CRF's Only Forums

I really seem to be going from one upgrade project to the next lol



Next on the list, I need to lean and do a top end.

For the most part, this looks very doable for me.

Picked up my 2012 250X six months ago, and was told it had 25~30 hours on it (take that as you will) this was the 6th of June 14.
Since then, I've stacked 75 hours, and a month of that I couldn't ride with a bad ankle.

For now, the bike is running great, oil burn is fine, no blue smoke, power seem fine etc. etc.
But, at 100+ hours today, and the amount I ride, it's only a short matter I've time till I'll have to.


But I have a few things I need to understand.

1: CRF Only sell's a JE Piston Kit http://www.crfsonly.com/catalog/product ... ts_id/1344 that has a higher compression ratio but says it fits the standard size bore.
Will this fit the stock cylinder without any mods, or is there more to it ?

2: If I'm pulling it apart anyhow, I should look at changing to stainless steel valves (I had to shim mine right after buying it, which makes me not trust the hours I was told, good since though, but I don't rape my gear)
Crazy as it sounds, I can buy a new Head, stainless steel valves and the valve seats cut off CRF Only for about the same as just having the valves changed here lol.
So maybe change to an R head, and just order the whole thing off Ken http://www.crfsonly.com/catalog/product ... ts_id/3139

Even a Cam change is on the table at this time, just need to understand what I can or cannot do, and where it may help.


What I'd like to achieve.

3: A piston change done by me, top of the list

4: Don't make it harder to start (it starts real easy now, I want to keep it that way)

5: A little more power everywhere, why I’m looking at the JE piston kit over the OEM

6: I ride ALOT, stack hours, stainless steel valves will be needed sooner or later. So do it now when it's all apart.

7: Cost here, means a Head change can be looked at, But I have No idea where that helps in the power range, if it's everywhere, cool, if it's only top end, don't really need it.

8: In order of where I'd like a little more power would be in this order, mid, bottom and top end is last.

9: Between jumps and out of corners a little more pick up would be nice (riding better and holding more speed would also do it, but thats not going to happen anytime soon lol)

10: And if I'm making a wish list, being able to hold a taller gear on some hills would be nice with out changing the gearing.


The above is a bit long winded, but if you know what I'm trying to do, you will be able to help me better.


Thanks for your time


Dean

Hi Dean...I thought I'd withhold my reply so others could chime in. However, if you would like to hear my opinion feel free to send this to me via email. I believe you have it.

Ken

I better to get the controversial one out of the way first - I do not like stainless valves. They are heavy (robs some power) and the wear to cost ratio is not enough to justify the change. A skilled machinist, the correct (beryllium copper) seats, and titanium valves are going to give you the most power with sufficient life.

Okay, now on to the rest...

If the valves have been shimmed or are not close to factory spec then get the head done while it is off. You are correct that a complete R head gets very attractive when looking at the cost of rebuilding the X head. I would opt for the new head.

'08 R cam is the way to go. It will fit in your stock head, or up to an '09 R head. You 'can' get by with the stock X valve springs, but you would be better telling the shop what cam you are going to if you are keeping the X head so they can put in the correct springs.

JE 13:5:1 is a great piston. That piston + R head with TI valves + R cam will produce the most power.

Some other stuff...
Open the airbox - cut the top off so it looks like the R airbox and remove the backfire screen. You will need to do both if you are doing anything more than the stock setup, and it will help with any setup.

Plan on rejetting.

Needle selection/position and jetting matter. Bad choices will kill any mechanical enhancements.

Adjustable leak jet will help you fine tune the off-idle performance.

The ScaryFast PowerNow and PowerNow Plus will provide better response on an R top end, but will not do much for the stock X setup.

A decent slip-on will likely be desired if you do much of any engine mods. It is not worth the money unless you are doing other mods - it may actually take away performance without other mods, but it does save weight.

JCR swapped out the carb for an '05 + A/P mods when they did their build. I did not research it, but I am sure they had a reason.

Other:
If you swap out the cam, allow money for a new cam chain - check the chain, guides, and adjuster regardless.

Get an OEM service manual if you do not already have one.

You will need both good inch-pound and foot-pound torque wrenches. Consider a wrist pin clip tool (manageable without it, but some folks struggle), send your cylinder to the machine shop for checking and deglazing before you put the piston in. You can deglaze it yourself, but shops do for not much money, plus they inspect it.

Don't forget to use regular oil to seat the new rings - synthetic will not allow the rings to seat properly.

--These engines are not hard to work on. The right manual, patience, clean work area, and proper tools goes a long way.

Hi riddler9,

Thanks for the reply


Very interesting, first time I seen someone say that about the wear to cost ratio of going stainless steel valves.

Not sure what the first owner of this bike was thinking what he took to the stock pipe, but it did nothing good for the bike, and made it soo loud.
I couldn't live with the sound or how bad it made the performance.
So I ordered a JD Jetting Kit, FMF 4.1, did the air box mod, took out the back fire screen and put in a super flow kit. Fixed all the issue I had with that.

Adjustable leak jet is on the list if I find I need it, to date, no real need.

Good to know, I'll budget for a cam chain... just in case I need to change it.

Good idea on the OEM service manual, I have the OEM owner manual, but I'm sure the service one will be of help as I try more of this stuff myself.

I have a good tool kit, which has 3 "good" torque wrenches (1/4 3~26NM, 3/8 20~80 NM and 1/4 40~200) they show inch-pound or foot-pound as well, but owners manual shows all settings, and I use newton meter as a rule.

The motorcycle industry here is not like any other I deal with, everything seems to turn into an issue.
Little is done on time, orders are often wrong and most of the staff in them are in full on race mode, and want to spec you out of this world and just wont listen to what the customer wants or is going to use it for.
So bolt in parts like a new head with stainless steel valves all cut that I could install myself seem like a no brainer.
I'm a measure twice cut once kind of guy, so other than I would be looking at deglazing myself before install the piston, that seems to be the only real "hard" bit that I need to be very careful with.

Good to know, use regular oil to seat the new rings.

Deglazing yourself is not necessarily hard. Just take it easy so you don't strip the nikasil coating - scotch-brite and ajax (very wet) at alternating angles.

I like to have the machine shop check my cylinders to make sure they are flat on the ends and that the bore is still round.

You can check to make sure things are flat with a straight edge and a flashlight (shine under the straight edge). Years ago when I did not send out the cylinders I would work the gasket surface by putting a piece of 600 wet sand paper on a slab of granite - worked in in circular motion until the surface was evenly polished. You need a cylinder bore dial indicator to check the bore. They run about $70 for a decent one.

I have not had to do any work on the JE piston rings, but you 'should' check and gap them if needed. If you find that you need to file you will want a hobby file kit (very small files). FWIW, I personally believe that most people never bother to check ring gap. I rarely make any adjustments when I do check.

If you really like to see everything that is going on (measure twice), then you may want to consider making or purchasing an engine cradle. I made one out of scrap thin-wall box steel and some all thread - and a welder. Pretty easy to do, but you need the welder. I suppose you could bolt one together but it may take some time to make sure you drill everything just right rather than being able to tack-as-you-go. I have seen cradles online. I think they run around $100. Worth the time or money. Much better to work on the engine while it is on a bench then in the frame, especially when you are dealing with the piston wrist pin.

I agree with Riddler about the choice of valve and seat material. I have an 04 250X put a 08 cam, an 09 R head and a JE 13.5 piston. This was not that much more than fixing the old head. The performance gain is remarkable. Good clean bottom end and big power gains everywhere else. I put over 50 hours of all kinds of riding this summer and the valves have not moved.
Obviously you need to make the proper changes to the intake and exhaust to gain the benefits.
I really haven't done much to the carb except main jet pilot and needle clip. I will put the proper mods in this winter when the shock gets rebuilt.

We prefer and use MoldStar-90 material for valve seats. Same material being used in all deep pocket racing these days. When using Ti valves to increase valve longevity the seat material must be changed to this material and the proper material for guides. Otherwise, your expensive Ti valves will get about a third of the time before sinking into the seats. We offer these head, seat and valve services:

http://www.crfsonly.com/catalog/index.php/cPath/258_282

If you have questions let me know.

Ken

Thanks for all the input from everyone, and big thanks to Ken for all the helpful replys to my endless e-mails.

After taking everything into account, have just ordered..

07 R Head with KW valves
08 R Cam
JE 13.5:1 kit
Shim Bucket - Decomp Spring Kit for the R Cam
Cam chain
3 X gaskets and some tools.

Taking into account how slow NZ customs is (as it's over $400), should all be in my hot little hand in about 15~20 days.

Can't wait to not only give this a try, but also see what it does for my motor

Going to be a great set up. Thank you for your support and business!

Ken

With a bit of luck I'll have my parts by next weekend.


On a side note, Ken/USPS took 5 days to get the parts, get them sorted, ship to Auckland, New Zealand, then pass them onto NZ Customes, Sweet!
/Start Rant:
Where they have now sat for the past 6 days and counting, you can't call them, e-mail them nothing, you have to wait for them to send you a letter via slow post to get a ref number to pay the import tax, they wont use the track and trace, they have to make up a new number that they wont tell you in any other way but in a letter, and with out that number, they wont let you pay and they wont look it up for you. And I still haven't received their letter, and no way to even know or find out if they have even done/sent it yet.
\End Rant

Can you guys help with the below 4, just getting my head round the last few things before I start pulling it apart, ready for my new parts.


Left Crankcase cover:
Is there any thing to look out for after taking the bolts out and pulling the cover off. ie hard to pull apart ?, something is going to fall out, or ..........

Cam Chain,
To get this off, as easy as lifting it off at the bottom and feeding it up and out (note I have a fly wheel puller ordered off Ken)

Cam Chain Tensioner:
As easy to undo the bolts and pull out, noting to look out for ?

Deglaze the cylinder:
What does the stuff I'm taking off look like, how to tell it's clean and ready to go ?

Most of the below is easy to say now, as I haven't started my bike yet to see if it goes bang lol


But as I wait for the last few items to land, I've got the new piston in.



Found it easy to work with the motor still on the bike, didn't even take the carb off, sub frame up, top bolt off the shock and push it back a bit.

Everything came off super easy, did take a few goes to get the oil rings to sit clean on the piston, and then to get the cylinder on over the oil rings with the piston already mounted.
Next time I think I'd put the piston into the bottom of the cylinder, then mount them as one, put the clip in for the piston and move the cylinder down the rest of the way.

To this point (see picture above) all up about 6 hours, I'd say about another two to get the rest mounted/remounted and be able to fire it up.


On a side note, spark plugs may, "may" need to be changed more than every 140 hours

Looking good! Make sure you check/gap the rings. It's often overlooked but very important for a correct piston install.

Also, make sure you consider the type of break in procedure you plan to use.

http://www.crfsonly.com/forum/viewtopic.php?t=36137

Failure to break in the piston correctly will cause it to use/burn more oil than necessary.

Good luck!

Ken

It's funny how you can read so many "howto's" and not really get it untill you have the parts in hand and are giving it a go.

Cheaking the ring gap was one of them, even though the how to on this site shows a picture of the gap being checked inside the cylinder, I was thinking (before I had the parts) how it must be hard to work out the gap LOL

As it turns out, the rings in the JE kit were bang on, didn't need to do anything.
I put the gaps as per the sheet that came in the kit, though every "howto" seems to more them around a bit.


With a bit of luck the other parts will be here mid week, and I can take an afternoon off to do the break in (make sure it's running right), as I have a big ride on Sunday, and riding an untested motor in the trees high up on the side of some mountain, doesn't sound like fun/good idea.

Last items turned up today


R Head and Cam are now on.
The shims on the X head were way to big, almost couldn't get the cam to seat, and all were zeroed out, quick phone call round and a mate had a whole shim kit to loan me...sweet!
Ended with
In Left: 1.75mm shim (.006in gap (calculator calls for a 1.77mm))
In Right: 1.85mm shim (.005in gap)
Ex Left: 2.35mm shim (.011in gap)
Ex Left: 2.25mm shim (.011in gap)

Just need to wire in my pink wire switch.
Put coolant and oil back in.
Pop some panels, gas tank and seat back on, and should be good to test/break in.
Late Wednesday night here as I post this, do the rest tomorrow night and I have booked Friday off to do that.

It didn't go Boom!


All done and even had time to do the break in tonight.



This is what I did for the pink wire switch.

Super Glue over size zip ties to the back of the switch.


Mount to the frame, with another zip tie over the top.


In just the right spot to be able to change it via the little cut out in the Radiator Shroud.



This is just a picture of my bike as I'm waiting for it to cool down to do the next heat/cool down cycle


With help from the members here and special thanks to Ken for all his help, this has turned out very doable and a lot of fun in learning something new for myself.

Have a big ride on Sunday, can't wait to see what it feels like with the new parts when I really open it up.