In a foul mood....

[Paul in NZ]

Argh! I've been looking at this in a funk and am just now going in
circles fast.. argh!

History.... When I rebuilt the TR6C I did two things 'new'..

1. I fitted a Boyer....
2. I fitted a brand new AMAL...

I've completed probably 6,000 miles and in general the bike runs
bloody terrific... I run it in the sprints and day tripped it 2 up over hill and dale and fanged it on the hill...

But...

Its always been a PIA in town and I just cannot get a solid idle. Its has a nasty habit of killing the engine coming to a halt which when 2 up is an utter pain in the behind. (never used to be this bad)

Now - tinkering with it (in ever decreasing circles) I have checked the compression (all good), set the valves (all sweet)....

Now - last time it acted up I pulled the plugs - sootier than a chimney sweep... Hmm...... Hadn't used the bike much for about 6 to 8 weeks and there was some gum in the needle jet - cleaned the plugs, blew out the jets, dropped the needle - bike ran really well... A bit pingy 2 up going over the hill (hot day) so knocked the ign back a couple of degrees and it ran perfectly - after a hard run, pulled the plugs which were both a loverly biscuit colour...

Tonight - decided to head off and top off the fuel and get the milk bread etc (ok ok it was nice and I felt like a spin) and as I headed home - back to running poorly off idle - can't get a solid idle and plugs sootier than a 50's kids book... argh!

Observation - I never had this issue with my really worn out original AMAL but it's slogged out so?? I'm thinking of re sleeving it?

Actions - I'll order a new filter element / needle / needle jet / float / float needle shut off thingy and fit new plugs. While doing that I'll check the float level (again) and staticly check the timing is within cooee (it seems to prefer a touch of retardation)

Question - what the heck else is escaping me?

[tri boy]

You said you refueled, is that when the fault reoccured, or was it playing up prior to the top up?
I'm picking you use the same fuel and supply company most of the time.

Can't help you with the Amals. Never got my head around the various charactor traits they have.

[Paul in NZ]

You said you refueled, is that when the fault reoccured, or was it playing up prior to the top up?
I'm picking you use the same fuel and supply company most of the time.

Can't help you with the Amals. Never got my head around the various charactor traits they have.

Moisture I could deal with... Why so rich though? But yes - usually BP 98 - same station...

Don't be scared of amals - simple things

[riffer]

Sounds to me like there's not enough lead in the fuel for the poor old dear... <_<

[limbimtimwim]

Moisture I could deal with... Why so rich though? But yes - usually BP 98 - same station...Considering the price of petrol, 98 might not be selling very well and the fuel has gone bad...?

[Motig]

If your bike is hard to start and fouls plugs- the boyer ignition can cause this symptom if you have the coils wired in parallel instead of in series. Dont know if thats whats happening to you but that came from www.oldbritts.com/boyer

[FzerozeroT]

carbs getting too hot in town with limited airflow, would give richer mixture therefore black plugs. Jimmy up a duct to direct air over it and see if it helps.

[Motu]

I take it the Boyer doesn't use the mechanical advance? If it still has mechanical advance I'd be looking there.Weak springs,strong springs,sticky....whatever - it changes for no reason and that's where I'd be looking for inconsistency.+ or - ground? Doesn't matter,but make sure everything is one or the other.Last Triumph I had a play with was a mix match.Boyer you can switch +/- I'm sure.Grounds.....didn't do too good a paint job did you?

Did you get a MkI or II Amal? I know nothing about MkII's....and know for sure MkI's are shit wrapped in crap.Check for slide wear,they flog out very quickly and get air leaks around the slide,completely stuffing up the idle....next time you stop it sits in a different place and is all sweet again.Get the body bored and a stainless sleeve fitted on the slide.

If all else fails I'll give you a couple of hundred for the shitter....

[Doogle]

How long between rides is it?Is it possible that the fuel is sitting in your tank too long and going off?
If what the poster above suggests doesn't work try buying 20l of avgas and running the bike on that.If it settles down then you've found your problem.

[imdying]

Don't know much about old carbs, but having a shit time in the garage is something I can relate to. I hope that you're having a better time of it now.

If you need it resleeved, I've seen some incredibly sleeving jobs done by CBC her in chch, in stainless steel... it wouldn't surprise me in the slightest if this was in their range of capabilities, but I'm picking they would want to see it.

[Paul in NZ]

Yeah, this is annoying all right...

Apparently the new AMAL's have an issue in this regard (holding a good idle) due to a faulty drilling in the idle cct which can sometimes be fixed by re drilling... However - not sure.... Its seriously rich at idle / off idle - say 2,000 rpm in 4th (pootling speed)

The Boyer is connected correctly (in series with 6V coils) and it uses electronic advance - earths everywhere - clean power - battery is good - problem seems independent of ignition settings.

I'll sus it eventually - it just annoys me... bah!

[Paul in NZ]

If all else fails I'll give you a couple of hundred for the shitter....

Bugger off - a new ceramic toilet costs way more than that.... ;-)

[Fatjim]

Sounds like a vtr with a blocked breather hose.

[Paul in NZ]

Sounds like a vtr with a blocked breather hose.

Actually - thats not daft - I'll check the breather tonight. Thanks

[vifferman]

Sounds like a vtr with a blocked breather hose.
Yeah, that was a goodun (not!)
Even road spooge on the end of it is enough to inhibit the ("solely by gravity") fuel flow. And those 48mm carbs sure do have a prodigious thirst.

[Motu]

Its seriously rich at idle / off idle - say 2,000 rpm in 4th (pootling speed)


What cutaway do you have? Normally Triumphs do well with a richer cutaway,like a 3 instead of 3.5.It's easy to richen them,just file a bit off the bottom....to lean you have to file the cutaway.But rich at those speeds is a bit odd.

Do you have the late model primary case with the cover you remove to do strobe timing? I'd run it up at those revs and see what the timing is doing....it could be advancing up too early,or late....or fluctuating.Just because you set it at idle or max advance doesn't mean it's doing it right at 2,000rpm.I chased this exact problem for years on the XS1 - I was sure it was carbs and went to Mikuni's,then Blue Magnums,then a good set of original carbs.After a couple of years of major mucking around I found it was retarded just off idle.But this gave an apparent lean condition...rich is a different matter.And it was points with mech advance.

I did have a concentric that ran rich at idle - strange,it was good as a single carb,but was way off when run as one of twin carbs.If it was a Mikuni you could change the primary jet......so how can you do that on an Amal...?...?

[koba]

Actually - thats not daft - I'll check the breather tonight. Thanks

I remember some of the old buggers around here getting very tecnical about breathing on old triumph twins, somthing about a more restictive US market system that made 'em run shit for the sake of emmisions control....

Not really adding anything here, just rambling!

[FROSTY]

How long between rides is it?Is it possible that the fuel is sitting in your tank too long and going off?
If what the poster above suggests doesn't work try buying 20l of avgas and running the bike on that.If it settles down then you've found your problem.
wot he said

[Paul in NZ]

Pretty sure the gas is OK (well its not OK but its as good as it gets here)

Soo... I got mr magnifying glass out.... The float needle (fuel cut off) was 'scuffed' on the rubber tip so i replaced it with a used spare in better condition (old coots never throw anything out).

I dropped the float level slightly (much debate in some circles where it should be and its a pia to measure / change), set the valve clearances back to where they should be (opened em up in case one was not sealing) and fitted new plugs - Instantly 75% better pootling ability even without twiddling......

Still a bit sooty on the new plugs so I re advanced the ign to try and keep a bit more heat in there to get the plugs to self clean. Little inprovements but not so foul tonight by a long way!

Next I will order a new needle and needle valve (prob $30 or so) and continue to tinker...

[Paul in NZ]

wot he said


Good to see ya back Tony? I thought you were off some place?

[FROSTY]

welcolm to the hotel kiwibiker. You can check out any time you like.--but you can never leave.
HOTEL KIWIBIKER UNDER NEW MANAGEMENT-- nuff said?

[pete376403]

AMAL? AKA the metered leak? Stick a Mikuni on it.
I had a (very) high compression single that originally came with a Del'Orto. Useless thing was replaced with an Amal mk II which was equally useless. That in turn replaced with a 40mm Mikuni. Not only did it make more power than ever, it would even idle at about 1500 and could be started by flicking the back wheel while on the pit stand.

(was a Jawa 4V speedway bike, about 14.5:1 compression and running methanol)

[Motu]

Ha! Wouldn't you know it....I'm chasing the very same thing with my latest acquisition,a 1977 TL125.I cleaned the carb last week,and the filter disintegrated.So last night I made a new element,oiled and fitted it tonight.I have a really bad stalling flatspot off idle,not good on a trials bike - and I can't get a steady consistent idle....keeps changing.Someone has made a really nice billet manifold spacer,but that will feed heat into the carb.....is that going to be good or bad I wonder?

Right,off to the TL125 forums to see how they cure flatspots - I know they have them,because my much more refined TLR200 is prone to the problem too.

[stanko]

Have you tried putting the old carbs back on?

[Paul in NZ]

Have you tried putting the old carbs back on?

Carbs? Whats this carbs thing - a gentleman only needs one...

Besides - after the wed night ride - down the drive and it idled like a good un.. sweet....

[F5 Dave]

Motu
I've made to odd filter but never had much joy & found a new or 2nd hand one worked properly, even when using unipro filter foam. Sometimes the internal drillings can be a sod to clean out (perhaps bits of old filter?)

I would imagine the billet manifold would be a nice source of vibration to froth the fuel. Mind you I can't imagine the original Honda resin thingy was much betterer.

Old bike, check the emulsion tube for wear.

[Motu]

Yes,I've used Uni foam - I have other foam,but it goes out of shape with oil.I use this dry for precleaners.Something inbetween is needed.

After setting the float level last night and double checking my rechecks,I used the old standby - turning off the gas.As it runs out of fuel the motor revs up and runs sweet.A sure sign of richness - I was sure it was lean.They say an XR100 carb sorts these TL125's out,same with the TLR too.Another weekend in the shed....but it's so damn hot in there!

So that's another trick to try Paul - turn the gas off at the trouble spot and see if it runs better or just dies.Tickle to richen.....I how I miss the tickler.....

[Paul in NZ]

I should post a link to the most amazing amal tuning guide ever - astonishing info - but I can't find it - just as well I have a paper copy...

Had a long chat with a hexpert in these matters (a man who not only runs classics to die for but whos everyday mech transport is a preunit 650 with sidecar)... He assures me I'm an idiot.. (adds to his credentials) as he has told me previously to run hotter plugs as the unleaded gas runs 400F cooler (than I cannot believe) and impairs the self cleaning ability of the plugs.. Whats more - when the unleaded 1st came out NGK advised the trade they would need to go 1 grade hotter to avoid low speed fouling.

he runs 2 grades hotter no prob in the outfit so I'm very safe going 1 ...

Interesting though!

[riffer]

So I was bloody right!!

Hah!

It is the bloody unleaded fuel at fault.

And you thought i was taking the piss. :laugh:

[Motu]

So how come the pre ignition with unleaded? You'd think running cooler there would be no problems.None of my old cars (Falcons,Escorts,BMC's etc) would run on unleaded without octane boosters....or retarded timing.The plugs look like they are running cooler,being black and all that....but I dunno if I'd take the risk.But I run the Lada 5 degrees advanced and use a plug that spans 2 heat ranges,standard and one up....and it's factory lean.

Try some race or aviation fuel,if that fixes it then you can stand with the fuddy duddies moaning about unleaded ruining their bikes.

[Dodgyiti]

The float needle (fuel cut off) was 'scuffed' on the rubber tip so i replaced it with a used spare in better condition (old coots never throw anything out)

:laugh::laugh: tight b'stard:laugh::laugh:



Next I will order a new needle and needle valve (prob $30 or so) and continue to tinker...

STEADY ON!:confused:

[Paul in NZ]

So how come the pre ignition with unleaded? You'd think running cooler there would be no problems.None of my old cars (Falcons,Escorts,BMC's etc) would run on unleaded without octane boosters....or retarded timing.

I think the lower octane is the answer and yes - I will knock the ignition back a couple of degrees as well ;-) I'm only going 1 grade hotter...

[Paul in NZ]

:laugh::laugh: tight b'stard:laugh::laugh:


Hey - enough of the 'tight' business - I'm very loose... :bleh:

[Paul in NZ]

Well - I've been mucking about with old gas tanks rather than attending to the rich low speed running like I should.. But I have been thinking and asking questions and developed a cunning plan..

Carb - I will strip it again and fit a new air filter, float needle jet and a No4 slide as I believe the main issue (engine dies when coming to a stop) is richness when riding at 30mph in 4th - this is just where the slide is coming into play so it's worth a crack.

Plugs - I have gone 1 grade hotter with a little improvement so the next step is to go to an extended tip plug. There is enough clearance and local 'experts' assure me they stay cleaner and run slightly hotter.

Observation - I need to verify this as it's just something I was told thus far but I believe Triumph themselves went 2 grades hotter in plugs when electronic ignition was fitted? If so - thats quite interesting.

QUESTION - Did Triumph ever specify an idle speed? I can't find one so I suspect not. What do others use as a rough guide? 1,200 rpm?? stuffed if I know

So today - test ride to Otaki for a bike thing...

Bike runs well at first at town speeds, but 1/2 way to Otaki the throttle jams and its pinking like a bastard... argh! NO - before you ask I have NOT overtightened it and warped it OK - when the engine cools down it is just rideable so we limp home with my tail between my legs in a foul mood...

The extended tip plugs came out dangerously white (gulp) which indicated that the No 4 slide and the extended tip plugs was a probably a bad combination.

The NEW slide stuck because it was such a crappy fit (I possibly could have hammered it in to start with) and I didn't relieve it enough last night. It got hot (its a stinker here today) and gauled the alloy sticking in the bore so I've relieved it more and now it falls out when inverted.

So - while the tools were out I rebuilt the original slogged out carb (its a left handed one of some old bonnie) with new gaskets and a reasonable No 3 slide from the pile of half worn junk. This carb was old when I got it and I've done 50,000 miles on it. Re fitted the B7ES's and guess what - bike idles 100% better. Even, crisp and reliable...... GAH.....

My guess is the new carbs pilot jet is miles too big. Sweet - hours and $$ wasted.... I think I'll have a beer now... and another cold beer and cooled down.... (its darn muggy here today) and twiddled a few bits and set the idle
again.

I picked some of the red doris plums which are just coming on and the child bride whipped up a rhubarb and red plum crumble which put me in a very fine state of mind and filled my belly so we thought we would pootle up the coast on a test run and maybe a fancy coffee... so.... off we go...

Feck - it's running like a sweetheart.... Hot damn...

Out to Raumati beach and up to Paraparaumu and through Otiahanga, on to Waikanae and out to the beach there where I nearly die with shock and fall off - the engine keeps running at the roundabout... Good grief - is it possible???

Delirious with joy we head for Peka Peka along the coast road where all the noice people are building beach houses through the twisty bids - beautiful...

Get to the open road and open the tap and........ eh?? Wheres the power gorn and why is it banging on the over run?? Fine up to 60mph in the old money but sluggish and then the door slams shut, gurgle splutter cough wheeze - roll the throttle closed and she picks up again... hmm - this sounds awfully familiar (text book lean main jet) but awfully dramatic and waaaay to low in the rev range..... but awfully familiar...

So we cruise home on a whiff of gas at 60mph, roll into the shed - idling like a trooper (at least THATS fixed)

Pull the bung from the float bowl and the main jet falls out... gah.... I guess I didn't tighten it enough when I was cleaning the old carb up...

So - refit the jet - restart and off for a raaack to McKays Crossing and back - faaark - shes flying again, and idling... So - I've ditched the expensive new carb - how long before the electronic ignition and oil filter follow? Blasted modern rubbish

[Sensei]

Mate has to run 2 hotter plugs in his T150 from standard , it has neally sorted out the same trouble you are having . Avgas just hides the problem .

[James Deuce]

Blasted modern rubbish

That'll learn ya :)

[Paul in NZ]

That'll learn ya :)

According to Vicki I don't....

Thanks Sesei - I'm running 1 grade hotter now - std tips and I'll see how it goes. I think those new amals have some 'issues'...

[Ixion]

Was the new carb one of them Concentric things with the fixed pilot jet?

They don't work they don't , stick with good old Monoblocs. Or the type 5 or 6. They work

Settle an argument, that'll put you in a good mood.

Did the pre unit Tbird , alternator version come ex factory ever with magneto ignition. An old geezer at the Classic races today says no (there was a 1960 6T there with a Lucas Mag). I say yes, cos I had a 62 with a mag. Motu agrees with the geezer, but then mumbles and equivicates and tries to change the subject to SU carbs - HEY -- THERE'S YOUR ANSWER ! (we all agree that the dyno model came with mag)

[Motu]

I did have a concentric that ran rich at idle - strange,it was good as a single carb,but was way off when run as one of twin carbs.If it was a Mikuni you could change the primary jet......so how can you do that on an Amal...?...?

Told ya so!

I set the points and timing on the TL125,set the tappets and lowered the float level waaaay down on the spec level....did my turn off the fuel trick until it was right.Now I have a good idle and throttle response....but is still rich just off idle.Now,if I had an Amal I could fit a leaner slide.Oh,it's a cruel world int it?

[Paul in NZ]

Was the new carb one of them Concentric things with the fixed pilot jet?

They don't work they don't , stick with good old Monoblocs. Or the type 5 or 6. They work

Settle an argument, that'll put you in a good mood.

Did the pre unit Tbird , alternator version come ex factory ever with magneto ignition. An old geezer at the Classic races today says no (there was a 1960 6T there with a Lucas Mag). I say yes, cos I had a 62 with a mag. Motu agrees with the geezer, but then mumbles and equivicates and tries to change the subject to SU carbs - HEY -- THERE'S YOUR ANSWER ! (we all agree that the dyno model came with mag)


Meh - concentric of course but theyre not so bad really.

Re the T'bird... Oh gawd - can of worms time. According to the 'book' no. In real life - yes. Prior to the TR6P many police depts used 6T's and 5t's and I think that the mag could be specified so the alternator could be used for the radio etc and frankly lots of people didn't like the whole distributor thing on them (me included)... I had a 57 Speed Twin with alternator (6V) and a magneto so.... (mind you it was a real pile of poo by the time I purchased it for $190)

Then there is the kiwi I can do it attitude.. Change everything etc. Originality is a wierd thing. I have people telling me 'that aint right for that year' all the time with mine. The usually spot about half the things and are wrong half the time....

[Motu]

As far as mags went I preferred the BTH,they were a bit more quality than a Lucas,apart from the competition model with the red screw in pickups.But did any twins of any make come with a BTH? Some mags were specific to makes - the AMC twins all had a kill button on the end cap,Norton twin mags were slotted for chain adjustment....but I've seen both types on Triumphs,obvious retro from people who didn't know.

But I prefered a dizzy,because mags had terrible discrepancies in timing between cyls,the distributors were more accurate in that regard.I fitted a Morris 8 distributor to my alternator T110 powered Triton.Don't you hate bastards who bastardies bikes?

Long live twin points.

[Paul in NZ]

This from the archives

It is surprising just how far into throttle ranges some things have an influence. For example, I would not have suspected that the pilot jet would have an influence up to 7/16 throttle, or the main jet as low as 1/4 throttle.

Idle - 100% pilot jet
1/16 throttle - 60% pilot, 40% cutaway
1/8 throttle - 46% pilot, 46% cutaway, 8% needle/needle jet
3/16 throttle - 49% cutaway, 37% pilot, 14% needle/needle jet
1/4 throttle - 45% cutaway, 27% pilot, 24% needle/needle jet, 4% main jet
5/16 throttle - 37% cutaway, 33% needle/needle jet, 21%
pilot, 9% main jet
3/8 throttle - 44% needle/needle jet, 25% cutaway, 16% pilot 15% main jet
7/16 throttle - 55% needle/needle jet, 23% main jet, 13% cutaway, 8% pilot
1/2 throttle - 63% needle/needle jet, 31% main jet, 6% cutaway
5/8 throttle - 57% needle/needle jet, 43% main jet
3/4 throttle - 55% main jet, 45% needle/needle jet
7/8 throttle - 92% main jet, 8% needle/ needle jet
Full throttle - 100% main jet

Here is some other perhaps useful information from graphs in the Haynes Carburettor manual.

- a .5 cutaway change (e.g. from a 3 slide to 3.5) changes the mixture ratio by about 9% at 1/4 throttle, and about 4.5% at 1/2 throttle
- a change of 1 needle position changes the mixture ratio by about 6.5% at 1/2 throttle, and about 3% at 3/4 throttle
- a change in needle jet by one size (e.g. 106 to 105) changes the mixture ratio by about 3.5% at 15% throttle, 6.5% at 1/4 throttle, and 1.5% at 1/2 throttle.

The latter two points suggest that the needle affects mixture for higher throttle openings than does the needle jet. This would suggest that the needle/needle jet stage mentioned by Schultz is really two stages: needle jet, and then at a higher throttle opening, needle. In other words, if your mixture problems seem to occur at throttle openings in that transition area between cutaway and needle/needle jet (3/16 to 1/2 throttle), then playing around with changes to the cutaway or needle jet may be most effective.

However, if the problem occurs in the transition area between needle/needle jet and main jet (7/16 to 3/4 throttle), then playing around with needle position may be most effective.

If you examine the two sources of information carefully, you will see that they do not entirely agree. For example, Haynes suggests that at 1/2 throttle, a cutaway change of .5 can affect mixture by 4.5%, but Schultz suggests that the cutaway only controls about 6% of the mixture at 1/2
throttle, which would mean that any change in cutaway would have minimal influence at 1/2 throttle. I am also somewhat suspicious of the Haynes claim that a change in cutaway has more effect on mixture at 1/2 throttle than a change in needle jet.

What is really quite striking though is how the different components overlap. Most other information on the components' effect on mixture tends to say something like cutaway governs mixture between 1/8 and 3/8, needle/needle
jet between 3/8 and 3/4, etc. They sometimes mention there is some overlap, but it seems to me that the degree of overlap is at least as important as the information on when a specific component has the greatest effect.

[Motu]

Thanks Paul,that's very interesting - I'll have to print that out and put it between the pages of a manual and lose it forever.....but remember that I have it all written down somewhere.....I hope the internet stays around for a few more years so I can do a search.

All the steps overlap each other much more than I thought,and the cutaway plays an important part.I always used to fiddle around with cutaways,but modern carbs don't have a selection,and tuners don't seem to change cutaways.
SU (sorry Ixion) needles are graduated every 1/8in,so you can tune them every step of the way.I always seem to have tuning problems going from idle circuit to needle....cutaway is involved here,but everything interacts.....and this is also the point where the ign starts to advance.You need to check your timing at this critical point before making mixture adjustments.

[Paul in NZ]

Settle an argument, that'll put you in a good mood.

Did the pre unit Tbird , alternator version come ex factory ever with magneto ignition. An old geezer at the Classic races today says no (there was a 1960 6T there with a Lucas Mag). I say yes, cos I had a 62 with a mag. Motu agrees with the geezer, but then mumbles and equivicates and tries to change the subject to SU carbs - HEY -- THERE'S YOUR ANSWER ! (we all agree that the dyno model came with mag)


Theres an odd thing... I was reading Classic Bike Guide and there was a picture of two duplex framed pre unit T/Birds, nicely restored and I could clearly see one of them was fitted with a magneto...

[Ixion]

I think all ther ones I've seen with mags have been duplex. You'd have to be fairly keen on a mag to retrofit one, given that they ain't cheap. I've heard of more people retrofitting dizzys in place of mags.

I wonder if Triumph, knowing that the unit 650 was coming down the pike, started fitting whatever they had excess of in the parts bins - or, more likely, whatever they had unduely large supply contracts for. The twin cylinder dizzy would have been specific to them by then, maybe didn't want to sign another contract.

[rogson]

This from the archives........

What about float level? In my experience changes in float level have a significant impact, especially on off-idle/low throttle running.

[Paul in NZ]

What about float level? In my experience changes in float level have a significant impact, especially on off-idle/low throttle running.

Yup - fiddled with that and even dropped it to below recommended and it made no noticable difference. The old carbs float level is a tad too high (but refuses to be adjusted despite enthusiastic encouragement) and it idles pefectly.

I have to say that personally I'm not sure float level is as critical on an amal concentric as it is on say a mikuni or the dellortos on the Guzzi.