Wanted: 74/75 850 Commando

[granstar]

I have this book and reiterates Paul's wisdom, viton seal, float levels, don't overtighten.

http://victorylibrary.com/CONC.htm

If I win lotto my commando will get a single carb head as a sensible mod...sorry slipped into a dream there.
I converted my T140 bonny from MK2 Amals to a single Tiger head with concentric with chromed slider, chucked the choke ( a spent .22 shell fills the hole) never run better, and no loss of power ( noticable).

[eelracing]

The bodies wear as much if not more than the slides and will sometimes leak enough air around them to make idle adjustment a real PIA. Having said that - IF everything else is right, ie ignition, valves, charging etc then you should be able to get some sort of idle...

Speaking of such... What sort of ignition system are you running? If not already some kind of electronic one will definately help.

Oh I can get it to idle following the manual to the letter,it's just that it's so bloody erratic.Once warmed up it will be fine but at operating temp and pulling up to a stop she will sit at idle but then sure enough slowly rise up in revs to the point it can be at 3000 rpm.I can give it a couple of blips on the throttle which will settle it down or if in gear let the clutch out to bring it back down only for it to eventually start rising again. By now i'm getting a bit sick of this so what does old muggins do?I will wind out the idle adjusters until she ticks over all ticketeeboo like.Only to pull up at the next stop and practically have the engine stop dead if I don't catch it on the throttle in time...So what does old muggins do?...you can see where i'm going with this eh
I'm basically at a compromise with the set-up now where if I stop I just blip the throttle.Open road cruising has never been a problem as is starting (kick only as electric start gutted out)& Boyer ignition fitted two years ago.

I guess ultimately I will have to face the fact that the carb bodies are worn out but I can live with it for now as any spare cash is going to go on that damn front brake.

[Paul in NZ]

Oh I can get it to idle following the manual to the letter,it's just that it's so bloody erratic.Once warmed up it will be fine but at operating temp and pulling up to a stop she will sit at idle but then sure enough slowly rise up in revs to the point it can be at 3000 rpm.I can give it a couple of blips on the throttle which will settle it down or if in gear let the clutch out to bring it back down only for it to eventually start rising again. By now i'm getting a bit sick of this so what does old muggins do?I will wind out the idle adjusters until she ticks over all ticketeeboo like.Only to pull up at the next stop and practically have the engine stop dead if I don't catch it on the throttle in time...So what does old muggins do?...you can see where i'm going with this eh
I'm basically at a compromise with the set-up now where if I stop I just blip the throttle.Open road cruising has never been a problem as is starting (kick only as electric start gutted out)& Boyer ignition fitted two years ago.

I guess ultimately I will have to face the fact that the carb bodies are worn out but I can live with it for now as any spare cash is going to go on that damn front brake.

Thats very odd.... Float levels too high?

[Voltaire]

I have this book and reiterates Paul's wisdom, viton seal, float levels, don't overtighten.

http://victorylibrary.com/CONC.htm

If I win lotto my commando will get a single carb head as a sensible mod...sorry slipped into a dream there.
I converted my T140 bonny from MK2 Amals to a single Tiger head with concentric with chromed slider, chucked the choke ( a spent .22 shell fills the hole) never run better, and no loss of power ( noticable).

I might be wrong but I don't think there is " a single carb head" just that you can get a manifold adaptor to mount a cough cough Mikuni on it.
I've been lucky with mine touch wood.I had not used it for a few months, and started in a couple of kicks ( when following the correct start procedure)
I have found that the 'modern' fuel fouls plugs very easily and they are best replaced and they never seem to be the same after cleaning.

[Paul in NZ]

I might be wrong but I don't think there is " a single carb head" just that you can get a manifold adaptor to mount a cough cough Mikuni on it.
I've been lucky with mine touch wood.I had not used it for a few months, and started in a couple of kicks ( when following the correct start procedure)
I have found that the 'modern' fuel fouls plugs very easily and they are best replaced and they never seem to be the same after cleaning.

Yes - there is a single carb manifold for Nortons. No so easy with a Triumph with the delta head with splayed inlets but doable with parrallel ones.

Nothing wrong with a Mikuni either. I've seen CV carbs as well as all sorts of 'solutions'...

Sparkplugs need to be at a certain operating temperature so that they 'self clean'. In the old fashioned combustion chambers that usually does not happen now as the modern fuels don't seem to allow it and I never found enough adjustment in a concentric to counter it. I have gone up 1 grade hotter in plugs and to an 'extended tip' plug to place it in a hotter environment. I can do this easily with the 650 as even Triumph themselves did this with the later T140's that featured the Lucas Rita electronic ignition. It works quite well and now I can ride at "town speeds" without stumbles....

I tried increasing the slide cut away but the engine ran stupidly hot. and playing with needle position had bugger all effect.

[Motu]

Once warmed up it will be fine but at operating temp and pulling up to a stop she will sit at idle but then sure enough slowly rise up in revs to the point it can be at 3000 rpm.I will wind out the idle adjusters until she ticks over all ticketeeboo like.Only to pull up at the next stop and practically have the engine stop dead if I don't catch it on the throttle in time...:

Do you have insulating blocks between carbs and head ? It's the carbs heating up and cooling down - as you ride down the road vaporising fuel cools the carb down, when you stop at the lights heat from the cyl head flows to the carbs (called heat soak) leaning the mixture out and increasing the idle. Carburettor car engines have heated manifolds to stop this. This was life for me in the '70's commuting by Norton across Auckland city - I set the idle for a hot idle, pull up at the lights and hold it at a good idle with the throttle, then as the carbs warm up you can let go the throttle and stretch that aching back and get circulation back in the hands...all real Nortons have low bars I think. My brand new Concentics were bolted straight to the head with no insulating blocks.

[eelracing]

Do you have insulating blocks between carbs and head ?

you can let go the throttle and stretch that aching back and get circulation back in the hands...all real Nortons have low bars I think.

Yeah they're there.But I take issue with the low bar comment as my bike is ex US and comes equipped with good ol' boy cowhorns No back probs here...yet.

[Paul in NZ]

Golly - AMAL really seem to have their stuff together here...

http://amalcarb.co.uk/technical/

Note the modified spray tubes for tridents and later 850 Nortons (rebuild section)

[T.W.R]

As it says looking for a Mk 4 850 in decent nick,and i am well fussy so decent means just that and not someones shabby attempt at a resto.

http://www.trademe.co.nz/Browse/List...x?id=635909059

[98tls]

http://www.trademe.co.nz/Browse/List...x?id=635909059

Thing is when i started the thread Bill i thought the TL was outta here,it wont leave so the Norton thing is back to the someday/oneday....did have a look at the yellow 750 on tardme.

[T.W.R]

Thing is when i started the thread Bill i thought the TL was outta here,it wont leave so the Norton thing is back to the someday/oneday....did have a look at the yellow 750 on tardme.

just keepin your interest up...I saw the thread a few weeks ago (20mth hiatus I've missed a few bits n pieces) so thought I'd throw temptation at ya
Ha the yellow Hi Back in ChCh? you know you'd have to bring it back to stock with the beastie seat
got to have something to keep the TL company the single has gone & bet the triple hasn't had anything done with it or has that gone too?

[98tls]

just keepin your interest up...I saw the thread a few weeks ago (20mth hiatus I've missed a few bits n pieces) so thought I'd throw temptation at ya
Ha the yellow Hi Back in ChCh? you know you'd have to bring it back to stock with the beastie seat
got to have something to keep the TL company the single has gone & bet the triple hasn't had anything done with it or has that gone too?

Yea mate thats the one,just looked thats all.The wee Honda went to a good home,was quite happy to keep it but a bloke had a dire need for it so off it went,the XS is still here but correct nothing done mind you it was always going to be a retirement projecteverything in good time eh.Had a ride on a Thruxton the other day but wasnt inspired,like the looks though.made the TL feel like a new bike next time i rode it.Fuck the Thruxton was bland.

[Voltaire]

Yea mate thats the one,just looked thats all.The wee Honda went to a good home,was quite happy to keep it but a bloke had a dire need for it so off it went,the XS is still here but correct nothing done mind you it was always going to be a retirement projecteverything in good time eh.Had a ride on a Thruxton the other day but wasnt inspired,like the looks though.made the TL feel like a new bike next time i rode it.Fuck the Thruxton was bland.

+1 on the Thruxton being bland. I had one for about 6 months and louder pipes just made it bland and loud, they look ok, but the proportions are a bit off.
Buggered if I'd pay 20K plus for a Gus Khun Commando when you can pick up Ducatis so cheap.

[AllanB]

+1 on the Thruxton being bland. I had one for about 6 months and louder pipes just made it bland and loud.

I still can't understand why Triumph has not brought out a 'hot-rod' Hinckley Bonnie engine. The existing one is so over engineered that a 80hp one with a bit of character is easily achievable for them.

Or supercharge one ......

But then I'd have to front up with some coin!!!!

[Kickaha]

Buggered if I'd pay 20K plus for a Gus Khun Commando when you can pick up Ducatis so cheap.

What like the Green frame on ebay at 122K?