Dirt Bike FAQ

Hi Sk8,,,
I'm going to make a guess and assume it's a Chinese Clone of a little Honda engine.

Normally,,all those type motors are very easy to start if the engine is in Good Condition,,,or even fair condition.
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Some things that can make them hard to start.

*Low Compression.
That can be caused by several things.
You Really need to have the compression checked with a gauge to determine if it's within proper range.
Should be about 120 psi minimum.

If it's Less than that,nothing will really help much.

"Low Compression" is usually thought to mean "burned-up / wore out Engine",,,,and that's often true.
But not Necessarily.

Valve Clearance Adjustment,,and Timing Chain condition will affect it also and make the compression a bit lower.

>>>Adjust the Valves to .003"
That's Looser than recommended setting of .002".

>>>Make sure the cam chain is adjusted right.
Sometimes the adjuster "sticks" and doesnt really work right.
Also need to check the chain for wear.
Both things are easy to do.

CARBURETOR:
These things are so small even the Tiniest amount of gum/varnish/deposits will make them behave badly.
Easiest thing to do is try some Cleaner added to the Fuel tank.
Use FUEL INJECTION cleaner,,,not "carb cleaner"—it works much better.
Chevron Techron ,,or Seafoam are 2 good ones.
Don't Overdose it thinking that "more is Better".

You may ultimately have to remove the carb and take it apart to clean it.

The Intake Manifold "never" gets loose on original,genuine Hondas.
On all the Clones,,,,it's a crapshoot.
If they Do get loose the Gaskets will leak air,,and cause hard start,bad running.
Or,,if Carb has ever been removed ,,,it's tuff to get them to re-seal without using new gaskets.

Ignition System/Spark Plugs:
Most of the late model versions all have electronic ignitions.
They usually work OK,,,and are Usually NOT adjustable.
When they FAIL,,,almost always it fails like a Light Bulb.
They just Quit Working at all,,,,no mysterious misfires,,no intermittent problems that come & go.

So IF it sparks,,and eventually Runs,,,
there's 99% Odds the CDI Ignition is working OK.

Spark Plugs.
Try an NGK Iridium Plug.
DO NOT expect it to "FIX" anything,,or even Cover-Up any sort of problems elsewhere.
Make sure everything Else is in good order First.

They are NOT Magic Plugs,,,but they DO improve starting because they can fire under a much wider range of conditions,,including Weak Ignition system,,,or partially flooded,,,very cold temps,,,etc,etc

They're expensive ,$8~10.
It Wont FIX anything,,but they can definitely help

Get a Service Manual if you can.

If You cannot find one,,,early Honda 50 & 70 Manual is Close enough to give You general basics

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You will have to register,,but You can get Free Manuals here

http://www.repairmanualclub.com/

These will help.
Remeber,,these are NOT Identical to Yours,,not even the same engines,,70's and 90's are Different.
But they can give you an idea how the things are laid out,,,and valve adjustment,timing chain stuff is basically the same.
Carb Clean/Rebuild PROCEDURE is sorta generic,,,things like that.

Consider them only HINT,CLUE,or GUIDE,,,,and NOT actual,accurate service manuals for Your bike

Honda S90-CL90-C90-CD90-CT90 Shop Manual

Honda SL70, XL70K1 Factory Shop Manual, English

Good Luck with it