Time to get the K2 out of the naughty corner

[EVguru]

The slides on my Sport are pretty sloppy, but I just set the idle a little higher.

That Zamak intake bellmouth has had it, you'll probably be able to crumble it away with your bare hands! The later plastic type are readily available.

I've probably got a spare pair of good carbs. I know I've got a set of the late style with plastic tops, but I think I've earmarked those for a project. I can barely get out to the workshop at the moment due to a hip problem and I certainly can't safely access the main Morini shelves, so I'll not be able to check the stock.

[72degrees]

The bellmouth isn't quite as bad as it looks. I tried to twist it off and it not only didn't crumble but resisted all attempts at removal. No cracks on the inside to interfere with smooth air flow Hopefully NLM have been able to sort penman out with something. The shed needed a sort out anyway. There is stuff in there I'd completely forgotten about, like two pairs of Marzocchi shocks.

Hope your hip is sorted out. Mine aren't that bad yet, though they make riding the GFR125 very uncomfortable for more than a very short time. It's also time I got a proper bike lift so that I don't have to squat and kneel so much while getting Morini engine bolts out, and in again.

[penman]

Morning folks,

Just an update. The spares guy at NLM (Rob) is away this week so I have to wait until he gets back. They did confirm that they have a number of VHBZ carbs and carb bodies in stock, so I'm hopeful. In the meantime, I gave my carbs another session in the ultrasonic tank. I don't think that's done anything in itself, but the wet surface was easier to see in the central tube where the atomiser goes. I spent some time with a magnifying glass and the only "defect" I can see is some significant pitting in that tube. For the life of me I can't see why that should make the engine run rich in the mid range. Both threads are OK - the one for the atomiser and the one for the main jet assembly.

I have done a bit of testing with different combinations of jets, etc. With my carb bodies, it runs a lot worse with the "K" atomiser than with the "BD". With George's carbs, there isn't much difference, though the "BD" atomiser pretty well eliminates the minor residual flat spot - I need to be pretty fussy to notice it. This does support the theory that there's something wrong with the way the atomiser is working in my carbs. Maybe that pitting means there is too much fuel around the atomiser, or maybe it disrupts the flow of air or fuel too much. Who knows!

Regards,
Joe.

[penman]

By the way, sorry to hear about people's dodgy hips, etc. I'm suffering with tennis elbow at the moment, which doesn't sit well with the Morini's rather heavy clutch. If anyone knows of a way to reverse the ageing effect, do let me know!

Bike lift - yes, I've been thinking about getting one for years and I always pick up a leaflet at the Stafford show. What stops me is the thought that it'll be in the way when not actually in use. I do have a double garage, but it always seems to be crammed full. Maybe if I was a bit tidier...?

[72degrees]

That really is mysterious. Do you mean the thread that the atomiser jet screws in to is pitted or the carb choke tube around that area? No sign of actual cracks?

I haven't stripped and cleaned the second VHB25 that I found in the shed yet but you are welcome to try the bodies from those with your jets etc. if Rob can't sort you out.

I just spent quite a while on the phone to Eurocarb ordering the PHBH28s for the 'project'. They are quite happy to supply jetted to requirements (plus with lever chokes rather than cable). Given the results of the test run yesterday with the carbs from the 375/L5 I was operating a bit on guess work, but I suspect the huge 132 mains may be largely to blame (though they work well on the 375 once it is wide open). Mind you, I may find that a brand new set of bodies brings an altogether different experience. As Evguru suggested I really must get it on a dyno somewhere. Not to depress me with the lack of it but to try to diagnose the carburation (or any ignition issue). It sorted out the CR33s on the big bore, race exhaust Nordwest when I built that. When I first put the 28s, on erm... 35 years ago? I took the bike to NLM when they still had a rolling road. That showed that it was pretty near at the top and suggested which way to go mid range. I've never got it perfect but it has had several different exhaust systems since then. I still reckon a 2:1 system brings complications in the mid range. I see you can still get a Gunson Colortune - though I'm sure I used to have one in the shed somewhere. The joy of Senior Moments

[72degrees]

Bike lift - yes, I've been thinking about getting one for years and I always pick up a leaflet at the Stafford show. What stops me is the thought that it'll be in the way when not actually in use. I do have a double garage, but it always seems to be crammed full. Maybe if I was a bit tidier...?

Ha - you must have seen inside my garage. I have a simple hydraulic cradle lift that can go under any bike with bottom frame rails but the lad's KTM 250 2T hill climber is currently perched on it awaiting winter fettling.

[EVguru]

I'm suffering with tennis elbow at the moment, which doesn't sit well with the Morini's rather heavy clutch.

It's not a one finger clutch, but it shouldn't be heavy. Perhaps a new clutch cable and careful attention to it's routing is in order.

[penman]

72degrees: Sorry, what I was trying to say is that the threads are in good condition, it's the outer tube where the atomiser, main jet, throttle needle and so on fit - not sure if it has a name! The central part of that tube, between the atomiser thread and the main jet assembly thread is deeply pitted on both carbs. The actual threads themselves are OK. In other respects, these carbs look practically brand new. There are definitely no blockages or partial blockages in any passages. By contrast, George's carbs are dead smooth in that atomiser area, no sign of pitting at all. The venturi area on my carbs looks as good as new and there are no visible cracks anywhere. I don't think the pitting is deep enough to have perforated anything, though of course it's hard to see down there! Nothing visible on the outside.

EVguru: I don't think the Morini clutch is unduly heavy as classic bikes go - heavier than my Bonneville, but MUCH lighter than my Trident. I have a new "featherlight" cable and the routing is as gentle as I can get it. It's just a bit too heavy for my damn tennis elbow!

As a general issue, the bike needs using, I think the clutch and gearbox action will improve with use and certainly I'll get more in tune with it. I constantly hit false neutrals on the Morini and never on the Bonnie, but I think that's partly because the bike's been unused for at least 20 years and partly because I'm not in tune with the gear pedal action. If I can just nail this carburetter issue I can start using the thing and I think these other niggles will start to disappear.

[Ming]

I use one of these, it stacks up against a wall when not in use (not very often at present!)
http://www.ebay.co.uk/itm/FoxHunter-150 ... SwYHxWQHvP

[72degrees]

I use one of these, it stacks up against a wall when not in use (not very often at present!)
http://www.ebay.co.uk/itm/FoxHunter-150 ... SwYHxWQHvP

Looks very much like mine.

[72degrees]

atomiser.jpg (61.82 KiB) Viewed 14763 times

Ah, do you mean the area in this not very good photo (though the atomiser is back in) ? I may try again on manual focus (with the atomiser out) on my cheapish DSLR rather than auto. Not sure how that could effect mid range carburation except possibly holding a tiny bit more fuel in the pits so that a smart opening of the throttle sucks more in than it should, but I don't really see that could supply fuel to the atomiser any quicker than the main jet is able to anyway.

From what you have said, it has never run properly in your ownership. I can find no mention of Dellorto motorcycle carb *bodies* being different for the USA market for emissions purposes, and if so you would expect them to be marked as such somehow, but it does make me wonder, when they have been identified as the variable at the root of your problems. I know from posts on the Euromoto list years ago that Guzzis in particular ran very nastily until re-jetted to Euro spec, but that was easily achieved.

Bon courage! I'll sure you will get there in the end and take it out and ride it to return with a proper Morini grin.

[penman]

Yes, that's the area I'm talking about. The pitting is further up than the slotted end of the atomiser and extends through the area between the two threads. Like you, I can't explain how this could so seriously affect mid-range mixture - and maybe it doesn't! It's just that this is the only defect I can find on these carb bodies. If this isn't the problem then I really haven't a clue. I would love to find a crack or a blockage because at least I'd be able to understand what's going on.

When I fitted George's "BS" carbs, the bike performed really well, with just a very minor flat spot at 4000rpm. When I tried it again with his "K" atomisers replaced by my "BD" ones, it was better again, more than satisfactory I'd say. From the hole pattern, the BD is leaner than the K in mid range. When I tried the Ks in my carbs, the result was worse than awful, practically unrideable. Even then, rolling on to full throttle, it would gradually clear and it would pull away like a train, though it took as long as 10 seconds of spluttering before it would clear.

I'm still waiting for the Morini grin! I can see it will be a great bike to ride on twisty roads, but up to now, opening the throttle coming out of a bend has generally resulted in it spluttering and dying - and some very undignified zig-zags as you try to avoid landing in the ditch! Of course when the engine isn't behaving, you can't see any of the bike's good points, it's all just a pain in the neck! I think I'm on the home run now though and I intend to follow this through.

[72degrees]

The symptoms do sound like too rich at 1/4 to 1/2 ish throttle. Are you sure the progression hole and "air channel" have been properly cleaned out by the ultrasonic process? Might still be some crud in there. Having said that, a session in my cleaner sorted out an old Keihin carb on my wife's CB250 that never ran right until then (lots of tiny passages inside it). I'd be inclined to give them a poke (particularly the air channel) with a bit of stainless lock wire and then squirt carb cleaner through under pressure. Not as if they are very finely calibrated tiny jets or have rubber bits to be affected, and it seems you have nothing to lose.

[penman]

The air feed to the atomiser is dead straight and you can poke a pretty thick wire through it, as I've done numerous times, believe me! As you say, this isn't a calibrated jet, so I don't think you can hurt it unless you are really rough with it. Anyway, I think I've given up with those carbs. There is good news though!

I put all my removable parts - jets, atomisers, floats, needles slides and so on into George's carbs and took the bike for a 50 mile ride today. Someone mentioned the "Morini grin" earlier and now I've experienced it at last. In my case part of it is amazement that a 350 can perform like that! OK, it doesn't do a lot below 3000rpm, but from then on it's amazing! Considering the age of the bike and the simple layout, the suspension's pretty good as well. My route included a nice twisty road, but I'd forgotten it's pretty bumpy as well. The K2 handles bumpy corners a lot better than I expected. I came back well pleased with it. Even the fairing, which isn't really a thing of beauty to be honest, works pretty well and kept the wind off me well on this chilly afternoon.

So, it's officially out of the naughty corner now and fettling should be straightforwards from now on. Hopefully I'll get some carbs next week - unless of course George would like to swap his boring old carbs for mine with a really interesting fault. OK, thought not!

Many thanks to all those who have offered ideas and support!

Joe.

[72degrees]

So, it's officially out of the naughty corner now and fettling should be straightforwards from now on. Hopefully I'll get some carbs next week - unless of course George would like to swap his boring old carbs for mine with a really interesting fault. OK, thought not!

Many thanks to all those who have offered ideas and support!

Joe.

If all else fails give me a shout and I'll send you these VHB25BS bodies 'on approval'. Though I'm wondering if it might not be a bad idea to replace the robbed bits and try them as an alternative to the 28s. They might work better at some hills. The late, great, Cornish hillclimber Roy Opie used to say the secret of good times at very short courses like Tregrehan (440 yards) was small carbs and sticky tyres.