Tys125f Mods

[james111089]

you hold the carb level and take the float bowl off and see where the fuel is thats what i was told.

James

[glenn]

you hold the carb level and take the float bowl off and see where the fuel is thats what i was told.

James

Or you hold the carb level and use the drain tube on the botom as a level guage.

[glenn]

The tube i was refering to is the tube atached to the drain point on the bottom of the carb. from having spoken to kevin seward, the mechanic at birkett's there is no specific mesurment, as it dosn't make a great deal of differance.

[scorpaf]

[Has anyone made the flywheel skimming down to 1,6 kg, recommended by Birks? ]

Yip, I machined our flywheel, weighs 1684g, revs much quicker than before, flywheel is about 80% of original weight but most importantly the weight has come off where it matters (around the outside). Probably the simplest and most worthwhile mod. It's not a difficult job and any small engineering workshop should be able to do it for

Edited July 14, 2005 by ScorpaF

[vinnied]

Yip, I machined our flywheel, weighs 1684g, revs much quicker than before, flywheel is about 80% of original weight but most importantly the weight has come off where it matters (around the outside). Probably the simplest and most worthwhile mod. It's not a difficult job and any small engineering workshop should be able to do it for

[scorpaf]

As stated it revs a lot quicker and returns to idle a lot quicker with it lightened, remember this is basically a road/trail engine not specifically designed for trials. As standard it feels more like a traction engine, its responds too slowly to opening or closing the throttle - its an easy mod and well worth doing in my opinion.

[glenn]

[Has anyone made the flywheel skimming down to 1,6 kg, recommended by Birks? ]

Yip, I machined our flywheel, weighs 1684g, revs much quicker than before, flywheel is about 80% of original weight but most importantly the weight has come off where it matters (around the outside). Probably the simplest and most worthwhile mod. It's not a difficult job and any small engineering workshop should be able to do it for

[steveo]

Any lightening of the flywheel will reduce crankshaft momentum at low rpm which in turn will enhance your chances of an easy stall.

[james111089]

what sort of money should i ask if i was to sell my 04 tys125f??

James

[lurch]

Orite lads, lets try and sort your problems out on - 125/175 four stroke set up - first start by fitting 17.5 pilot jet, 102.5 main jet. set float height to 18mm (turn carb upside down, bottom off, gasket off, measure from base of carb to top of float). Also blow out the 2 small jets in back of carb to make sure that 145 is at the top and the 80 at the bottom as you can get them mixted up and causes it to run sick, the mixture screw should be set at 1 and 1/2 turns out, but this can vary.

Make sure there is ample play on the choke cable when turning handle bars lock to lock to ensure the choke is not coming on.

Removing exhaust baffles, only remove the 2 middle restrictor bars, DO NOT TAKE THEM ALL OUT!

Flywheel modification, standard is 2.1 kg, skim to 1.6/1.7 kg, this will improve performance at the bottom end.

If your bike is a long ride version, you need to contact me for the airfilter modification, but all the above aplies to the long ride also.

Clutch, there is a different hydraulic clucth kit available, (not Hebo) this is the best that you can buy, it gives the clutch a more progressive feel, this only aplies to the earlier 4-strokes as the new 05's come with an improved Magura system which equaly as good, but these clutch kits will fit on any year 125/175 long ride/racing models.

If you have any other problems, please do not hesitate to ring me at Birkettmotosport Uk Ltd.

Tel.01229-716806

Hope this has helped, Kev Seward.

[james111089]

Removing exhaust baffles, only remove the 2 middle restrictor bars, DO NOT TAKE THEM ALL OUT

why not bjracing do......?

If all these mods make it a proper trials bike why dont scorpa just do them before they sell them to the public so there right in the fist place...

James

[downunder]

James

Keep in mind most manufactures try to make a middle of the road type of thing when selling to the general public. Not all Subaru Impeza STi's are rally cars you know!!!

So Andy has one huh.....(added much later...grin)

As far as pulling out all the baffles, I'm of the thought "WHY" rather than "Why not?". Over the years I've played with many exhaust systems and seen many different outcomes. I have even stuck 4 hot dogs (small straight thru mufflers) on a Lambo Contach only to hear it backfire on every gear change and try to set fire to the front of cars at the lights.

Half the time a louder system makes you use less thottle and revs than a quiet one. Some engines respond to "X" amount of back pressure and others don't, it comes down to how well they breathe. These little motors such air through a key hole, process it with a cam with almost no lobes and pass wind through a pee shooter. That is what makes them tame and trialsable. In 1978 Honda made the CB125T twin commuter bike with twin 18mm carbs and a cam that would let it rev to 16k (the Tacho finished at 13k but the needle went to "RPM") I know I owned one. Trouble was it had a shelf life like milk if you used the rev's. If you want more go than a 125 has to offer move up to a 200 or a 250.

BJDownunder

Edited August 2, 2005 by downunder

[g4321]

In 1978 Honda made the CB125T twin commuter bike with twin 18mm carbs and a cam that would let it rev to 16k (the Tacho finished at 13k but the needle went to "RPM") I know I owned one. Trouble was it had a shelf life like milk if you used the rev's.

You must have been unlucky, I had the same bike and never had any reliability problems (18,000 miles when I sold it if my memory goes that far back). I would not have described it as a commuter bike - even now where anything smaller than a 650 is seen as a commuter bike.

Lovely to drive reving up to 12 or 13k through the gears ALL THE TIME (with another 2k in hand) - great to see the surprise on some of the slower 250 riders faces as you passed them - Honda Superdreams were a favourite bike (not mine I hasten to add) but the little 125 twin was a fater and better bike all round.

[lastplacebrad]

Removing exhaust baffles, only remove the 2 middle restrictor bars, DO NOT TAKE THEM ALL OUT

why not bjracing do......?

James, look who has sent the post you are replying to ..........the mechanic from Birketts , he should know !!

[vinnied]

I have a 175 (143) in the thirty odd years i have been riding i think it is one of the best bikes i have ridden.

I have taken out all restrictors, lowered gearing that is all, i have the new pilot jet as recommended but dont think there is any reason to put it in yet. I competed in a trial last weekend with very tricky sections, tight turns, up 3ft plus faced banks, she did not miss a beat, buckets of power, and i am 15.5 stone.

If you want a bike that is responsive and does not run away with you when you are on the last lap of a trial and feeling a bit nackerd, i cannot recommend it highly enough.

She has been in Birketts but that was because she was using an excessive amount of oil, there was no mods done. Birketts know there stuff and are great to deal with.

Vinnie

Edited July 22, 2005 by Vinnied