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New rm-z

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Just picked up a 2012 RM-Z 250. Was running an 07 yz250f and I'm loving the FI over the carb. When I bought it, it would not kick start and would only bump start. 30 minutes after getting er home and the head cap was popped of and we were shimming the valves. Got it back together and she started on one kick. Got one hell of a deal on it! The intake valves need swapped and I'm wondering which brand is best? And i think i have to get new valve spings for SS valves correct? Anything else I should know about for the rm-z?

 

Not real happy with the engine or bike yet but I've only rode it once. I love the feel and agility of it in the woods, but in the fields and straights it seems to lack the a$$ i was expecting. Any mods to help with that?

 

Also, the clutch wont engage until almost completely out...adjustment on the cable is all the way out and the quick adjust does nothing to help...do i need a new cable or new fibers? maybe something else?

 

Thanks all!

 

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Privately. The PO blew it up (crank) and had a shop rebuild the bottom but never touched the valves. The valves are shimmed within spec but one intake valve is on the tight side with the smallest shim (120). So I'm going to replace the valves in it. I know it sounds sketchy, but for the price I could buy a new engine and still sell it with a profit. Just couldn't pass on it. Plus I love the look of these things. 

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A factory 4.1 really opens up the power on those rmz 250s. Also I know Suzuki has given their 250s 12 tooth front sprockets before (I have no idea why) so check that

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The stock muffler can be derestricted for a noticable performance improvement, though also notably louder but not unreasonably depending where you ride. 
Does your clutch cable have any freeplay when the lever is out? 
Lean FI coupling gives more punchy power. 

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The in valves on this bike are pesky. Mine for some reason move all the time. I clean my air filter a lot and change my oil way too much as well. Not sure why. I had to have my intake valves shimmed at like 30 hours. Not excited to replace them when that comes around.

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I'd go with the SS valves for a z 250. Weight won't make much difference or the change the gyro effect of the motor, their valves aren't that big. Oem will always be the best imo but when it comes to the valves steel doesn't hurt

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I just wanted to point out that your front brake line should be routed on the inside of your fork guard rather than the outside of it.

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If you replace valves-replace the springs,seals and keepers. OEM parts are fine. I like delwest valves and springs also. If you have an aftermarket cam-may need different springs. I prefer to have the seats cut if the head has a lot of hours or the seat surface shows wear/sealing issues. An issue to watch for on 250f's is valve guides and buckets. These parts see a lot of wear due to high rpm of these bikes. The bore in the head,where the buckets ride should also be inspected for wear or scoring. Think it was delwest or exceldyne that has the diamond like coated buckets.

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If you replace valves-replace the springs,seals and keepers. OEM parts are fine. I like delwest valves and springs also. If you have an aftermarket cam-may need different springs. I prefer to have the seats cut if the head has a lot of hours or the seat surface shows wear/sealing issues. An issue to watch for on 250f's is valve guides and buckets. These parts see a lot of wear due to high rpm of these bikes. The bore in the head,where the buckets ride should also be inspected for wear or scoring. Think it was delwest or exceldyne that has the diamond like coated buckets.

PC sells them too but are hella expensive. What would cause intake valves to go out of spec besides a dirt air filter? I can't figure out why my intakes move but exhaust don't?

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I have found once a valve starts to close up/keeps needing to be shimmed-it typically means the coating is worn on the valve. The titanium starts to get hammered by the valve seat. If you compare a worn valve to a new valve,you will see on the edge of the valve that it won't have a clean contour to the valve seat. Sometimes the valve will cup and start to bend over. This is when it starts to get dangerous. The valve starts to get brittle and will eventually snap. As to why they wear out- its nature of a valve. Especially titanium. If a valve zeroes out and doesn't get reshimmed-that can burn the valve. Hot combustion gas will try to push back out of the valve and burn the coating off the valve. As it gets hot,slammed into the seat it gets heat and pressure-this softens then hardens the valve,which makes it brittle. The valve springs are also part of this-over time they lose tension and fatigue. This can let the valve float easier and not follow the cam as designed. On a 250f or even a 450,the valve train should be examined and possibly rebuilt with the top end. Some will get 100+ hours and others 30-40 hours. Once the valves start moving its time to replace.

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I was told that all new bikes will need adjustment after about 30 hours. Like a post break in thing. My valves didn't zero but the intakes were about .01 out of spec and were shimmed when I got a top end about 5 hrs ago. I've always wondered how accurate these hour meters are too.

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