First run of the year, Problem!

Bob,
Are you seriously saying that you are doing all this throttle opening /closing etc on an unfaired jota at about 130mph in top while the wind tries to pull your head off? :o At that kind of speed I'm just hoping I put the thing together right and did up the rear wheel spindle properly...oh and that there are no mobile speed cameras about ;)
Nick7
 
I stick by what I said.
At 130mph/7300rpm an unfaired Jota is just about flat stick.
Gearing plays it's part, as does aerodynamics.
I reckon you are pissing against the wind (on standard gearing) to think you will fix it with carb/filter/fuel flow changes.
 
Right, just finnished checking the float heights and all seems ok.

To the best of my measuring the floats seem to be at about 17 to 18mm, as per the manual.  Bearing in mind that there is a degree of "interpretation" as to the position of the floats.

Next step?
 
Reckon you'll just have to accept the bike reaches its natural ceiling at 7300 in 5th... not TOO bad, many don't even go to 7000!

piet
 
Why did you replace the old fuel taps? We're they leaking slightly or pissing it out, to me the path of least resistance would be to try another set of taps before pulling the carbs. If the old taps are just weeping a little then probably good for a test. Sometimes if you are a bit careful and lucky you can diss assemble the taps and turn the seal over. If the plates are the rivetted on type you can drill some small pilot holes but don't go too deep and use some small self tappers. Won't last for ever but would give you chance to prove if the new taps are the problem. Who knows maybe the internal drippings are not fully done or the tap part doesn't open fully
If it used to run ok before and all you changed was the taps then
 
chriskay said:
... 208kph. There should be more in it yet, bay far!
Click to expand...
reckon i agree,
me '79 Jota could pull to 8,000 rpm in top, (220 ?) standard gearing, no problem, and it wasn't wound right out, but bloody close too it!
was a bit windy, laid down on the tank, and a bit dumb trying to wave to ya mates. 
 
Piet

Everyone seems to think it's a gearing problem but it's not.

At about 7.3K in top the engine looses power and almost dies untill you shut the throttle for a couple of seconds then it pick up again but won't go past 7.3K.

It'd definitly a fuel problen.

Anyway I digress, I've put the carbs back on, new plugs (Kempton auto jumble at ?2 each) and turned the fuel on, look at pipes, fuel flowing from left side pet cock but nowt from the right.

Methinks this is not correct!

Turn tap to res possiotrion and fuel flows and before any one states the obvious, yes the tank is full.

Looks like I have a dodgy tap which would confirm my theory of not enough fuel getting into the carbs at high revs.

Next step is to drain the tank, remove said tap  and strip it down.

Watch this space for thge next enthralling episode!

Have a nice day chaps I'm off for a blat on the KTM.  :D
 
Look at it this way at least now you have fresh plugs and clean carbs so cant be all bad.

Never thought it was a gearing problem as can still remember my first introduction to Laverda's. A black 79 Jota which a friend of a friend owned he took me or a ride on it can still remember peering over his shoulder and looking at the speedo...was well over 200kph let me tell ya....I was shitting my pants....however the very next day went out and bought my own... that was back in 79 ......bloody hell that was over 30 years ago.

If you have recently bought the taps then before you pull it apart maybe contact whom you bought it off... he they might surprise you and offer to replace it.
 
Trust the KTM cheered you up?! Be careful out there  had more close shaves last Sunday than I care  to renember the pwarm weather brings out all the Sunday drivers/cyclists etc
Nick7
 
Your test,bike stops revving at full throttle,close throttle a touch and reopen throttle to more power is the old cheap and cheerfully test for running lean on the main jets.Or as found fuel starvation.Handy to have you confirm this old rumour
 
Right chaps, fault found.

After removing the offending tap I found that the tube, inside the filter tube, was so long that the end of it was pushed against the end of the filter tube so no petrol would flow through trhe tap.  Cut about 10mm off and all is well and it flows as god intended.

So, if you fit BAP taps check the internal tube leanth.  On my "good" tap the little tube is about 10mm from the top.

Hope you understand what I've said.

Regards to you all for your hints and ideas.
 
So what will it do now Mr.I would have to go a long way from the close supervision around here  to find somewhere to try that.
 
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