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Discussion Starter #1
hey guys new here ,i got an 07 450er on trade recently well first time out f my driveway she seized up so got it down to split cases both are destryed rod bearing blew up now here comes the big question, im gonna have to buy a new bottom end cases so,i have a weisco stock stroke crank for a crf 450 from a build i did a few years ago its brand new. now mostly everything i could mesure was just about the same as the crank that came out of the trx minus the shaft that would come out of the right side case now is the lenght of that only longer on the trx er model to accomadate the electric start gears ?? the flywheel fits on the crank that side is the same as trx crank so,If i could use this crank would i be able to just ditch the electric start and go kicker only?i have a whole kickstart assembly from the crf i understand the trx kicks forwards and the crf kicks back ,but from what i can see on pictures its just one gear that changes the direction of the kick so i would save 300+ dollers if i only had to buy 1 gear ,and for the cases do i need cases from a er model to match the cylinder height and head ?is there a big differnce in cases from looking at parts fiche i see the differnt trx models have differnt part numbers for the cases and lastly,i also have full transmision from the crf gear tooth counts are differnt then on the trx but looks like it would all work would there be an up or downside to changing tooth count in the trans?,gonna be slowly rebuilding over the next couple months until spring just trying to see what i can use or if im gonna have to buy a new crank along with the cases thanks guys!!
ps ,sorry for the run on sentences and alot of questions hope someone has some input for me.
 

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I would just get the correct crank, and correct cases... Unless the part numbers are the same or cross compatible... then sure you can mix match what ever you want. You can use rockymountainatv/mc website and look for the part numbers and see what are the same and what not.

If I were you I would just get an OEM crank and OEM bearings and stay away from after market cranks and bearings. As for buying case half's... I would just buy the ones for the TRX450ER. The reason I say this is... One I have no clue what year CRF450 crank you have... Two the CRF450R and CRF450X have changed so many times over the years that the cranks are all different sized Rods and such, also not to mention the Wrist Pin holes very in size I'm sure.


The CRF450X is the closet to being the twin almost to the 06 to 14 TRX450ER, but from what part numbers that I just looked at they're not the same, though yes they look identical.


Here is what I am getting at. The TRX450R only changed once from 05 to 06. Basically you can swap parts from any 05 to another 05 all day lonf but you can't use 05 pars on a 06 or newer machine, same goes with the CRF450X and XRF450R and so on they look the same I'm sure maybe parts are compatible between a 2004 and a 2005 CRF 450R or X but Honda changed them a lot every couple years... So I don't know which CRF case could be compatible (If even compatible at all) with the 06 to 2014 TRX450ER, and even if you did the next question is will the Rod on the CRF ecrank have a shorter and or longer stroke then the TRX? For all we know the case it's self may sit higher or lower where the cylinder sits on the case then when assembling and the piston might sit to high or to low in the cylinder (Once again if the CRF Crank did fit the TRX450R cases). I'm sure there are guys out there who have custom built these engines exactly how were are thinking but cost a lot of time and money to do so that is not necessary unless you're building a strictly drag/race bike of some sort and have the tooling to do so.


The TRX450R and the CRF Transmissions Ratios are totally different, they would maybe fit and work but who knows how weird the gear ratio might be when you finally ride it you know since the TRX450 and the CRF450 have differnt sprocket gearing as well, You'd hate to find out it's geared strange then you gotta tear in back down again.


As long as both of your crank case half's are not damaged you should be okay to reuse them. But if you know they're destroyed then of course go ahead and replace them.


Don't take this as me trying to shoot you down or anything but what I would do is sell that crank you currently have use that money to buy a new TRX450ER crank, I would at least start there. just get all of the stuff to do it right save your self a Head Ache.
 

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Discussion Starter #3
yea i figured as much, i know the cases are diffenrt i have a broken crf cases here theyre not the same as the trx . but i really just wanted to know if i could use the crank i emailed a rep for weisco to ask them if the vrank woukd work since buying a new crank if i didnt have to would be a waste of money ,but i havent gotten a reply yet so i was wondering if someone here has done it the crank i have for the crf is from years 2002-2004 but how would i go about mesureing the rod lenght to see if it will clear height wise the make drop in stroker cranks which would change height without having to add anything oir maschineing anything ,and the gear ratio i new would change but i was wondering if would be for the better or worse? how does one figure this out ??thanks for the reply though and does anyone have a lead on some cases cant find any on ebay people are asking more for used ones then what the would cost new its crazy and theres only like 4 ads no ones parting any out in my area :(
 

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Pretty certain the crank will not work as when you remove the electric starter gear there is actually a spacer that goes in its place and if it is not there the other gears will not line up properly. I would look on fb and try to find cases, I know there are a couple places out there that part out bikes that keep a fairly good stock of parts. On the trans stuff you can search the bike info to see what the gear ratios are but they are going to have to be changed in a set and make sure that all the splines, dogs, forks and all line up properly. I do not know of anyone putting the crf gears in a trx, not sure if it is something worth trying to do or not.
 
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