Coldblooded Engine?

Question

I have an older bike (81' kz) and it is awfully cold blooded. It takes probably about 5 mins of running when I first start it to get it to where I could start to ride it. It also doesn't seem to stay warmed up for that long. Like if I ride it for a hour and let it sit for 1/2 hour, its need some more wamr up time again Is there anything I could do to decrease the amount of warm up time needed (other than bike a newer bike)?

Answer 1

depends on where you live, pull the choke out  or change the grade and viscosity of the motor oil.

Answer 2

a bike shouldn't be that hard to start.... time for a tune up...

Answer 3

Nearly all j*p 4 stroke engines of that era had similar tuning & construction  characteristics.

*Lean primary fuel circuit

*Weak-ish Ignition voltage

*Wide range ignition advance curve

What we Call "Cold-Blooded Engine" is actually Cold -Blooded Tuning.

The How's & Why's of it all,,,,,is a long complicated story.

One thing to understand about is this.

All Tuning parameters  have a RANGE of EFFECT,,,which tends to Blend,or Overlap,into Next Incremental  Calibration.

Let's say for Example,,"A BIKE" is Perfect with

* #50  Idle Jet

*and 20* ignition advance at Idle

That can be changed +/- a Jet size or 2,,,

and Timing changed a couple Degress +/-.

Results WILL be DIFFERENT,,,bike WILL act Different------but when Starting from "Perfect",,,the bike will still work OK after those changes.

But,,,There's Only So Far you can stray from Ideal.

Any Change from  That Max Variation and Bike performance will fall off a cliff.

In each aspect of tuning there's a point of

"The Straw that broke the Camel's Back",

so to speak.

Most Bikes of Your bikes Era were Tuned for Emission Purposes just a "Couple Straws short of that FINAL STRAW"

Any Drift from the original Specs makes for Unusually Bad Performance.

"Performance">>NOT Meaning Dragstrip Times,,,

but Driveability,Cold Start,Throttle Response,,etc.

Overall Engine Operation Characteristics.

.........................................

What Matters ,,,is what You can DO about

So,,,back to dealing with

*Lean primary fuel circuit

*Weak-ish Ignition voltage

*Wide range ignition advance curve

''''''''''''''''''''''''''''''''''''''...

Fuel:

You can adjust the air s***w on the carbs and make a Small Improvement.

Results are LIMITED because the Pilot jets themselves are a "Minumum" size.

The BEST thing is to go UP 1 Size on the Pilot Jet.

If You happen to have free-flow air filters,,or exhaust mods go up 2 Sizes from STOCK Pilot Jet size.

Either way,,,Open the Air Screws as much as Possible>>

Tuning Wise,,Not Physically.

With Engine at Operating Temps and Idling,,

a)Adjust Screws to yield Highest Idle

b) Open the screws FURTHER,,,which Richens it,,until engine JUST begins to Lose RPM

c)Set Idle Speed with Adjuster

d)Open Air s***w an additional 1/8 to 1/4 Turn,,,which is even Richer

e) re-set Idle Speed  with the Adjuster

*****ADD some Fuel Injection Cleaner to gas and reset Idle in a few days if necessary.

USE a  actual CLEANER,,,PEA based products like Techron or Redline.

................................

IGNITION:

It's a "Must" to use NGK Iridium Plugs.

They're a bit  expensive,,oh well.

And I Really dont care what anyone Imagines about spark plugs,,,rare few people understand the Electrical Effect  different type of plugs yield upon the Ignition Circuitry.

I dunno which KZ you have,,,but in '81 I think they all still had POINTS,,,except the 1300??

I can't recall.

Anyway,,,if Yours has Points----New and Properly adjusted Points are always Good.

That addresses one set of issues.

What's seldom done,,yet addresses an even More Important set of issues is the Condensors.

The Marginal,,Naturally Weak  Ignition System  NEEDS a Condensor Upgrade.

It's a very minor(and Cheap) Mod.

Install some Mallory #400 or #401 Condensors.

Only difference in the 2 is wire length.

Ebay usually has them,,,Race-Car/HotRod places always do,,,Jegs,Summit,etc.

It's Critical they be WELL GROUNDED.

I always use an auxilliary ground.

At This Age of your bike---Replace the Plug  Caps.

And make certain the plug Wire ends are fresh and clean---clip a Little off to expose fresh cable.

"Hot Coils" are an unecessary expense.

*Good & Right Points,,

*New Plug Caps into clean cable

*NGK Iridium Plugs

*Mallory Condensors Upgrade

Those few things are cheap & easy,,and will  Optimize the Stock Ignition in the most Cost Effective Manner,,,and provide a remakable boost in overall ign performance.

It Dont make a Welding Machine---but it moves it Well beyond it's Original MARGINAL performance.

It'll Fire Consistent & Reliable,,

and WILL light the Gas....

Cranking speed,,,idle,hot/cold,,closed throttle cruise,,high load acceleration,,,max rpm.

As-is,,,original ignition is sorta dubious.

Part of Cold Start/Run difficulty with the Originally Lean mixtures is attributed to Misfiring which is nearly imperceptible.

EZ to feel a Bad Missfire going down the road.

NOT so obvious when bike is idling,trying to warm up.

Every skipped beat is a "Cool Down Cycle",,with raw Fuel and Relatively Cool Air carrying combustion chamber heat AWAY....lengthening warm-up time.

Another Aspect of "IGNITION SYSTEM" is their Timing Advance Unit.

It swings a RANGE to alter Ignition Timing.

That's TOO WIDE----it Delays Plug Firing  TOO LATE.

Initial Timing is simply Too Retarded.

Their purpose & Intent was to make the engine Start Easier with Less Load on the Electric Starter

3 ways to remedy that----

#1)Simply Advance the Overall Timing,,,which shifts the entire advance curve more advanced.

That's NOT A BAD way to go,,especially for the Do-It-Yourself crowd.

You get a a few degrees advance improvement at Idle,,,Plus a Few Degress FULL Advance which most engines generally LIKE.

I'm talking 2~3 Degrees.

#2) You can fool with the Springs and alter the RATE at which the advance unit changes the timing,,,aka "The Advance Curve".

This method is especially beneficial at Part Throttle Cruise.

Becuase it  allows a Lot of Increased Advance at Medium Speeds without Changing TOTAL Advance.

And it allows more INITIAL advance at LOW speed,,,,,,while at Cranking Speeds it's pretty much Normal.

The Trick is to get it to "FLOP Open" some initial amount,,as soon as engine starts.

The Original RANGE is Retain,,,but the "1st half" of the range is achieved almost Instantly.

Pretty Easy to Do (famous last words,,lol,eh?)

Seriously--- Strech ONE spring in a CERTAIN way.

The OTHER Spring  and the Drag of the Points will Close the advance unit back to Full r****d,,like Normal.Great for Starting w/ electric Starter.

Soon as engine starts and revs above Cranking Speed,,,the Advance Unit flops open a small amount to raise the Initial Timing a bit more advanced---and that carries thru the entire advance curve.

You get a Bunch at MidRange RPM--which is Great,,,,and as engine revs the advance curve slows.

Ultimately,,it stops advancing in the stock,original place.

So,Full Range is STOCK,Original.

But the Early Stage of advance come in  very fast.

It's actually considered very sophisticated Tuning Mods.

And way too Tedious to PERFECT.

But Incredibly Simple to DO,,and get a large improvement,,,,even if not "perfect".

It dont have to be perfect to get desired results

HOW-TO:

Fishing Tackle uses a  Ring,,,usually Stainless Steel which is a couple coils---like a KeyChain Ring.

Get a few that are the size of the Advance Unit Pegs where the original Springs are anchored.

Connect the Original Springs to the New Ring,,,,and use the new ring as the "spring end" to anchor it onto the Advance Unit.

One Ring on One Spring is usually enough.

It creates an Extension,,,makes the Spring LONGER.

So that spring appears to be "Missing" to the Advance Unit.

As Centrifugal Force begins to Open the UNIT,,,it only feels ONE SPRING (Half-Normal Tension).

So it opens Faster,

When it's opened far enough to take up slack of the Exntended Spring--then the 2nd Spring begins adding IT's tension  and slowing Unit down so it dont advance too quick and cause pinging.

There's a variety of "Options"

*1 Ring on 1 Spring.

*1 Ring on EACH Spring.

*2 Rings on One spring----1 at each end.

*2 Rings on 1 Spring ,,,With  1 Ring on Second Spring----3 Rings Total on the 2 advance springs.

* 4 Rings TOTAL,,,one each end of each spring

ALL that does is Change the RATE at which the Unit Advances.

The More RINGS,,the Faster/sooner it advances.

TOO FAST will cause Pinging when you accelerate.

Which is bad news.

The Increased rate of advance can also be combined with a physically Advanced  Ignition timing.

Simply set Initial Timing a couple degrees advanced.

IT CAN be TEDIOUS and "Fine Tuning" is almost Entirely Experimental.

I'm Not Suggesting this as any sort of "TEASER",,,but it's POSSIBLE to get Any Bike I know of to  Start>Blip the Throttle a couple times,,,and Ride away COLD.

Down to 50~60*F ambient weather anyway.

#3) Advance Mod Method,,,I'm not even going to go into.

Not Necessary and beyond most folks' capability & facilities.

It involves modifying the Physical RANGE of the advance unit.

The "Slack Spring" method in #2 above accomplishes same basic effect ,,,and is actually BETTER for street bikes/stock bikes/and anything with electric starter

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,...

A quick recap to avoid getting lost in all the Spam spewed above

A) Richen the Idle  Mixture --

either as best ya can with the Air s***w,,

or even Better is to increase size of Pilot jet

B) Do Minor Upgrade to Ignition System

-NGK Iridium Plugs are a MUST

--New Plug Caps,,screwed onto "Fresh Plug cable",,,to "Freshen" simply clip a small bit off the end

---Replace the Original Condensors with Mallory 400 or 401 from "a hot rod shoppe",or often available on Ebay

----And of Course,,make certain Points are Good,C

Answer 4

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