Jump to content
Sign in to follow this  

2008 250f 269 Works connection Big Bore

Recommended Posts

Just found out that the bike I bought has a 269 BB installed less than 10 hours ago. I did a little research and the piston it comes with is a 12.5:1 compression instead of the 13.5:1 compression. Is this true? I dont see why anyone would want 19 more cc's if you lose all that compression. Has anyone installed one of these and did you notice much of a difference? Thanks

Share this post


Link to post
Share on other sites

I am sure the guys that have installed one will chime in. Everyone, I mean everyone has enjoyed a bigger Bore. Lowering compression is not necessarily a bad thing. Lower compression lets the engine rev more freely.

Check the jetting. Once you get it jetted properly it will really rip. The 269 does not lose overrev like a 290 does

  • Like 1

Share this post


Link to post
Share on other sites

I am sure the guys that have installed one will chime in. Everyone, I mean everyone has enjoyed a bigger Bore. Lowering compression is not necessarily a bad thing. Lower compression lets the engine rev more freely.

Check the jetting. Once you get it jetted properly it will really rip. The 269 does not lose overrev like a 290 does

 

Good to know, thanks! It came on the bike with very little history. Dont know anything about BB kits. Quality components at least. The guy before installed a JD jet kit and it looke like it has a 180 main since that is what is missing from the pack. Anybody running a similar setup as me and want to chime in including jetting:

FMF power bomb and Ti powercore

twin air filter

Works Connection 269 BB kit

Boyesen Quickshot 2 Accel Pump

JD Kit, not sure what jet and needle except i think 180 main. Live in NY with 300ft elevation, 50-80 degrees, mid humidity, have access to 100 octane pump

 

Thanks

Share this post


Link to post
Share on other sites

i did a stealth 269 with a cp 13.75to1 and a set or gytr cams and springs,along with a ported head.pilot jet was a 45,main 165,red JD needle and adjustable leak jet.the bike was a midrange monster,and it def revved out better than my freinds 290.I kept the cams and springs from that bike(2009)and if you are looking for a low hr set of cams let me know,i also have a 269 cylinder that millenium did for me,and a cp piston with less than 5 hrs on it.i think our 2010's and 12's and 13's all ran better from mid to top than the 09 did with just the 269 kit,and my oldest sons 14 is better than the 09 was in full race form.the 08 that we had was a great bike,all we did to it was put on a full fmf and fix the carb,set-up the suspension and rode the wheels off of it.the piston that comes in the cylinder works kit will work fine,when you raise the compression you only notice just a bit more of a snappy low end.i was actually able to run a 48t rear on the 269 bike,as it was a very strong motor from low to mid.

Share this post


Link to post
Share on other sites

i did a stealth 269 with a cp 13.75to1 and a set or gytr cams and springs,along with a ported head.pilot jet was a 45,main 165,red JD needle and adjustable leak jet.the bike was a midrange monster,and it def revved out better than my freinds 290.I kept the cams and springs from that bike(2009)and if you are looking for a low hr set of cams let me know,i also have a 269 cylinder that millenium did for me,and a cp piston with less than 5 hrs on it.i think our 2010's and 12's and 13's all ran better from mid to top than the 09 did with just the 269 kit,and my oldest sons 14 is better than the 09 was in full race form.the 08 that we had was a great bike,all we did to it was put on a full fmf and fix the carb,set-up the suspension and rode the wheels off of it.the piston that comes in the cylinder works kit will work fine,when you raise the compression you only notice just a bit more of a snappy low end.i was actually able to run a 48t rear on the 269 bike,as it was a very strong motor from low to mid.

 

Ya i might be interested in those cams, shoot me a message with the details. I dont know a whole lot about cams. I do a lot of HS so i need the low-mid range the most. Top end isnt as big a deal unless im on the MX tracks. Where did you have the port done and what type of port was done? What valves did you run?

Share this post


Link to post
Share on other sites

i put the exceledyne ti valves in it and the porting was done by me.you might have to put a race piston in your motor to allow for enough clearance with the yamaha race cams,thats why i said that i have a cp piston that you could use,i dont really know if you would loose any of your bottom end with the gytr cams,the motor had plenty of it to work well for ax,but we dont race any woods stuff so i cant really say how they would work for that type of racing.Even with a full-on pro-level engine in the older yammies,they just dont have the top-end power and over-rev like a comparable honda or kawi.i have always been willing to give up a bit of peak h.p. to have the good reliability of the 5 valve yammies.the only other thing that might be a downside for woods racing would be that the engine did run hotter with the stealth overbored cylinder,but your set-up might not be that way since the cylinder works kit was made to use the bigger piston.i put a 450 kawi radiator cap on the 09 after the mods were done so it would not dribble out of the overflow in hot weather on the starting line.as far as porting the head for woods racing,you will need to weld up the exhaust port and then re-shape it,otherwise a mx port job probly wont help you much if your in the woods alot.

Share this post


Link to post
Share on other sites

I agree with noslo on the sprocket. I got to ride mine today since I changed to 13/49 this year. And i was pleasantly surprised that it never felt like I didnt have the power i needed...and this is on a sand track that had some mud in some areas due to being spring time. Far as the 269 kit, i thought i heard they didn't do it because of the added compression + already being a big bore would be more crank strain (have no opinion on if thats true at all, just something i seen). I have a CW 269 kit in my 07 and it isnt a crazy WOW its sooo much more powerful feel...but i thought it add a bit more low end bite.

 

I also have a JD jet kit, and i just followed the instructions. 180 doesnt sound crazy with this kit...but you should be able to tell when you are in the range of the main (in throttle turn) how it feels or sounds. I do remember initially thinking that the kit was a lil "richer" then you'd normally do. Again, if you can find the instructions, just go through that..if you can't find them, lemme know and I could send ya some pics of the sheets to read.

Edited by J_YZ2fittyF

Share this post


Link to post
Share on other sites

I agree with noslo on the sprocket. I got to ride mine today since I changed to 13/49 this year. And i was pleasantly surprised that it never felt like I didnt have the power i needed...and this is on a sand track that had some mud in some areas due to being spring time. Far as the 269 kit, i thought i heard they didn't do it because of the added compression + already being a big bore would be more crank strain (have no opinion on if thats true at all, just something i seen). I have a CW 269 kit in my 07 and it isnt a crazy WOW its sooo much more powerful feel...but i thought it add a bit more low end bite.

 

I also have a JD jet kit, and i just followed the instructions. 180 doesnt sound crazy with this kit...but you should be able to tell when you are in the range of the main (in throttle turn) how it feels or sounds. I do remember initially thinking that the kit was a lil "richer" then you'd normally do. Again, if you can find the instructions, just go through that..if you can't find them, lemme know and I could send ya some pics of the sheets to read.

 

Ya I got the bike second hand so there are no instructions, just the plastic box with the parts. Ill have to rip around at the track this week and find out how it feels. 165 seems so small! I think stock on these is 175. If you have quick access to the intructions that would be great, Ill try googling it too.

Share this post


Link to post
Share on other sites

There is a 2nd page, but it is all about the O-ring mod instructions (which can be found anywhere). If you can't read it, just open it with something that you can zoom on. And I agree 165 seems pretty small for your area (elevation). This thing says for our range of elevation - 185 MJ...which seems really high, but the thing is it works in conjunction with his needle.

Instructions.jpg

Edited by J_YZ2fittyF

Share this post


Link to post
Share on other sites

There is a 2nd page, but it is all about the O-ring mod instructions (which can be found anywhere). If you can't read it, just open it with something that you can zoom on. And I agree 165 seems pretty small for your area (elevation). This thing says for our range of elevation - 185 MJ...which seems really high, but the thing is it works in conjunction with his needle.

Awesome, Thanks!

 

Do you guys think a stage 1 I/E hot cam would be worth the money? I dont want to lose much low end, dont care as much on the top end.

Share this post


Link to post
Share on other sites

Well you wouldnt lose low end with a Stage 1 setup since thats where they are degree'd to help. Stage 2's are degree'd to move it up more higher end. However a very popular combo is a stage 1 intake and stage 2 exhaust. Supposedly gives a pretty good all around boost. Then you can also get the kit to mess with the degree of the cams if you choose to kinda make them custom to you if you wanna go that far.

 

I have a stage II intake cam sittin here, just havent gotten the exhaust cam yet. I may run them at some point this season and I'd imagine it will make some difference. I just dunno how much since I have never run them before. I was planning to re-degree the intake more like a 1 though as I dont need ALL top end either. But since the 269 kit moves power down a little, i figured id try a stage 2 set up and see if i like it first. A lot of of our tracks are sand, so that top end power comes into play keeping the rpm up to churn through it. If i was only doing tight trails where I need grunt...it'd probably not work out.

 

End of the day I ride 30+ c tho, and I feel like my bike does what I need it to do. Most of the time when I dont "have the power" its because I screwed up. So that is why I haven't been in a rush to get the cams done...it was just a good price on it so I grabbed it. I did the CW 269 kit because I had to do valves, and when i took the head off, i seen my cylinder was gouged. So instead of a re-plate or new cylinder + piston kit...i just did the 269 kit. Its been a good kit so far @ about 10hrs on it (per hour meter).

 

If you need to get a new piston kit for that bike (now or in the future), make sure you read the instructions on the ring end gap. Mine (which all came together as a kit) wasnt just a total drop in and forget it. I had to file the compression ring a little to get it into spec before I installed it. May not always be the case, but it was for me.

Edited by J_YZ2fittyF

Share this post


Link to post
Share on other sites

Thanks for all the info, I'll start scouring eBay for the cams. If I can get them cheap enough, I might give em a try. Never done cams before. Are they pretty much drop and go? If they help so much, why doesn't yamaha run that profile from the factory? Yami always seems to be underpowered

Share this post


Link to post
Share on other sites

They cover a WIDE range, since these motors didnt change much for a very long time, lol...Far as hotcams, they are a drop and go because they arent aggressive enough to need new springs to prevent floating valves. And why Yamaha didn't....who knows. I dont know how it all works but maybe they have parameters they shoot for as far as engineering a bike for the masses essentially. I mean, if you think about it like a Stage I kit moves power down low...maybe they didnt wanna move all the power down there. That may be why a stage 1 & 2 combo just overall boosts the power the bike has is so powerful. Not like most people who ride these bikes do ONE thing. If you were an A rider who was ragging the thing out all the time, didn't end up in the wrong gear in a corner and need a ton of low end, etc....maybe you'd want all the top end you could get. But for Yamaha...they cant make it THAT way only because of the diverse crowd buying the bike.

Edited by J_YZ2fittyF

Share this post


Link to post
Share on other sites

Ya valves was the big one. That makes sense, I guessing you don't peak more horse power, just move the curve around a little bit

Share this post


Link to post
Share on other sites

FYI I too have the gytr cams and I can say that it took the stock powerband and just amped it up. It didn't trade low for high or vice versa, just more everywhere.

These cams require lighter valve retainers found on the '10 and up but I can't see hot cams making a better cam than gytr

IMHO I'd check out the gytr cams.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×