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Ive got a 08 CRF450R with 18 hrs on it, I bought it new in 09 but havent ridden much from non motocross injury. Anyway, Im starting to get serious about the riding now and I know maint. needs to be done on the bike but Im new to 4strokes and have some confusing questions to me that have probably been answered many times here, I tried the search option and it wasnt very efficient. First, I have always ran Bel Ray gear oil in the tranny side and Mobil 1 motorcycle oil in the engine but after reading many posts of seals failing and tranny oil moving over to the engine side would I be better off for the sake of the engine to run the same engine oil on both sides? Second, I found many jetting posts of the 450X but they are scarce for the 450R. Recently the bike is popping on decel but I havent removed the header to cause any damage to the seal there. I was hoping for the jetting info to see if thats the culprit. Third, I havent checked the valves yet or removed the cylinder head to damage that gasket but nonetheless Ive got oil coming from the spark plug drain hole on the right side of the engine, What would be the likely culprit? I have removed the spark plug and its possible the seal there, what do u guys think? Suspension is a whole other can of worms on this bike and I want to feel better about the engine problems before spending time on that. I enjoy this site and the caliber of people that are willing to help a new non lurker. Thanks in advance for your time and know it is very appreciated. Ty

tyyoung wrote:Ive got a 08 CRF450R with 18 hrs on it, I bought it new in 09 but havent ridden much from non motocross injury. Anyway, Im starting to get serious about the riding now and I know maint. needs to be done on the bike but Im new to 4strokes and have some confusing questions to me that have probably been answered many times here, I tried the search option and it wasnt very efficient. First, I have always ran Bel Ray gear oil in the tranny side and Mobil 1 motorcycle oil in the engine but after reading many posts of seals failing and tranny oil moving over to the engine side would I be better off for the sake of the engine to run the same engine oil on both sides? Second, I found many jetting posts of the 450X but they are scarce for the 450R. Recently the bike is popping on decel but I havent removed the header to cause any damage to the seal there. I was hoping for the jetting info to see if thats the culprit. Third, I havent checked the valves yet or removed the cylinder head to damage that gasket but nonetheless Ive got oil coming from the spark plug drain hole on the right side of the engine, What would be the likely culprit? I have removed the spark plug and its possible the seal there, what do u guys think? Suspension is a whole other can of worms on this bike and I want to feel better about the engine problems before spending time on that. I enjoy this site and the caliber of people that are willing to help a new non lurker. Thanks in advance for your time and know it is very appreciated. Ty

i run different oils in the trans and engine and it's not a concern. the main thing is to keep the oil clean and monitor the level before each ride. on the jetting, check the jetting database to see what others are using. personally i'm running the JD jetting kit and it works great. decel popping, besides what you mentioned, is also a symptom of a lean pilot circuit so adjust your fuel screw open, around 2 turns out, and/or increase your pilot jet one size. also, check your hot start cable and nut and make sure it's functioning correctly as this also introduces air into the fuel mixture.

the spark plug drain hole only goes to the spark plug so either oil was accidentally poured there or more likely the valve cover seal is bad or not in correctly in place.

let us know how it goes.

ken