Paul,
I'm hoping to be there on Sunday, I'll drop in and speak to you if that's
oK. Any bright ideas, I'll be more than interested!
Joe
Time to get the K2 out of the naughty corner
Re: Time to get the K2 out of the naughty corner
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Re: Time to get the K2 out of the naughty corner
Hi Joe,
A random 5 cents worth. Noticed you said you have a BD atomiser. The standard one my K2 had and it's replacement was a 260CM, as per the Dutch site and what Harden sent me.
Fiona ( '86 K2, Sydney, Australia)
A random 5 cents worth. Noticed you said you have a BD atomiser. The standard one my K2 had and it's replacement was a 260CM, as per the Dutch site and what Harden sent me.
Fiona ( '86 K2, Sydney, Australia)
Re: Time to get the K2 out of the naughty corner
Hi all,
Sorry it's taken me a week to get onto this, but I swapped the carbs over today and it was a success! Now I know it's possible to make these bikes run properly, I can feel a bit of enthusiasm coming back - I was beginning to think it was just a joke, like I was on "Candid Camera" or something! Thanks also to Fiona for her posting, you may just have provided the missing bit of information, though I have a few steps to go through first.
OK, well the bike runs pretty well with George's carbs, so what's the difference? First I notice I have the pilot mixture screw just about 1 turn out, maybe a bit less, so that's telling me something has changed. Comparing George's carbs with mine we have:
---------------------George's----------Mine
Carb type---------VHBZ 25 BS------VHBZ 25 HS
Main jet------------112---------------108
Starter jet----------50----------------50
Pilot jet-------------42----------------44
Atomiser-----------260K------------260BD
Slide-----------------50----------------50
Needle---------E17 (middle)----E17 (middle)
Float needle jet---200--------------200
I don't know what the significance of "BS" vs "HS" in the type number is. My carbs have two breathers for the float chamber and a vacuum take-off, normally linked by a balance pipe. George's carbs have neither of these, but otherwise look identical.
All these carbs are nice and clean, but certainly I'll go over mine carefully again and check for the umpteenth time that all passages are clean. I think I'll first try putting all my jets, etc in George's carbs and see how that goes. I suspect it'll make little or no difference, but it'll be another question ticked off. I'll also put back my ignition parts and confirm that they work OK with good carbs. Not sure what the next step is after that, but this is a big step forward, surely it must be possible to home in on the fault pretty quickly from this point!
By the way, I still have a flat spot at 4000rpm. But this is a "proper" old-fashioned flat spot like we used to get years ago, where just rolling on a fraction more throttle pulls you through it, not this engine dying malarky like I've been seeing!
I'll be sure to let you know what happens next! In the meantime, comments and suggestions gratefully accepted!
Regards,
Joe.
Sorry it's taken me a week to get onto this, but I swapped the carbs over today and it was a success! Now I know it's possible to make these bikes run properly, I can feel a bit of enthusiasm coming back - I was beginning to think it was just a joke, like I was on "Candid Camera" or something! Thanks also to Fiona for her posting, you may just have provided the missing bit of information, though I have a few steps to go through first.
OK, well the bike runs pretty well with George's carbs, so what's the difference? First I notice I have the pilot mixture screw just about 1 turn out, maybe a bit less, so that's telling me something has changed. Comparing George's carbs with mine we have:
---------------------George's----------Mine
Carb type---------VHBZ 25 BS------VHBZ 25 HS
Main jet------------112---------------108
Starter jet----------50----------------50
Pilot jet-------------42----------------44
Atomiser-----------260K------------260BD
Slide-----------------50----------------50
Needle---------E17 (middle)----E17 (middle)
Float needle jet---200--------------200
I don't know what the significance of "BS" vs "HS" in the type number is. My carbs have two breathers for the float chamber and a vacuum take-off, normally linked by a balance pipe. George's carbs have neither of these, but otherwise look identical.
All these carbs are nice and clean, but certainly I'll go over mine carefully again and check for the umpteenth time that all passages are clean. I think I'll first try putting all my jets, etc in George's carbs and see how that goes. I suspect it'll make little or no difference, but it'll be another question ticked off. I'll also put back my ignition parts and confirm that they work OK with good carbs. Not sure what the next step is after that, but this is a big step forward, surely it must be possible to home in on the fault pretty quickly from this point!
By the way, I still have a flat spot at 4000rpm. But this is a "proper" old-fashioned flat spot like we used to get years ago, where just rolling on a fraction more throttle pulls you through it, not this engine dying malarky like I've been seeing!
I'll be sure to let you know what happens next! In the meantime, comments and suggestions gratefully accepted!
Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Re: Time to get the K2 out of the naughty corner
I am hoping to have another go at this today, but in the meantime I have more carburetter questions!
My throttle slides are stamped 8896.50 and George's are marked 7447.50. The only one listed on the Eurocarb website is 7447.60, though that probably just means they no longer have stock of any other variant. I am assuming 8896.50 and 7447.50 are the same? They certainly look identical.
My carbs originally had 258BD atomisers. These are not in great condition and NLM recommended changing them for 260BD, which is what I have now. George has 260K - does anyone know what the difference is? In an earlier post, Fiona recommends 260CM, though this is another item not listed by Eurocarb, so maybe not easy to get. As far as I can see, the difference is in the number and position of the holes in the side of the atomiser tube. There is an air feed to the outside of the tube, so the hole positioning will affect the mixture at different throttle openings. I don't know how much difference this makes or if it has any real bearing on my problem - any advice, comments, recommendations gratefully received!
Finally all these breathers. My carbs have two breathers connecting to the top of the float chamber. These were connected to two plastic tubes running forwards along the frame and stopping just short of the steering head. George's carbs have no breathers. All the Amals and Mikunis I am more familiar with have two breathers, though the tubes are brought downwards normally. Is this the difference between the "BS" and "HS" carb types - and why?
OK, I'm off to examine every mm of these carbs with a magnifying glass!
Regards,
Joe.
My throttle slides are stamped 8896.50 and George's are marked 7447.50. The only one listed on the Eurocarb website is 7447.60, though that probably just means they no longer have stock of any other variant. I am assuming 8896.50 and 7447.50 are the same? They certainly look identical.
My carbs originally had 258BD atomisers. These are not in great condition and NLM recommended changing them for 260BD, which is what I have now. George has 260K - does anyone know what the difference is? In an earlier post, Fiona recommends 260CM, though this is another item not listed by Eurocarb, so maybe not easy to get. As far as I can see, the difference is in the number and position of the holes in the side of the atomiser tube. There is an air feed to the outside of the tube, so the hole positioning will affect the mixture at different throttle openings. I don't know how much difference this makes or if it has any real bearing on my problem - any advice, comments, recommendations gratefully received!
Finally all these breathers. My carbs have two breathers connecting to the top of the float chamber. These were connected to two plastic tubes running forwards along the frame and stopping just short of the steering head. George's carbs have no breathers. All the Amals and Mikunis I am more familiar with have two breathers, though the tubes are brought downwards normally. Is this the difference between the "BS" and "HS" carb types - and why?
OK, I'm off to examine every mm of these carbs with a magnifying glass!
Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Re: Time to get the K2 out of the naughty corner
I'd recommend downloading the Dellorto tuning guide, it's available in various places on the web.
Holes at the bottom of the atomiser let in fuel, ones at the top let in air and the fuel level in the chamber varies under acceleration. A change of atomiser can help with the flat spot.
260K atomisers can be modified into B or BD by drilling extra holes; http://www.compton.vispa.com/Morini%20atomisers.jpg
The last number on the slide is the cutaway in mm, so a 40 slide is 4mm. You can always machine the slide to increase the cutaway, putting material back is much harder!
The last letter on the carbs denotes Dexter or Sinister, right or left handed. I think the preceding letter indicates the presence of a vacuum takeoff port.
There are always floatbowl vents on the VHB(Z), but it's often just a hole. The stubs are for emissions control, allowing you to route the vapours into the air filter assembly.
Holes at the bottom of the atomiser let in fuel, ones at the top let in air and the fuel level in the chamber varies under acceleration. A change of atomiser can help with the flat spot.
260K atomisers can be modified into B or BD by drilling extra holes; http://www.compton.vispa.com/Morini%20atomisers.jpg
The last number on the slide is the cutaway in mm, so a 40 slide is 4mm. You can always machine the slide to increase the cutaway, putting material back is much harder!
The last letter on the carbs denotes Dexter or Sinister, right or left handed. I think the preceding letter indicates the presence of a vacuum takeoff port.
There are always floatbowl vents on the VHB(Z), but it's often just a hole. The stubs are for emissions control, allowing you to route the vapours into the air filter assembly.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
Re: Time to get the K2 out of the naughty corner
I've started having another look at my carburetters and the first thing I've noticed is this:
This shows the value of having a known working carb to compare with. Mine is the top pilot mixture screw and it has a much longer taper on the end. No doubt this explains why my screw needs to be a good 2 turns out. It doesn't explain the balance pipe issue, but maybe this isn't the only difference in the pilot area. The mixture screw illustrated on the Eurocarb / Dellorto website appears to be the lower one with the short taper.
I have also had a look at the atomiser area. The air feed is via the small brass tube which protrudes into the intake at an angle. This leads down at an angle into the emulsifier tube and (I think) there is a groove running round the inside of the outer tube. There was still some muck in that groove which was difficult to shift, I got it out with a dental pick in the end. There is also some corrosion in that outer tube, I don't know if it's bad enough to affect anything.
If I have another go this afternoon, I'll take one of George's carbs off the bike again and start a full A-B comparison to try to understand the differences and see if I can spot an actual fault somewhere. Any fault has to affect both carbs....!
Joe.
This shows the value of having a known working carb to compare with. Mine is the top pilot mixture screw and it has a much longer taper on the end. No doubt this explains why my screw needs to be a good 2 turns out. It doesn't explain the balance pipe issue, but maybe this isn't the only difference in the pilot area. The mixture screw illustrated on the Eurocarb / Dellorto website appears to be the lower one with the short taper.
I have also had a look at the atomiser area. The air feed is via the small brass tube which protrudes into the intake at an angle. This leads down at an angle into the emulsifier tube and (I think) there is a groove running round the inside of the outer tube. There was still some muck in that groove which was difficult to shift, I got it out with a dental pick in the end. There is also some corrosion in that outer tube, I don't know if it's bad enough to affect anything.
If I have another go this afternoon, I'll take one of George's carbs off the bike again and start a full A-B comparison to try to understand the differences and see if I can spot an actual fault somewhere. Any fault has to affect both carbs....!
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Re: Time to get the K2 out of the naughty corner
Hi Joe,
I'll have a look at the breathers on my bike. Mine is ex US import, which I think had been stored for many years and not fiddled with much. I presumed the carbs jets in it were "contemporary" for when the bikes were newish and being serviced by the US dealer. The main jet is a 115 not 112, and a 50 idle jet in HS carbs - if that helps. She does occasionally foul the plugs a bit in traffic, but otherwise runs sweet. K2 carbs are one of their differences to the earlier bikes. The CM atomisers are specific for the K2, and the only source I found was Herdan Corp in the US (the original dealer who sold my bike new and is still in business!). Give Herdan a phone call - he doesnt seem to reply to email much
Good luck, and glad my 5 cents might have helped.
Fiona (Sydney, Australia 86 K2)
I'll have a look at the breathers on my bike. Mine is ex US import, which I think had been stored for many years and not fiddled with much. I presumed the carbs jets in it were "contemporary" for when the bikes were newish and being serviced by the US dealer. The main jet is a 115 not 112, and a 50 idle jet in HS carbs - if that helps. She does occasionally foul the plugs a bit in traffic, but otherwise runs sweet. K2 carbs are one of their differences to the earlier bikes. The CM atomisers are specific for the K2, and the only source I found was Herdan Corp in the US (the original dealer who sold my bike new and is still in business!). Give Herdan a phone call - he doesnt seem to reply to email much
Good luck, and glad my 5 cents might have helped.
Fiona (Sydney, Australia 86 K2)
Re: Time to get the K2 out of the naughty corner
An update, followed by the points raised by Paul and Fiona - many thanks!
Just to cross off another question mark, I tried my throttle slides, needles and carb tops on George's carbs and as expected, the bike performed well. I then tried George's jets and atomisers in my carbs and it was as bad as ever, possibly worse. I had previously checked all the passages for blockages and they are clean. The fact that the bike idles well tells me that the pilot hole on the engine side of the slide is clear (shoot me down if you disagree!) and as for the hole on the other side of the slide, you can see straight through that if you remove the pilot jet. The air feed to the atomiser is straight, so you can poke a wire through there, quite a thick wire. I really don't think this is being caused by any blockage. I can't easily check the air feed to the pilot, but again wouldn't a blockage there stop it idling? - and it would get better as the throttle rises, not worse.
I am now wondering if my problem may be down to the corrosion in the central tube, where the atomiser sits. It's quite deeply pitted on both carbs and the original atomisers were similarly pitted. I've seen other evidence to suggest that the bike has spent time in a damp atmosphere and I don't know if you get some electrolytic corrosion between the brass and the mazak, or whatever the carb body is made from. Whatever, it's corroded in there and I wonder if this affects the flow of fuel. Other than that, I'm running out of ideas. The carb body is a lump of metal and if it's the right size and shape it has to work. I've compared my carbs with George's point by point and they are identical other that having plain holes for breathers with no stubs and mine having vacuum ports, which I've blocked off anyway.
Fiona - thanks for your info. It's particularly interesting because yours is a US model K2 which must be very similar if not identical to mine. I will follow up Herdan if/when I get the main problem sorted.
Paul - thanks for the atomiser info. This is what made me look more closely at the corroded central tube. Not sure what my conclusion is yet though! I did find the breather holes on George's carbs. Those holes exist on mine, but they are blanked. There are some minor differences in the carb body casting, but they really are minor and wouldn't affect how it operates. Destra and sinistra - haha I should have guessed! So I have two left-hand carbs, somehow appropriate!
Now if anyone has a pair of known good carbs for sale, I may be interested......
Joe.
Just to cross off another question mark, I tried my throttle slides, needles and carb tops on George's carbs and as expected, the bike performed well. I then tried George's jets and atomisers in my carbs and it was as bad as ever, possibly worse. I had previously checked all the passages for blockages and they are clean. The fact that the bike idles well tells me that the pilot hole on the engine side of the slide is clear (shoot me down if you disagree!) and as for the hole on the other side of the slide, you can see straight through that if you remove the pilot jet. The air feed to the atomiser is straight, so you can poke a wire through there, quite a thick wire. I really don't think this is being caused by any blockage. I can't easily check the air feed to the pilot, but again wouldn't a blockage there stop it idling? - and it would get better as the throttle rises, not worse.
I am now wondering if my problem may be down to the corrosion in the central tube, where the atomiser sits. It's quite deeply pitted on both carbs and the original atomisers were similarly pitted. I've seen other evidence to suggest that the bike has spent time in a damp atmosphere and I don't know if you get some electrolytic corrosion between the brass and the mazak, or whatever the carb body is made from. Whatever, it's corroded in there and I wonder if this affects the flow of fuel. Other than that, I'm running out of ideas. The carb body is a lump of metal and if it's the right size and shape it has to work. I've compared my carbs with George's point by point and they are identical other that having plain holes for breathers with no stubs and mine having vacuum ports, which I've blocked off anyway.
Fiona - thanks for your info. It's particularly interesting because yours is a US model K2 which must be very similar if not identical to mine. I will follow up Herdan if/when I get the main problem sorted.
Paul - thanks for the atomiser info. This is what made me look more closely at the corroded central tube. Not sure what my conclusion is yet though! I did find the breather holes on George's carbs. Those holes exist on mine, but they are blanked. There are some minor differences in the carb body casting, but they really are minor and wouldn't affect how it operates. Destra and sinistra - haha I should have guessed! So I have two left-hand carbs, somehow appropriate!
Now if anyone has a pair of known good carbs for sale, I may be interested......
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
-
MickeyMoto
- Posts: 2586
- Joined: 22 Nov 2008 17:41
- Location: Even further oop North
Re: Time to get the K2 out of the naughty corner
Two left hand is correct.
As the carbs face different directions, you can fettle on the outside.....
As the carbs face different directions, you can fettle on the outside.....
Re: Time to get the K2 out of the naughty corner
Car bodies can and do 'go bad', I have a storage crate full of carb bodies that are apparently ex WeeVee/Phil Smith.
I can only assume that they are faulty items removed from bikes. Some may respond to ultrasonic cleaning, but I'm not hopeful.
It's possible to test carburettor spray patterns with coloured liquid, but it's quite a lot of hassle to set up.
Remember that US carb settings will be modified for the different US fuel formulations and emission requirements.
I can only assume that they are faulty items removed from bikes. Some may respond to ultrasonic cleaning, but I'm not hopeful.
It's possible to test carburettor spray patterns with coloured liquid, but it's quite a lot of hassle to set up.
Remember that US carb settings will be modified for the different US fuel formulations and emission requirements.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
-
MickeyMoto
- Posts: 2586
- Joined: 22 Nov 2008 17:41
- Location: Even further oop North
Re: Time to get the K2 out of the naughty corner
Sorry, it was meant as a joke! This doesn't work so well on triples....MickeyMoto wrote:Two left hand is correct.
As the carbs face different directions, you can fettle on the outside.....
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Re: Time to get the K2 out of the naughty corner
Yes, a good point, but since it ran well with George's carbs, I think it "should" work with his jets, etc in my carb bodies. But it doesn't. If I can summon the energy, I'll give them a session in the ultrasonic tank yet again, but I'm not at all hopeful and I'm running out of ideas. The original carbs are no longer made and even if a pair come up on ebay, they may be no better than mine, so I may be investigating the Mikuni route. I'm no big fan of Mikunis, but on present performance, I'm no big fan of Dellorto either! Eurocarb want £125 to "service" a carburetter, plus any extra work needed, plus replacement parts. Really, that's a non-starter. If you've any other ideas, I'd be delighted to hear them!EVguru wrote:Car bodies can and do 'go bad', I have a storage crate full of carb bodies that are apparently ex WeeVee/Phil Smith.
I can only assume that they are faulty items removed from bikes. Some may respond to ultrasonic cleaning, but I'm not hopeful.
It's possible to test carburettor spray patterns with coloured liquid, but it's quite a lot of hassle to set up.
I think that would test my patience a bit too far!
Remember that US carb settings will be modified for the different US fuel formulations and emission requirements.
Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Re: Time to get the K2 out of the naughty corner
Thanks for that, he has a pair in stock for £185 (ouch!) I've sent him an email with a couple of questions. These are the earlier "BS" carbs, but as I now know, they will work fine.
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
-
MickeyMoto
- Posts: 2586
- Joined: 22 Nov 2008 17:41
- Location: Even further oop North
Re: Time to get the K2 out of the naughty corner
Its the way you tell 'em....penman wrote:Sorry, it was meant as a joke! This doesn't work so well on triples....MickeyMoto wrote:Two left hand is correct.
As the carbs face different directions, you can fettle on the outside.....
Some days I get it, others not!
today was not a good day....