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Broken crankcase, can I fix it myself?

42K views 216 replies 7 participants last post by  Kubi07 
#1 · (Edited)
Broken crankcase, could I fix it myself?

Long story short, I blew my motor and now there’s a hole right where the balancer is supposed to be on the right crankcase. So, I would basically need to buy a new right side crankcase and transfer or replace everything to it and I wanna know if it's doable to do myself even though I don’t have much knowledge as to how I would do that. I have the service manual but want to know your guys’ opinion if it’s something that’s possible. Thank in advance.
 
#2 ·
R&R of the motor is a pain in the arss if you ask me . I plan on doing it my self again this winter . for you it would be a great time to do some mod's
 
#4 ·
install stoker crank . may want to replace oil pump , cam chain
 
#6 ·
Can install a big bore later. That does not require pulling the motor and splitting the cases. The crankshaft does. Hot Rods +3mm. Do a search on this site. You may need to notch the piston skirt for the connecting rod. Cataway has some pictures of how he notched his piston for clearance.

This is the cheapest I found the stroker crank.

TRX700XX Hot Rods Complete Bottom End Kit
 
#7 ·
Yea, you’re right. Are there any other options out there for the stroker? I don’t mind spending more for a better bottom end kit. I just don’t know which ones are good.
What do you mean about notching the piston skirt? I’ve tried looking for cataway’s thread but couldn’t find it.
 
#8 ·
#9 ·
Thank you M_Quick. Upon reading that thread another question came up. Would I need a fuel programmer if I install the stroker? The ATV right now is all stock except for the K&N air filter. So I don’t have an exhaust or fuel programmer or know how well to use one.
 
#10 ·
I would have to say yes. And if you purchased the controller through EHS racing, just let Eric know your list of mods, and he probably would pre program the controller for you with the proper map needed.

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#12 ·
Goto his website click on contact information and call him directly. That way you can talk him into a free t shirt or something with your order.

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#13 ·
Lol okay, sounds good. Now that I know what to upgrade, let’s go back to my original question. Is it possible for me to tear everything open and put it back together with no problems? I don’t really have much experience when it comes to stuff like that. It I have been thoroughly looking at the service manual and it seems doable. What do you think?
 
#14 ·
Depends on your knowledge, and or expertise. I've tore down many auto engines in the past, and I've done a lot of work on the quads I've owned. I have never split a case, and have herd it's a pita! If you have the proper work space, & tools, including but not limited to a parts washer, then I'd say you should be okay. There may be a few specialty tools needed, for pulling crank bearings and what not. I had a heck of a time getting the cylinder head cover separated! I tried and tried and then my wife came out, and pointed at a spot and it came right apart with one easy tap! lol.
 
#16 ·
I am grateful I have a overhead lift to get the motor back in the frame . oh I feel you can take it apart ,but after you get in to it you may ask your self , why did I do it .
 
#17 ·
If your engine case is cracked like you said, then you have nothing to loose by taking it apart. I'm interested in knowing what came apart to crack the case.

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#18 · (Edited)
Yea, you have a point. I'll take pics when I get into it. Might take a while since I'm kinda busy. Just taking apart everything else right now to get the engine out.
And I also wonder what happened. When I drained the oil, coolant came out first followed by oil and some metal shavings.
 
#19 ·
sounds like piston came apart.
 
#21 ·
Man, most of you guys got it for 2500? I knew I over paid for mine when I bought it earlier this year for 3600. But I really appreciate the link. If I can’t figure it out in my own and completely ruin it trying to fix it that’ll be what I have to get. Only thing I saw was a rebuilt motor for 2800, this is a way better buy.
 
#22 · (Edited)
2,150 for motor isn't bad, but only 30 day warranty. Makes you wonder why he parted it out, and has no other 700xx parts listed! And you didn't even get one season out of your motor. So I'd roll the dice and try and fix your motor. Depending on what you replace inside the cost will be probably less than 1k. Making the $2800 rebuilt motor sound better than a oem was running good for $2150. But who knows how well of a job they did on the rebuild? Just my opinion, but I'd try to rebuild your own.
 
#23 ·
Yea, and I'm planning big upgrades if I rebuild it my own too. Gonna definitely rebuild the bottom end with the +3mm stroker and gonna go big bore kit as well since I'm already there. Change out the exhaust since my stock one is all old and rusted plus it'll be dumb to do engine work and not even change out the exhaust. Only thing I'm worried about now apart from rebuilding the engine is how to go about the fuel programmer. I have no idea how to set it right and I wont be going with the big 3 from EHS since I really like the HMF blackout exhaust. It's a better deal and looks better than getting the Barker's exhaust powder coated and ceramic coated from EHS.
Also, which fuel controller would you guys recommend? It seems like they're all the same. Or are there one's that do extra stuff that the others don't?
 
#24 ·
I love the HMF black out exhaust too! As far as programmers go the PCV is a good choice. But quad would need tuned, either by adding the auto tune, or on a dyno, or d/ load and install a map from power commanders Web site.

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#25 ·
I've been thinking PCV as well. You think it'll be okay to break in the engine without a tune until I can get it tuned professionally?
Oh and another thing, what's the best way to take off the spark plugs boot? It's in there tight and I don't wanna break the cable.
 
#26 ·
The spark plug boot is a pain for me as well. It should be pretty easy to get a hold of once the tank and shield is removed. As far as the tune, I'd d/load one from the site. They have at least a couple with HMF pipes availible to pick from.
 
#27 ·
The auto tune is worth it, IMO. For the price it is about what you could pay someone to put on a dyno and it will adjust itself every time you do a mod.

Just will need to find someone to install the bung on the header for the sensor.
 
#28 ·
What’s so different about the PCV compared to the other ones? Is it the only one that’s like that? How’s the installation on it? Seems like you need to splice it?
And when I took off the throttle body I noticed it was a little bit open, I’m guess that’s normally since the engine needs to breathe right?
Oh and I saw that if I get the PCV from fuelmoto.com, they’ll map it for me so that’s good.
 
#29 · (Edited)
Pcv compared to a dobeck, you can get a full range tune/ with a dyno. Dialing in the air fuel ratio to a perfect mix, all the way through the rpm range of the quad. Vortex also makes a programmer, but I'm not familiar with them, other than they cost more. Pcv can also hold two maps, and you can install a switch, to toggle back and forth between the 2 loaded maps.

Random screen shot of tuning screen below.


As far as installation on a Pcv, yes you have to splice 1 wire. And the wire for the pcv is a lot shorter than the dobeck style controllers, so you have to leave the pcv ontop of the battery cover. With a dobeck you can put it to rear of seat, in the air box, or pretty much where ever you want. ? Fuelmoto will send it mapped for a stock trx700xx or will they remap it somehow to your mods? All Pcv for the Trx700xx will come with whats called a zero map, "for a stock quad".

Also not sure what you mean by throttle body open?
 
#30 ·
What I mean about fuelmoto mapping it is that you tell them the mods you have and they'll give you a map for what you have. And if I decide to add more parts, they offer unlimited maps. So I feel like that's a good way to go.
And what I mean by the throttle body is that it isn't fully closed, there's maybe like a millimeter left open. I'll take a pic when I get a chance. I'm almost done taking out the engine, just need to take out the oil tank. You were right about the spark plugs being a pain. Wasn't bad since I had it all taken apart but it would've sucked to do all that just for a spark plugs change. That also makes me wanna change out the spark plug too. Any suggestions? And thanks for the reply, I thought you gave up on me haha.
 
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