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New top end time...Stock or aftermarket?

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It is time for a new top end. I was wondering what you guys think. Should I use the stock stuff or go with a sligthly higher compression piston and if so, Which one? Or should I go aftermarket with stock compression? Are aftermarket pistons better than the stock ones..i.e. lighter or better quality?

I would like to still run pump gas though, so compression can I run? It's an 04 fo fiddy.

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IMO, Stock is the safest but once you go to the higher comp pistons reliability starts to fade a little. Most are still reliable though. Weisco i have heard are kind of sketchy because apparently they slop around in the cylinder a little more than stock and are less reliable. I've been sticking to stock pistons.

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The stock 04 piston is 12:1 much higher then you will need to run race gas. IMO the 04 piston is the way to go. If you want more power then run the VP U-4 fuel, or a cam. I know when I do my top end im going for the stage 2 cam. 😢

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I figured stock would be better. I ran U4 and really didnot fell an HP difference. Anyway, I guess I will stick to stock unless someone can tell me that an aftermarket piston is of better quality, but I doubt it.

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I just bought a well-cared-for '02. Reading the owners manual I was 'suprised' 😢 by the maint. sched. recommendation of changing pistons/rings every 15 hours - same as the oil! What do you-all experienced owners think? How often for pistons/rings?

(I am planning to change oil every 2 rides/4 hrs & filter every other).

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I change the oil in my bikes after about 5 hours, and the filters every other oil change. I did the rings on my 450 after about 30 hours and im putting a new top end in at about 50. its at about 42 hours right now and still runs strong.

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I know when I do my top end im going for the stage 2 cam

The guy im having do my motor work (MVR) has know a few people that put in the stage 2 a blew up their pistons. It pushes the valves further into the cylinder causing them to come in contact with the piston. This is just what i've heard. Apparently wiesco makes a piston with deeper dishes for the valves to fix this. I dont know for sure though.

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hmm...I heard a similar story from someone else. Anyone running the stage 2 cam and had any problems?

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You guys might want to check your sources and information!!

do a search on here.

RHC generally recommends the J&E high compression. If I recall correctly it has .0015 clearance while the Wiseco has .003. Both work fine. If you get stock, 04 is the way to go. I'm pretty sure pump gas is OK for all of them.

There are also people using the Hotcams Stage II cam on here with no problems. Not sure if they recommend it with stock valve springs though, but again do a search. There is a wealth of information on here!!

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STOCK, STOCK, STOCK, I'M A SERVICE MANAGER AT A HONDA DEALERSHIP AND I'VE SEEN MY SHARE OF PROBLEMS WITH CRF450'S, PEOPLE THINK THAT BECAUSE IT'S A FOURSTROKE THE MAINTAINENCE ISN'T A ISSUE, BUT IF YOU HAVE MORE THAN 50HRS ON A TOP END I WOULD RECOMMEND REPLACING THE PISTON/RINGS AND THE ALL THE VALVES, TITANIUM IS NOT REAL GREAT WITH THE HEAT, THEY BECOME BRITTLE AND THEY ALSO STRETCH, POUND INTO THE VALVE SEATS AND BECOME OUT OF ADJUSTMENT, IF YOU ADJUST YOUR VALVES AND GET DOWN TO 140 OR LESS SHIM SIZE YOU KNOW IT'S ABOUT TIME FOR NEW VALVES, SIZES FOR THE SHIMS STILL WITHIN SPEC SHOULD BE ANYWHERE FROM 155-230, I'VE SEEN ON SEVERAL INSTANCES THE PISTON PIN AND SKIRT PULLING OUT OF THE PISTON, VERY EXPENSIVE, THESE WERE BIKES WITH 50 OR MORE HOURS ON THEM, BUT I'VE ALSO SEEN TRAIL RIDERS GET AMOST 100HRS WITH GREAT MAINTENCE. DEPENDS ON RIDER AND MAINTAINENCE SCHEDULES, YOU DON'T HAVE TO GO DIRECTLY BY THE MANUAL THEY ARE A LITTLE CONSERVATIVE ON HOURS EXCEPT OIL/FILTER CHANGES, HOPE THIS HELPS?

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By the way Dirt Rider not only rated the Hotcams Stage 1 a perfect 10 but also gave it part of the year status & they haven't ridden a Stage 2 bike yet.

It sounds to me like checking sources, info, & having personal experience with this stuff would be wise because the posts I'm reading are comparing apples & oranges. The stock piston is cast, the JE is forged, & the Wiseco is forged [different type of forging]. Each piston type & each different compression ratio will have a different clearance. The current Wiseco 12:1 is .0015" & the 12.5:1 is .002". When you move up into race spec pistons like these you add clearance because the increased heat [due to increased power] expands the piston more. As for Wisecos being too loose & slopping around I've never had it happen in 30+ years of professionally using Wiseco pistons, the only time I have seen it is when owners fail to properly check their bore size & stuck a "stock" size piston in their bike. The most common victims of this I see are CR250R owners. Buy the way the Wiseco CRF-450R piston is forged & has a skirt slightly wider/longer so it tolerates detonation better, lasts much longer, & the ring seal is better over time, in fact it will pay for itself with use when compared to the stock piston service interval. I've found that if the buyer follows the directions, properly installs/maintains the parts, & properly checks clearances they will have no problems with any of the above parts. The Stage 2 cam is a racing camshaft intended for Supermoto, desert, & fast motocross racing, that's it. All racing cams regardless of manufacture require careful installation & complementary parts for peak performance. The only owners I know that have had problems with the stage 2 failed to check or correct clearances like you must with all race cams, stuck it in the existing weak valvetrain, or they overrevved the piss out of it because with a Stage 2 it has a lot more power & rev-ability than stock. It is possible to run the stock valve springs with a Stage 2 if you carefully watch your RPM but that's a stupid gamble since it's common knowledge that the stock valves/springs are problem plagued to begin with so sticking a race cam on them isn't going to help things. My current test mule is an '03 CRF450R, Wiseco 12.5:1, Hotcam Stage 2, Kibblewhite valves, R/D spring set, & a 1/2 day worth of head work. It's very fast, very dependable, starts first kick cold or hot. I checked the valves at 30 hours & there was no clearance change, a leak down test showed the piston/rings seal better at 30 hours than a stock piston does at 5 hours. It doesn't overheat [i do use a HP rad cap]. I like this combo so much it's going to become my "trail" bike & the only change I'm going to make is swapping the Stage 2 for a Stage 1 because I prefer my trail powerband a little lower. Hotcams are too cheap/easy a mod not to give at least one a try. As for how long the stock piston lasts if you do a leak down test & measure the piston at 30 hours most are losing compression & some are loose enough that they are wedging in the cylinder. I've got photos of a destroyed 30 hour engine with a wedged piston skirt & piston black from blowby if you need graphic proof.

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