[Ray Lovestead]

Phil – do you have those exact Birel/Freeline brakes?  Are you using the recommended brake bleeder kit?

[Ray Lovestead]

Two karts, one truck??  You sick $@#$!.  They should have never released that video in the first place.

 

[Ray Lovestead]

No – I wasn’t clear enough.  I meant, elaborate on the piston crown on the intake side versus the idle circuit and then the exhaust side of the piston crown versus the main jet.  I just have never seen that described anywhere.  How is the intake/exhaust side of the piston crown affected by the pilot/main jet?

 

Ray

[Ray Lovestead]

Been there and done that a number of times.  Totally solved it.  Tighten it.

(hehe)

Seriously though.  What I like to do is, make sure I’m using the same indentions from the previous use, tighten it down really really good, use lock-tight, and voila..  presto.

The next time you have to remove the axle, clean the spot with a file and then when you re-assemble, hit the same exact spot again, and tighten, tighten, tighten, with lock-tight.

Done.  Don’t be afraid to indent the axle, in fact, it helps keep it in place.

Ray

[Ray Lovestead]

Can anyone out there elaborate on what Christiaan was saying about the jetting with respect to the pilot circuit (intake) and main circuit (exhaust port)?  I’d like to know more.
Ray

[Ray Lovestead]

This is what you want.  Take out your spark plug and peek inside using this light.  It’s a great, bright, well made model.

http://www.amazon.com/gp/product/B0042VILIQ/ref=oh_details_o08_s00_i00?ie=UTF8&psc=1

Christian.  Can you provide a little more detail about what kind of color/etc you’re looking for on the piston top?  I’ve never come across anyone who tunes by looking at the top of the piston like this.  I go by EGT, feel, spark plug color and pitting on the piston (detonation).

Ray

[Ray Lovestead]

Awesome!  I wish we had the fan base and advertisement interest ($$$) to have this kind of quality coverage for our racing.  Most Americans don’t even know this kind of thing exists.

Ray

[Ray Lovestead]

you can use the CR125 manual for the model year to check all the various clearances, tolerances and lengths of things.  I’d say it is likely that your used crank is just fine and that it may only need a balancing/straightening.  That is, if it isn’t your crank that is the problem..

I also wouldn’t bother honing the cylinder if the lining appears fine.  Unless you actually smeared aluminum (from a melted piston) up the side or broke off something in there, it should be fine.

this site has info on drilling holes for lubricating the piston.  I don’t see any reason why you wouldn’t (unless your race org doesn’t allow it).

http://www.kartweb.com/TechArt/125Stock/stock_moto.htm

BTW – if you’ve never split the cases before.  You either need the honda tool to do it or a big f’in hammer (and subsequently damaged crank assembly) and a lot of patience.  After the first time, and after honing your crank for future dis-assembly, you’ll have no problem separating the cases.

Ray

[Ray Lovestead]

How about that for another question.  How do you look past a driver who is directly in front of you?  I have bumped several people who are a couple feet in front of me because I’m watching their bumper and can’t respond fast enough when they brake into a corner.  Do you try and look past them?

Also, all the driving articles (and two lessons I’ve had) talk of looking as far ahead as possible.  Not the next apex, the next turn entirely.  I had a driver tell me he looks as far to the next turn as his vision will allow.  Even 2 turns ahead!  How is this even possible?

Ray

[Ray Lovestead]

I believe that lifter only would spin when you have the clutch lever pulled (putting pressure on the plates).  It sits on a ball that essentially is the only friction reducing mechanism.

I don’t believe this would have anything to do with a seized engine.

Don’t be afraid to split those cases.  Get in there and figure it out.

Ray

[Ray Lovestead]

I’ve got four bathroom scales and I used them.. once.  If I could do it again, I would have gone to my local kart shop and used their scales.  The only time you’d ever use them again would be after a good crash to check to see if you bent the chassis.

Ray

[Ray Lovestead]

Thanks for input Donnie.  Probably time to go seat shopping.

Eric – I don’t just keep my knees near the gas tank, I squeeze the tank with my knees to keep me stable.

Don’t get me wrong, karts are pulling 2Gs around a corner, you have to brace yourself some.  But it just seems like I am trying too hard.  I should be more relaxed.

Think I need a better seat.  Do you guys have a preference for the deeper fitting seats?  I see a lot of guys using the very low seats that just fit the hips and some of the waist.   My seat is up to my armpits.Ray

[Ray Lovestead]

Alex

How are you measuring the on/off spikes in the data?  Throttle sensor?  Just looking at speed (GPS or rear axle)?

Could you provide an example in a graph to explain how you are doing this?  I’d really appreciate it.

 

Ray

[Ray Lovestead]

My advise would be to play with the rear track.  If you go really narrow (like 1.5inch either side) you’ll not lift the rear inside tire and you’ll bind up the chassis.   You’ll probably find that it causes push (understeer) on the entry to the turn and has great grip on the exit (no oversteer at all).

Doing this will give you some idea of what that bind feels with respect to power and acceleration.  On entry if you take it slow in and then get on the gas early, you’ll likely not get any longitudinal acceleration out of the kart.

Conversely, if you set it up really loose (max rear, loosen the third bearing, remove struts) you’ll find it will eventually want to hop as you go through the corner.

This is probably the best reference out there:

http://www.crg-america.com/pdfs/CRG_Kart_Tuning_Manual.pdf

read page 5.

 

Ray

[Ray Lovestead]

Is the track mainly right hand turns?

How does the tread look (does it look like long wavy grains in the tire)?   Does it look or feel like it is understeering?  Too much negative camber can cause some understeer on the exit of the turn – but I find that I always use a little bit of negative camber.

Did you get a chance to check the tire pressures on all 4 tires?

Ray

 

 

 

 

[Ray Lovestead]

Really the worst is to have an old piston ring break apart.  Does a lot of damage to the cylinder walls.  But an old piston, nah.  You lose the original concentric grooves on the surface of the piston that helps with distributing an even coat of oil on the piston.  And you might have some wear on the piston body that causes an increase in blow-by and a subsequent reduction in compression.

Only reason I suggest looking for an air leak in the inlet path is that I’ve got two pistons that look identical to what you have (no clear indication of detonation, melted on exhaust side).

Look for excessive oil around the seals of your carb boot.

Also, what oil to fuel ratio are you running?  What engine is that?

Ray

[Ray Lovestead]

Andy – to be more complete:

Running rich would cause the motor to bog and have a strong hesitation when you hit the throttle.  Couple of things to look for: 

1.  Excessive smoke out of the exhaust.  Note that you will always have some smoke, but you shouldn’t be creating a cloud.

2.  Oil/fuel dripping out of the end of the silencer.  Oil/fuel leaking between the manifold of the engine and the pipe (causing a messy block!).  Oil/fuel leaking between the silencer and pipe. 

3.  Oily gummed up plug.  The plug will go black over a time, but it shouldn’t have a build up of goo.

Running lean or correct, you’d not see any of the above.  But running lean you’d see the plug burning itself up/whitish, you’d see pitting in the piston top near the edges, you feel like the engine was zingy (basically it’d feel ‘too’ responsive).

In that photo you can see pits all around the edges of the piston.  BUT, note that this same phenomenom can come from poor cooling (which is the same as running too lean, the oil cools the system).

 

Ray

[Ray Lovestead]

need more info Pete. Was this the first time you ran it? I’ve stuck two pistons like this (melted down at the exhaust port) and they both were due to severe lean condition due to a leak in the carb boot. I kept running larger and larger jets, but just couldn’t keep up with the leak.

Probably not due to the low end circuit. Bogging when quick off the throttle is usually a rich condition. What the the exhaust pipe (exit) and spark plug look like?

Ray

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