Derestrict Bandit 600 N ?

Dr Pepper

Hi,

My Bandit has a restrictor kit of some kind.. It was not originally (factory) restricted. This was added before I bought it.
As far as I know, it involves some modification to the carbs.
The problem is, it's not a 'good' restriction. I can feel the power coming and going (there's regular lulls) and it feels groggy at 7-8000rpm and above.
I found this on another bike forum:

De-rsetricting a Bandit n 600 is easy. All that restricts to 33bhp is 4 large washer type things (I'm sure there's a technical term) in each carb. They are simply hole size reducers between carb mounting to head. Thats all.

Does anybody know how to do this? Can I just remove these 'washers' or do I have to replace them with slightly 'larger-holed' washer? Are there any other parts I need to add or does it just involve removing parts?

Thanks

PS - don't worry, I'll be ringing the insurance company to inform them if I do decide/manage to derestrict it..

madrab

if you dont know much about bikes, then messing with your carbs is the last thing you want to do, your best bet is either take it to a mechanic or get a haynes manual for it & it should give you a good indication of what to do

Dr Pepper

Thanks Madrab.. I have a Haynes manual for it (which is EXCELLENT and I would strongly recommend them). I've have been tinkering with a couple of bits and bobs on it and I'm fairly competent. I used to have a GN and stripped and cleaned the carb on it a couple of times (so I know what one looks like! ). I also have a Dad whose a veteran motorbike enthusiast and seems to know about everything bike-related.

Anyway, don't think there's anything in the Haynes about it but I'll have a more thorough look through it this evening. In the meantime, has anyone done it or anyone got any more tips/advice?

Thanks

madrab

i havent de-restriced a bandit before but if it shouldnt be too big a job, just take the carbs off & remove the restrictors, then put the carbs back on

Dr Pepper

Cool cheers.. I'll have a look at the weekend.

PS - If anybody else has any info, let me know. Thanks

Pigeon Reaper

If you take the washers out will you not have to adjust the carbs so they don't run lean?

madrab

dont think so, the washers only limet the amout of fuel that can get in, effectively shortening your throttle, taking out the washers should only allow more fuel to enter above certain revs, but then again im no expert

but just incase check the plugs after running the bike

Dr Pepper

Pigeon Reaper wrote:

If you take the washers out will you not have to adjust the carbs so they don't run lean?

Cheers.. Do you mean change the fuel/air mix (As in, increase the air to compensate for the extra fuel getting into the carbs)? Sound like a good idea alright. I'll check it out.

I'm still not convinced about just 'taking the washers out' though. Surely, you would need to put in new washers with slightly bigger holes for the carb to work properly. Anybody know if this is the case?

Dr Pepper

madrab wrote:

dont think so, the washers only limet the amout of fuel that can get in, effectively shortening your throttle, taking out the washers should only allow more fuel to enter above certain revs, but then again im no expert

but just incase check the plugs after running the bike

Thanks.. Just saw that after my last post! Guess I'll just have to test the exhaust emmisions (colour) and check the plugs, as you say after a test run (if I am successful!).

Dr Pepper

Well, I had a good poke around the carbs on Sunday. It seems the restriction on mine is on the diaphragm 'slider' (The part under the diaphragm that the needle fits into and slides up and down). This slider has 4 holes in it (2 just under the diaphragm and 2 on the bottom where the needle comes out) limiting the suction of the diaphragm, and so the general effectiveness of the carb.

The solution: just replace the sliders/diaphragms with unrestricted ones (no holes).. Speaking of which - Does anybody know where I might get them cheap enough. New ones cost €80 each (and I need 4 obviously). Alternatively, is anybody interested in swapping?

madrab

try city spares/gorey bike breakers, & get a second hand pair or alternatively try ebay

bushy...

I think you need to go back for another look at your bike,all CV carbs will have bleed holes in the slides,check that you can lift the slide fully open (carefully with your finger or something soft that wont mark them) and that the brass butterflies open fully when you open the throttle.
Then open both the slide and the throttle and look into the carbs , you will probably see a washer-like plate in each of the carb rubbers between the head and carbs (it will be very obvious if its there,hole in centre = ~ 12mm maybe) ....If there remove them. Then check that the main jets & needles are the same as mentioned in manual.
Make sure that the clips around the rubbers are exactly as they were before,sometimes the screws on them are long enough to catch the pulley or balancing screws between each carb (on the shaft butterflies are on).Usual T+C applies to this advice,if your not sure of what your doing get someone who is to do it.

Hotblack Desiato

There are two ways of using washers to restrict a bike, one in the carb top to limit throttle opening, two between the carb and the head to restrict fuel/air flow. The effect of both is to prevent you from reaching full throttle. Neither of these methods of restriction should require any change in carb settings or jets.

bushy...

Neither of the methods should require jet changes but the carbs will be out anyway and it only takes a few minutes to be sure.

Dr Pepper

Done!

Thanks for all the advice guys. I finally located the diaphragms in Cotter's on Friday and he fitted them and all for me on Saturday morning (€150 total and I got to keep my old diaphragms too in case I want to switch back). It was the diaphragms in the end. Regarding the holes: the restricted ones have 4 holes (2 on the top/side of the slider just under the diaphragm and 2 on the bottom, one on either side of the main hole that the needle goes through). The unrestricted ones only have the holes on the bottom (must be the 'bleed' holes as bushy suggseted).

She's running beautifully since. Smooth all the way up through the revs. The power is amazing too!!

Anyway, thanks again for all your help

bushy...

Cool you got sorted out at a decent price ,meant to say come back if you didn't find any of the famous washers.The 'washer' system of restriction is patented by FI international i think , this must be someone elses brainwave of how to reduce power,must've been an utter dog before Saturday tho...