D
Deleted member 12676
Guest
that
is
ridiculous
Just type any way you want to. Smart people can figure out what you're saying.
is
ridiculous
Just type any way you want to. Smart people can figure out what you're saying.
Off set key
- Thread starter 45u
- Start date
HeadSmess
Well-Known Member
- Local time
- 7:04 AM
- Joined
- May 17, 2010
- Messages
- 3,048
Steve Best
Well-Known Member
Wow, so much to digest, I forgot what all the questions were...
Jag was right on about stock timing being aggressive as it is, and needs to be for the poor volumetric efficiency (port flow) and compression. Once you increase flow and speed up combustion chamber turbulence (and burn speed) you will need less timing or Jag's CDI.
In another post I was playing with chamber shapes and squish sizes and experiencing detonation at top speeds. I did try higher octane fuel and it worked but killed power a bit in the midrange. I didn't install the CDI yet.
My Grubee GT5A was doing 55-66kph (~40mph) with the 44t sprocket on 26" tires. Mathematicly that figures to 8000-10,000 rpm. This was with a ported cylinder and squish type hemispherical head. A piece of wristpin circlip broke off (rpm?) and scored that cylinder so I am running a stock cylinder again. Speeds are back to 40 kph (~25mph) range and increasing with head testing.
Be aware that ring break-in is about 4 tanks of fuel, or about 300 kms or 200 miles, with most of it happening in the first couple tanks. Performance is pretty sluggish on that first tank. I used 32:1 synthetic oil mix and my stock jetting for the break-in with no problems.
My mod for the stock head is to plane it down (file and sandpaper) and also re-cut the squish area to match the piston crown out to 47mm (or 40mm on the smaller engine). I did this with sandpaper on an old piston earlier but now cut it with some mild steel plates welded to a bolt and chucked in a drill press, a home-made cutter, to cut the proper radius. Better results. The piston is a 3" radius and you want about a 2" raduis on the squish area. The modified head makes even the stock cylinder liven up.
Working on a 48cc shifter also. Putting lots of miles on everyday and feeling much more comfortable with bicycle riding in general. I pedal more often too. Getting about 50-80 kms (30-50 miles) to a 2.5 litre tank at mostly full throttle. Loving it!
Steve
Jag was right on about stock timing being aggressive as it is, and needs to be for the poor volumetric efficiency (port flow) and compression. Once you increase flow and speed up combustion chamber turbulence (and burn speed) you will need less timing or Jag's CDI.
In another post I was playing with chamber shapes and squish sizes and experiencing detonation at top speeds. I did try higher octane fuel and it worked but killed power a bit in the midrange. I didn't install the CDI yet.
My Grubee GT5A was doing 55-66kph (~40mph) with the 44t sprocket on 26" tires. Mathematicly that figures to 8000-10,000 rpm. This was with a ported cylinder and squish type hemispherical head. A piece of wristpin circlip broke off (rpm?) and scored that cylinder so I am running a stock cylinder again. Speeds are back to 40 kph (~25mph) range and increasing with head testing.
Be aware that ring break-in is about 4 tanks of fuel, or about 300 kms or 200 miles, with most of it happening in the first couple tanks. Performance is pretty sluggish on that first tank. I used 32:1 synthetic oil mix and my stock jetting for the break-in with no problems.
My mod for the stock head is to plane it down (file and sandpaper) and also re-cut the squish area to match the piston crown out to 47mm (or 40mm on the smaller engine). I did this with sandpaper on an old piston earlier but now cut it with some mild steel plates welded to a bolt and chucked in a drill press, a home-made cutter, to cut the proper radius. Better results. The piston is a 3" radius and you want about a 2" raduis on the squish area. The modified head makes even the stock cylinder liven up.
Working on a 48cc shifter also. Putting lots of miles on everyday and feeling much more comfortable with bicycle riding in general. I pedal more often too. Getting about 50-80 kms (30-50 miles) to a 2.5 litre tank at mostly full throttle. Loving it!
Steve
Diamond Back
Active Member
- Local time
- 5:04 PM
- Joined
- Jun 11, 2016
- Messages
- 137
Cool Steve,,, thats awesome thank you
I would love to talk to you more when I get back from hardware store...Got an Awesome upgrade working on and if it works I will be selling it in a kit,,, Its what these bikes need !!!
A WALBRO WYK -192 15mm carburetor with HIGH and LOW speed adjusters,, I have the adapter / heat insulator intake mount (hard plastic/composite ) that has to slightly be modified to work,,, also there is a pulse hole on these carbs since they are diaphragm type and I need to find a way to connect it,, these carbs are also used on the 49cc 2 stroke scooters (( I HAVE ONE, THATS WERE I GOT THE IDEA)) on those engines the pulse hole connects to the engine thru a hole underneath the intake opening on cylinder..
If you look thru the tiny pulse hole opening right under the intake flange opening you can see the piston skirt going up and down creating an open / shut action as it passes by tiny hole..
I am trying to figure a way to hook up pulse hole and where too... I can hook up a little brass elbow tube coming out of isolator block ( as shown in picture)) ,, but where do I run a tube on it too...???? I saw one guy on here that ran it to a small nipple/tube fitting that was drilled and tapped into the transfer port on the bottom left of engine,, below cylinder where the cylinder meets the bottom case transfer port.. into the case wall thru the transfer port...
will this work and give it the pulse it needs ???? please help me with this Steve or anyone that is familiar with this...please!!!
If this works it should be like fuel injection,, as on the scooter there is no 4-stroking and screwing with main jets and needle clips... i got this Walbro WYK-192 off a brand new 72cc industrial leaf blower engine,,, so should work on 66cc... will try to get a bigger 18mm diaphragm carburetor in future if this works out good..
Attachments
Frankfort MB's
Well-Known Member
Fabian actually made multiple YouTube videos on the walboro carb. It works well on these engines ONLY if your good at tuning them. Air:fuel mixtures change constantly, when your engine warms up it tends to get richer, the colder the temperature outside the leaner your engine is (don't quote me on that). Exhausts can differ your A:F mixture. So your constantly adjusting, I just like to get it in the ballpark then leave it alone
Diamond Back
Active Member
- Local time
- 5:04 PM
- Joined
- Jun 11, 2016
- Messages
- 137
Fabian actually made multiple YouTube videos on the walboro carb. It works well on these engines ONLY if your good at tuning them. Air:fuel mixtures change constantly, when your engine warms up it tends to get richer, the colder the temperature outside the leaner your engine is (don't quote me on that). Exhausts can differ your A:F mixture. So your constantly adjusting, I just like to get it in the ballpark then leave it alone
How do i get to Fabians video's ???? I think I saw a few on youtube,,, does he have an accent when he talks..???? Well I am real Awesome at tunning the WALBRO CARB's... I had them in mt weed wacker's,, 1/5 scale R/C CARS and TRUCK's,, in mt 36cc and 49cc scooters and pocket bikes,, so I am good with the HI / LOW screws...The hardest part is the initial settings cause if one is off by a half turn it wont start...
Electric start is nice to have to find the initial start up settings cause you can turn screws while you are spinning over engine..I am going to have to adjust then pedal,,,,adjust some more then pedal,,, adjust some more then pedal...BBRRRp BBRRRPPP BBRRBBRRBBRR there we go !!!!! then its warm up and take choke off adjust idle a little high,, then LOW speed screw back out until it burbblleess and runs rough then 1/3 turn in opposite direction....
The HIGH screw is lift or raise back wheel off ground and hold throttle WOT wide open and turn HIGH screw clockwise (in) which LEANS the air/fuel mixture out and listen for the engine rev's and RPM"s to increase to MAX where it is screaming and then back it off counter clockwise 1/3 a turn,, then re-adjust IDLE screw,,, and there YA GO...!!!!
Then do (2) plug chops,, one for low-mid and two for TOP end,,, you then can back off a little on LOW speed screw to get it to run a little rich and if you can get it to 4-stroke on demand just a hair little bit,, like going down hill with no load is even better cause 4-stroking richness will help cool the engine down and lubricate it better with the extra oil going in...
It should run smooth as butter from Idle to MAX RPM (10,000) with no problems.. I have a Tachometer and I cant get it past 8,000 rpm at 34 mph with the 44 tooth rear sprocket,, I am a light weight 150lbs,, and I have plenty of low-mid range power between 3,000--6,000rpms which is starting off,,, hill climbing,,,and cruising speed at 25--28mph...
I do have some steep hills and long distant inclines around here where I live,, but then some nice back country flat roads also that I want to cruise fast on..!!!
So my question to you is should I go with the common 36 tooth for 8 mph top speed increase to 42 mph max and 32 mph cruising speed,,, or go with the other common 40 tooth for a little more speed and better low-mid power and 38 mph top speed,,,.. OR WHAT I FOUND was some one that makes a 38 and 39 tooth, 40 mph top speed...
I think with the NEW CARB setup and hopefully upgrade to a 18-19mm WALBRO (if they make one)) I cant find a diaphragm CARB bigger then 15mm.....DO YOU KNOW WHERE TO GET ONE ???????.... and put a Dirtbike KX 65 Pro-Circuit Torque pipe which exits into (2) two short stubby silencers and RSE REED CAGE setup with Piston windows (ports) and intake side cylinder 3rd transfer port like on the GT80 engines that will give it the extra LOW-MID power and 2,ooo extra (10,000) RPM's needed to pull the 36 tooth sprocket nicely topping out at 45 mph......WHAT CHA THINK BOSS ..???!!!
HEY one last thing to answer for me,, your opinion ???? If i do a good job and done right the best way,, custom installing this 15mm WALBRO carb and a 5mm half moon or flat squarish cutout on the piston skirt intake side where it over hangs the intake port by 2mm at TDC and then take my Chrome Banana expansion pipe that I have on there now and add a 2"--3" inch header pipe *((should give me more LOW end torque))** and last but not least RETARD the Timing a few degrees, like 2-5 degrees only with my woodruff key that I filed a little off on the top half**((the untouched stock magneto already has a few degrees SLOP in it to begin with))**..........Do you think doing all this will give me a big noticeable POWER gain thru out the whole RPM range and have the POWERBAND HIT to come on earlier ....The PIPE dont hit until about 6,000 rpm's now,,,way to late......YOUR OPINION IS--??????????
SORRY about being so long and much but please anyone that knows there stuff ...please help answer all my questions,,,!!!!!!!!!!!!!!!!!!
Currently have the GT5 47mm X 38mm 66cc engine with JAP 202 bearings and needle wrist pin bearing with the short type A piston with the wrist pin in the middle and .60 dome top,,, real nicely done perfect bottom case and gasket port match to cylinder which has a extra thick base raising my exhaust and transfer port duration/height timing. can still probably use another base gasket to go even higher but will lose my 1.2mm squish band using one aluminum head gasket on the RSE compression round 6cc Billet Head...
Have the rest of the cylinder ported and polished a hair and casting flaws cleaned up, little extra wider on exhaust port and raised 1.5mm and mirror polished,, little extra wider intake port and scuffed for better fuel atomization,,, just took casting lip off on transfer ports only,,,NO piston mods done yet..
An exact 66cc volume Awesome custom built BOOST bottle with wide 3/8" 4"inch hose with drilled out and internally flush 3/8" fittings,, .65 main jetted NT carb with thicker 4 clip needle in the top position, .05mm back bottom of carb slide sanded down((leans out idle better)) and lean/low float 23mm adjusted forks and O-ring sealed.... shorter 8mm shielded copper core spark plug wire and NGK cap and NGK B8HS .030 gapped plug..... 96 octane sunoco fuel w/Bel Ray synth. oil / 32:1.....and a Chrome Banana Expansion Pipe !!!!!!!!
Custom Turbo Kit to come soon,,,, Right after Ram Air intake kit......Lol...LOL Thanks Guys for bering with me and reading all this,,, Look forward to your REPLY's....
Attachments
Diamond Back
Active Member
- Local time
- 5:04 PM
- Joined
- Jun 11, 2016
- Messages
- 137
Will a Walbro 192 15mm diaphragm CARB even run and run the right way with the pulse hole covered up..???? someone just told me to plug it up..!!! .. I Thought you needed the vacuum pulses from engine to work the diaphragm in the carb acting like a timed fuel pump...??????
And what do I do with the fuel return line . ??? Run an over flow tube off it...or splice into upper fuel line with a one way check valve..???? please help again....thanx
Frankfort MB's
Well-Known Member
I doubt the upgrades you do will get your engine to revv to 10k, it would need to have a new CDI to be able to accommodate for the increased compression. Plus, the top end bearing almost destroys itself at prolonged RPMs of about 8k
A boost bottle does nothing, reeds are better but still have downsides (which I have figured out) you have to shave the piston to get full effect.
The exhaust you have picked out will not be any good because the pipe is tuned for higher RPMs than these engines can handle. You should have your engine tuned for low rpm torque since it is a lot more usable..... It also prolongs life of your bearings.
Ram air intakes aren't very good on an engine like these because your full throttle all the time (at least I am) and the faster you go the leaner your fuel mixture will get, so it will be really rich at low speeds, or really lean at high speeds.
Turbos are a great new thing BUT, they won't help these already sick engines. They make electric turbo kits for like 60$ on eBay. It would help a little but you have to have a very large intake and carb for it too be effective......
The spark plug should be good but just make sure your not too cold. I haven't tried NGK plug wire or boot so idk about that.
That head has very high compression from all the compression tests I've seen (I do look up a lot of YouTube videos of Fabians work, because he also did a vid on high compression heads.... Ironic huh?) but it doesn't have very good cooling abilitys.
My highest speed I've ever been able to get was on a bike with bad tires that were at only like 20psi, a wore out motor, badly tuned carb, but it had a shaved head with a b6hs plug, accel HP wire, MZMIAMIPARTS expansion chamber, 44 tooth sprocket. And with all that I was able to hit 40mph
A boost bottle does nothing, reeds are better but still have downsides (which I have figured out) you have to shave the piston to get full effect.
The exhaust you have picked out will not be any good because the pipe is tuned for higher RPMs than these engines can handle. You should have your engine tuned for low rpm torque since it is a lot more usable..... It also prolongs life of your bearings.
Ram air intakes aren't very good on an engine like these because your full throttle all the time (at least I am) and the faster you go the leaner your fuel mixture will get, so it will be really rich at low speeds, or really lean at high speeds.
Turbos are a great new thing BUT, they won't help these already sick engines. They make electric turbo kits for like 60$ on eBay. It would help a little but you have to have a very large intake and carb for it too be effective......
The spark plug should be good but just make sure your not too cold. I haven't tried NGK plug wire or boot so idk about that.
That head has very high compression from all the compression tests I've seen (I do look up a lot of YouTube videos of Fabians work, because he also did a vid on high compression heads.... Ironic huh?
) but it doesn't have very good cooling abilitys.My highest speed I've ever been able to get was on a bike with bad tires that were at only like 20psi, a wore out motor, badly tuned carb, but it had a shaved head with a b6hs plug, accel HP wire, MZMIAMIPARTS expansion chamber, 44 tooth sprocket. And with all that I was able to hit 40mph
Diamond Back
Active Member
- Local time
- 5:04 PM
- Joined
- Jun 11, 2016
- Messages
- 137
I doubt the upgrades you do will get your engine to revv to 10k, it would need to have a new CDI to be able to accommodate for the increased compression. Plus, the top end bearing almost destroys itself at prolonged RPMs of about 8k
A boost bottle does nothing, reeds are better but still have downsides (which I have figured out) you have to shave the piston to get full effect.
The exhaust you have picked out will not be any good because the pipe is tuned for higher RPMs than these engines can handle. You should have your engine tuned for low rpm torque since it is a lot more usable..... It also prolongs life of your bearings.
Ram air intakes aren't very good on an engine like these because your full throttle all the time (at least I am) and the faster you go the leaner your fuel mixture will get, so it will be really rich at low speeds, or really lean at high speeds.
Turbos are a great new thing BUT, they won't help these already sick engines. They make electric turbo kits for like 60$ on eBay. It would help a little but you have to have a very large intake and carb for it too be effective......
The spark plug should be good but just make sure your not too cold. I haven't tried NGK plug wire or boot so idk about that.
That head has very high compression from all the compression tests I've seen (I do look up a lot of YouTube videos of Fabians work, because he also did a vid on high compression heads.... Ironic huh?
My highest speed I've ever been able to get was on a bike with bad tires that were at only like 20psi, a wore out motor, badly tuned carb, but it had a shaved head with a b6hs plug, accel HP wire, MZMIAMIPARTS expansion chamber, 44 tooth sprocket. And with all that I was able to hit 40mph
Thank you for the reply,,, but you think next time you could include some positive helpful remarks,,, you were negative and shot me down on everything.. I know I am new at this engine setup and learning the pros and cons and trying to learn from other peoples mistakes and trial and error results so I can save some time and money and do things right the first time....not trying to be rude,,,,SORRY
and i was just kidding about RAM AIR and TURBO,,, I owned a 1986 & 1987 Honda Fourtrax 250R racing QUAD that I put thousands of $dollars$ into both,, I mean I had every upgrade and mod you could think of and then some,,,,,was crazy...... ANYWAY in stock form those Quads for those two years came with a Ram Air setup and even there own Boost chambers that came off the intake boot and into a plastic box that they called an intake resonator..
your right though about Boost Bottle,,, they dont add power at all,,,,, but does make it run smoother and idle better for sure,,,, and i had damn fun making it for $6 bucks... ya see there pal, I am A AVIATION STRUCTURAL TECHNICIAN on military jets and helicopters....I am basically a modern day BLACKSMITH and Fabricator and jack of all trades... so I love tinkering with these 2-strokes and bikes....thats why I got one and in two stroke model also.... so i can have fun and fabricate things and put my pride into it,,,,,there is no competition and mine is better then yours bulls**t in my book over here,,,,,if i wanted a boring done right reliable machine,,,,, I would have bought a 4-stroke st down 50cc scooter for basically the same price RTR shipped to my door,,,,,, now where is the FUN in that.... i get one of those in a 3 wheel model for the winter time....!!!!!
you must be revved at 10,000 rpm's to do 40 mph with a 44 tooth or some big ass tires....lol.. that why i want to get even more low end and pull a 36 tooth at 5000 rpm's average
putting a header (couple inches) should give me some noticeable low-mids... and make pipe come on sooner.. thats why i a learning,,, the Banana pipe is still better then stock restricted crap...
WINDY CITY BOB
Member
Yah know, I made my ride out of a diamond back so I thought COOL! SAME BIKE, MILITARY, DIFFRRENT BRANCH, HOWEVER! FRANKFORT was being cool with you. If that kind of talk upsets you. And your this " BKACKSMITH EINSTEIN GURU" what do you need this forum for? That was rhetorical. Don't really care to here from you. Be safe & have fun.
Similar threads
