More pwr fr stock hpi s25

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Magonsterz

Magonsterz

New Member
Messages
1
Location
sunny so. calif
How to: Power Porting
HPI Nitro Star S-25

has anyone else tried the mods listed in an article from radio controlled hobbies? here is the link http://www.rccaraction.com/articles/htpporting_1.asp. i totally followed the steps and my s25 i royally spanking a wasp 26 and a mach 28. it is easy to start, does not die and runs cool. tons of torqe and gobs of mid range with clean top end. if you have any good dremel skilz you have got to try it. i am running 19 cb and 47 spur and not only flys but has xlnt midrange. i did have a 15cb and 49 spur but i could not keep the front tires down. it was a full on wheelie king on demand. if i could manage to get off the line without flipping over it would float the front end until it hit mid second gear....toatal monster no joke. i will have video soon of the drag between the mach 28......the owner of the wasp 26 does not want to play anymore. also heads up with an unmodified s25 just for comparoson.
 
Yea I ported just my sleeve on mine and run a 30% mix and use a cold plug, and oh yea mine will flat out scream. Its even way cooler haveing the 3 speed in it, it really really hauls now.
 
i really want to do it to mine but i don't know anyone experienced enough to do it, and I'm not risking messing it up...
 
I'd give it a whck...can anyone copy and paste the How-To or type it in here? I'll make it a sticky for the Engine/Mods section.
 
It really is easier than it looks. I tried it and had a blast. The only thing I had a problem with was finding the carbide cutter for my DREMEL.
Porting an engine is the last frontier! And the s-25 is the perfect engine to start on!
 
I have done it several times on several different engines, and it is awesome! You will have tremendous results, and the engine actually runs cooler.
 
i've done all of my engines from the .12 to the .30:eek: had good results with all of them.just map everything out and take your time its easy.:D
 
I'm going to try it. I thought I had th 4.6, But all my literature says it is in fact the 4.1, and I can always use more power. What duration do you guys recommend?
 
Do you just make the one groove to the intake port like shown in the istructions, or both sides. How deep of a groove is ok.
 
Well aside from the questions I had that nobody answered, I figured it out after all, and I am very pleased. Thank you Magonsterz for posting that website. Very impressive power increase. Boy those little carbide bits sure are pricey.
 
I was nervous about porting mine, but just took a deep breathe and just didn't think about and jumped right in. My hpi25 was my first and it came out fine. I found my dremel bits at walmart, lowes, and homedepot. I know one very important tip is take your time and take off little at a time and then pull back and inspect take a little more pull back and inspect untill you get the desired angle and material removed. All and all my p&p took about hour or so and I was pleased with it, I know if I get another motor I am pulling it apart and looking and if it will take a p&p I will do it again.
 
Yes Hockey, this the first one I have ever ported and polished. I do consider myself very experienced with a dremel, but I know you can do it. It's not that hard. I know you know where the instructions are, and it really gets you in tune with how the motor really operates. Once you figure that out it helps . If you are porting a motor that has run for a little while or more, the stains help you understand where the fuel is rushin up to the cyl., even more,because exept for the crankshaft, the hardest part, is mapping out the intake port grooves. Just keep in mind how the air or fuel is moving in or out of the cylindar. It you have a Hpi 25 just follow the instructions to a t . If you have any Questions just ask, I just did it and it is fresh in my head, and it has brought out the beast in my savage.
 
Yeah savage kicknmaxx, I was nervous, Especially since they say that if you cant afford to trash your motor, don't try it. I still did, and it worked. Thank god. It was alot of pulling back and inspecting, and being super anal. Somehow my printer cables got lost in the move, and I had to run back and forth from the garage to the house to compare parts to the website. That is why it probably took me two evenings to do. I find myself now parking my truck close to my bashing place, so I can stand on the tailgate so I don't crash into my ankle again now.
 
I could not be anymore pleased with the port and polish. I urge anyone to try it who has ever used a dremel. The only downfall that I can see, is it cuts your runtimes down a little.
 
garagedoorguy, what did the port and polish do? i need to go and re read the article. was it just matchiing the sleve to the ports in the block or was it changing the shape and timing of the ports?do you think using that article for a guide on a 4.6 would work or was it really instructions on your specific engine?
 
I can't say if it will work or not. The .28 is not a big difference though, and it can be done to alot of different motors. From what I understand, It gets more use out of the stroke. You make the intake in the crank larger so it stays open longer. You carve little grooves leading up to the intake of the sleeve to help rush fuel to the cyl. You grind the edges off of the bottom of the boost ports, and intake ports to smoothe the air flow, and cut out the piston skirt, because at the very bottom of the stroke the skirt blocks fuel and air would go to the boost port. I am sure I just summed up the instructions, but I've heard it done on alot of motors, and I went the low side of all the measurments. From what I see, you are just matching the sleeve to the block. Maybe a little research might be at hand, and I am curios myself so I will keep my eyes open. As what it does to the power, It's very impressive, and very noticable. I have to learn how to drive this thing again. It spent more time on its top today than ever. It was alot of fun though. I got 3 full tanks today with no problems what so ever. Well I broke the body from flipping over backwards too many times. It's unreal, and all I have done is the 3 speed and the port and polish for power. Can't wait until I get the pipe.
 
When you get the parts in your hand and read the instructions, it helps alot, especially with your engine experience. If you don't know the flow of the motor, trust me it doesn't take long to figure it out, and is like no other 2 stroke I have ever worked with.
 
yep from what i remember it looked like it was just making the ports match the block and then moding the crank a little.what i might do is get a second cyl and piston and break it in an then take it an port it . when i had my 4.6 appart i saw where there was some room to open the ports some and smooth the edges.but for a stock engine the ports looked pretty good. i have a wasp/diablo .28 engine and that thing is a pos. i don't see how it runs. the ports look like they used a sawzall to cut the ports. everything was rough and didnt look very good.but thats all i need to get into is starting to port and polish these engines. my buddy says ill be doing that soon. he always brings his cars and trucks for me to tune for him he says they go a lot faster after i tune them, and run better too.i don't know if i really want to start moding my engines yet,because ill jump in with both feet and modd every engine if got once i learn how to do it.oh well.
 
I would buy a cyl and piston in case it goes wrong on you. I wish I could have done that, but my engine is not that old, and I had some confidence. The feeling I get from the instructions is they took precise measurments of their cuts. I think you can kinda ballpark some things. It does cut your runtime down so if you are happy with the power you have now you might not do it.
 
jrstorm said:
garagedoorguy, what did the port and polish do? i need to go and re read the article. was it just matchiing the sleve to the ports in the block or was it changing the shape and timing of the ports?do you think using that article for a guide on a 4.6 would work or was it really instructions on your specific engine?
Click to expand...

The p&p takes and angles and smooths out the sleeve and crank, and piston for better air/fuel flow. Just think of trying to take a turn at a 90 degrees now do that same turn with more of a angle you can take it faster. WHen you port the sleeve you angle the ports so the af mix gets more and faster to the cyclinder. On two strokes the faster you move the af the better horses you are going to get. On the crank all you are doing is taking off the casting marks, those creases you see are the casting marks, getting rid of those reduces turbelence and increase flow better and smoother. I don't member if that article says anything about it, on the old site we had a sticky thread on p&p work that explain it but thats simply putting it. I could research it more and go into big depth but its simply makeing less angles take out rough edges and reduceing turbelence and increaseing flow, and when you increase the af mix you also increase oil and cooling affects as well. Hope this explains it.
 
You summed it better than I could, I just don't know about taking just the casting marks off though. I probably got carried away with the polishing but I took off alot more than just the casting marks. Especially off of the crank. I have noticed that richening the mixture does have a substantial effect on temperature, but not performance. If Jrstorm comes back with good news on the nova cooling head. I think I will do that first off and I can really lean this baby and get some serios hp's.
 
Help...I want to port and polish mine .25 too, but i can't get the piston sleeve out of my block..I can lift it up for abbout 3 milimeters, thats it...
Do i need extra tools or is this normal ?
 
Yes its normal fo rthe sleeves to be hard to get out sometimes, if you can get it up far enough past that lip you get a screwdriver under it and pry it the rest of the way out, or use a plastic rod and push up from the crank side.
 
Its tough but it will come out, use something gentle like a plastic rod and push up from the bottom, or use something like a zip tie and stick it into the exhaust port and get it to raise up enough to reach under the lip of the sleeve and pry or grab it to pull it out, just take your time and watch what your doing you cna chip the chome plating off the inside of the sleeve or scratchit if your not careful.
 
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