my performance oriented thread

[a.graham52]

i have not done a comparason yet. but i plan on it. first test was 175, then i removed a fair amount of materal from the combustion chamber, 150 sounds very plausible.

do you have anymore info on what you just recommeded. waht part is the counter weight cover exacly. as well as roof angles?

 

[Theon]

The older style 40mm cranks have counter weight covers which improve the primary compression, on my 3 piece crank engines I make case stuffing discs from alloy sheet that are the right thickness to get crank to case clearance down to around 1mm.
have also used .5mm copper discs 10mm dia to close the ends of the gudgen pin, sitting between pin and clip.
When increasing the compression benefit can be had by making the transfer port roof angle closer to horizontal. so that gasses exit transfer ports and flow across top of piston rather than up at 45 deg.
I use one of these.

 

[PIGEONHAWK]

standard plug after i shortened the wire threads:


first attempt at an isolator:


puch head with standard plug:


puch head with short plug, (also note: changed crush washers on plug and that gained me probably a mm.:

brother your air filter is not functioning.

 

[a.graham52]

brother your air filter is not functioning.

What do u mean?

 

[PIGEONHAWK]

im a little confused by the last two pictures but it looks like burnt dirt gone thru the from intake side?

 

[PIGEONHAWK]

im not picking on you btw I just didnt have anything else to say.

seeing the spark plug wire again now and i want to say well done. I see the merit this time/ before i passed it by. its kinda cool!

 

[a.graham52]

It was actually fuel/oil build up on the head. I put it together, rode it around the building ( with the choke on) and then shut it off and pulled the head. Definitely wasn't dirt/oil.

Oh and I have since upgraded the sparkplugg wire to a much better setup

 

[a.graham52]

here it is today. you can see the new napa spark plug wire i stole from a 79 buick.
its worked flawlessly at this point.

 

[a.graham52]

well my exhaust is on hold until further notice, so i replaced and upgraded tires. with aprox 300 miles on the bike, totally trashed the "oem" mtb tires.

i went from 29-1.95 what ever they were to some 29-1.9 Geax Evolutions. rated for asphalt use but still have a fair aggressive tread.



here is my front and rear oem tires with 300 miles. i run 45psi in the front, 55psi in the rear:

 

[mapbike]

Just wanted to bump this thread since the first few posts are related to squish clearance which is something other may enjoy reading about.

 

[Davezilla]

Good idea on the bump... I'm also setting up the squish and the port timing on my newest engine build. Got the basic porting done and everything where I want it so the next step will be setting the jug hight for the best port timing, then cutting the deck down and playing with head gasket thickneses to get the squish clearance where it needs to be. I'll take pics tomorrow and make a new post expaining the whole process tho since the timing and duration can be effected by where the jug is located in relation to teh crank, and then setting up the compression and squish clearance after this step is done... Right now I got my GT5 SR set up with the new jug temp installed along with the dial indicator and degree wheel installed and ready to take the readings... This part has a lot of build up, tear down, make adjustments, build back up, take measurements, tear down, shave this, cut that, then build up for more measurements, tear dwon for more adjustments etc, etc... It's not hard to do but it can become time consuming on a new engine, or even if doing a top end rebuild like I'm doing to my other engien while I'm fixing the bike...

 

[mapbike]

I just put one of my dax GT5 lowers together yesterday, shav3d the jug .080, not s7re of port timing since I dont have a degree wheel, but I'm using 1.7mm of base gasket, and my final squish clearance is .70mm using a .040" head gasket with a Jake/MZ Diamond head, did same type port clean up I usually do, only widened exhaust about 1mm and just cleaned intake port up nice, cleaned up transfers, notched piston skirt b8t not comepletely wide open on intake, piston ramped on exhaust port side width of port and only about .030 removed.

I didnt want to take to much away from the bottom end of the 38mm stroke engine, but give it a little extra kick at the top, since I dont know what my port timing is for sure Im hop8ng this turns out to run like I want it to, but time will tell.

I pulled both of my dax lowers out and started looking over them close and rotating the crank in each one, I builtwhat I think is the best one since the rank spins very untrue in one of them, Ill have to take it down and straighten the crank out before I uild this one or it will be a vibrator, when crank is rotated so rod is at lowest point the counterweights are probably about .060 closer together between each other than they are on the rod end, thats a good bit of wobble and will no doubt translate into serious vibes at high rpms, f8rst dax engine Ive seen with this issue, sure wish he would go back to the good ole 40mm stroke engines he had before, the newer GT5 engines just aren't the same quality as for as the ranks are concerned.

 

[Davezilla]

I also gotta say I'm a bit disapointed that Dax went with a 38mm stroke crank setup in his last batch of engines, and that he doesn't have any bottom ends in stock at the moment...
after getting my customer's bike running yesterday and doing a few good revs of the engine, that thing vibrates HARD at about 6000 rpm... I'm seriously thinking about taking the jug off and lightening up the piston to cut down the vibes before I call him and tell him it's ready to ride... my Dax based engine doesn't vibrate anywhere near this bad and it revs nearly twice as high...

 

[mapbike]

I also gotta say I'm a bit disapointed that Dax went with a 38mm stroke crank setup in his last batch of engines, and that he doesn't have any bottom ends in stock at the moment...
after getting my customer's bike running yesterday and doing a few good revs of the engine, that thing vibrates HARD at about 6000 rpm... I'm seriously thinking about taking the jug off and lightening up the piston to cut down the vibes before I call him and tell him it's ready to ride... my Dax based engine doesn't vibrate anywhere near this bad and it revs nearly twice as high...

yep that customers engine is what a big majority of the older engines did, I know since I have several of them, some run real good up to a certain rpm and then the jackhammer wakes up and tries to knock your fingernails off when the revs get to a certain level, some are worse than others but many of those older engines and even some of the stuff still out there is like that.

The Half Breed engine I got recently inspite of Fred saying the balance factor was good on them is a mini jackhammer above 30mph, it does smooth out someonce the revs get to the upper end of what it will do, but its way rougher than any of my 40mm stroke dax engine have ever been.

Ive yet to see any eof the engines that are smoother than what the older version GenIV are or were, Duane told me he could still get those engines so Im sure hoping he'll see some of these post and get another batch, Id sure like to have 3-4 more of those good lowers.

Ive got one of the newer GT5 versions built up now and hope to get it on the Huffy and running soon, Im sure hoping it is a nice smooth and strong runner, Ive got my fingers crossed......

The second one needs crank trued b3fore Ill even consider building it up, serious wobble in counterweights, ver6 dissapointed in that one for being that way, none of the 40mm stroke engines were ever that way, best cranks Ive seen in any of the china girl engines hands down.