Dax Balanced lower...?

Tom, Reallllllyyyyyy stop it. I hope this help you sleep better tonight. Way way back in the day back when I was a newbie and this was a long long time ago I bought a BIG BLACK ROLL-A-WAY TOOLBOX. And I even bought a long shine wrench that go's "CLICK" when I use it to "retorque" (check) my head bolts I bought from Pirate Cycles that are made from 300 series Stainless Steel. I truly hope this well remove any further dout of my mechanical ability.

mapbike said:

Thought I'd share something I discovered today while looking through some of my stuff stuck back in the corner, which by the way should have been done by now...LOL!

Anyway, somewhere about 1.5 to 2 years ago I bought a lower engine assembly from Lucky Early Bird LEB/BGF, I had noticed back then that the crank in this engine looked to be much better made than all the others I have or have seen, turns out after taking a good look at the crank that is in the "balanced" lower that I just received a few days ago from Duane at Thatsdax, it is the same crank that is in the Pk-80 looking engine that I had gotten from LEB back then, seems if I remember I had posted pics and commented on the crank being drilled in a way that looked as if they were intending for it to be a better balanced lower, it also has very good looking bearings in it including the wrist pin bearing that is made so that the rod will not have that typical side to side play that has been claimed to be the possible cause of that upper bearing failing in many engines which I have experienced myself.

So it looks as if I have two of these "beefier" built better "balanced" lowers now.

Pics I have listed here are pics of the crank removed from the LEB engine which is identical to the crank that is in the "balanced" Dax lower I just bought from him, Duanes lower looks really good, great upgraded bolts and studs and everything about the case looks to have a really nice even fit, excited to get started putting this engine together as soon as I get the other parts rounded up and get me some good gaskets made up.

Peace Map

Click to expand...

My crank looks like that too, but it's not the same. Dax's are custom built (from what I got from his post) and have tighter tolerances (straighter, rounder, thicker) and made from a slightly different material. While they may look the same, there may be minute differences between them. However that isn't to say you may have lucked out with the older crank and gotten a good one. I've seen 2 cranks now and my old one was much straighter than my new one.

I asked Dionel of JNMotors about whether or not the racers were using the Jaguar CDI and he said over 60% of them were. He goes to almost all the races so he should know.
On my ride the Jag let it rev much higher and smoothed it out. Vibrations were bad before. But the low rpm vibrations didn't go until I changed the wrist pin for a lighter one.
Concerning getting these engines to rev up to 9, 10, or 11 thousand, I'm not sure that's a good idea. The transfer ports are too limited. Look at a good engine and you'll see two transfer ports on each side of the cylinder and a huge boost port. That is what you need to get the intake charge instantly transfered into the cylinder at really high rpm. If it partially transfers then it can still rev high but at less power.
The standard flywheel doesn't counterbalance the weight of the piston/pin/upper-conrod enough and so that, in combo with excess compression from overly advanced ignition (from the 4 stroke CDI of the Grubee), causes excess vibration. So the Jaguar CDI in combo with either a lighter piston/pin/conrod or balanced flywheel will smooth the engine right out. I myself would rather just pull the cylinder and replace the heavy wrist pin with a lighter one than split the cases and replace the crank. I'm guessing that fixes about 75% of the low rpm imbalance, so the balanced flywheel would be a 100% fix.

48ccbiker said:

I asked Dionel of JNMotors about whether or not the racers were using the Jaguar CDI and he said over 60% of them were. He goes to almost all the races so he should know.

Click to expand...

really 60%?
more like 6% or actually 2? guys at the last race.
sounds like you copy and pasted some of jaquar's writings.

Where are all these races you are talking about?
I only missed one of the last nine races and the same guys were at the
one I missed.

The last 9 motorized bicycle races in the whole country since June 2011
were in California and only a couple of guys were using the jaguar CDI out
of a lot of China Girl racers.

The fastest 66 cc 2 stroke racers don't use the Jaguar CDI and the slower
ones don't too.

MotorBicycleRacing said:

really 60%?
more like 6% or actually 2? guys at the last race.
sounds like you copy and pasted some of jaquar's writings.

Where are all these races you are talking about?
I only missed one of the last nine races and the same guys were at the
one I missed.

The last 9 motorized bicycle races in the whole country since June 2011
were in California and only a couple of guys were using the jaguar CDI out
of a lot of China Girl racers.

The fastest 66 cc 2 stroke racers don't use the Jaguar CDI and the slower
ones don't too.

Click to expand...

You actually used the J word........the nerve

Hey MBR, D@JNMOTORS is a good dude been known to stretch the truth a bit to sell his Jaguar product . and you're right a stock CDI will run faster with the race motor. but I like the smoothness on my race motor because I just rip around town . however up underneath my wizard replica tag is a stock CDI in case the Jag fails or I come across somebody in St Louis this got something close to it might be worth running against .And in regard to the comment about guessing how to straighten out the vibration on the bottom and well that shows shows the difference between an amateur and experience builder / racer

My motor's never been run without the jag so I can't attest to any difference. But if it reduces vibrations, isn't it worth it just to save the lower end? People say to keep WOT riding to a minimum but I do it everywhere, all the time, at 38mph, my milage is garbage (80MPG) but I've never had an issue. Racing applications are vastly different than street/daily driver. Maybe the stock CDI is faster, I dont know, remember the jag CDI is tunable (and yes it has given me mild gains and even introduced ridiculous vibrations if I set it differently), but in racing when the motors are rebuilt frequently, reliability only needs to last the race. I've never blown a bearing, despite how frequently people say it happens, wrist pin, lower, crank, not a single one, even after ripping the motor apart and cutting... pretty much everything.

So, I'll have to say, from how few problems I have with the motor, I'd say the jag is worth it, in conjunction with other anti-vibe mods (balancing, lighter reciprocating weight, good mounting, etc.) you could have a motor running in 4-stroke reliability territory. Not to mention my exhaust barely gets hot enough to boil water after running for hours @ WOT (I know because I ran it non-stop until I ran out of the 2L of gas). is it the CDI? maybe, I don't really want to run a stock CDI but if it will put the argument to rest for good, I'll do stock CDI, and each of the 9 settings on the jag and post hill climb speed/time, top speed, temperature, and 0-60(kph) time. I don't really have a way to quantify vibrations and we all know after a while of having vibrations you get used to it or you go numb, either way will bias the next test.

I dont like bias, I prefer solid numbers because they're unquestionable (unless people say the numbers taken are biased, but... I hate misinformation and this'll be a good way to see if it'll be worth it on my next build anyway so, why not?)

OK, check this. The first day I ran a stock CDI on my new DAX360GP bottom to see how smooth the balanced crank felt. I know the vibes of a GT-5 and a PK-80 running stock CDI. The DAX ran like my old PK-80 ran WITH THE JAG ON IT, SMOOTH. NOW WITH THE JAG on the DAX there is almost no vibes at all !!!! My mirrors tremble a tiny bit at an idle. Crack the throttle and my mirrors still as if they hanging on the wall. I can't feel it running when I'm riding it . Vibes what the He!! are vibes???

Maybe all the misfortune comes from the naming connection to the automobile company who stubbornly used Lucas electronics til the bitter takeover.

"Why do Englishmen drink warm beer?, Lucas electronics in their icebox."

Lucas-The prince of darkness.

Huffydavidson said:

OK, check this. The first day I ran a stock CDI on my new DAX360GP bottom to see how smooth the balanced crank felt. I know the vibes of a GT-5 and a PK-80 running stock CDI. The DAX ran like my old PK-80 ran WITH THE JAG ON IT, SMOOTH. NOW WITH THE JAG on the DAX there is almost no vibes at all !!!! My mirrors tremble a tiny bit at an idle. Crack the throttle and my mirrors still as if they hanging on the wall. I can't feel it running when I'm riding it . Vibes what the He!! are vibes???

Click to expand...

It's probably fixing to break.

Huffydavidson said:

OK, check this. The first day I ran a stock CDI on my new DAX360GP bottom to see how smooth the balanced crank felt. I know the vibes of a GT-5 and a PK-80 running stock CDI. The DAX ran like my old PK-80 ran WITH THE JAG ON IT, SMOOTH. NOW WITH THE JAG on the DAX there is almost no vibes at all !!!! My mirrors tremble a tiny bit at an idle. Crack the throttle and my mirrors still as if they hanging on the wall. I can't feel it running when I'm riding it . Vibes what the He!! are vibes???

Click to expand...

Hows your top speed and did you have to jet down from the standard crank f80? I had to jet down from a 68 I ran on the normal crank f80 to lower than a 66, I went to the lowest I have(66) but I had to order some smaller jets cause Im still too rich, Im at sea level. I think a 64 will do it but we will see.

Did you notice a difference in acceleration or miles per hour?

Good thread. just found this a few ago and its funny because I ordered a new f80 bottom and top end yesterday for my bike. it will be about 2 weeks before I have it in because Im haveing the piston ported by a friend first.

I sure am getting sick of hearing people say, " I just ordered one, I'll going to tell you how it went when you get old and a fat, and I get around to doing something with it."

I'd like to hear from someone who already put one together, and can now say how good it's running, and what they did to it.

Stuff like,

" This DAX bottom end really rips 4 strokes a new one".

" Since I bought my DAX if I race 4 strokes, they blow, and can't keep up with me."

" I rejetted after the DAX, and now even if it backfires all 4 strokes within 20 yards drop a ball."

But I hope not,

" My bike was so pitiful before my DAX balanced bottom end that every 4 stroke could beat it, and now after my DAX install, they still beat me wtf." LOL

I'm more of an objective guy myself. I love solid numbers but sadly some things cant be put into comparable numbers. Some people are more sensitive to vibration than others, so while you could get numbers and show which vibrates less, but that doesn't really tell me how it compares to my bike. I imagine it can pull much better top speeds on a windless day because it doesnt have to fight its own vibrations as much but the question is how much power does it add to overcome air resistance? Whats acceleration like? where's the power band now?

Though it's great news to hear you have to jet down some, it'll help my milage a bit.