Author Topic: Black sparg plug, heavy oil use, new build up engine  (Read 11726 times)

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stinkwheel

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Reply #105 on: June 17, 2024, 11:39:24 am
If one of them worked before, I'd try it with that and see how it's running. If it's lean, try bigger.


winsun-enfield

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Reply #106 on: June 17, 2024, 11:43:08 am
Besides the engine /barrel has to run in, best not with a lean mixture, how to determine.. With the current fuel reading the plug is not possible anymore..


stinkwheel

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Reply #107 on: June 17, 2024, 02:22:19 pm
If you're worried about that, could you just run it in with the mikcarb which is a very known quantity then dial in a less well known carb later? You'll pick up a set of pattern VM series main jets for less than the cost of half a tank of fuel.


winsun-enfield

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Reply #108 on: June 17, 2024, 02:27:57 pm
I don't have this carb, but.. would the mixturen be reliable/the same between these imitation carbs?


Adrian II

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Reply #109 on: June 17, 2024, 03:07:22 pm
Hitchcocks' posted a jetting guide for the Mikarbs on their web site, see attachment.

Don't pay top dollar for a Mikarb, there should be hundreds kicking around spare where Bullet owners fitted Amal or Mikuni carbs.

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winsun-enfield

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Reply #110 on: June 17, 2024, 03:10:46 pm
I know.. but that still leaves my uncertainty about the different muffler.. so these diagrams are yes/no no guide?
I wonder if this exhast has infuence on the carburation.. The stdt vale overlap of a bullet is quite tame.. Would think it has very little influence?


Adrian II

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Reply #111 on: June 17, 2024, 03:19:22 pm
According to The Lore, if not the Law, free-flowing exhausts (less back pressure) and air filters need richer jets, otherwise the engine gets too lean a mixture which leads to overheating problems. Fuel starvation can result in holed piston crowns, engine seizures, etc.

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stinkwheel

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Reply #112 on: June 17, 2024, 06:09:47 pm
I doubt it's going to be a long way off, if you're running in, you aren't going to be running it for a protracted period on wide open throttle. It's heat build-up that will cause a seizure/burning/nastiness. Put in something close to what you estimate to being right, warm up the oil, take it for a short run, check the plug. If it looks to be running lean, up the jet. Rinse and repeat.

There's a lot of myth, or I don't really know what floating out there in the ether/peoples heads about "running in". You are wearing the piston rings against the honing marks on the bore so they make a seal. This will generate more heat than in normal running. As such you need to be mindful that heat doesn't make the piston expand so much and so quickly that it jams in the bore. That's all there is, as far as i can see, anything else people might have in their heads is just voodoo. Your bearings are as round and smooth as they are ever going to be, your oil pumps are as sealed as they are ever going to get, your valves are clean and sealed, if your floating bush ever touches anything but oil again you are in trouble. The only bit of your engine that needs to learn to do what it needs to are the piston rings.

So being a little bit off in your carburettion may increase that heat. Going for a 20 mile run at full road speed with an uncertain carb setup on a freshly rebuilt engine would probably be a bad idea. Warming your engine up on the idle circuit then having a half mile pull and stopping to check the plugs is unlikely to result in a disastrous heat build-up. The more normal your plug chops, the longer you can confidently make those pulls.

Puting my money where my mouth is, I jumped on my 612 with a new piston and rings and a roughly ballpark TM32 carb using baseline settings from people running them on 535 bikes and did some runs and plug chops. I was way out on all the settings even getting some detonation under load but I was careful, did short runs and listened to the engine and walked my way into the correct settings. I started on some 1/4 throttle runs and got the pilot jet dialled in. Then I did some 1/2 throttle and got the correct needle jet. 3/4 to full took a bit of getting and I went through various combinations of needle size, needle position and main jet before I was happy. Nobody died.

I'd suggest you do similar. Go out for a few short 1/4 throttle runs and check the slow running is where it should be. Then go for some 1/2 throttle runs and check that. They'll probably be right, or near enough. Then work your way up to the main jet. It'll probably be damned near run-in by the time you've got it and multiple heat cycles with steadily increasing engine pressures and rev speeds isn't a bad way to do it.


AzCal Retred

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Reply #113 on: June 18, 2024, 06:17:07 am
The 28mm Mikcarb is perfectly fine. The jetting chart works well. As Stinkwheel points out you'll have a known place to start.

It's pointless searching for big power gains. A well running 500 Bullet making its 24-26 HP will drag you along quite well. Big power costs big money and you'll still have 1940's brakes, chassis & suspension tied together by an India-built home-market frame.

If it starts easily and "runs out" well, that's a good stopping point. Leave real speed to the modern equipment, it's way safer & more cost-effective. The pre-unit machines are affordable time machines, a great window into how things were. Get it running well, put some miles on it, THEN decide what you want to do.

A trifecta of Pre-Unit Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


winsun-enfield

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Reply #114 on: June 23, 2024, 03:39:41 pm
Re-assebled the engine, ready for a run in.
Second trip about after 100 k'ms,
Had some trouble with war start.
Removed the spark plug.
It was oily with carbon deposits..

I really do not know anymore.
Feel very much setting the bike onto fire..



AzCal Retred

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Reply #115 on: June 23, 2024, 04:42:14 pm
It was oily with carbon deposits..

Dry carbon is a too rich mixture. Glossy black is baked on oil. Which is it?

What are you using for an air cleaner? The OEM unit is attached to the crank breather and can suck in oil.

Run a hotter plug and see what's what. I normally use a PB6ES NGK, occasionally a BP5ES.

Ring break in is reliably a 500 mile (800 KM-ish) process. Install a hotter plug and continue the break in. My Hitchcock's forged slug/steel rings needed 250-400 miles or so before it was "happy".

Before you torch it, try these things. If they don't help, post an address and one of us will roll by and haul it away and give you $100. Better than burning.

A trifecta of Pre-Unit Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Adrian II

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Reply #116 on: June 23, 2024, 06:35:11 pm
Quote
Feel very much setting the bike onto fire..

Don't forget to cancel the insurance policy first, eh?



A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...