Unofficial Royal Enfield Community Forum

Royal Enfield Motorcycles => Bullet Iron Barrel => Topic started by: amritc on November 21, 2013, 10:43:24 pm

Title: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on November 21, 2013, 10:43:24 pm
Hi all,

I have a question. My iron barrel has suddenly started to spit from the carburettor puffs of grey smoke when starting and then not running. Is my mix too lean?

Also, can anybody offer advice on how to replace the entire distributor unit? I am toying with the idea of doing so as my points plate is at its max on retard setting and has no more space to move the plate which means everytim the timing needs to be set the plate is taken off and the shaft needs to be pulled out

Many thanks
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on November 21, 2013, 11:29:22 pm
It might be too lean. Or it might have an exhaust leak or intake leak which is causing it to run lean.
Or maybe it has water in the fuel.

To refit the points deck, you loosen the Allen screw in the middle of the distributor shaft, and give the shaft a hard tap with a plastic screwdriver handle or something like that, then you can move it where you want it, and can move the points deck into a position which gives adjustment range in both directions.  Then proceed with the ignition timing process.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: cyrusb on November 22, 2013, 12:11:34 am
In which direction is your plate maxed out? Clockwise or anti?
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on November 22, 2013, 12:22:07 am
hi, it max'd out in the clockwise direction (i.e. full retarded)
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: cyrusb on November 22, 2013, 01:01:59 pm
Doesn't the dist shaft spin counter clockwise? That would make that fully advanced, no? Edit; I appears i am quite retarded also, it does spin clockwise.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on November 24, 2013, 08:18:15 pm
All sorted now. It was the rubber pipe at the carburettor manifold intake that had perished. It had a large tear that was not visible until I removed it. Replaced it and the bike runs sweet...

Though still unable to work out why I only get 10V output on the two violet wires coming out from the alternator....

cheers
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 01, 2013, 08:20:32 pm
Hi, A question for all.

Will removing the cylinder head for a decoke need me to re-time my ignition? I removed the head for a decoke and in the process also moved the pistion up and down (using the kick start) to check for play. I then put the head back on. Upon starting the engine - it starts eaasily - but the beat does not settle back to the enfield thump thump sound and sounds very erratic. Also trying the mix at the carb doesnt help. Screwing air screw completely in seems to help but not really.

Do I need to re-time?

Any words of wisdom?
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: Arizoni on December 01, 2013, 09:44:28 pm
If you didn't mess with anything that controls the ignition then there should be no change.

Cranking the engine over wouldn't change things.

There is some likelihood that there is an air leak between the cylinder head and the carburetor/fuel injector.  That would cause the engine to idle at a higher speed.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 01, 2013, 10:13:48 pm
No, you need to re-jet and re-adjust your carburetor.
If you can screw your air bleed screw in all the way without the engine dying, you have the wrong pilot jet in there.What pilot jet is in there now?
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 01, 2013, 10:22:26 pm
Hi Ace,

My pilot jet is a 110
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 01, 2013, 10:33:20 pm
Hi Ace,

My pilot jet is a 110

110 is a main jet number.
Your pilot jet is the little one, with a number like 25.
And unless you live on top of the Himalayas, a 110 main is too lean for a main jet anyways.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 01, 2013, 10:49:18 pm
Thanks Ace. I will find out the jet number and revert. But previously my main jet was a 120, the local royal enfield guy asked me to change it to a 110.

Auckland is about 150m above sealevel.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 01, 2013, 11:29:57 pm
Well, I live about 250 meters above sea level, and my Mikarb 28mm needed a 27.5 pilot and a P2 needle jet, and a 127.5 main jet.

The bike comes stock with a 110 main jet, and a 25 pilot jet, and an O8 needle jet. The 25 pilot is sometimes okay for higher elevations, but the needle jet and the main jet are too lean for your elevation. They jet it this way because it comes from the factory all plugged-up at both ends, and also needs to pass emissions testing, so they don't put any fuel into it.
If you have a decent air filter and have dumped the crappy stock bazooka muffler, you need richer jets.

"Hunting", which is a term for an unstable idle speed which cannot seem to settle down, is a symptom of lean mixture. If you can close down the air bleed screw, and the engine doesn't die, then it's too lean in the pilot jet. This comes right from the Mikuni tuning book.
Not too sure what kind of dealer you have in Auckland, but it sounds to me like he isn't too knowledgeable.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 02, 2013, 08:08:47 pm
Hi Ace,
the main jet is 110 and the pilot jet is 25
The needle jet has a marking that says 8???

what would you recommend?
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 02, 2013, 09:59:16 pm
They are all factory stock, as supplied with a new bike.

What year is the bike?
What air filter system do you have, and what exhaust/muffler system do you have?
I need to know these to answer.
I already know the elevation.
Thanks.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 03, 2013, 12:31:31 am
Hi, thanks for your help. appreciate. details as requested below -

Year 2000 bullet 500cc Indian import
Stock air filter (rectangular box with paper element filter)
Stock exhaust (short bottle type, I think it has a baffle)
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 03, 2013, 02:31:48 am
Hi, thanks for your help. appreciate. details as requested below -

Year 2000 bullet 500cc Indian import
Stock air filter (rectangular box with paper element filter)
Stock exhaust (short bottle type, I think it has a baffle)

Okay, well you have kind of a "halfway-there" kind of arrangement with a fairly decent flowing exhaust system, and a very poor-flowing intake system. This isn't the typical arrangement, so I can only give a guesstimation about it, trying to make some sort of adjustment for the plugged up intake.

I think that you should try the 27.5 pilot.
I would also use a 127.5 main.
But the critical part will be a P2 needle jet, which is not a Mikuni jet, but must come from Hitchcock's or NField Gear, or somebody who deals with either of them. Most riding comes on the needle jet, so it is responsible for most of the effects on the riding.
The pilot affects idle, and the main jet affects top speed running, but the needle jet and needle position are mostly controlling the middle throttle positions, so they are critical.

In the meantime, while waiting for the needle jet to arrive, you might try putting the needle all the way up in the richest groove on the needle.
Your current jets are too lean in all aspects.

I would strongly suggest getting rid of that OEM air filter system, and getting something at least halfway decent on there.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 03, 2013, 03:44:11 am
Thank you Ace. With regards the P2 needle jet, what series should I be looking for?
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 03, 2013, 08:41:00 am
Thank you Ace. With regards the P2 needle jet, what series should I be looking for?
There is only one series of needle jets for the Mikarb 28mm. These Mikarb have needle jets which are not compatible with any Mikuni needle jet series. No Mikuni needle jets can fit it.
So, you must get them from Hitchcock or Nfield Gear.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: amritc on December 04, 2013, 08:46:48 pm
Hi Ace,

I have an online supplier here in Auckland who can supply a P2 but he keeps asking for the series!! He says he has 167 P-2, 159 P-2, 389 P-2 plus another 20 varieties of the P2 needle jet.

When I looked at Hitchcocks and Nfield Gear they only say a P2. The reason I would rather purchase locally is that the shipping cost from our host and Hitchcocks is exorbitant to New Zealand.

Any assistance provided is most gratefully received.
Thanks again.
Title: Re: Carb on Classic 500 spitting with puffs of grey smoke
Post by: ace.cafe on December 04, 2013, 09:31:45 pm
Your guy in Auckland is trying to sell you a Mikuni jet.
For the third time, this Mikarb 28mm does NOT take ANY Mikuni needle jets. It takes a proprietary needle jet that comes from Hitchcock or NFIELD Gear or your RE distributor in Taranyi.
Yes, I know that they cost a lot.