mirage tank

DoC! said:
Tell me to bugger off if I am wrong, but there are approx 1.2 US gallons to 1 Imperial gallon.
Click to expand...

OK Doc, much as I'd like to honour your request, you are almost completely right, a US gallon is actually 1.20095 Pommy gallons. Although a US pint has only 16 ounces, so if the ounces were the same a Pommy gallon would be 1.25 Seppo gallons. But the ounces are not the same (for reasons not clearly understood any more, although it's actually the fault of British Parliament, in 1824 they changed the value of the gallon and ounce after the US had adopted the old values as their standard), a Seppo liquid ounce is 1.04084 Pommy ounces.
And metrication is just not an issue in this country. Probably just as well, they'd probably come up with a US metric system anyway, similar to but slightly different from the rest of the world. Like the French  :D :D.

Ken
 
Yep, transposed the figures in the calculation and didn't notice.

1 UK gallon = 1.2 US gallons
1 US gallon = 3.8 litres
1 UK gallon = 4.54 litres

The Queen Anne gallon (231 cubic inches) was introduced in 1706 and adopted by the US.
The UK adpoted the imperial gallon in 1824 (approx 277 cubic inches) but by that time the colonials had declared independence.
 
Clem,

You must have special 3C round badge tank, because mine will hold approx 19 liters when filled from bone dry to the brim of the filler orifice. Same goes for my round badge 3CL tank. With the dells I fill up every 200-215k's, depending on how hard I push the engine. 7.5 liters per 100km seems to be my average, whatever that is in MPG.

Regards,
Gerald
 
I had POP and the 3C side by side one day and noticed the tanks were subtly different in shape.
There were a couple of centimetres here and there difference.
The 3C tank is an early round badge version and POP's was a late version with no badge recess.
Either way I would struggle to fit more than 19 litres into each of them.

 

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UPDATE
this morning I removed the carbs and checked jets etc 145 main 65 idle 70 starting jet ,what  do people think I can reduce the main jets to ,I have 115 & 128 would these do to try .I realise it involves plug chops etc just looking for a starting point and to use someones experience .Also checked the chokes were seating which they were, all O rings and jets are new  Its got 4c cams and I think standard pistons .Whilst doing this I am thinking of going the extra mile & getting the valves & seats  seats refaced as I have a friend who owns a serdi valve machine just to make sure all is ok with the head, and timing the cams
dave
 
Dave there's another thread on this same topic just finished a couple of days ago, do a quick search. Most people here feel that 120s or even a bit less are about right for mains with modern fuels, 115 may be a bit small but it depends on the rest of the motor of course. Try 120s anyway. The idle and starter jets are probably OK.
But if you're thinking of redoing the valve seating, do that first, get you valves shimmed absolutely right, then work on the carbs.
And be careful with the valve reseating. If your shims are already on the thin side, taking another mm or so off may mean you've run out of adjustment, then you'll have to have the seats replaced. Which aside from being expensive, you have to find someone who'll do it right, and there's a lot of people out there who'll do it wrong and permanently buggar your head.

Ken
 
i checked my notes: 122 main, 55 pilot, K14 needle

with K1s i expect the mains would be smaller. try the 128s and go riding
when you get back do a leakdown on the warm engine before you think about pulling the head. it may not be necessary.
the plus side of having the seats cut on the serdi is an improvement in low lift valve flow and having the seats all at equal depth
then if you find the cut seats and valves leave you short of valve clearance get a set of F1 cams from keith. the reduced base circle will generally give you back what was lost in the cutting of seats/valves


if there are 8 pints in a gallon then the usa pint is the original light beer
 
American beer is like having sex in a canoe.

Fucking close to water...  :-*
 
Grant said:
I had POP and the 3C side by side one day and noticed the tanks were subtly different in shape.
There were a couple of centimetres here and there difference.
The 3C tank is an early round badge version and POP's was a late version with no badge recess.
Either way I would struggle to fit more than 19 litres into each of them.
Click to expand...

Grant,

You will find the tank bottoms differ a bit too, would explain why some have clearance issues when fitting Mikunis and others don't.  They fitted OK with my 1200/Mirage tank though.

piet
 
So true!  Reading this thread has been a bit of a puzzle to me.  My Mirage 1200TS has never caused me to fret over a limited touring range. It usually returns about 44 miles per US gallon.  It also has been a challenge to fit the fuel tank over the Mikuni RS36 carbs. Others here report the tanks easily accommodates these carburettors, but I've adjusted, shimmed, hammered and bent all sorts of things trying to find the needed clearance.  Now I know why.  I'm the owner of a "big" Mirage tank!  :LOL:
 
Hey Lawrence.. is your 1200TS Mirage running 4C cams 55 idle and 145 mains? my '78 Mirage is and has similar poor fuel consumption to Merlin's..

Recently it would do as little as 8km/Litre (22.75 miles per ImpGall or 19 miles/US-Gal): didn't matter whether I rode it at 60mph or 100mph either.. I slackened off the choke cables completely and replaced the choke o-rings and instantly the fuel economy improved to 32.7miles per ImpGall (yes folks ~44% improvement overnight :o) ). Slow speed running improved significantly too.. plugs seeming to foul less..  8)

I don't need to hammer it to the ton and can't see much point going faster (can't hang on :o) ) so am also considering using 128 mains to see if the consumption and fuel range improves: I can pass many things on my Mirage but not a petrol station..  :-X  Point noted CLEM  ::)

AndyW
 
I may have mislead a few of you here, TOG1 has three tanks, the standard puny tiny pathetic (for a tourer!) tank, the second is a round badged tank enlarged to 25 litres from dry (but very hard to tell)  Both of these are painted in 1200TS colours with milimetre perfect red coach lines on silver metallic,the last is a 1200 tank hugley enlarge by being both wider and taller, and hold 42 litres, as yet it is unpainted.


it does remain that an unaltered  round bafge Jota/3C tank is larger than the standard 1200, neither of them are big enough!
CLEM
 
merlin said:
UPDATE
this morning I removed the carbs and checked jets etc 145 main 65 idle 70 starting jet ,what  do people think I can reduce the main jets to ,I have 115 & 128 would these do to try .I realise it involves plug chops etc just looking for a starting point and to use someones experience .Also checked the chokes were seating which they were, all O rings and jets are new  Its got 4c cams and I think standard pistons .Whilst doing this I am thinking of going the extra mile & getting the valves & seats  seats refaced as I have a friend who owns a serdi valve machine just to make sure all is ok with the head, and timing the cams
dave
Click to expand...

Sorry Dave,

But imho, you're on the wrong track.

I'd suspect your carbs/engine are/is either completely clapped or not correctly set up... but I cannot see them from here.  As long as you're not constantly on WOT, smaller mains will have little effect on consumption.  Neither will freshly cut seats, etc.

Are the cams fitted with the correct sprockets?  A11, ie, standard sprockets fitted to C4 cams and timed as A11s will give away considerable power with poor fuel consumption.  Early A11 sprockets are un-marked, C4 sprockets were always marked as such.

Which needles and needle jets are fitted?  Condition?  If you cannot reliably assess them, chuck 'em out and replace!  These 2 components have the greatest influence on consumption within the carb.  Next on the list is float height and condition of the float valves.  Which slides are fitted?  Condition?  How are the pumpers set?  Do the choke sliders seal properly?  If the sealing rubber is too worn, they won't seal, even if they are seemingly seated correctly.

Check carb linkages for play, out of synch carbs play havoc with consumption as well.  To get them properly balanced, the valves need to be set to correct clearances, and try to get them even, with no great variations between the individual valves.  

What sort of values do you get when checking compression?  Engine in reasonable nick with C4 cams should show at least 8bar/110psi, good ones manage 12bar/160psi.  No point in continuing if you stay below 110psi... would recommend a leak-down test first.

Base line for a 1200 with flat-top pistons, C4 cams, either empty air filter box or v-stacks and a relativly free-flowing exhaust would be around; 125-130 main, 60-65 idle, K1 needle, 256AB needle jet with 60/2 slide.  I find the 1200s benefit from the 1000 set-up, are a bit crisper in pick-up than with the K14s.  These were fitted for the mega-obstructive stock 1200 air filter box.

Some food for thought, before you build a bigger tank just to make it to the next filling station.  Range to reserve should be around 170-190km/105-120miles, ie 40-45 miles/imperial gallon.  I'm quite glad for the chance to get out of the saddle for a couple of minutes by then...

piet
 
AndyW, I doubt our bikes are comparable.  Mine has Axtel cams on the standard low-compression pistons. I've been running Mikunis for about 3-4 years now, and the ignition was upgraded to digital long ago.  It's a torquey, tourer, just what I prefer.
 
Say, Tim.. welcome to this Mirage thread.. :D what fuel consumption do you get from yours? what carb settings have you got? etc etc..

Share and Enjoy! :D

AndyW
 
had a bit of time this morning ,took off the cam cover and as piet suggested checked for markings on the gear wheels nothing can be seen with the cams still fitted .so this afternoon after work I will remove cams and have a good look
 
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