Proper Tuning... how to?

[pisten-bully]

Okay, first I should state that carburetors and I have always suffered from a "difficult relationship"…. I'm probably batting .300 on all the rebuilds I've ever done on carbs… those are minor league statistics!

So my "problem" is dialing in my Linkert 344 to my Chief (I think). I thought I had it pretty well dialed in, coffee brown plugs, started well hot or cold, throttle response good, etc. etc….. then I changed out my exhaust system and I've been chasing ever since. Done about 2700 miles this season with about 50/50 on old exhaust and new exhaust… but I can't get the carburation exactly right with the new exhaust. (Explanation, the new exhaust is one piece and seems to have fewer restrictions in it… from Greer's. It does not leak.)

So the question I have is where can I find some reliable comprehensive trouble shooting tips for tuning with the Linkert on an Indian, for example:
1)backfiring through the exhaust could indicate too rich of a mixture
2)won't start with choke applied could indicate too rich of a mixture
3)"flat spot" in the acceleration phase could indicate too lean of a mixture
4) "popping" on deceleration is normal
5) etc, etc. note: I don't warrant the above diagnostic conclusions to be accurate!

It's not that the bike isn't a satisfactory ride, it is…. it's only that it's not quite as good as it was… almost, but not quite…. there's a slight hesitation mid-range RPM's on acceleration right now.

So, is there a source like a book that simplifies the whole enchilada of proper tuning? I've got the Indian Riders Guide, Modern Motorcycle Mechanics and Speed Tuning, Kiwi's chapter on carburetors, and of course the internet… but none of those are very comprehensive. And I understand that I might be blaming the carburetor for something it has nothing to do with… could be plugs, points, timing, or what?

Just curious… any good reads out there?

[alanc48]

Generally when I've changed out exhausts on any of my machines I had to correspondingly change out the jets. depending on what kind of exhaust I was running I increase or decrease the size of the jet.

[T. Cotten]

Harry wrote: "carburetors and I have always suffered from a "difficult relationship"…. "

Me too!

(But Linkerts are far, far more forgiving than Scheblers.)

Have you thoroughly bubble-tested your manifold, as discussed at http://virtualindian.org/11techleaktest.html?
(I know I outfitted it for you, but it still must be tested, and the nuts snugged with regular maintenance).

Beware also that modern digestive fuels confound traditional plug-reading, and any color at all indicates over-enrichening (usually to accomodate a vacuum leak).

On to the carb itself, did you re-cut the manifold flange to flat?
Is the body bore worn with an eyebrow groove from the throttledisc?
Is the venturi loose, with daylight around it?
Does your float actually float?

Things add up sometimes,
but a change in exhaust should only need a tickle on the needles.

...Cotten
PS: I hope it not just points bouncing or something electrical.

[pisten-bully]

Ahhh… Cotten! I think that's exactly the sort of advice that needs to be put into a single resource… why don't you write a book… I'll purchase one! (surely that old Windows machine you've got has MS Word on it!)

Well.. I did leak test the manifold when first installed with the those new state-of-the-art seals you set me up with… couldn't make any bubbles and I've snugged up the manifold nuts twice since then. The carburetor was re-built in 2012 (long story… I purchased a carburetor kit from Greer's, then I remembered the Marvel/Schebler carburetor that I rebuilt for my Ford 9N… and I chickened out and sent the kit back along with the carburetor for Greer's to install so that it wouldn't turn out like the 9N carburetor episode a few years back… enough about that!)

I'm just looking for some reading… something that tells me for example, "if your Linkert equipped flathead hesitates, it could be caused by this or that so you should check these things….."

Make sense? Anything out there like that?

[T. Cotten]

Harry!

If I were a decent writer, I would not have been barred, or driven off from at least five other vintage motorcycle forums.
This forum is not only unique that I have not been barred, but it is the only one where I have been purposefully contrary! (Referencing my campaign against the destructive 'restoration' judging rules.)

My approach to all Historical pieces is that if they became legendary icons, then they had to be user-friendly, and the designs are genius.
Our problem is to return them to spec, and not over-complicate them with "better ideas" any more than necessary.
If problems persist, then our patience, observations, and attention to detail have failed, not the machine.

If this site's search function does its job, then just our discussion, and hopefully resolution, should be the best for all.

So after a re-check of your ignition, valve adjustment, etc,... what's in your floatbowl?

....Cotten

[Tom Lovejoy]

Very well said Cotten !

[c.o.]

Harry, there is a "Linkert" book available. I'll dig out my copy tomorrow as I can't recall the details at the moment. Having said that... there is no better advice in my estimation than Cotten's when it comes to Linkerts! Some of the symptoms you mentioned sound electrical to me. (Just thinking out loud here...) Have you checked your timing? Changing your exhaust could be just a coincidence??? Your carburetor shouldn't have needed too much of an adjustment as Cotten has mentioned.

Cotten.. your "approach to all Historical pieces" bit should be adopted as the motto for this club!

[pisten-bully]

there is no better advice in my estimation than Cotten's when it comes to Linkerts! Cotten.. your "approach to all Historical pieces" bit should be adopted as the motto for this club!

I'll second that motion! And Cotten, I'm no English professor but I think your writing is fine, very good in fact... maybe it's your opinions that got you "in trouble" and banned, someone didn't share your vision!

Cory, I've seen mention of The Linkert Book but haven't seen one or heard anybody recommend it as a good source?

Things are turning cold here and approaching the time to put the bike away and deal with some of the issues that cropped up this summer. I think, quite basically, I'm looking for a shortcut! Sometimes searching this and other forums makes my head spin... and I'm looking for some good reads I can do by the woodstove this winter that will substitute (not really possible, I know... but..) for experience!

[T. Cotten]

One thing is for certain, Folks,

There is no guarantee of Freedom of Speech on the Internet.

My copy of the Victory Library pamphlet is quite dated, and most of it is a pre-Palmer's synopsis of models and application. Some theory is presented, but it only paraphrases the Armored School Handbook.
It does however, raise some very interesting questions about vintage hop-ups.

....Cotten

[c.o.]

Harry, my copy of the "Linkert" booklet is dated from 2008. There is some material in it that you may find useful.... http://victorylibrary.com/books1.htm It's about 58 pages so it won't keep you by the woodstove for long!

Cotten... are you referring to the "Armored School Handbook" from Ft. Knox? I was lucky enough to stumble upon a copy when I was going through my 45.

[T. Cotten]

Cory!

Yes, Armored School Handbook is a literal school program textbook, and go into the details and theory like no other that I am aware of...

Maintenance and operation are quite brief, as one would expect with a young carb, and ready spares. The only problem it addresses is enigmatic, as it describes the excessive build-up of "crust".
I rarely encounter 'moderate' carbon or other deposits, even on "barn-find" pre-war models that cross my benches.

It leads me to suspect that wartime fuels had their issues.

....Cotten

[pisten-bully]

One of the catalysts that got me to ask this question was how different sources had different recommendations for initial needle set-ups for the Linkert. I was and am hoping to understand the whole relationship between symptoms of poor engine running and the various tuning procedures (e.g. carb adjustments, timing, ignition, etc.) Here's a look at how five different sources have recommended a Linkert be initially adjusted prior to tuning (and I decided to use the Indian Rider's Guide... it was good for my non-modified Chief!):

[T. Cotten]

Harry!

It looks like one of them deals with a lot of vacuum leaks.

I send them out at 3½ and 1½.

Please note that a rich lowspeed setting becomes a lean one when the venturi kicks in!

....Cotten

[c.o.]

Cotton!!!

Yup... the "Armored School Handbook" even teaches the riding of the motorcycle!!! It's a great book. The "new" factor is a good point. That's why I ask questions in addition to doing the reading. You can't beat "good" modern day answers for our "old" bikes. If not a book... then maybe a booklet???? I'd buy one.

Interesting compilation of "initial" settings Harry. Again.... I'd go with Cotten's recommended settings. Once the machine is dialed in... make sure you resist the urge to fiddle with it if the bike starts acting up. In my experience it usually means electrical problems... I've been guilty of cranking on those needles trying to fix the mysteries of electricity!!! It was all frustrating but I learned sumthin'!

[T. Cotten]

Cory!

Students shouldn't try to write textbooks.
I would only raise more questions than I answer.

....Cotten