Honda TRX250R Forums banner
1 - 20 of 25 Posts

·
Registered
Joined
·
1,019 Posts
Discussion Starter · #1 ·
I'm sure this topic has been brought up before but looking for more of machine specific...mine!!

I'm not looking to beat them with raw power...yet but looking for something that will atleat run with a piped and jetted 450.

My current setup is an 86 bottom end, 86 cylinder that was ported for what, I don't know but runs pretty good, Cool head with I think a 25cc dome, Procircuit pipe and silencer, v force 3 reeds, stock carb and ESR intake.

I haven't raced against any 450's in an MX race yet but my guess is they might pull on me in the longer straight aways. I'm thinking for now up the compression some to get into the race gas pressures? Are the Vforce3 reeds helping or hurting me for MX?

Any suggestions for this engine or next years MX engine is fine with me. Thinking next year a 265pv engine or a 310 or 330 non-pv engine? If I run either on of those engines do I need to run the 88-89 crank/rod combo?

Thanks!
 

·
Premium Member
Joined
·
13,284 Posts
I'm sure this topic has been brought up before but looking for more of machine specific...mine!!

I'm not looking to beat them with raw power...yet but looking for something that will atleat run with a piped and jetted 450.

My current setup is an 86 bottom end, 86 cylinder that was ported for what, I don't know but runs pretty good, Cool head with I think a 25cc dome, Procircuit pipe and silencer, v force 3 reeds, stock carb and ESR intake.

I haven't raced against any 450's in an MX race yet but my guess is they might pull on me in the longer straight aways. I'm thinking for now up the compression some to get into the race gas pressures? Are the Vforce3 reeds helping or hurting me for MX?

Any suggestions for this engine or next years MX engine is fine with me. Thinking next year a 265pv engine or a 310 or 330 non-pv engine? If I run either on of those engines do I need to run the 88-89 crank/rod combo?

Thanks!
Yup…perform a search and you will find a lot of information to help answer your question…

My standard answer is increased displacement equals increased HP/TrQ…that simple. Yet…if I had to pick one 250R engine set up that would give me the power to stomp on 450’s and yet be a reliable set up, without spending a small fortune, I would pick the 330 ProX or ESR, with ProX being my first choice from a quality perspective.

For MX: 330R, 110 race Fuel, High Compression, Ported/Flowed, 38MM carb, MX Pipe (Sparks, ESR or PT), Boyesen or VForce reeds, properly jetted…450 killer!

Carlos.
 

·
Registered
Joined
·
1,103 Posts
I think you could better your current setup alot. Get a 18-19cc dome (I think) for race gas and ditch the stock carb. Just upgrading these 2 will be a noticable difference.
 

·
Registered
Joined
·
1,019 Posts
Discussion Starter · #4 ·
PC340 PV,
Do you think the 38mm Air Stryker carb is a good choice? I was thinking that but wasn't sure if it would be too big.


Carlos,
Yes the saying no replacement for displacement is true! Maybe the 330 next year will be on the build schedule. DO I have to modify the cases for the 330?
 

·
Registered
Joined
·
1,245 Posts
When I first got my R, it had the stock carb on it. I had a heck of time jetting and switched to a 38AS and loved it. Easy to jet and great throttle response.

I ran a stock cylinder locally ported with VForce reeds and a PT Mid Range pipe. Before the newer 450s, I could hang with the modded 400s. Once the newer machine hit (and I got back into racing MX) I found that I had to ride my butt off to keep up. Coming out of a turn, they would just pull on me.

Then I got a Sparks 265cc cylinder. What a difference! Of course the cylinder came with a full Walsh chassis but...I could tell that motor wise I was doing much better! I was only able to race that cylinder for one season, (lost a gear and case half) but loved the power. Last season I had to resort to the stock cylinder and sure enough...back to riding my butt off to keep up.

In my research of other's opinions, you really don't need much more than a good 310 motor to put a hurting on the 4 strokes. My Sparks 265 is in the process of being sent to Neil for a bore/piston (still need to package it up and mail it) but I am curious how it will be this season.

I would say 100% to up the compression and run race fuel. Send you current cylinder off to be ported, find a matching pipe and up the compression. Easiest way to get it done.

As for the 330, you can buy a "bolt on" that does not require case mods or a regular 330 that you need widen the case hole.

My "dream" cylinder right now is the LED 300 NIK cylinder. It is a Sphynx cylinder by LED and a hand formed pipe to match...but a lot of coin for that!
 

·
Registered
Joined
·
383 Posts
JoePA,

I think that you could make some inprovements on your current set-up for this season. the 38mm AS carb is the way to run, as what most say. Plus, you are going to have to get it later anyways, if you run a 310 or 330. Also, I have been told that a Boyesen Rad Valve will help with low end. So I think those are two things that you could get now, for this racing season. If your MX is anything like the MX here, you are going to need grunt out of the corners to keep up with the 450's. Maybe those 2 upgrades will get you some of that.

As for the 330, I was thinking of going 310 if I bought a new cylinder. I didn't want to bore my cases, or get too big. I am not looking for a drag or dune bike, i want a reliable grunt machine. But that is next year or the next bike. For now i am trying to do what i mentioned to you above.

Justin
 

·
Registered
Joined
·
1,019 Posts
Discussion Starter · #8 ·
I think I'll look into getting the 38mm carb and a smaller dome.

As far as domes. If i'm running say a 25cc dome and pusing out say 170-180 psi. Do I move up to say a 22 or 20cc dome? Also what fuel do I need to run in relation to how many psi i'm pushing out?

What is the Pro Circuit pipe built for? Mid to top?
 

·
Premium Member
Joined
·
13,284 Posts
QUOTE(JoePA @ Apr 11 2011, 01:06 PM) index.php?act=findpost&pid=67107I think I'll look into getting the 38mm carb and a smaller dome.

As far as domes. If i'm running say a 25cc dome and pusing out say 170-180 psi. Do I move up to say a 22 or 20cc dome? Also what fuel do I need to run in relation to how many psi i'm pushing out?

What is the Pro Circuit pipe built for? Mid to top?

Agreed an immediate improvement will come from a 38Mm carb, a MX pipe and High Compression…however; we can't just start tossing dome CC numbers without really knowing what your UCCR is, however; most of the time you will be around 20CC for 205-210PSI and 16-17CC for 235PSI on an OEM cylinder with a .040" squish, both running 100% +108 race fuel…

Again; this is only a reference point on dome CC's, a full UCCR should be performed…

And as jdh250r stated; No 330 bolt on cylinder kits...

Carlos.
 

·
Registered
Joined
·
1,245 Posts
Carlos..."UCCR" lol...been awhile since I read (for the 100th time) the "2 stroke performance handbook" by a guy (I forget his name all the time). Seriously Joe, get the book. I can search around for it to get the author later. But great book to not only get the basics but complex stuff as well.

I do not have replace type head. I just run the CR head gasket and was told by the local motor builder to run 112 octane fuel. (smells great too!) With domes, I don't have a clue. I just know more compression made a huge difference when I switched over to higher compression.

Here is a question that I have been curious on, and might help Joe...

If you had a more top end port job would it be better to run a top end pipe to get the most out of the motor?
Similar to if you have a bottom end port job you should run a bottom end pipe.

How much do you loose overall by putting a low end pipe on a low end ported cylinder?

I have raced MX on a piped Banshee and know that you just need to ride the motor differently to get the speed. Same way 4 strokes, you need to ride the motor differently (more grunt). If Joe did a port timing map to get if the exhaust duration, he could match the pipe to the porting.

Don't worry Joe, it is easy and fun to do. Sure it may not be 100% as if Neil or Carlos mapped it but you can get a general idea for the season. I have been running a ported cylinder on my R and over the years tried different pipes. I have no clue on the port mapping. I did the map, but never measured it out. But different pipes made a big difference in how the power came on.

I have a couple pipes downstairs. Let me see what I have, some have dents/holes.
 

·
Registered
Joined
·
1,019 Posts
Discussion Starter · #11 ·
theres more to this 2 stroke thing than I thought!! The whole port timing thing and stuf throws me for a loop. 4 strokes...no problem!! 2 Stokes....well I'm still learing!

I always thought you wanted to match the pipe to the port job??
 

·
Registered
Joined
·
1,245 Posts
Here is what I have and tried...similar to you, stock cylinder with unknown porting.

PT Race pipe. I think I like this one the best. But I switch to the Sparks cylinder so it was a couple years since I used it, until it backfired (jetting off that day) and put the usual dent/hole by the A-arm. Side bar...I have two PT pipes with the same hole. One is chrome and the other is ceramic coating, inside and out. (Failed $350 experiment, 5 minutes on the motor when it happened) The chrome PT pipe I am going to take to a place near by that repairs pipes.

LRD adjustable. I tried this one on both motors and I did not really like it compared to the others. But I had the least amount of time on it.

Sparks TT pipe. This is currently on the stock cylinder. Runs pretty good but I think the PT pipe was better. Again..been too long to do a straight compare.

Dynoport. Don't know much about which pipe and it is brand new. I am waiting on a silencer (since the ones I have don't fit) any day now. Hoping to try this out this year.

I am in the process of getting my Sparks cylinder to Neil for a new piston. Hopefully I can play a little experiment. Have Neil tell me the exhaust timing so we can guess which pipe works the best...then seat test to see which one does feel the best.

I don't remember Pro Circuit pipes being a big name at the track, even back in the heyday. And from the difference I have seen in my pipes I am willing to bet you can get more from your current port job with a different pipe. Which one? No clue! :) Hopefully if you get a close number on exhaust, you can narrow your search down to which pipe. Shot in the dark, a big name mid range pipe might the ticket.

Question is...how much you willing to open your wallet to spank those 450s...?
 

·
Registered
Joined
·
1,245 Posts
theres more to this 2 stroke thing than I thought!! The whole port timing thing and stuf throws me for a loop. 4 strokes...no problem!! 2 Stokes....well I'm still learing!

I always thought you wanted to match the pipe to the port job??
That is what I thought as well. Get that book.
http://www.amazon.com/Two-Stroke-Performan...l/dp/1859606199
I think there was a link with a pdf somewhere. I brought it years ago.
 

·
Registered
Joined
·
1,019 Posts
Discussion Starter · #14 ·
Well the wallet thing is somewhat flexable. If I don't have to take a big chunk out at once I can live with spending a little more. Also it gets to the point where I have to stick $1000 to $1500 just to hang with the 450's when I can just go buy one for a few $$ more....not that I want to.

I'll have to go through it and see how the porting looks to get an idea as to what the hell I have. I like the idea of letting Neil build the engine for what I/we want and get a pipe to work with it. I know things have to be a matched set as everything works together it's just sometimes tough and expensive finding that right combonation!!!!
 

·
Registered
Joined
·
556 Posts
I have both 2 stroke tuners handbooks in PDF format if anyone needs them (Gordon Jennings & A. Graham Bell). Just send me a PM and I can email it to you. Maybe someone can be kind enough to pin them to this site for everyone.
 

·
Premium Member
Joined
·
13,284 Posts
QUOTE(JoePA @ Apr 12 2011, 03:54 AM) index.php?act=findpost&pid=67221Well the wallet thing is somewhat flexable. If I don't have to take a big chunk out at once I can live with spending a little more. Also it gets to the point where I have to stick $1000 to $1500 just to hang with the 450's when I can just go buy one for a few $$ more....not that I want to.

I'll have to go through it and see how the porting looks to get an idea as to what the hell I have. I like the idea of letting Neil build the engine for what I/we want and get a pipe to work with it. I know things have to be a matched set as everything works together it's just sometimes tough and expensive finding that right combonation!!!!

Joe & Lasher-19:

Here is a good, basic link to UCCR:

http://www.sacoriver.net/~red/uccr.html

Engines performed best when built and designed to run as a package; porting, pipe, carb, fuel and application. A top end ported cylinder would work best with a pipe designed for top end performance. Normally, a top end engine (drag racing) will have a high exhaust & transfer timing requiring a pipe designed to take advantage of the higher port duration. The reverse is true for an engine built for low-mid end with lower exhaust & port timing; different port duration requires a different pipe to get the best performance.

Discuss with your builder your specific application, your performance goal, expected HP/TrQ, porting & bench flow and cost…a complete package design is what you want. You don’t have to purchase all the pieces at once, you just need to have an engine build direction and set performance goals.

Carlos.
 

·
Registered
Joined
·
41 Posts
rad valve, cool head with high comp dome and bigger carb can be done without knowing the variables. a used pipe for midrange as a temp pipe would be ok imo for now...

my lt250r has rad valve w/carbon reeds, roost boost, pipe and 38mm AS and cool head with some decent compression dome even though it's not running properly and I need to rebuild the entire motor, it still has power to it. it leaks at the center case all the crank seals need to be replaced and the top end needs to be freshened up if that says anything :D
 

·
Premium Member
Joined
·
13,284 Posts
QUOTE(Hawaiianbasshead @ Apr 17 2011, 12:13 PM) index.php?act=findpost&pid=67643rad valve, cool head with high comp dome and bigger carb can be done without knowing the variables. a used pipe for midrange as a temp pipe would be ok imo for now...

This can present some problems…adding a “high compression” dome without knowing your squish clearance, dome volume or overall combustion volume, and UCCR can lead to detonation, piston seizure and eventual engine damage.

Carlos
 

·
Registered
Joined
·
113 Posts
I raced my Duncan racing 265cc PC2000 Sunday against the 450s, 2 of the 450 where Baldwin built motors. My little 265cc had no problem keeping up with my fat ass on it till I got wore out. Track was as slick as an oil coated concrete floor also.
 

·
Premium Member
Joined
·
13,284 Posts
QUOTE(BigShow @ Apr 17 2011, 04:33 PM) index.php?act=findpost&pid=67665I raced my Duncan racing 265cc PC2000 Sunday against the 450s, 2 of the 450 where Baldwin built motors. My little 265cc had no problem keeping up with my fat ass on it till I got wore out. Track was as slick as an oil coated concrete floor also.

Yes, 265R's or well ported 250R’s can be very fast, just not fast enough to keep up to properly set-up 450’s…

If your 265R kept up to those 450’s, just think the punishment you would have dished out on a well set up 330R…

Carlos.
 
1 - 20 of 25 Posts
Top