Jetting vs. Engine break in

[deeeebeeeeee]

OK proper jetting takes a few 30+ second long WOT runs to set the main jet.
Proper breaking requires no WOT until at least the end of the first tank, no sustained WOT till after the second tank, at least many hours of running before properly setting the main jet.
P I realize that recommendations tend to be quite conservative as a particular bore may not be well honed, and certain ring /cylinder (nikasil) combinations take a little longer to seat.

After proper heat cycles, and getting a good pilot jet/airscrew setting, I figured on going ahead and doing a couple half throttle chops, using a Main jet that is known to be rich.

After this I am not sure what to do
I figured after a couple hours of running I could at least open it up onto the Main jet enough to be able to lower the jet size one step at a time until it clears out and pulls smooth at WOT and just leave it there, even though it may still be a little rich, until I get a few hours and a few good long run it cycles (fully cooled after an hour or more of riding) on it.??

I guess my question is how do you go about making sure you are jetted at least closely and a bit rich on the main jet, while still on the first tank of the run in period?

Fortunately I am running a KOR cylinder and I am sure it would initially endure a go or blow style run in.
But i wouldn't purposely do anything to shorten the life of my cylinder.

I have watched and am going to watch again the KOR vid on break in process,


Ideally you should not go WOT during the run in period, but I don't want to chance being at 3/4 throttle and running lean.
Maybe adjusting the throttle stop screw to allow up to 3/4 throttle and maybe keep me off the happy trigger for a little while. Might set the throttle screw at 1/2 for needle chops and back it out a thread or two each ride, might be ovrkill?

I know more people here than anywhere run Blasters and KOR cylinders. How do you handle, nearly from scratch jetting on a fresh motor?

 

[Blaaster]

It is recommended by many including myself that for the first 2 tanks of fuel 3/4 throttle not be exceeded.

That way one never gets onto the main jet circuit.

If one runs a main jet that one knows will be too rich, it will not interfere with anything below 3/4 throttle.

After the heat cycles and re torque of the head and cylinder nuts it is fine to perform a plug chop at 1/2 and 3/4 throttle to confirm the needle.

6 to 10 second plug chop runs will give a readable smoke ring, there is no need for 30 second runs.

It is a great idea to limit the throttle stop to 3/4 throttle, that way the urge to give it more is foiled.

 

[deeeebeeeeee]

It is recommended by many including myself that for the first 2 tanks of fuel 3/4 throttle not be exceeded.

That way one never gets onto the main jet circuit.

If one runs a main jet that one knows will be too rich, it will not interfere with anything below 3/4 throttle.

After the heat cycles and re torque of the head and cylinder nuts it is fine to perform a plug chop at 1/2 and 3/4 throttle to confirm the needle.

6 to 10 second plug chop runs will give a readable smoke ring, there is no need for 30 second runs.

It is a great idea to limit the throttle stop to 3/4 throttle, that way the urge to give it more is foiled.

I will most definitely be using the throttle stop screw, when the band hits I habitually pin the throttle, even as a70lb 12yr old on an Pro Circuit banshee
I guess 30 seconds is really a long time although when it comes to holding it down across a rough field it FEELS like alot longer.

I had a few dollars left over on a prepaid card, and was looking at a 93 cr125 reed cage with fiberglass reeds(requires additional parts and work), a Mikuni adjustable power jet kit, and a tiny tach style hour meter /digital tach.

I ended up goinng with the tach /hour meter, I would like to and may eventually get all of the above, but I felt the hour meter should come first.

So basically I will need to put at least ten hours maybe more on the engine before going WOT?
IIRC I get around 1 to 2 hours riding per gallon 2 tanks probably closer to 4 gallon since I try to never use reserve.

So if I use an hour meter, maybe 6-8 hours of mixed riding, various rpm and throttle position?

 

[jvb]

I do 2 heatcycles, and one tank of gas as break-in.( and I do give it wot with short burst when the tank is about half full)
Not sure of you mean with that as a "go or blow style" ? Lol but it always works perfect for me.

 

[joeak47]

The hour/tach meter is a very inexpensive, but awesome tool. Money well spent deeeebeeeeee! I run those on almost everything. As for the reeds, save your money and get the Vforce 4 reeds. Don't jack around with anything but those. I know they cost more, but are well worth it. Besides you can get those later. The stock reeds work perfectly!. Don't waste your money on boysen dual stage,etc, etc. No gain and a waste of money.

The adjustable power jet will only come in handy on super long full throttle runs like...
going across a dry lake bed at full throttle. How often do you do that? Just another item to give you problems. Proper jetting is the key!

 

[deeeebeeeeee]

I do 2 heatcycles, and one tank of gas as break-in.( and I do give it wot with short burst when the tank is about half full)
Not sure of you mean with that as a "go or blow style" ? Lol but it always works perfect for me.

Some people seem to think the way to go is run your heat cylces, then go out the next day, start it, warm it up, and go run the dog snot out of it, giving it all its got. The idea is it will either go or blow right then so if the cylinder clearance is a bit tight, rings slow to seat, or any other irregularities it will fail immediatelty..... it will either go or blow.

What they don't seem to get is if everything is good and it doesn't blow , they have just cut it's life nearly in half, as well as probably reduced it's initial compression numbers and power.

Anyhow my biggest reason for setting the throttle stop is because I know that I can't ride what amounts to a whole day and keep out of the throttle. Once I hit the band I tend to pin the throttle and hold it until I have to get off the gas and on the brakes.

So If I set the throttle stop it will let me pin it at wherever I set it, during break in..
I can't wait still on cable brakes but I have rear brakes so I can now slide the corners under power or braking if I hit it too hard. Plus the extra power, plus shift star mod, getting ready to order the HD clutch and hoping to get some fresh 20 inch rubber soon.

Can't wait, can't wait, can't wait ......won't be much longer now.

 

[jvb]

Some people seem to think the way to go is run your heat cylces, then go out the next day, start it, warm it up, and go run the dog snot out of it, giving it all its got. The idea is it will either go or blow right then so if the cylinder clearance is a bit tight, rings slow to seat, or any other irregularities it will fail immediatelty..... it will either go or blow.

What they don't seem to get is if everything is good and it doesn't blow , they have just cut it's life nearly in half, as well as probably reduced it's initial compression numbers and power.

Anyhow my biggest reason for setting the throttle stop is because I know that I can't ride what amounts to a whole day and keep out of the throttle. Once I hit the band I tend to pin the throttle and hold it until I have to get off the gas and on the brakes.

So If I set the throttle stop it will let me pin it at wherever I set it, during break in..
I can't wait still on cable brakes but I have rear brakes so I can now slide the corners under power or braking if I hit it too hard. Plus the extra power, plus shift star mod, getting ready to order the HD clutch and hoping to get some fresh 20 inch rubber soon.

Can't wait, can't wait, can't wait ......won't be much longer now.

Doesn't matter if you limit the throttle, it's a 2-stroke it will go "on the pipe" at a certain rpm , no matter the throttle position.
So if you allow your engine to go "on the pipe" during break-in, I would rather see it getting it's mixture through the main jet ( more gas/oil mixture).
You can also "hear/feel" when an engine can handle more load and rpm during break-in period..!
Not to mention ring seating ( rings will only seat properly when having enough gas pressure behind them that means wot once in a time...)

 

[deeeebeeeeee]

I will keep that in mind, and probably back the screw out at about halfway through the first tank and see if I can keep out of it a little bit.

 

[jvb]

I will keep that in mid, and probably back the screw out at about halfway through the first tank and see if I can keep out of it a little bit.

Just trying to help
But if I was you I would look it up , ask different engine builders etc. there's enough knowledge around this subject.
And the Blaster is air cooled so that is an advantage, you can hear pretty good how the rings are handling itselfs in the bore!
When they are getting almost not noticable(to the ear) you can put some more throttle and rpm at it, graduately...

 

[joeak47]

And the Blaster is air cooled so that is an advantage, you can hear pretty good how the rings are handling itselfs in the bore!
When they are getting almost not noticable(to the ear) you can put some more throttle and rpm at it, graduately...

Say whaaaat? I say "Hmmmm". I've NEVER heard that one. If you can hear your piston rings in the bore, you definitely got issues with that engine. Just saying.

 

[jvb]

Say whaaaat? I say "Hmmmm". I've NEVER heard that one. If you can hear your piston rings in the bore, you definitely got issues with that engine. Just saying.

New bore new piston new rings if you have delicate hearing you can hear...
I'm sorry you are not capable of that..!
There are also automotive stethoscopes..

 

[Blaaster]

Above 3/4 throttle, even though there is more fuel/oil entering the engine, the amount of oil that is able to come out of suspension is limited by the amount of time it has to do so.

An engine at full throttle may not provide enough oil to fully lubricate the crank rod bearing sufficiently.

The above problem is addressed by those who ride 2 strokes for long periods of WOT, by increasing the amount of oil in the mix, and jetting to suit.

As to hearing the rings over the noisy Blaster engine, that is a hard to swallow statement.

 

[deeeebeeeeee]

I could imagine if you have redone the the top of a particular engine, or rebuilt many engines, that you might be able to hear,feel, or otherwise somehow sense, how the motor is doing during break in.
On the flip side of the coin, I don't have any idea of how to guage this, not do I have the experience to know. Although I often feel in tune with my machines. can often easily hear or feel any changes or if something is not right,
But in this case the carb, head, cylinder,and exhaust configurations are all new to me. And so Is breaking in an engine.

So I really don't believe I will be able so sense how the breaking is going, or when it's ready for more. I could see how there could be a bit of a difference in the exhaust note or the ring of the fins if a engine was pushed to the point of either blow by or grinding the rings into the cylinder hard enough that the oil layer was comprimised. But once again, even if I could hear it as I am partially tone deaf (if you ever heard me sing karaoke you would know for sure), I really don't have enough experience with it as to know just what happens when over stressed during break in or what to listen for.

I have heard there is a fine line that represents the perfect run-in, I do t think there is such a thing, and it depends on the engine, the rider, and intended use.

I read Kennedy powers break-in post.
And have got similar info from the KOR blaster breakin vid.

I intend to gather as much info as possible but ultimately I will pretty much go with whatever the engine builder says, and let's face it i am no engine builder, it is for the most part a KOR motor. As even the work I done on my own, although certainly subpar to a seasoned hand, came about primarily as a result of the KOR blaster home porting video series.






Last thing I got new was a Honda 300 4 stroke and that motor was bullet proof, had a buddy take off up the paved road on it came back with the pipe glowing cherry red, finally a bent lower A-arm and a bad launch caused the front ball joint to snap. While at college I found out my dad (who had bought it for me) had gave it to someone to install a 4cyl in an 81 mustang for my brother.
Last I heard the guy still rides it at hunting season and it's a '91 model.