PLEASE HELP SOMEONE, DEAD AT 7,560 rpms

[Diamond Back]

consider this: if the pipe is tuned to come "on" at 11,000rpm then what you are experiencing is the dead zone right before it comes on the pipe.
chunk that crap and put the stock pipe back on.

Hey JAG,, good to see you buddy,,,I got to talk to you about the status of my WALBRO conversion kit,,, but in private some how,, dont want all my secrets out there,,, but it came out awesome,, start testing tommorow if no rain,,, you have a regular e-mail that i can send you pics and talk about sales???

ok..on the bike issue,,, dont know why i am stressing it since we are getting a carburetor upgrade tomorrow but i just want to know and learn i guess.... i dont have stock pipe,, i traded it for the RSE HEAD which i thought would be crap,, but i have learned to love it,, my midrange is grunty and got some snot to it,, if i am at 3000 rpms and gas it, it wants to lift front end almost but it pulls you back hard and is at 7500 in seconds,,, just have to run some lucas octane boost with sunoco 93 and its CRISP..

i have read JENNINGS guide and everything else i could find on expansion pipes,, at first it was confusing but then it was pretty easy and straight forward,, the Banana pipe really just needs a 27 mm diameter header pipe and they say the Banana pipe comes into the pipe around 9,000 rpms. not 11.. POWERBAND really only hits hard for 2000 rpms then drops off so by tuning the header length you can control when you want it to hit,, My RSE head gives me crazy torque and pull from 3,000 to 6,500 so i want my pipe to hit from 6,500 t0 8,500...(i want my Motor to live reliable and healthy))) so i am picking 8,500 as my final let off WOT redline. So i need to drop my pipe 2,500 revs.... for every 1" inch of straight header pipe you drop 400 rpms,,, so i need to splice in 6.25" of 1" inch diameter pipe, that will make the pipe start working at 6,500 rpms and out to 8,500..perfect !!!! also need to due some flange mount opening to 1"inch, and the length measurment starts from piston skirt..

also by cleaning your piston top and make about (2)) 1 mile WOT speed runs you can see where the burnt section is happening on your piston,, if the burnt marks are in the exhaust port then your pipe flange is too narrow and creating to much suction and needs to be increased till the burnt marks are in middle of piston,, to big and you dont have enough suction to pull up your transfer ports,,, it all has to be just right or suffer lose in power,, I looked at my piston and my burnt marks are in my exhaust port cause my pipe flange and header are 3/4" inch, so i need to increase to 1" inch ..

NOW THIS PART IS COOL,,,(THE STINGER))... the banana pipe has a 1 inch nub stinger,, sucks does nothing.. The stinger should be half the size diameter of the header,,, so 1/2 inch and by making it longer makes the powerband come on earlier too,,, you dont want to make it to long cause the longer it is the more pressure and HEAT you create in the pipe and can ruin everything you just worked on building so perfect,,, your best bet is to play around with different sizes and lengths,,, but a good stinger is the same length as header and half diameter.. THE PART I AM GOING TO DO IS SEAL IT UP,,, I WANT A SIDE BELLY BLEED OFF ,,, BY DOING THIS YOU CAN SEVERALLY SILENCE YOUR EXHAUST TONE BY 84 %%%%%% AND IT SOUNDS COOL HAVING IT THIS WAY,,, CHECK OUT VIDEO .....

 

[Diamond Back]

Hey JAG,, good to see you buddy,,,I got to talk to you about the status of my WALBRO conversion kit,,, but in private some how,, dont want all my secrets out there,,, but it came out awesome,, start testing tommorow if no rain,,, you have a regular e-mail that i can send you pics and talk about sales???

ok..on the bike issue,,, dont know why i am stressing it since we are getting a carburetor upgrade tomorrow but i just want to know and learn i guess.... i dont have stock pipe,, i traded it for the RSE HEAD which i thought would be crap,, but i have learned to love it,, my midrange is grunty and got some snot to it,, if i am at 3000 rpms and gas it, it wants to lift front end almost but it pulls you back hard and is at 7500 in seconds,,, just have to run some lucas octane boost with sunoco 93 and its CRISP..

i have read JENNINGS guide and everything else i could find on expansion pipes,, at first it was confusing but then it was pretty easy and straight forward,, the Banana pipe really just needs a 27 mm diameter header pipe and they say the Banana pipe comes into the pipe around 9,000 rpms. not 11.. POWERBAND really only hits hard for 2000 rpms then drops off so by tuning the header length you can control when you want it to hit,, My RSE head gives me crazy torque and pull from 3,000 to 6,500 so i want my pipe to hit from 6,500 t0 8,500...(i want my Motor to live reliable and healthy))) so i am picking 8,500 as my final let off WOT redline. So i need to drop my pipe 2,500 revs.... for every 1" inch of straight header pipe you drop 400 rpms,,, so i need to splice in 6.25" of 1" inch diameter pipe, that will make the pipe start working at 6,500 rpms and out to 8,500..perfect !!!! also need to due some flange mount opening to 1"inch, and the length measurment starts from piston skirt..

also by cleaning your piston top and make about (2)) 1 mile WOT speed runs you can see where the burnt section is happening on your piston,, if the burnt marks are in the exhaust port then your pipe flange is too narrow and creating to much suction and needs to be increased till the burnt marks are in middle of piston,, to big and you dont have enough suction to pull up your transfer ports,,, it all has to be just right or suffer lose in power,, I looked at my piston and my burnt marks are in my exhaust port cause my pipe flange and header are 3/4" inch, so i need to increase to 1" inch ..

NOW THIS PART IS COOL,,,(THE STINGER))... the banana pipe has a 1 inch nub stinger,, sucks does nothing.. The stinger should be half the size diameter of the header,,, so 1/2 inch and by making it longer makes the powerband come on earlier too,,, you dont want to make it to long cause the longer it is the more pressure and HEAT you create in the pipe and can ruin everything you just worked on building so perfect,,, your best bet is to play around with different sizes and lengths,,, but a good stinger is the same length as header and half diameter.. THE PART I AM GOING TO DO IS SEAL IT UP,,, I WANT A SIDE BELLY BLEED OFF ,,, BY DOING THIS YOU CAN SEVERALLY SILENCE YOUR EXHAUST TONE BY 84 %%%%%% AND IT SOUNDS COOL HAVING IT THIS WAY,,, CHECK OUT VIDEO .....

SO JAG,,, HIT ME UP SO WE CAN TALK ABOUT SELLING WALBRO KITS AND PUTTING it all together from getting inventory,, making the parts and adjustments needed,,, and advertizing,,, and selling price...... my regular e-mail is jimmyleomay@gmail.com please e-mail me there so i can send you pictures and info , prices, and performance issues good and bad,,,, start testing in a few hours..

i am thinking of calling my company DYMOND BACK THRILL CYCLES. I BUILD THEM TOO STARTING AT $350-400 BASE MODEL ON UP..

 

[Deleted member 12676]

Actually changing where the powerband hits is not as dead set as you make it sound. Best to use my free expansion chamber software to know how long to make the header for it to harmonize with your plans.
you wrote "if the burnt marks are in the exhaust port then your pipe flange is too narrow and creating to much suction and needs to be increased till the burnt marks are in middle of piston,, to big and you don't have enough suction to pull up your transfer ports"
One factor that figures in to this is the angle of the transfer ports. Stock isn't angling backward enough which also tends to let intake charge go out the exhaust port. I explain that on my site and tell how to use JBWeld to angle them correctly.

 

[Steve Best]

Diamond, one principle in industrial troubleshooting is to go back to "as designed state" before modifying out of problems. Get it running "as designed" rather than modify because the modifications often add new problems and it becomes impossible to solve what is causing what.
1) Put it together as simple and as close to stock as possible and get it running well,
2) Do one modification, get it running well and see what the effect is
3) try another modification, get it running well and see if it performs as expected.
This is the way. Just like cooking.
You cannot pour dry noodles and tomato sauce in a pot and expect spaghetti.
Gotta follow the recipe and know a little about the process.

The NT carb is very tunable in the mid-range and top end. Mid is the needle and top is the jet.
I'm running 10,000 with it, you can too. Keep playing with jets and cutting plugs apart to check WOT result.

I love the RSE head too, for same reasons as you, but it limits rpm to 9000 or so. Pipe may bring it down too.
The limiting effect is that of "hitting a wall". No amount of carb tuning or size will overcome resonant tuning.

Hope there is some help there. Look in my past threads for picts on my bike and things I've tried.
I'm on the road and cannot repost much now.

Steve

 

[Diamond Back]

Actually changing where the powerband hits is not as dead set as you make it sound. Best to use my free expansion chamber software to know how long to make the header for it to harmonize with your plans.
you wrote "if the burnt marks are in the exhaust port then your pipe flange is too narrow and creating to much suction and needs to be increased till the burnt marks are in middle of piston,, to big and you don't have enough suction to pull up your transfer ports"
One factor that figures in to this is the angle of the transfer ports. Stock isn't angling backward enough which also tends to let intake charge go out the exhaust port. I explain that on my site and tell how to use JBWeld to angle them correctly.

Your right JAG... I am shure it is not cut and dry as you read it in books,,, plus every book has its own variances to differ with,,, i can settle on learning the ball park for now and tweaking as i go,,, they are all different monsters,,, i will play with the Banana Pipe for now and seal up the end and have a side belly exit bleed off to quiet it down too,, I will try a 6" header and see what the results are....

JAG how do I get to your software program, ????? eventually I will just get a pipe... i cant make one from scratch,,, sorry JAG but i can buy the right idea and tweak it.........I am upset cuz I missed a 2003 KX 65 stock pipe and silencer for $20 bucks last night,,,, so they are out there and i will find one with in a month

 

[Diamond Back]

Your right JAG... I am shure it is not cut and dry as you read it in books,,, plus every book has its own variances to differ with,,, i can settle on learning the ball park for now and tweaking as i go,,, they are all different monsters,,, i will play with the Banana Pipe for now and seal up the end and have a side belly exit bleed off to quiet it down too,, I will try a 6" header and see what the results are....

JAG how do I get to your software program, ????? eventually I will just get a pipe... i cant make one from scratch,,, sorry JAG but i can buy the right idea and tweak it.........I am upset cuz I missed a 2003 KX 65 stock pipe and silencer for $20 bucks last night,,,, so they are out there and i will find one with in a month

OOHHH,,, SHOULD I play with my off set magnetto key,,, and should i retard 5 degrees, or advance 5 degrees ????

 

[Deleted member 12676]

Just go to my page explaining how expansion chambers work and click on the download link from the next page about the calculator.
Stock ignitions need to be retarded.

 

[gary55]

I have one of Jag's cdi's with tunable advance curve on one of my bikes, and it works real good. I've had it for three years and no problems. You do all the same mods that I do on my personal bikes. I also deck the jug around .030 or 2.710 base to top and ramp my pistons at the exhaust and transfer ports then trim the skirt for the clear intake shot. On my best running bike I broke down and ordered a real sha 16\16 from delorto. Almost 100.00 with shipping. Night and day diff. from Italian Delorto and chinese knock off. I had to mess with jetting but now I have a chocolate colored plug and no 4 stroking. I would really like to hear how the walbro setup works for you. they look like quality and I'm guessing they are probably easily tunable.. My next build is tha exact same bike in this pic. but with a nuvinci 360 rear hub, and one of those gas bike engines with the 3 port jug and the giant assed reed valve and carby. We'll see.

 

[Deleted member 12676]

Gary tell me if your cylinder has stock exhaust port height and max speed on level ground with your pipe.

 

[Steve Best]

I've used ramped pistons to gauge where to cut expensive cylinders (on other engines, sleds and CR250).
The cut cylinder always worked better than the ramped piston.
I think the reason is because of the effect on squish turbulence.

I noted and like the idea of the ramp helping to smooth flow into the cylinder, but my personal results differed.
I too have been decking the jugs. First about 0.010" to get them flat, but recently did one almost 0.030" to see effect on powerband when lifted with base gaskets and teflon headgasket. Even that little made a difference but I do like the low rpm torque of a low exhaust port. There is a problem with the exhaust port not being completely uncovered. Your ramps may help that, but so will lifting the cylinder.
If the intake and exhaust ports are wide enough as they open, there is no need to change port timing unduly to get rpm.

I have a couple of the Delorto "RT" clones. Sad to hear they are poor copies. How do they differ from the real thing?

Steve