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Author Topic: Lame Top Speed - Lean Condition???  (Read 2440 times)

High On Octane

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Lame Top Speed - Lean Condition???
« on: May 08, 2013, 09:51:39 PM »
I strapped my phone to my gas tank today and tried out the GPS speedometer app I downloaded yesterday.  I tested the app in my truck 1st and it is VERY accurate.  So, I headed out to the back country roads to see what was going on.  I immediately noticed that the Smiths speedometer is pretty much 15mph fast throughout the range of the speedo, starting off at 15mph (30mph indicated).  It stayed consistent and true to this all the way at least 55mph (70mph indicated).  Unfortunately I forgot to compare the GPS to the speedo at 75mph.    :-\

I got out into the country a bit and from 45mph in 4th gear I rolled WOT.  It took about 3/4 of a mile to reach a top speed of exactly 75mph.  I know this bike is capable of at LEAST 95-100mph and I wasn't even close to red line, (working, but not red lined) but it just had nothing left.  I noticed that the bike isn't accelerating as quickly as I thought either.  I also know it's not the timing, I hit that shit with a digital Snap On light and I KNOW it's correct.

I got home and pulled the #1 plug.  I have brand new E3 plugs with about 3 hours on them and it was completely dry.  It seems like it's running WAY TOO LEAN.  Lack of power and acceleration and absolutely no carbon on the plug.



Here's what I have set up right now:
Carburater: Amal 930 Concentric
220 Main Jet
3.5 Pilot Jet
106 Needle Jet
Needle clip in lowest of 3 positions - Air Screw only about 1/8 of a turn out

Someone please throw me a bone here and tell me what changes I need to make to the jetting to get better throttle response and actually get everything out of the motor.  Thanks!

Scottie
Bulldog Kustoms - Denver
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The Blackhawk
1958 Enfield/Indian 711cc Twin

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ace.cafe

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Re: Lame Top Speed - Lean Condition???
« Reply #1 on: May 08, 2013, 10:36:04 PM »
I don't know Amal tuning, but if it's lean and weak at wide open throttle you should try some bigger main jets.
You already have the needle all the way up, so you can't do much with that unless you get a richer needle.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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High On Octane

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Re: Lame Top Speed - Lean Condition???
« Reply #2 on: May 08, 2013, 10:39:22 PM »
Ace - Maybe try 2 sizes bigger on the main and 1 size bigger on the needle?

Scottie
Bulldog Kustoms - Denver
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ace.cafe

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Re: Lame Top Speed - Lean Condition???
« Reply #3 on: May 09, 2013, 02:02:58 AM »
Ace - Maybe try 2 sizes bigger on the main and 1 size bigger on the needle?

Scottie

I usually like to move one step at a time.
The main jet will primarily be for WFO.
The needle will be for a wide range at medium to large throttle openings.
But the main jet is the limiting factor for how much fuel can move thru the jet system.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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Bullet Whisperer

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Re: Lame Top Speed - Lean Condition???
« Reply #4 on: May 09, 2013, 08:11:48 AM »
A 220 main jet is what I would use in a 350. I would go for 250 - 270 in that carb for a 500, especially if the engine is tuned in any way. The MK I Concentrics are not very good in my opinion, the Monoblocs and MK II's are much better by comparison and what I usually fit to my tuned Enfields. I have recently worked on two separate MK I equipped machines which have suffered from fuel starvation, due to the float needle seating being too high in the float bowl - one even needed me to blow into the tank while I held the tickler button down to flood it for cold starting  ::)
 The float needle seating can be moved in the float bowl by tapping it with a suitable drift. The float needle wants to close, just as the top surface of the float becomes parallel with the top edge of the float bowl - many I have seen close well before this level is reached.
 B.W.
 B.W.
« Last Edit: May 09, 2013, 08:15:30 AM by Bullet Whisperer »

High On Octane

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Re: Lame Top Speed - Lean Condition???
« Reply #5 on: May 09, 2013, 01:35:50 PM »
This a is a brand new Premier 930 concentric with maybe 5 or 6 hours on it.  It's just that I haven't had a chance to diagnose the the jetting until yesterday.  Originally the bike had a 30mm Monobloc, but that carb is 55 years old and the and the sleeve is so worn out that the slide was getting cocked and stuck between half and WOT.  I have a local guy that sells the new Premier 930s for $190 USD, so it was hard to pass up.

Scottie
Bulldog Kustoms - Denver
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1958 Enfield/Indian 711cc Twin

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ace.cafe

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Re: Lame Top Speed - Lean Condition???
« Reply #6 on: May 09, 2013, 01:54:21 PM »
I think I'm a little leery of that E3 spark plug.
It looks to me like it's blocking 2/3 of the flame path with all those ground straps.
At the very least, please index that plug so that the open side is facing toward the center of the chamber.

I really think that a regular spark plug would do better.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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High On Octane

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Re: Lame Top Speed - Lean Condition???
« Reply #7 on: May 09, 2013, 02:20:18 PM »
Here's the deal.  I had to run 5K ohm resister caps with the Sparx battery eliminator.  The only GOOD 5K ohm resister caps I could find are the NGK 8031, and they only accept spark plugs with a threaded nipple.  THE ONLY PLUG I could find with a threaded nipple for my bike was the E3 plug.  And I checked, the spark comes right out the center of the ground strap.  I'd also like to add that I have a friend that has a '83 S10 and a '91 IROC Camaro, both street/strip set ups with 400hp 383 strokers.  He runs nothing but E3 plugs in them and swears by them.  And I feel his word is worth it's weight in gold.  He's been building high performance small block Chevys with his Hot Rodding dad since he was 8 years old, and was working as an engine machinist while he was still a senior in high school.  Maybe it's possible they are good for cars but not motorcyles, I don't know. 

I will try to index them, see if it makes a difference.  I'm in doubt of it, but hey.  Here's my concern, the plugs were 100% dry with absolutely no carbon build up after running cranked at full throttle for almost a mile, and various throttle positions throughout, and it just doesn't feel like a spark issue.  It runs and idles fine, just has no accelerating power.  Even if the bike's not under load just revving it up, just doesn't seem as crisp as it should be.

Scottie
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

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Re: Lame Top Speed - Lean Condition???
« Reply #8 on: May 09, 2013, 03:00:33 PM »
O.K., I stand by what I've said already, but you could try a 107 needle jet, this might help, my own Indian 350 has one in its' well used 389 Monobloc, along with a 230 main jet.
 We also have two Enfield racers here, 350 and 500 [Redditch], which produce up to 37 and 46 bhp respectively, neither of these has fancy spark plugs in - just boring old NGK B7/8 E/HS with their twin spark PVL ignitions. Both machines have won numerous races in the 8 years they have been around since I built them. You need to get more fuel into the cylinder, I.M.H.O.
 B.W.

High On Octane

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Re: Lame Top Speed - Lean Condition???
« Reply #9 on: May 09, 2013, 05:08:11 PM »
I'm beginning to wonder if this bike had the wrong plugs in it when I got it.....

Does anyone know what plug a '58 700 twin is SUPPOSED to have? ???

Scottie
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building The 1st Ever Ace Performance Twin

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ace.cafe

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Re: Lame Top Speed - Lean Condition???
« Reply #10 on: May 09, 2013, 05:40:01 PM »
I'm beginning to wonder if this bike had the wrong plugs in it when I got it.....

Does anyone know what plug a '58 700 twin is SUPPOSED to have? ???

Scottie

According to the info that I found, if your engine number is prior to SMQA 4687, then it should have a short reach plug which would be a Champion L7 or equivalent. NGK cross reference would be B6HS.
If your engine number is SMQA 4688 onwards, then it should have a long reach plug which would be a Champion N5 or equivalent. NGK cross reference shows B6ES.

I would recommend checking the heads for plug reach dimension, because on an old bike there may be parts put on there from a different engine over the course of the years, and I don't know if the other heads are interchangeable or not. It won't hurt to verify the plug reach dimension.

Here's a link that should be very valuable for you. I would recommend downloading this and keeping it, and maybe print off a copy or two for your workshop.
http://www.pearsy.co.uk/Manual/RoyalEnfieldMaintManual.pdf
« Last Edit: May 09, 2013, 05:49:20 PM by ace.cafe »
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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High On Octane

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Re: Lame Top Speed - Lean Condition???
« Reply #11 on: May 09, 2013, 06:01:30 PM »
Ace -  I pulled out the repair manual, it calls for a Champion L10.  I called NGK directly and you are right.  The correct plug for this bike is the B6HS, which does in fact have the threaded terminal.  Horray!!!    :D   I think I may have solved half my problems right there.  I'm picking up bigger main jets tomorrow after work, hopefully hit The Ton this weekend.

Scottie
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building The 1st Ever Ace Performance Twin

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Re: Lame Top Speed - Lean Condition???
« Reply #12 on: May 09, 2013, 07:16:44 PM »
Sorry, Scottie - I misunderstood and thought you were talking about a 500 Bullet for some reason, but even so, try jets around the size I stated, they should help you. A late '50's Big Twin should be good for around 110 mph in tip top order. What gearing have you got - if you have 46t on the rear wheel, you need at least 20t on the front [gearbox]
 B.W.

High On Octane

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Re: Lame Top Speed - Lean Condition???
« Reply #13 on: May 09, 2013, 08:46:28 PM »
I never counted the gears so I'm not sure what's on there.  Good news!  Got to work and I have the plugs I need on the shelf.  Score!   ;D

Scottie
Bulldog Kustoms - Denver
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building The 1st Ever Ace Performance Twin

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Arizoni

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Re: Lame Top Speed - Lean Condition???
« Reply #14 on: May 09, 2013, 11:55:48 PM »
I was looking at some of the photos you've posted of your "Indian" and had a thought.  (Scarey, I know.)

Just looking at it, it looks like the pancake air filter you have mounted could be pretty restrictive.
While your out testing your bike the next time, you might remove the air filter and give it another try to see what happens.

I would be the last person to recommend running the bike without a air filter for very long but it would be okay for a one run test to see what happens.

If some noticeable gains in speed are found, one of the thicker filters (more depth between the back plate and the mouth of the carb.)  might be the answer to your lack of power.
Jim
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