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Yes the day has come, my RMZ-250 has become a complete pain in the arse to start. But its not the rings because Ive chekced the compression...Which makes me beleive that yes it is the valves because it also backfires when i decelrate...Anybody got some input. Thx Kyle

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Ya from what I always hear you definetly need to check your valves, and do it quick before you get any severe damage. How much life did you get out of them by the way? And have you shimmed them yet?

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jetting doesn't just go like that. It is the valves, they should have been checked before now. The popping isn't a valve issue it is how many bikes run from the factory because they aren't jetted properly.

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Yes the day has come, my RMZ-250 has become a complete pain in the arse to start. But its not the rings because Ive chekced the compression...Which makes me beleive that yes it is the valves because it also backfires when i decelrate...Anybody got some input. Thx Kyle

1) How do you check the compression in an engine with auto-decompression??

2) If the valves have lost all clearance and are hanging open, then you will have lost compression with that also.

I have done this at least 3 times already. Bike was running great... started getting harder to start.... finally, the only way to get it started is to push start. Intake valve closest to the cam chain has lost all clearance. Don't screw around, just spend the bucks and buy the new springs (either the conical springs from WMR or a few people make double wound springs.) Also replace both intake valves (at least... better to replace all four) with stainless steel valves. The whole deal should cost a bit over $300 in parts. Don't complain... just do it.

Jimbo

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the ss valves and springs aren't proven yet. I would replace the stock valve spring anyway it's only 8 bucks. It should last you until we know for sure whether the ss valves are the way to go.

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It is probably a valve(s) that need to be re-shimmed. However just because they may need to be re-shimmed, doesn't mean you have to immediately go to buying new valves, or springs, or head etc.

I had to re-shim mine once the bike was fully broke in, however since then they have remained in spec..

As for popping, it is possible that as the weather cools, the bike will run a bit leaner than on the warm days.. Go out 1/4 turn more on the fuel screw and see if this solves the popping..

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the ss valves and springs aren't proven yet. I would replace the stock valve spring anyway it's only 8 bucks. It should last you until we know for sure whether the ss valves are the way to go.

The dual wound springs HAVE been proven through many applications. It is the cheap $8 stock spring that has been proven NOT to work. If you are loosing clearance on an intake valve (like I bet you are), you can pull the head and take out the valve. The face will almost surely be cupped. If it is cupped, there is no need to reshim... it will continue to cup.

As for the popping... that is a jetting issue. You are too lean on your pilot jet and/or your fuel screw.

Jimbo

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Srry i wasn't clear about that Jimbo, i meant that the valve and spring combo isn't proven to last say 2-3 yrs. as on the yzf 250, etc. I know that the valves have been tested seperately and the springs have been tested as well however we don't know if the valves will last without losing clearance.

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