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Crank Disassembly
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Posted by: GJG083---------------------
Hey everyone,
I am new to the forums here and I just picked up a an 88 KDX200 which is a project bike. Major work to be done: engine rebuild, top and bottom end...as far as bottom end goes how do you split the crankshaft halves to access and replace the rod bearing? I am assuming you need to press the pin out and is this nearly impossible to do, and how about reassembling it afterwards...I guess im looking for a difficultly level here to see if I can do it or I need to send it out somewhere? I did just order a service manual but I was hoping to get some others experience doing this.
Also anyone have experience with spec bolt hardware kits? they claim to have majority of the oem style bolts not sure i can justify spending 50 bucks on it tho...
Posted by: JohnRaven.exe---------------------
I took the bottom end of my '86 XT350 to the local shop. They had to ship it to a guy that does all their crank splitting for them. It cost me around $125 for them to ship to them and split it open. To replace the bearings, rod, and a few other parts... + labor came to just under $700.... since you have a smaller engine, maybe it will be cheaper(?) Anyways, good luck with the rebuild!!!
Posted by: mideastrider---------------------
You can disassemble the engine and split the crankcase but it’s a big job. When you get your service manual it will clear up a lot of your questions and you will get a better idea if you want to tackle it yourself or send it out somewhere. You will need some special tools though, like a flywheel puller which is not very expensive. To rebuild the crank you need a bearing separator and a hydraulic press to remove the main bearings and the bottom rod crank pin. Those tools if you don’t already have will cost more than a shop will charge to rebuild the crank for you. You can save some money though by doing all or part of the work yourself.
Posted by: bad96z71---------------------
well it can be done yourself but ya gotta have the tools, i came to this delima about 2 weeks ago with my kdx250, i had all the tools to do it and do it right, but also was worries about screwing it up i had chose to take it to the bike shop but after i thought about it some more i just did it myself , but i also work in a fab shop with all tools that you need , its just risky some would say but the labor was free for me and i have it all with in specs so its all good,the bike shop said 100-150 if i took the crank in to them that was splitting it and putting a new rod in ,woulda been about 250 total with me buying a hot rods assembly, but instead it was only 81$ off the big auction site , as far as splitting the cases its pretty simple as long as you take your time look it over see what ya need to remove to get that crank out service manual will help , maybe you will get lucky an get a bike shop to split the crank and put a new rod in for a good price good luck AND HEY MINE RUNS NOW HAS ABOUT 8 HOURS ON IT 
Posted by: GJG083---------------------
I have the engine apart...just trying to make a game plan for that crank
bad96z71, Glad to hear it worked out for you...I figured a hydraulic press might be needed, think I could get away with using a arbor press with a long handle? haha Can I ask how you lined up the two halves of the crank? Also did you balance the whole assembly by weighing the rod?
John, I looked up the price for a new assembly for my bike straight from kawasaki and its like $400, so if I couldnt get it done for less than that I would just buy a whole new crank assembly.
Thanks for all the advice
Posted by: glad2ride---------------------
Congratulations on the bike!
I don't think that you will be able to use an arbor press to remove or install a 200cc crank pin. Someone who rebuilds them told me that it would take a 25 ton press to do a 250cc pin. I got the general impression that he meant NOT a Harbor Freight press either, but a real one. :-)
Send it to www.r-bdesigns.com ( I think that is it (google if not) (www dot r - b designs dot com if it doesn't come up right). It's around $100 or so for parts and only $30 labor, plus shipping both ways. Not a bad deal at all.
Posted by: Zenith---------------------
I'd also say it would be a lot easier to just send it somewhere to be done, over here it would be no more then $140 for the conrod kit and maybe $80 for the labour so it shouldn't be more then that over there.
Have you looked at a complete crank from Wiseco? They tend to be quite reasonably priced compared to OEM...
Posted by: bad96z71---------------------
well i used a hydraulic press on mine , and mine was made easy i guess ya could say it had been apart before and had scrive marks to line them up, i built a jig when i pressed it all togther and checked it all from there everything is great , i wouldnt think you need in a new crank just a rod and pin glad2ride looks like he has the way to go that cheap good luck
Posted by: adam728---------------------
I've seen some interesting things done, but don't attemped a crank rebuild without a hydraulic press and a jig to true the crank in.
Just an interesting note. I broke a crank on an Artic Cat EXT580 sled before. Bought just the PTO end and we were going to do all the work at the Polaris dealer I worked for. But we didn't have anything that would work to press that end off the crank. The resident "old guy who's seen it all" wacked a few wheel studs out of an old axle and did some fancy grinding, and used three of those to press the crank apart. Put it together like any normal crank and trued it up. I just thought his specialty tool choice was interesting.
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