getting the most out of my motor

[hartwill]

ok guys I wanna get everything I can out of this thing everything is brand new. I want something that's great in the trails but that I can still whoop some 450 4 pokes in a drag race. I have an 86 motor, brand new oem long rod crank, new 67mm wiseco piston, I have a well known guy doing touch up porting on my cylinder, cr head gasket, stock carb Baldwin helped me dial it in, and I have a fmf sst pipe and turbine core 2 silencer. where can I improve this setup? I'm sure I'm gonna hear pipe and carb and reeds. what do you guys suggest. also I was told that reeds are kinda over rated, the guy that told me this said that two strokes for a long time never even had reeds maybe someone can clear this up. thanks guys.

[CorvetteZ06]

ESR reeds, a real port job by C-leigh, 38mm or 35mm airstryker, IMO, the sst pipe is a good low-end pipe. If you go with a aftermarket jug, a nice ESR 310 powevalve is good for the trails, and makes fun reliable power, but make sure it gets a good port job. :cool:

[hartwill]

the guy doing my porting was a research development engineer for ktm in the 90s he said they did tons and tons of test porting. he also said if you took a two exact bikes and 1 had good touch up porting and the other didn't have any you could definatly pick out the one with, he also said if you took 2 identical bikes and one had good touch up porting and the other had a good full port job it would be a lot harder to tell the two apart. what do you guys think. I'm sure the guy knows his stuff but he is probably not a Honda 250r pro like Neil. would love to hear his comments too.

[wilkin250r]

Reeds are important, almost all two-stroke engines have SOME type of intake control (reeds, rotary valve). They are kinda over-rated in the same sense as 4-stroke pipes, because it's a bolt-on modification. There are lots of people that ONLY do bolt-on modifications, especially the younger crowd, people that don't really know, but want to pretend they know.

Now, the only piece of advice I can give you is that the "best of both worlds" really doesn't exist, or at least is incredibly expensive. You're not going to get something with good low-end power that's great in the trails, and still have screaming top-end power that will run circles around the 4-strokes. It's just not possible.

Now, the 250r is a GREAT motor, and it's true power lies in its ability to be dedicated to a specific style. You can build a drag-racer that will make a new 450 look like a joke, but it won't be good in the trails. Or you can build a good trail bike, but it won't do so great in a drag race. The best and greatest of everything doesn't really exist.

[hartwill]

I know that I'm not gonna have the best of both worlds. I guess maybe what I'm looking for is a happy medium.

[Lasher]

I 1/2 disagree with wilkin250r

If you want to beat a drag set up 450...then you need a drag motor, which will not be good in the woods.

But if you are talking a "mostly stock" 450 (ie. bolt ons)...I would think you could very easily in both worlds.

I have a similar set up to yours.
A 38 carb would help the motor breathe...
CR gasket (your running race fuel, right?) to up the compression.
Exhaust to match your porting.

Which is where I disagree with your friend, on porting. To me there are three stages of porting:

1) Stock...cylinder is not touched.
2) Clean up...casting flaws removed, things touched up no realy changes to port layout.
3) Full port work...this is where a "master" can really shine if they know what they are doing. The porting must match your riding style and your pipe must work with the port timing.

I think you could easily tell the difference between all three. But as wilkin250r said...you cannot have the BEST of both worlds. Drag motors (top end) require a different timing/duration than woods motor (low end). Can you have a happy medium...you bet if you find a good motor guy to do the work.

Now...go bigger (310, 330) and forget them 4 strokes. I ran a Sparks 270 cylinder for the last year and that has no problems handling most 4 strokes in power.

Oh...don't forget that any amount of power is nothing without handling.

[hartwill]

yes i do run race fuel. i have had this motor running less than a year and have had it apart 3 times allready 1st time was when my chain busted the case, 2nd time i dont really remember the reason, and third and last time is when my wiseco crank broke apart and tore up every thing. i now am putting it back together with a new oem crank. and i want to make sure that it is gonna be 100% how i want it so i dont need to do this any more for quite some time. i appreciate everyones info i really just want this to be a great all around running machine, which it was before. i had no problem beating most 450s in a drag race and it still had plenty of power through the trails but i just want a little more out of it. oh and also he said the touch up porting and full port would be harder to notice unless you were a seasoned rider. he also stated that due to running the long rod crank with the 86 cylinder and piston that the spacer plate would allready change my port timing for better performance.

[Lasher]

I am not a "motor building" in the sense that I can port a motor but a couple things in my limited knowledge don't add up.


he also stated that due to running the long rod crank with the 86 cylinder and piston that the spacer plate would allready change my port timing for better performance.


I always thought that the spacer plate needed was made to be the correct length to put the port timings back. Once you start playing with spacer plates thickness (or milling the base of the cylinder) you will change the timing, but now you have to worry about your head squish. Can of worms if you ask me.

I am curious to what he considers "touch up porting" and "full on porting"...my book reading on porting and seat time tells me you should not have to be a seasoned rider to notice.

[hartwill]

again porting is all new to me and I am playing telephone with what he said to me and translating it here so maybe I miss understood him. but I'm sure he know what he is doing I have heard nothing but good things about him and like I said he did test porting for ktm and I'm sure that unlike most of us here ktm has the funds to do trial and error to find out what really works. I do appreciate all the help from everyone though so please keep the advice coming. thanks again

[ballzdeep38]

it sounds like you have already made up your mind to let the ktm guy work on your motor. so why not explain to him what you want and let him set your motor up with what he recommends (his pipe, carb, reeds, porting, head work). if he is halfway decent he should be able to put together a solid combination if he has all this experience. if you dont like it well hey, and ESR 310 kit with a good port job will probably fix that...

Like I said on the other forum; you can “hang” with 450’s and even beat them with what you got as a baseline, just the complete system from engine, porting, flow work, head design, +230PSI compression, pipe, carb and intake + race fuel needs to be correctly re-built, and as Neil stated; you need to be spot on with your shift points.

Also consider going to a 310R-330R, the larger displacement (up to 330R) will give you a good healthy power increase, make your builder’s job easier and you get to keep the reliability a 250R is known for.

Anything larger than a well built 330R or any displacement putting out over 70 HP will require an extensive amount of additional work needed to your bottom end, including gears and rod.

I am a big fan of 330R’s as you can see by my footnote, I feel they are the correct displacement for the ESR & Pro-X cylinders designed optimum bore size of 74MM, yet; they seem to be very reliable if kept under 70HP…

And yes; you cannot have it both ways, a duner & a drag racer without compromising both ultimate performances…pick one; build to it.

Carlos.