180 Jota jetting for modern fuels

T

Tetley Laverda

Senior member
Hello Gents
I have read several times that it would be beneficial to reduce the carb settings on a 180 Jota as set by the factory because of todays fuels . What are the feelings here among the experienced and what changes would be recommended.

Many Thanks
Regards
Tetley

 
Smaller mains- modern petrol more like lighter fuel IMHO.  145 mains as recommended by Slaters?  Ahahaha.  No.

Reggie
 
  I am setting them up using a real time exhaust gas analyser connected to a lambda, a good healthy 1000 runs best on a 125 -130 main jet. Make no jetting adjustments until you are absolutely sure everything else is as it should be.


    Keith.
 
that is interesting, Keith..my Jota is running 130 mains and seems fine (well it did before the engine was removed literally carried through the garage and plonked on the workbench by me on Saturday!). there are those who say the factory / dellorto knew best..including the restorers who initially re-did my carbs some 6 years ago now, but the weight of opinion seems to support this downjetting from 145..which is what mine were. Some, like me remove the accelerator pumps based more it has to be said on intuition than knowledge, with no ill effect..indeed better fuel consumption and less carb fouling.
Interesting to hear that was my new head,Keith ,was  the one being worked on in the recent classic Bike feature of your firm. Am fearing fishing for missing half of cam tensioner is a lost cause, so looks like the cases will have to be split..
Nick7 (sorry for going off on a tangent!)
 
Hey Nick,
Stop dithering and split the cases, if you are removing the head and barrels then it is a must.
Takes no more then 20 mins extra and all is revealed.
Then you can thoroughly clean everything and check everything and when you re-assemble you have the peace of mind of knowing that all is correct.

 
hey Red,
It is going to happen for sure...actually not quite so easy  as it may sound, as  my primary drive  sprocket will not be removed (loctited etc to shaft because of spline wear) so I am told it should be possible to reove the chain by removing the clutch with a bit of juggling. If there is any gearbox damage...I have  an entire spare! Can the seal between the cases be got on its own? Does it have a spec to quote? Any thoughts on best gasket cement for the cases? Never had a leak or weep when I did this before but used  stuff silver, non  setting which I got from Chris Applebee (of crank re-con fame) and it was his last tube! Its all the surface cleaning i cant stand...btw Red, I have made meself some nice ring compressors per your article on the subject..
Nick7
 
  Got a bag of crankcase O rings Nick, want one?

  I use Loctite 5980 or similar on the case halves, getting all of the old stuff and making everything absoultely clean is more important than what you use to stick them together with (within reason  :))

  Hard work, grit and determination is what you need Nick....tally ho.

  Keith.
 
Yeaa Nick, you can, simply remove the clutch sprocket and wiggle it off the rubbers... remove the cover plate and away you go... done it many times, and even, with new chains and cush rubbers, refitted it..bit of good spray lube helps a lot..and a light mallet.. ;)

No chance of fixing the worn spline while you're at it I suppose..?!

Keith, Also read your article in Classic Bike, good information, and a good chance to promote Laverda Scozia...good luck with that.. and it tweaked my interest... been having troubles myself with the RGS, as you know, and it has Jota pipes. 160s fitted now, and I'm looking forward to trying the move to 130..often thought there was something a bit "flat" about the motor, and have suffered some of the symptoms you described... What do you mean about making sure about everything else being well though..what might I miss, what's the signs if the 130 is wrong..?

Thanks
Ian
 
Hey Nick,
Resolve yourself to splitting the cases and then you don't need to remove the primary chain sprocket unless something is amiss.
Leave all in place, split the cases, lift the crank out and slip off the chains.
Is what I do, pulling down and build up.
I always have the primary chain in place before installing the top case.

See attached photo showing the motor I built today.
Easy way to do them.

I use Loctite Master Gasket, not certain of the number, will have to check.

Tchau
Red
 

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Keith,
Yup, put an o ring on the list please. I am hoping the small end bushes are ok..Clem found problems recently (done at same place)and frankly , if I were to find the same I might be inclined to send the thing to you ,Keith for the carillos and a new end piece of the crank thereby sorting the spline issue too...but hope that will not be needed.
Red, noted, thanks...so no need to remove the clutch , either...sounds good to me!
Anyone know if there are some nice blind nuts made suitable for crankcases..you know the ones at the front..always seems odd to me that the threads are left exposed to the elements and the nuts are quite thin, though I assume adequate or they would not have used them...
Nick7
 
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