing the road, so at least leave the engine in a state where it can go on ebay when you give up.

[Nobby the Bastard]

Back in the day RGV owners were swapping piston rings to try and protect the engines with nitrate plated barrels every 12k miles.

NSRs have nitrate barrels so before even looking at putting a bike together I'd be checking the engine even works.

Like I said before, it's all much above the OPs pay grade. Even getting an NSR125 commisoned would require me to seek advice and potentially cost me fuck loads and that assuming standard intake and exhuast.

Anything else than that it'll not run or likely melt itself within the first 2 minutes.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[WD Forte]

I'd use my beautiful hot air gun to reshape/flatten the back of the box until doesn't foul on the shock
simples
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bikers smell of wee

[slowasyoulike]

OP - there used to be a lad on here called arcane, I think you and him would get on well.

[Zen Dog]

Given that all the sensible advice above is clearly going to be ignored in favour of creating this monstrosity, the only two bits which matter are Robby's "don't cut anything off the engine" and WD's, which is the actual fix for the problem at hand.

Other than that, I just want to know more about this bike OP is making. He's already not using the NSR frame, which was the basis of one of the best handling bikes I've ever ridden, in favour of apparently a Husqvarna steel cradle motorcross frame(?). This has disaster written all over it, and we've only seen the shock mount area. I'm feeling there may be a real contender for the "eBay's Most Miserable Bike" thread at the end of this. I want details, more pics of the bike please! What's the concept? What are you attempting exactly with this bike OP?
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Current - '94 VFR750FR, '00 VFR800FI Previous - '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win (chinese copy of an old Honda design with a C90 engine)
My bike trip around S.E. Asia 2010/2011

[Bhud]

Wasn't there an NSR125 specialist on here once upon a time, called Alain?
Not to speak for him, but I think he might be horrified and tell you not to fuck with it.

[mentalboy]

I'm surprised there are any NSR125 engines still running, putting a highly strung two stroke into a machine aimed at greenhorn boy racers was never going to end well.

I spent 30 years twerping and derping with 4 strokes, great fun to mess with, anyone with half a clue can do all sorts of things to them.
I also spent a lot of that time tinkering with two strokes, as Marjay said, they are finnicky things. Just in case anything was lost in translation, they can be a complete bastard to get running, especially after some herp-de-derp has tried to 'improve' it.
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Make mine a Corona.

[Easy-X]

Sounds like taking a saxophone and replacing the reed mouthpiece with one from a recorder
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Nobby the Bastard]

[Rob Fzs]

OP will deal with this by cutting the airbox up and use bathroom sealant to stick it all back together


Actually did work for a while on a Cg i had, but not an nsr
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30> Yamaha RD350 YPVS F2 > Kawasaki ZZR 600 D1 > Yamaha TZR 250 2MA >Suzuki TL1000R > Yamaha TDR250 > Honda 929 blade > Suzuki SV1000 > Honda H100
Mod 2 Passed 09/06/2011