Suzuki katana 50cc to 70cc , advice please

[paul2304]

Hi guys , just acquired a 70cc big bore kit and dellorto 19mm carb to try and give my moped a bit of oomph , not expecting mind blowing power just want it to be able to keep up with traffic in a 40 zone

need advice on jetting and roller weights etc really and also advice on how i need to adapt the intake manifold to accept the new carb

as the moped stands now it is struggling to do a steady 25mph on the flat , this could be down to normal wear on parts but i dont have the funds to random;ly replace things in the hope it cures the problem

the only mods i am aware of at the mo are a de restricted xariator and tecnigas sports pipe

[karthead]

i would imagine you might need a new exhaust also, im not sure tho... to see how its running you will need to do plug chops at different throttle levels.
wouldnt the big bore kit come with a bigger manifold? if not then perhaps you will need a new manifold. you could bodge it by putting electrical tape around the outside of the manifold that connects to carb to make it thicker, probably not the best bodge for your engine tho!
other than that i dont have anything else to offer..

[stevo as b4]

I would suggest not fitting a 70cc kit and other mods until the machine is running as well as it should be and is de-restricted if not already.

You say that you do not want to work though the common performance reducing issues and replace all the transmission parts that suffer with wear and tear, but the cost of a new drive belt, new roller weights, and a full service including de-carbonising the engine and the exhaust system, would be less than the cost of a new 70cc cylinder conversion and all the associated parts and setting up that would be needed to get it to work effectively.

[TGB]

in most cases new mopeds are restricted by the ignition system ie an advance/rpm limiter. a big bore kit and suitable carb will help in providing more torque. but you will need to look at changing the ignighter box to allow for more advance/rpm. the exhaust upgrade is not always needed but is a good finisher.

[shippy]

or just get a bigger bike? 125?

[Clutchy]

Me and 2 mechanics did this, was fine for a few months, piston went tits up, rebuilt it with the standard 1 mm oversize piston the katana has, and had nothing but problems.

Get a de-restricted liquid cooled 50 cc if you're still 16, the katana I had was the worst moped I've ever had by a mile, looks ugly too, used to do 48mph with a 70cc and viper exhaust and upjetted accordingly. Then when re-built went down to 28mph horrible on national speed limit roads.

Compare that to my completely standard (other than de-restricted) NRG power DD liquid cooled which looks 10 times nicer and does 60 mph all day long, and as it's liquid cooled it adds a bit to reliability IMO and better mpg. (80 mpg).

Also feel safer on roads as I can keep to speed limits!


Get another ped F12 which is AC was also very good.
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Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
*33 BHP restriction up on 10/12/14* Current bikes/car: SV 650 S/ MKIV GOLF
Guide to pass your test with no lessons!

[SpannerMonkey]

[stevo as b4]

Good advice, because as you say few of us have our own mixture reading exhaust gas probe and equipment. With regard to jetting a 2stroke, people who know what they are doing can with experience jet it pretty close by feeling, and also by exhaust temperature if you a have an EGT guage and boss to take a reading from.

Most people with a 50cc scooter will not want to pay £50-70 p'hour to have thier machine dyno tested and set up properly however.
I had about 2.5hours of dyno time and parts swapping etc done when i put all the tuning gear on my Speedfight, and it cost me about £180 i think, 9 years ago!

[Alpha-9]

Why dont you just get a 125?

I mean you might as well if you're going to make your 'moped' illegal and not a moped anymore, hell you might aswell get a fireblade, might have a bit more 'oomph'
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Fzr-600 1999