Triumphrat

Old Cafe Racer

Now another story ....

Getting the jetting right with ulp... who else has had the privilege of setting up a pair of non standard carbies with the bloody stuff ?

After the second build I removed the 626 Amals (a mismatched pair) and fitted a brand new set of 900 series 28mm Wassels.
These came setup std with 180 mains, 3 slides, 106 needle jets and needles in the top groove., ran like crap, made black porridge on the piston tops and felt like the cylinders were full of slow burning wool.
I tried different main jets and every needle clip combination to no avail.
2 weeks later and I'm now finally cooking hard brown/grey/black carbon on the piston crowns and can run flat out for an hour in 100 degree temperatures with no issues on BP Ultimate 98 ron unleaded.
I gave up trying to get intelligent plug reads with ulp and started reading direct from the piston crowns with a cheap usb plug in boroscope.
What did I end up with?
Well a phone call to Preston at British Bike Spares in Brisbane to ask did they in fact stock 105 needle jets revealed a well known Norton Commando tuner in Cairns now routinely fits 105 needle jets to all the bikes that came with 106's so he had a good supply of them in stock so that was my first clue.

Further digging told me that BP Ultimate and Shell Vortex, the locally available high octane (98 ron) fuels here will both cause rich running right through the range on carburetter engines due their increased density over the old leaded and lead replacement fuels. (I found details of that on the BP and Shell websites)

Enlarged hi-res photos of the spark plugs also showed slight traces of alloy balls on the insulators caused by detonation, so I knocked the timing back to 37 degrees which completely cured that one.

I ended up with #3 slides, 105 needle jets, needles in the middle position, a 170 jet main on the right cylinder and a 160 main jet on the left cylinder.
Don't ask me why it needs different main jet sizes... I don't know.
Since the initial startup this has been the case with this engine, the valves all seal perfectly, the compressions are dead even, the tappets are set identical the timing is the same on both cylinders with the TriSpark ignition.. So, it is what it is although a half jet size smaller on the right cylinder would make it almost perfect.

Another minor detail that came to light when talking to Steve Kelly from TriSpark, he asked me what plugs I run (I run NGK Iridiums in all my bikes) and he told me all Iridiums are resistor plugs so as I was running the spark plug caps he supplied with the dual lead coil which are apparently the resistor type I in fact had double the required resistance in the ht cables (10k hot instead of 5k)
(I had no idea all Iridiums have internal resistors)
Now with a modern TriSpark setup it probably made no difference but I can imagine with an older 6 volt twin points set up or a Boyer with a wonky charging system it could well be an issue.
Anyway I changed the plug caps out for NGK non resistor ones today and it might be the placebo effect but the bike does seem to run stronger at 5500rpm plus in top gear.
I've attached a photo of the spark plugs after a hard 10 mile run this morning in 92 degree heat.
I'm also getting very little black soot at the ends of the Dunstall style mufflers now compared to what it used to make.

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Snakeoil

First, I would like to take issue with you mentioning more than once in your post that the temps in Oz are over 90F when it is boarding on 32F here and drizzling rain. HAVE YOU NO COMPASSION, MAN??!!

Okay, I feel better now.

I was just about to type, "what is ulp" when a dorment synapse fired and I realized it is Unleaded Premium.

Interesting how the new fuels run rich. I wonder if we have similar nonsense going on over here, too.

Glad you got it sorted out. Also interesting to hear that you have two different main jets in there. I've read other posts where left jug runs hotter than right and single carb bikes seem to run lean on one side and not on the other. Makes you wonder what might be going on here.

Nice to hear the Wassels worked for you. I've read a few posts that would indicate they are cheapo carbs and don't work well. So much for "it must be true if you read it on the internet".

regards,
Rob

Timinoz

It's going to be 32 here today too! 32C

Snakeoil

I'll be needing your address. I'm sending the Tartaglia brothers down to Oz.

regards,
Rob

Old Cafe Racer

Address:

Davy
C/O:
The "I built my dream bike and now I'm broke house"
(Also in the dog house with the girl friend )

Reading the plugs in now a real art form with ulp and I've read many articles on it, most of which do contradict each other
on certain aspects.
That's why I just read the piston tops instead as I don't have a gas anyliser.
Two good reads:

http://www.4strokes.com/tech/sparkplg.asp

and: http://www.4secondsflat.com/plug_chart.html

And for what it's worth the plugs I use (hard riding) are NGK BR8EIX Iridiums gapped at 25 thou which are perfect heat range wise and even through all early rich running and poor mapping issues never missed a beat in now 600 miles with the last 200 at full throttle wherever possible (around 70 % of the time on the country backroads I used for testing.
The replacement non resistor caps are also NGK..LBF 8309's which have waterproof rubber boots at both ends.

There is however one detail still bothering me... the exhaust pipes.. they are still as shiny as the day I fitted them all through the hard riding and bad mixture issues, some of them on the lean side of things.
Am I alone in not having blue (or even a tinge of straw) on the pipes?
The only thing I can think of that would help in that regard is the welded in alloly exhaust port stubs this engines cylinder head came with.



Davy

Snakeoil

Davy,

I was going to send the boys down to see Timi.

Thanks for those links. Should be some good reading. I'm not sure if I mentioned it here or in another post or forum, but I see a lot of carbon on plugs with the new fuel. My FI HD is dyno tuned and I was there thru the entire process. Fuel map is perfect, yet I still see soot on the plugs and on the ends of the muffler.

As for straw pipes, I would think they are a factor of mixture and cooling air. I'd bet that more of the color in pipes is done while revving the engine at a stop light after a fast run than when the bike is moving down the road. So, those big mutha heat sinks you have in the form or welded on exhaust stubs are probably drawing a lot of heat away from your pipes. Not having your pipes blue is a complaint I've never heard before.

As for the girlfriend with attitude: Girlfriends don't get a vote on what boyfriends spend their money on. That's why they are girlfriends and not wives. When girlfriends act like wives, they tend to get replaced. That of course is based on the assumption that you spent YOUR money on the bike and not HER money.

Remember, a good motorcycle will get you thru times of no money better than money will get your thru times with no motorcycle.

regards,
Rob

Old Cafe Racer

Rob,
Finally dug up the correct info on those pistons, seems they are in fact the correct E6884 9.75:1 pistons for my engine.
(I was lucky enough to find some original boxed genuine Triumph spare parts ones)

davy

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Wanderer63

Great job on the bike Davy :-)

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Growing Younger

Cariboo_kid

Davy, what a fine job you've done with the Daytona. I'm glad to see people taking the 500 twins seriously and doing a proper job with them. I have the same tank from Glass from the Past on my '71 Daytona. Bret does good work.

daytonaman

OCR- You are my hero! Your bike is fantastic and I really enjoyed reading about all the work you put into it. I wish I had your engineering skills. Could you please tell a little about the rear sets that you used and specifically the linkage for the shifter. I tried enlarging the picture of the right side, but it just got blurry. Much appreciated. Again, your bike is absolutely beautiful.
---Dayman