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Rain eh? Birds are searching for water down here.
John

Aye John, I've got blue tits and robins imitating power boats across the bird bath, whilst there's a crow on the roof looking like an old copper in a dripping cape! Bit "off message", sorry! BillR

To me it sounds like false air. When idling give a bit of brake cleaner spray around the rubber manifolds cilinderhead-carb. when idle is increasing you know where the air comes in.

Good evening, after another day exploring the guts of the K2! Also, my thanks to Norbert for the brake cleaner spray trick. I prefer to use WD40 as it doesn't deteriorate the 'rubber' seals, in the way that brake cleaner can.

I believe that I have found the gremlin that caused the revs to hit 3,200rpm and blipping the throttle and undoing the throttle stop screws, 2 full turns each, didn't cure.

Having rebuilt both carbs I decided to fit the rubber boots to both of the throttle cables. The old rubber boots were in poor condition and appeared to have ridden up the cables above the cable adjusters. Having fitted everything back on the bike, including the standard aircleaner housing, I noticed that on the left hand side the housing had been cut away to allow the cable a better route into the cable adjuster. This modification had not been carried out on the right hand side. The sliding of the rubber boots down the cables to cover both adjusters proved difficult and I had to lift the cable outers to allow the rubber boots to slide down onto the top of the carbs. In lifting the cable, the ferrule of the left hand cable seated on top of the adjuster, rather than in the bottom of the adjuster cup. When I initially measured the height of the slide above the base of the carburettor venturi the right hand slide was 5.0mm above the venturi, whilst the left hand slide was 6.7mm above the venturi, hence the high revs and inability to reduce them!

So, it appears that by fitting the rubber boots, the now kinked cable route can cause problems, even if the air filter body is modified to gain some clearance and try and prevent chafing of the cable outer that had revealed the cables steel core and allowed water ingress into the cable above the rubber boot! Repaired with heat shrink tube. I slid the rubber boots up the cables so that they no longer interfered with the air filter housing. Checked that the slides rested on their bases within the carbs and adjusted the throttle stop screws so that they just touched the base of the slide, but didn't raise it. This was acheived by sitting a 15cm piece of 3mm stainless steel rod just under the edge of the slide and watching for the free end to drop. I know it's rough, but I didn't have any cocktail sticks! The centre of both the slides cutaway is now 4.5mm above the floor of the venturi.

The slow running jets are both the same number of turns unscrewed from lightly touching their seats (1 turn). Also the cable adjusters have been adjusted so that when the throttle is turned VERY slowly, both slides rise at the same time from their seats, using the steel rod method again.

Tomorrow, I shall turn the throttle stop screws in one full turn each and after fitting the tank, see if I can get the engine to fire up and idle. I have a manometer, but not used it before, so will try getting my head around that and see if I can get this beastie to run well. Thank you All.

Good health, BillR

Excellent work, common sense applied and a solution found. Welcome to Morini ownership.

That’s good to find.My K1 airbox has similar come to think of it, but I cannot remember if it was actually cut or just worn through. You will now enjoy a marvellous bike.
John

Ming wrote:... Are you sure the slides are the right way round and the throttle cables not trapped above the adjusters?

Aha! Glad you found the problem.

Aye,
Thank you for your compliments, Italian 'designers' parental credentials are often called into question when I'm working on the fruits of their labours!

Found that I couldn't find the manometer! So decided to just get the bike running and see how it went. Single cold start 'ON' and second kick the engine started, so caught it on the throttle, shut the cold start and let things warm up at a steady 2,000rpm for a few minutes. No nasty noises or new leaks, so released the throttle and the engine died. Raised the slides by turning the throttle stop screws in by one full turn each. Started on the throttle but no idle. Repeated the process by a further three, one quarter turn in of both stop screws stages. This had the motor settling to a lumpy tick over at 1,000rpm afore dying. Gave the stop screws another eighth turn in and Hey presto! A steady 1,300rpm tick over, with a clean pick up on the throttle. "Dinnae play wi' it loon, get it oot and stretch its legs!".

So, accompanied by my wife on the Bros, we filled up the tanks and went on a 155Km jaunt round central Perthshire. Apart from the odd motorhome (Pantechnicon) drifting across the central line going up Glen Ogle and then nearly having our front ends wiped out by a **** on a GS1100, who had to get to the front of the queue at some temporary lights. On arrival at a rate of knots, he realised that he had overshot the lights that were still at 'RED', there was a 25 tonner coming towards him and the motorhome had to reverse to let him in out of the 25 tonners path! Why are GS owners generally a bunch of *****? We carried on our tour via Killin, Kenmore, Aberfeldy and home by the back roads. The engine pulled well up to 6,000rpm through the gears, including top, I know it'll do more, but....... is quite fast enough.

Maybe weaken the pilot jet screws a wee bit from their one full turn out from seated, but that can wait until I find the manometer. I'll maybe open another thread on the faffing required to remove the lower chain guard to check, adjust and then lubricate the rear chain.

Good health, Bill

Great stuff Bill, I was going to suggest looking at the adjusters.
Now all you need to know is that 6K on the rev-counter is your entry to the sweet-spot. That's where the fun really starts!
Cheers,
Dom

Bill,

No need for the manometer for the pilot jet screws. Turn up the revs a bit and turn each one both ways until it stumbles then bring back to middle of the two points then re adjust tickover. That is all I do I think the default is 1.5 turns out.

Aye MickeyMoto,

Thank you, I'll give it a wee go. I have 'Tipex' marks on the screws and notes, so that I can always go back to my previous settings if required.

Good health, Bill

Just thinking about waking my Sport up and got thinking about my low rev stumble. I know that the jets probably need reducing BUT I’m not clear what size is recommended. It’s a ‘79 Sport with electric start.
Any help gratefully received.

If your pilot jets are 50 received wisdom is to try 45 or 43. I had to fiddle a bit with the mixture screws now 1 & 1/2 turns out after dropping to 43 but it soon improved things.I never modified anything else but have rebuilt the carbs with new 112s and needles ages ago.Bike has always revved well.This on a 350 K1.
What jets are you currently running?
John

I've been leaning towards increasing the slide cut away as a better solution, but new slides are expensive. Old ones can be modified.

Thanks guys,
I’ll start with reducing the jets, I’m pretty sure they’re still as they left the factory. I like the idea of modifying the slides (but doubt my competence at getting it right!)
I’ll let you know how I get on.