Kicking Back When Starting

[0007]

Found this photo and it shows that it can be adjusted is that right????

is this what you mean nzralphy & charlie chitlins

I'm no mechanic but took to a good mechanic the other day and after looking he said he would have to drill out the holes to adjust the timing????

He seems to think it is the CDI that is to fault.

I don't know what to think now??? lol

The big question is who gets to buy the CDI when it turns out to not be the problem

Once again, a timing light will answer all your questions in a matter of minutes

Guess and by golly is very time consuming

And find a guy with the same bike and have him start your and you start his

You might find what we call TMDT

(That Machine Does That)

[copemech]

Once again, I have seen too many of the machines doo this randomly to presume there is a CDI problem if it runs normally otherwise.

I am not positive the stator plate will rotate further to retard the timing without modification. Yet another thing one may do is add the additional flyweight, which helps prevent kickback due to the added carrythrough mass.

[clarky]

Hi are you sure its not your kick method that is at fault. I don't know much about Betas but I ride a JT350 and you never want to give this a lazy kick or a prod because it will kick back like a mule. I always give it a good long kick using my body weight and it will start first time nearly all the time.

Gently find compression first then let kicker back to top then start.

Find someone else with a 300 and compare.

TLTEL

I am Kicking the **** out of it and it still kick back, so it not that,

going to see a m8 on the weekend with the same bike so will try his,

Thanks for your help tho.

[clarky]

Once again, I have seen too many of the machines doo this randomly to presume there is a CDI problem if it runs normally otherwise.

I am not positive the stator plate will rotate further to retard the timing without modification. Yet another thing one may do is add the additional flyweight, which helps prevent kickback due to the added carrythrough mass.

Yip Thanks, Not changing CDI now and I am going to retard it a little, But the thing is to how much should I retard it??????

[charlie chitlins]

On the trials bikes I've seen (except for one "breathed-on" World Round bike) all of the range is useable.

But you could start with 3-4mm from stock.

If you have an impact gun, experimenting is quick and easy.

For beginner/Novice riders, and some other situations like folks who ride i very slippy/muddy conditions, I like to retard them all the way.

Advanced timing for advanced riders, retarded timing for...well....me.

Seriously, though...advanced timing is best for folks who commonly use the top of the RPM range.

[0007]

There is a thing called a degree wheel

Check the ignition timing with a light

Adjust

Recheck

You cannot manage what you cannot measure

Maybe what you have is a bike that does not have the timing set correctly from the factory

You are going to move this part 1 or 2mm which is less than a pencil width

[morton]

I have a 2013 300 and it needs a real hard kick or it bites me, I have recently changed spark plug from a 5 to 7 and it has improved it's starting a lot .

[clarky]

Thanks guys, I will go 1/2mm from standard and let you know after weekend how I get on.

Thanks again

[copemech]

I would say go with a 3mm swing from factory setting for a noticeable change. One may roughly relate the distance in mm to degrees.

I have not done this on a Beta, but I have done all my 2.9 Shercos in the past and makes them much easier to live with in respect to the kickback and inadvertant stalling.

[billyt]

Clarky

I have a 300cc Beta. If you do not kick it COMPLETELY through its stroke it WILL kick back on you!

The key is to kick COMPLETELY through its stroke EVERY TIME.

A bike will rarely kick back when all the way through its stroke as it gets past its cranking angle once fully down.

This can be proven by being able to hold the kick starter fully down even though the bike has started. The bike can be running but the starter will not kick it will just sit there and grind the crap out of the gears.

NOT recommended to try, but just said to prove my point.

[dan williams]

OK the key here is why has its behavior changed. I assume you had it for at least 6 months when it didn't kickback? What may have changed? Did you start using a different fuel? Have you changed the wiring at all? Maybe disturbed a connector that changed how the CDI box is reacting to the firing signal from the trigger coil.

First thing is when a mechanic tells you can't change the timing on a competition bike RUN! He WILL screw it up badly.

Tell us more detail. Does this happen when the engine is cold? Does it occur with the choke on? Does it only happen when the engine is already warm? Was there any event that preceded this happening like a crash that revved the engine? Have you checked the condition of your reeds? Once the bike starts does it run normally? These are high compression engines and even something as simple as low octane fuel will detonate without much provocation.

Help us to help you.

If you got Billy T's attention you have access to one of the smartest Beta guys on the planet.

[0007]

2 minor points of note

A kick start does not grind the gears once the engine starts, it's a ratchet mechanism

You could grind it lots and it won't hurt a thing

Low octane fuel can and will detonate but if here is a problem with this bike it's not that

Detonation is when the fuel mix explodes upon spark ignition rather than burning in a controlled manner

Pre ignition could cause combustion without spark ignition but it could not happen on startup

But I agree that is either TMDT or a starting practice issue, that's why I like duplication, have another beta owner start the bike and you start his

There are times when my 290 kicks back but it's not unusual to me

[dan williams]

Just trying to get him thinking and providing more information.

Pre-ignition is when the mixture ignites before the spark due to a hot spot in the cylinder, fleck of carbon, hot plug electrode, pocket of free radicals in a poorly designed engine. This causes combustion chamber pressure to peak before the piston reaches top dead center instead of slightly after it where the pressure increase in the combustion chamber generates power. This means inertial energy stored in the flywheels/crank is wasted compressing a higher pressure gas. That energy manifests as heat raising the engine operating temperature often leading to detonation.

Detonation is an uncontrolled burn that occurs due to extreme pressure/heat condition causing significant portions of the mixture to reach their auto-ignition point, and depending on the shape of the combustion chamber, starting multiple flame fronts which cause a rapid rise in combustion chamber pressure. Far more rapid than the pre-ignition scenario. This rapid pressure rise is akin to hitting the top of the piston with a hammer and is mechanically devastating to an engine.

[billyt]

2 minor points of note

A kick start does not grind the gears once the engine starts, it's a ratchet mechanism

I am not talking about the drive gears but rather the ratchet gears!

You could grind it lots and it won't hurt a thing

Low octane fuel can and will detonate but if here is a problem with this bike it's not that

Detonation is when the fuel mix explodes upon spark ignition rather than burning in a controlled manner

Pre ignition could cause combustion without spark ignition but it could not happen on startup

But I agree that is either TMDT or a starting practice issue, that's why I like duplication, have another beta owner start the bike and you start his

There are times when my 290 kicks back but it's not unusual to me

[billyt]

I have a brand new Beta 300cc EVO 2T Factory that I picked up last week. The bike runs great, no CDI problems, no changes.

If your bike runs great once started then there is no CDI issue or wood ruff key issue. If you have no pre detonation (pinking) issue once the bike actually runs then then pre detonation is not an issue.

The bike will kick back when it is not pushed through its entire stroke PERIOD. I had a 250cc Beta before the 300cc Beta and I had to modify or be more forceful and committed in starting the 300cc. I do not not have any kick back now that I learned how to take the kick starter all the way through.

The bigger the bore the more pronounced this affect will be.

Once you get the kick starter all the way down it will not and can not kick back even if the engine is running.

Your are experiencing a mechanical issue (starting technique) NOT a CDI issue.

Even if it is a pre detonation at start up, the force you apply through the committed aggressive long and fast travel of the kick starter will drive it on through the pre detonation.

A little mind game that was taught to me is:

Stop trying to start the bike by kicking it down until it starts. Instead think of a technique goal or action where you are trying to just get the kick starter down all the way and overcome the resistance in a quick forceful maner. Once you get this technique down the bike starting is just an attribute of this action.

The other KEY is the speed in which you push the kick starter down. The perfect blend of force and speed is critical in starting a big bore bike.

If you where to analyze the stroke of the piston to the stroke of the kick starter, you would find that if the piston reaches the firing point before the kick starter nears the bottom and the first fire of the plug ignites the fuel successfully the bike will try to kick back. The goal is to get the kick starter down near the bottom of its stroke before

the piston reaches the top of its firing stroke.

The other little trick is to pre load the piston with the kick starter so that it is just broke over TDC and has to travel down and then up on the next kick. In other words push the kick starter down gently until you just get it past TDC and then give it the almighty fast and heavy kick with a long travel.

Edited May 29, 2013 by billyt