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05 cr250 motor is slow...

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I just bought a 05 cr250 that was all set up for the woods, thought it would be a great bike, and it is, other than the motor is not what I was expecting.  It was set up by an A rider and he did it right, but it's just not anywhere near what my 99 cr250 is for low end, mid, and even top end power. 

 

The 05 has had the base milled by Eric Gorr and the head worked so the bike would have more low and mid, it needs race gas but so does my 99 so no big deal.  It also has v force reeds and a works pipe.  Great compression, power valve is adjusted properly, clean air filter, runs good, starts good.  From what I read and researched before I bought the bike I thought this would be a great setup. 

 

My 99 has a gnarly pipe, I milled the head down a little with a palm sander (hillbilly I know but it did the trick), and a 14oz flywheel weight.  I also had a 98 that was stock except for a pipe and it was super fast, a little faster than the 99 on the top end but the 99 has more low end than any other 2 stroke I've ridden.  It has more low end than my tm300 and my buddies ktm300, but the ktm300 is not too tough to beat.

 

I'm wondering if I should just swap the motors from the 99 to the 05 and be done with it or should I try to work on the 05 and make it better.  I am tempted to just swap the motors, but it seems like it would be stupid to put my old engine in the new bike, especially considering the new bike was worked on professionaly and I haven't really done much to the 99 engine that I would call professional.  The 99 engine I really like though, it runs awsome, isn't finiky, has increadable amounts of low end and mid range power, and it NEVER stalls, the 05 will stall in the tight stuff on the trail. 

 

Any help is appreciated.  Thanks!

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It has the original carb, I was thinking of trying to just swap carbs and see what happens.  I also haven't played with the jetting on the 05 yet, but I am already pissed at the motor and didn't want to spend hours and hours trying to get it to work right when I know the 99 motor is rock solid


And yea, I am now willing to admit I drink the same amount of kool aid as the ktm guys, just a different color :)

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Start with a squish band measurement. Then if it's good carb swap and get the pwk a/s you should put on it. As well as take the motor apart and make sure stuff was really done and done right. These mirrors aren't great stock. But as opposed to the common kool aid they are good motors. Simple and reliable

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I'd like to keep the original motor in the bike, so I'm willing to do some stuff to keep it in there, what should the squish measure?  even if I do get it dialed in and put a new carb on it will it really be like my 99 motor though?  What I'm thinking is instead of buying a new carb, flywheel weight, gnarly pipe, and playing with jetting, it would likely be easier and for sure cheaper to just swap motors and sell the 99 to some jackass that thinks having a newer motor is a great upgrade.

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I just read up on some squish band stuff, seems like Gorr would have done that when he did his work to the head.  What he did was mill the base .040 and then modify the head to match, so if it's been machined already by someone who is good it seems like it should be okay.  The compression on the bike is around 240psi, and my 99 is 220psi.  I thought about getting a bunch of different color springs and jamming them in the motor in random places, that seems to really do the trick for the orange kool aid guys :)

Edited by red.kool.aid.drinker

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Haha yeah it does. Im no 250 expert..... yet, next buy is a last gen cr250, and *supposedly has gorr with, of which I've heard both good and bad things about. Did it come with any kind of proof of motor work?

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no proof but I trust the guy I bought it from.  He was from Craigslist so you know he's honest. 

 

On second thought maybe I should start taking things apart and looking into the motor a little deeper...

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I would try, stock carb on stock meeting of normally pretty rich. I'd look into the motor first then get it jetted perfect

There's a little taking needed to make it a solid motor

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What´s your squish measurement?

 

It can be as low as 0.8 - 1mm. I bought a HC head insert from VHM and it has a squish of 1.4mm stock from the factory with my 2002 setup.

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I just read up on some squish band stuff, seems like Gorr would have done that when he did his work to the head.  What he did was mill the base .040 and then modify the head to match, so if it's been machined already by someone who is good it seems like it should be okay.  The compression on the bike is around 240psi, and my 99 is 220psi.  I thought about getting a bunch of different color springs and jamming them in the motor in random places, that seems to really do the trick for the orange kool aid guys :)

.040' is .010' too much.  Use an 04 base gasket, and buy a new stock head.  Squish should be .050' when done right.

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I just read up on some squish band stuff, seems like Gorr would have done that when he did his work to the head. What he did was mill the base .040 and then modify the head to match, so if it's been machined already by someone who is good it seems like it should be okay. The compression on the bike is around 240psi, and my 99 is 220psi. I thought about getting a bunch of different color springs and jamming them in the motor in random places, that seems to really do the trick for the orange kool aid guys :)

Eric does nice work, but I found out first hand he uses a larger squish than what is really needed for these bikes. I had him take .30 off my cylinder base and recut the head for pump fuel. When I got it back the squish was opened back up to around .65 which is to much. I simply had a local guy cut it down to .50 and its been gravy since then. .40 seems like a lot to take off the base of the cylinder so unless the PO specified that's what he wanted then I doubt Eric took off more than .30. I'd measure the squish and if its more than .50, which I'm sure it probably is, then either buy a new stock head or have the current one reworked if possible. 240 psi compression is already high so if you need to take much off then you may be further ahead to buy a new head. Honda east Toledo has them for cheap cheap cheap and RB designs does great head work. If .30 was taken off the cylinder base then a stock head will be perfect on the squish but you will need to run at least 100 octane. Your nuts to put the older motor in the 05. Trust me once you get that thing dialed in you will see why.

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Eric does nice work, but I found out first hand he uses a larger squish than what is really needed for these bikes. I had him take .30 off my cylinder base and recut the head for pump fuel. When I got it back the squish was opened back up to around .65 which is to much. I simply had a local guy cut it down to .50 and its been gravy since then. .40 seems like a lot to take off the base of the cylinder so unless the PO specified that's what he wanted then I doubt Eric took off more than .30. I'd measure the squish and if its more than .50, which I'm sure it probably is, then either buy a new stock head or have the current one reworked if possible. 240 psi compression is already high so if you need to take much off then you may be further ahead to buy a new head. Honda east Toledo has them for cheap cheap cheap and RB designs does great head work. If .30 was taken off the cylinder base then a stock head will be perfect on the squish but you will need to run at least 100 octane. Your nuts to put the older motor in the 05. Trust me once you get that thing dialed in you will see why.

Thanks for the info, I wasn't going to mess with measuring it before, but I will now that you say that.  Also I did some jetting today and it seemed to help some but still it just ins't what the 99 is.  I also ordered a gnarly pipe and a flywheel weight today so I imagine that will help too.

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Okay, just measured my squish, it's .073

Apparently that is too much?  Good news, I sanded the head down on my 99 and I'm completely willing to do it to the 05 :thumbsup:

I also checked compression, it's 190; not 240 like the guy I bought it from said. 

I'm starting to think I should have just put the trusty 99 motor in this thing and sold the 99 with an 05 motor.  I still might...

Edited by red.kool.aid.drinker

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Okay, just measured my squish, it's .073

Apparently that is too much? Good news, I sanded the head down on my 99 and I'm completely willing to do it to the 05 :thumbsup:

I also checked compression, it's 190; not 240 like the guy I bought it from said.

I'm starting to think I should have just put the trusty 99 motor in this thing and sold the 99 with an 05 motor. I still might...

Get a top end, break it in right, fix the squish, and install the a fatty and weight then rethink that lol

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Eric does nice work, but I found out first hand he uses a larger squish than what is really needed for these bikes. I had him take .30 off my cylinder base and recut the head for pump fuel. When I got it back the squish was opened back up to around .65 which is to much.

 

How is the engine guy suppoosed to know the height of your cylinder and piston including all the tolerances that they come with from the factory?

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How is the engine guy suppoosed to know the height of your cylinder and piston including all the tolerances that they come with from the factory?

This is the reason why RB Designs requires test solders to be supplied by the customer when requesting head/cylinder machining.

Edited by APBT

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How is the engine guy suppoosed to know the height of your cylinder and piston including all the tolerances that they come with from the factory?

Very good point. I forgot to mention that I specified the squish was .84 when I sent him the parts. And said I wanted to be around .50. He felt the need to open it back up again anyways for some reason. I wouldn't have noticed it had I not had a heck of a time trying to jet the bike. I decided to check it and found it where it was and just let a local guy flatten it out a little bit for 15 bucks. Needless to say problem solved. Still runs on pump fuel just fine. I do want to buy a new stock head and run some higher octane to see what the bike can really do. I have a gnarly pipe and flywheel weight on it now and its a tractor. I think I am actually going to take the weight off since I have a heavier clutch basket than factory as well.

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