3TJ bhp in restricted form?

[Mike Shelby]

Hi all - Just curious if anyone knows what the bhp is of a 3tj in restricted form (with the jap 112mph limit)?

The reason I ask is my sons have passed their tests (restricted to 33bhp for 2 years) and are using both my FZR400RR's (1 is a 4DX and the other a 3TJ).

At the moment I have restricted the throttle on both by attaching a clip to the throttle cable under the air box - but have no way of knowing if they are 33bhp. (The top speed now is 90mph ish)
I know the Aprillia RS125 are 33bhp and they do 120mph - so I'm hoping I'm somewhere near to what they should be - especially since the engines are well worn by now and probably not achieving whatever Yamaha claimed they put out when new.
I don't know of any dyno testing places around here to get them checked properly but at least if they get stopped by the police they can physically test the throttle movement at the roadside and see there is limited movement.
I did consider buying the washers on ebay that sit between the carbs and inlets but seemed a lot more work than restricting the throttle.

Many years ago my 1st 3TJ I ever bought was a jap restricted one and had no M-Max derestrictor fitted and it wouldn't rev out through any of the gears - so I'm wondering what the bhp would have been on a bike such as that?

Any info much appreciated -

Mike

[Clanky]

Hello Mike,

The mod to limit the throttle cable to reduce the top speed will not be enough for the legal requirements. The engine has to be mechanically castrated to reduce its maximum output to 33 bhp so it will need the proper restrictors put in the exhaust.

The police wont accept the temporary mod to the throttle cable because it would just take minutes to undo but the restrictor washers are a far more involved and time consuming thing to change so are less likely to be tampered with.

If the police show that the bike was still capable of producing more than 33 bhp (regardless of the throttle restriction) then it could amount to a couple of offences. Probably looking at driving otherwise than in accordance with a licence and driving without insurance (Any insurance held may well become invalid if they are breaching the restrictions of the licence) and both offences will quite probably mean seizure of the bike.

Too many points on the licence and too many fines. Far cheaper to buy the kit, do it right and have the peace of mind knowing that everything is above board.

[Phil Norton]

I'm pretty sure Triumph restrict their bikes to 33bhp by limiting the throttle movement only.

[Evilchicken0]

Some bikes do have throttle restrictors Kwak ER650. The thing is you need to produce evidence that the bike is 33hp. At the moment they go up to about 90 ... I think a 33 might just get above that but equally it might be below.
I think somebody on here makes the washers it could be pornodog but not sure.
Either way you need a dyno run

[dobbslc]

An RS 125 that does 120mph..........





















is actually an RS250

[pearson*]

The RS125's can sometimes hit 120 on a 33bhp engine but thats down to the 45kg less weight you carry on one. If you make an RS125 33BHP it voids the power to weight ratio that's also set by law so it'll simply be crushed there and then if they catch you. (they're cleverer than you think - no 33bhp on a 50kg bike )

If it helps, i've still got a set of spare 33bhp washers for a 3TJ somewhere although i've only got the one set.

[dobbslc]

Must be 120 on the clock then! ....

[Keny73tj]

I'm with dobbsic on this one, can't see a 33bhp 125 doing anywhere near 120mph. Some people seem to think because they derestrict there aprillia's that makes them 33bhp but they've never been near a dyno!

[benny]

No problem with a throttle stop (A few kawasakis use these as well as Triumph) but you should really check it is producing 33bhp, otherwise might as well be running full power. Remember if they are riding over 33bhp they are riding without a license and all the problems that come from that (void insurance etc.)

[dobbslc]

I had a fast RD 125 lc back in the old days that made about 21 bhp and it would take me to 95 mph on the clock, a friend had a Cagiva Mito that was deristricted that was a bit faster on top end acceleration then had a Gillera GFR 125 that would piss all over a Mito and an RS 125 but that was nowhere near 110 mph let alone 120.