RMZ250 vs. 270 vs. 290

[honda34]

Hi guys,

I'm looking for a little feedback from the guys that have/have ridden some big bore RMZ's. I have a 2013 with about 15hours on it, I haven't gotten to ride much in the last couple years but it looks like I will have some time to next year, so this winter I will be working on the bike a little. I think I am pretty much sold on the big bore idea, I like the RMZ but compared to my 2006 RM250, it leaves a little to be desired. I haven't been able to decide between the 270cc and 290cc kit. I am 6'0" 180lbs, 32yrs old and an aggressive/mid to front of the pack B rider (mx) when I get to ride and practice, so i'm thinking the 290 may carry me a little better but I bought a 250 instead of a 450cc because I have a little more of a "rev" riding style from growing up on 2 strokes.. suspension and chassis is all dialed..

 

Current setup is:

2013 RMZ250

Yoshi RS4? titanium/carbon full system

Vortex ECU

 

Parts I have already:

Hot cams stage 2 cams Intake and exhaust

 

Plans:

270 or 290 BB kit from cylinder works-compression is up for discussion, I am not against running race gas

porting, valve work, probably by Jesse from motowerx

looking at polishing transmission ( I have a tranny to do for my RM250 also, so I might as well do both at once)

Injectioneering throttle body upgrades- is this worth it, or all hype?

Black ops coil-again, is this worth it?

I am assuming that this will kill my stock clutch in short order so a hinson will be in order after I kill the stocker. (not before)

 

I can do all the motor work (assembly), some machine work and the porting myself, I have heard good things about Motowerx so that is why I am considering sending the head to him.

 

Any input will be appreciated, I have been reading all I can from ac717 and a few others bikes.

 

Thanks,

Cody

 

[JFM43]

The issue I have read about with BB 250's is they tend to pull hard off the line and flatten out pretty strong on the top. Most people will go with stage two hot cams for better mid to top end, and you may have to play with the gearing a bit. You will probably love it after you get it dialed.

[motodavermz450]

I literally have or had the exact same setup as you. I have a 2013 bored to a 270 and I had a 2006 rm250 as well and I am 6 foot 180lbs and a fast C to slow B rider. My rmz250 has the exact same exhaust setup. I bought the bike from a good friend of mine who rode it as a 250 for quite sometime but when he had it rebuilt he put a 270 on it and said that he felt a little more pep but nothing to get too excited about. I dont believe him. I rode a 2007 kx250f last weekend and my bike hard a significant increase in power over that bike. I have also rode a freshly rebuilt 2007 KTM250sx and noticed a difference as well. I think the 270 is an amazing setup and doesn't rip your arms off, the bike never bogs down on me and runs great. Im interested in what people have to say about a 290, talk about a perfect setup

[slowgs2001]

The Injectioneering mod is no joke. I have it on my 2013. It made the power come on so smooth. No more jerky feeling. That's the biggest thing I noticed. It helps with throttle control.. No joke. Call Wade Wilcox.

[JFM43]

The Injectioneering mod is no joke. I have it on my 2013. It made the power come on so smooth. No more jerky feeling. That's the biggest thing I noticed. It helps with throttle control.. No joke. Call Wade Wilcox.

I read up on this mod also. Sounds really good. You have to send off you throttle body to Wade, right?

This mod is only like 200.00 isn't it?

[slowgs2001]

I read up on this mod also. Sounds really good. You have to send off you throttle body to Wade, right?

This mod is only like 200.00 isn't it?

yes you need to send in entire throttle body and the TPS sensor wire harness.

[codyl]

im also thinking about a 270 kit on my 15 for woods racing, anymore first hand experience would be awesome!

[slowgs2001]

im also thinking about a 270 kit on my 15 for woods racing, anymore first hand experience would be awesome!

pm this dude on TT. His avatar name is ac717. He has first hand experience

[Yokomo]

I REALLY like my RMZ.  But it I were racing I'd get a KTM of whatever flavor you prefer.  My 250 XCFW with a worn piston and horrible jetting would still smoke my RMZ on the top end. 

I recently installed the CW 280 kit into my KTM.  It made a huge improvement in the bottom end for the price, some improvement in the midrange, and no improvement on the top end that I can tell.

[honda34]

Thanks for the feedback so far guys.

I am still really torn between the 270cc and 290cc kits, to the point where I may buy both eventually to test back to back.. I'm thinking if I go that route, I will most likely start with the 270cc kit.. I hate to buy both if there is a clear winner though..

 

The injectioneering mod sounds like it will be worth it, so that will be on the list of to do's as well.. I was a little curious about this, being that it seems no one else in the industry is supplying the same mod..unless I've missed something..

 

Depending on money at the time that I tear everything down, I think I've talked myself into polishing the tranny as well.

On another note, the vortex ECU was a major upgrade over the Yoshi PIM2, tested back to back, it was an impressive difference.

 

if you guys have any more feedback it would be much appreciated!!

 

Cody

Edited October 16, 2015 by honda34

[ac717]

I have the 290. Still have it. Actually...just got done riding it! Lol. I really like it. Haven't had any troubles. It will flatten off sooner up top but it's not much. It feels very much like a mini 450. The bottom end power is usable. It will pull a taller gear without issue. Definitely more of a midrange torque motor. The 270 feels more like the stock bike just pumped up. Both are good. If you want more of a torque/450 feeling motor=290. If you want a really strong "mod motor" 250f than 270 is better. My friend has a husky txc310 and I test ride a Sherri 300. Big bore rmz290 had a lot more hit and much stronger feel. The husky and Sherco are endure bikes though and tuned for traction and wider ratio trans. If the Rmz had a gearbox like the sherco it would be much better as a 290. So-I would say that is the downside to the rmz290. Gearbox,clutch,etc are made for a 250cc revver. Don't get me wrong though-I won't be going back to 250cc lol.

[slowgs2001]

I have the 290. Still have it. Actually...just got done riding it! Lol. I really like it. Haven't had any troubles. It will flatten off sooner up top but it's not much. It feels very much like a mini 450. The bottom end power is usable. It will pull a taller gear without issue. Definitely more of a midrange torque motor. The 270 feels more like the stock bike just pumped up. Both are good. If you want more of a torque/450 feeling motor=290. If you want a really strong "mod motor" 250f than 270 is better. My friend has a husky txc310 and I test ride a Sherri 300. Big bore rmz290 had a lot more hit and much stronger feel. The husky and Sherco are endure bikes though and tuned for traction and wider ratio trans. If the Rmz had a gearbox like the sherco it would be much better as a 290. So-I would say that is the downside to the rmz290. Gearbox,clutch,etc are made for a 250cc revver. Don't get me wrong though-I won't be going back to 250cc lol.

good to see you chimed in. Hope all is well Ac!

[ac717]

good to see you chimed in. Hope all is well Ac!

Doin good bud. Just been busy with life. I'll have to come and chat more.

[honda34]

Well I think I've decided on the 290cc kit for the first round, I kind of doubt that I will want to downsize to the 270cc kit after that, but we'll see.. Still debating on polishing the tranny.. has anybody ridden a bike that has been fully polished? I usually polish the shift drum/detent/etc for smoother shifting but I haven't had a whole tranny done yet..

[honda34]

I wanted to update this thread with the progress that I made over the winter..

 

I just got the bike complete and put back together and finally got to ride it yesterday.

 

First off, the parts list:

2013 RMZ250 with about 20-25hrs since new

Athena 290cc big bore kit

CNC porting by Williams Motowerx

Dimpled valves (stock size)

Custom cams by Williams

ISF polished transmission

Moto Pro detent spring and detent lever

Black Ops coil

corrected throttle body

Vortex ignition

Twin Air filter, still have the screen in it

Yoshimura TI pipe and carbon silencer

VP U4-4 gas

 

After getting the bike together, I had a hell of a time starting it. I have never had trouble with this bike, it has always been a one or two kick thing even from dead cold. I found that I had to lean it out with the hot start when cold to get it to start. Other than that, it ran perfectly.. after getting it fired up, I had to open the idle about 12-13 clicks, which puts me at about 18-19 clicks out from stock.. Also, set TPS to .615v

 

The break in ride went good, the bike felt a little flat, but I wasn't at a track to where I could really tell what it was doing.. after getting to the track yesterday I started testing with fuel and ignition settings a little. After the first round I could tell it was running way lean, so I turned low mid and high up to 7 on the Vortex, running Map 6. after the second round, I pulled the plug to check and still wasn't seeing any color.. still very white. Went up to 9 on low, mid, and high and the bike started responding better and finally sounds a little rich. I wish I knew a little more about the fuel maps on the Vortex, does anyone know if Map 7 or 8 has more fuel delivery built in? I don't mind starting rich and coming back down...its starting lean on a new motor that I don't like. 

 

This bike is a monster now! I couldn't believe how smooth and powerful it was. At first, it felt a little slow, until I realized that I was in 4th gear in most of the corners! I honest to god thought I was in second or third the whole time when I was actually switching between 4th and 5th. I could not believe how easy it was to roll on the power and control the way the bike reacted with the throttle..

 

still a lot more testing to do but I already have a 14 tooth front sprocket on the way.. I may try map 7 and see if it helps what seems to be a lean condition..

 

One question I don't have a lot of experience with VP gas since the dreaded first design of U4, does the 4-4 still gum up the way the original did? Can I get away with leaving it in the bike for a week or so at a time?

[slowgs2001]

Post pics of this monster... Sounds awesome.. I also have my 2013 mapped for u4.4. I have never had any issues with this fuel.. If anything, it's super awesome. IV left fuel in my tank for 4 months.. I'm sure it wasn't good but at the time, I didn't have a choice. I couldn't get any fuel. Still ran good and started 2 kicks

[honda34]

I will try to post a picture if it will let me.. I dont have any of it completely together yet but I have some of the ports, tranny, etc while it was going together. One other note I forgot to add was that my local track is a little over 5500' elevation, so that sucks for power production. Our tracks around here are hard pack clay and blue groove most of the time, so I can't wait to get to a good track and see how it pulls through some loam..

Slowgs2001, you are from new mexico, correct? If so, what part?

[slowgs2001]

I will try to post a picture if it will let me.. I dont have any of it completely together yet but I have some of the ports, tranny, etc while it was going together. One other note I forgot to add was that my local track is a little over 5500' elevation, so that sucks for power production. Our tracks around here are hard pack clay and blue groove most of the time, so I can't wait to get to a good track and see how it pulls through some loam..

Slowgs2001, you are from new mexico, correct? If so, what part?

buddy, I sent you a PM.. Hit me up.. Let's ride together some time.. I'd love to see that monster of yours. Also, where you getting your U4??? I have to travel almost an hr one way to buy 5 gallons.. The person selling it is a good friend and sells at an awesome price.. I could buy it closer but I'll be paying 4$ more per gallon Edited March 15, 2016 by slowgs2001

[honda34]

buddy, I sent you a PM.. Hit me up.. Let's ride together some time.. I'd love to see that monster of yours. Also, where you getting your U4??? I have to travel almost an hr one way to buy 5 gallons.. The person selling it is a good friend and sells at an awesome price.. I could buy it closer but I'll be paying 4$ more per gallon

I'm buying it locally...for full retail price, or higher, I think it's about 89 dollars for 5 gallons. I guess not getting to ride much will save me some money..

[ac717]

Sounds like one hell of a build Honda34. Is it hard to kick over or is it just hard to get it to fire up? I had issues with the 13 rmz ignition system and ended up going to one from a 2012. It would always take 3-5 kicks and I assumed it was from the ecu update/new starting procedure. Even with the 2012 ignition and vortex it took some tweaking of the decompressor and the tps to get it to be a one-kick starter. After finding a map I liked-I basically fine tuned it by the fuel trims and by adjusting the tps. I don't think any of the stock vortex maps are rich enough for the 290 big bore. By adjusting tps it's basically just adding fuel % across the board. It may move fuel from a little based on throttle position and rpm but it was only way I could get it right. I still have my rmz290. As far as 4 strokes go it's the best I ever rode. I only run u4 occasionally. Most of the time I just burn pump gas. Runs a little flatter but saves money. Athena has different thickness base gaskets that will bump up compression even further and tighten squish on cylinder to piston clearance. If you head was killed when ported though it may be too tight for thinner gasket.