Bent Connecting Rod

Howdy Folks,

First post, but been lurking for a few months. I picked up a brand new 09' WR250R about 4 months ago. It had zero miles and was just sitting at the dealer waiting for a rider, so I gave it a home. I have been enjoying the bike and riding it every chance I get. I have done the following mods to the bike:

AIS removal
EXUP eliminator
K&N filter
GYTR pipe
PCV
DJ Autotune
Athena big bore (more on this below)

I was trail riding in the sticks with my buddy yesterday, and we ran out of trail. The trail dead ended into a creek. The water didn't look to deep (yeah right), so I decided to cross in shallowest part. I got about 5-10 off the bank and before I knew it the water was over the rear seat of the bike. It all happened so fast I didn't think to hit the kill switch. Long story short water got sucked into the intake and hydrolocked the engine. I've spent about 3.5 hours this morning tearing everything down. Much to my suprise, no sand appears to have gotten into the engine although there was plenty of water in the oil You can see from the attached picture that the connecting rod is bent at the top close to the wrist pin. I've since removed the piston and wrist pin. The piston looks OK. The wrist pin was a little hard to get out, so I need to check it for straighness. Amazingly the Athena cylinder and the top end of the engine (both cams, valves, etc....) look unharmed to the naked eye. I'm wondering if someone on the board might be able to tell me whether I can remove the crank/rod without removing the engine from the bike? I have the factory service manual and of course it says remove everything

The sad part of this all, aside from the obvious damage, is that I had just spent nearly 20 hours last weekend putting the Athena kit in. I only had a little over 100 miles on the kit (and just under 3k miles on the bike) before I went into the drink. The bike was running beautifully, and shortshifting (didn't want to rev it too hard until I had some more miles on it) it was running neck in neck with my buddy's DRZ. I put the kit in myself. It's the first time I've been that far into a motorcycle engine, but I'm no stranger to wrenching as I've drag raced cars for years and built numerous engines (Mostly chevys and one Furd, many transmissions and rear ends).

Any pointers would be really appreciated. I'm going to go over all the parts with a fine toothed comb and replacing anything that looks suspect. Right now it doesn't look too bad. I just need to get the crank and rod out with as little drama as possible. I'm hoping Athena will sell me the parts I need (head gasket, wrist pin and new retainers, etc.....). I'll order all the Yami parts from Yamaha Sports Plaza unless someone has a better suggestion.

Not looking for any sympathy from this post. It sucks, but it's my fault. I learned two lessons yesterday.... 1). The kill switch is there for a reason, and 2). When in doubt determine EXACTLY how deep the water is before attempting to ride through it.


Anyway,

Thanks for any pointers or info....

-Kenny

Damn...that's a rather nasty thing to have happen...yeah these bikes don't really like swimming. Not sure what happened but your pic didn't come up. Keep us posted on how everything turns out on this; you aren't the first one to have gone scuba diving with the bike and have it drown on you. Good luck!

Depth is one factor. How swift it is movin', another.

I had a friend lose a brand new, never to be seen again bike in a stream crossing. Another we had to fish out downstream. Lucky we had the ability to ride the bikes down parallel to the river and then have rope to get to him. Our only visual on him was a helmet bobbing downstream. Both were lucky to survive.

Although it is difficult to calculate, water moving ten feet in 2.5 -3 seconds is somewhere around 5 knots (if I am remembring correctly).

In such cases, and depending on the downstream topography looks like, one might consider otherwise for anything axle deep (or greater).

That sucks, man.
However, sounds like you learned what I did the hard way, as well:

Better to be cautious with unknown terrain (or water crossings), return with a functioning bike and body, and maybe wonder if I should have thrown caution to the wind vs. going for it, finding out you didn't know the terrain as you thought you did, and really screw something up.

Yeah, the engine comes out of the frame, the crankcases (which are vertically split, with left and right halves) come apart, and then you remove the innards.

Thanks for all the replies and advice. What specialty tools are need to separate the crank and rod? The PDF service manual I have shows two tools are required. Anyone know where I can buy the tools? I'll dig around a little more and see what I can find.

A decent Yamaha dealer can order the tools shown in the Yamaha Service Manual from the official Yamaha tool supplier called K&L Supply. :)

quick66 wrote:

What specialty tools are need to separate the crank and rod? The PDF service manual I have shows two tools are required. Anyone know where I can buy the tools?

I don't know the policy of MC service departments in this regard, but it seems like you'd be able to take the crank/rod assembly to the Yami service department and have them do the separation and replacement of the rod (you supply the replacement parts). Probably be cheaper than buying the tools that you are likely to use only once.

Did some calling around today to see what my options are. Called the Yami dealer where I bought the bike. Their shop rate is $89 per hour and said it would be a 1.5 hr job to separate the crank halves, R&R the rod and true the crank. That doesn't include the parts cost. The service manager actually suggested that a better route to go might be to just buy an OEM crank assembly from Yamaha. I checked the price on that and it's about $240. I think I will go that route for peace of mind. One thing I'm having trouble with, however, is finding where to buy an Athena top end gasket set for the big bore kit. I looked on Athena's website and it says the part number for the gasket kit is P400485850017. I found a few sites selling that part, but when I look at compatible vehicles listed for that part it only shows a Yamaha YSR-50 (50cc) bike. And the bore on that from what I could tell is 40mm, so that can't be the right gasket set. Anyone know where I might be able to purchase the right basket kit for the Athena jug?

Thanks...

Yamaha dealers can order it like any other part with this part number:

GYT-0SS56-31-21

Thanks very much, YZ!

Anyone have any experience with Hot Rods crankshaft kits? I ran across the crankshaft kit that the offer for the WRR. Looks like a pretty nice kit. I like the fact that the small end of the rod has a bushing as opposed to the stock rod without one. I also noticed that they offer a 3mm stroker crank for the WRR. Not sure what all would be invovled in stroking the bike. I would assume I would need a thicker head gaster to maintain adequate P/V clearance and quench. Not sure how the extra 3mm of stroke would affect the timing chain length and camshaft timing. I want to get the bike back together so I can ride soon, but would like to make the bottom end more bulletproof if I can in the process.

I don't know if Hot Rods fixed the issue yet. But I would read this thread over on SMJ first.

http://www.supermotojunkie.com/showthread.php?112765-WR250X-Motor-Noise-Still

Well, I decided to go with the Hot Rods stroker crank assembly. I talked to the folks that make the stroker kit, and they openely acknowledged problems with the cam gear on the OEM replacement crank kit. They said they've had no problems with the stroker kit. I've got all the parts ordered and will put everything back together once I have everything I need. I'll post back my results when I get the bike up and running. Maybe I'll be the first person with a WR306R

What did they ding you for the stroker crank?
If I were you I would replace the piston, the force that bent the rod was transferred by the piston and wrist pin, it is too hard to measure possible distortion of all the critical areas, it would bug me every waking moment I own the bike if I left it in there

0007onWR wrote:

What did they ding you for the stroker crank?
If I were you I would replace the piston, the force that bent the rod was transferred by the piston and wrist pin, it is too hard to measure possible distortion of all the critical areas, it would bug me every waking moment I own the bike if I left it in there

I shopped prices on the stroker crank as best I could. Hot Rods didn't have any in stock. I found a couple on Ebay for ~$380. Dennis Kirk had the best price I could find at ~$330. I'll take your comment on the piston under advice. I can't see anything wrong with the piston from a visual inspection, but I understand your concern. I'm going to magnaflux the piston and check all the ring lands/webbing. Might be worth it to get another piston/ring set just for peace of mind. Thanks....

Well, thought I would provide an update to this thread. I ended up tearing the engine down completely. The only damage to the engine was the bent connecting rod. I installed a new set of crank bearings and the Hot Rods 3mm stroker crank. Mocked everything up and checked the clearances to make sure that the added 3mm of the crank didn't cause deck/piston-to-valve clearance issues. Got the engine completely reassembled last night (been working on it in my spare time for weeks). Will put the engine back in the bike this weekend, and then put the rest of the bike back together. Baring any problems with electrical components from the swim I hope to be riding again soon. Here are a few pictures from the teardown/rebuild.

Lookin' awful purdy. :)

I'm interseted to hear about how it feels with the new crankshaft/stroke.

Wow! Hope it buttons back up without a hitch. We want to hear all about it.

Sarah

If I'm doing that math right that should bring the bike up to 306cc....

Make sure you report back on it, I'm concerned about the compression ratio on pump gas. The Athena kit is normally 12.9 IIRC, so with the stroker kit it's going to be getting up there.

Arkmage wrote:

If I'm doing that math right that should bring the bike up to 306cc....

Make sure you report back on it, I'm concerned about the compression ratio on pump gas. The Athena kit is normally 12.9 IIRC, so with the stroker kit it's going to be getting up there.

I had calculated it at 316cc, I better recheck my math :) The Athena kit.documentation shows 12.7:1, but you're right it's getting up there for pump gas. I'm hoping the improved cooling of the Athena cylinder will keep temps reasonable, but I'll be keeping an eye on the plug for any signs of detonation. Too bad E-85 isn't more readily available around here (assuming the fuel system could support the fuel and increase in demand).

EDIT: You were correct.
306.24cc to be exact :)

Stock is 77 dia x 53.6mm stroke

Athena is 83mm dia

Stroker crank is + 3 to stroke so 56.6

Did you do your math with +3/side making it 39.6?

I was hoping someone would do this soon... I've been seeing those cranks around and was really curious to see what they'd do. I'd say you would probably benefit considerably from cams at this stage.

Arkmage wrote:

Stock is 77 dia x 53.6mm stroke

Athena is 83mm dia

Stroker crank is + 3 to stroke so 56.6

Did you do your math with +3/side making it 39.6?

I was hoping someone would do this soon... I've been seeing those cranks around and was really curious to see what they'd do. I'd say you would probably benefit considerably from cams at this stage.

I used Pi/4 x bore² x stroke / 1000 Rechecked my math and it comes out to 306.24cc ;)

Agreed on the cams... problem is I couldn't find anyone making them for the WR. Hot Cams makes aftermarket cams for the YZ, but not the WR²

There are a few companies that will custom make them for you. Try calling hot cams, tell them what you have, and see if they can give you a quote.

One thing that I found interesting when checking the clearances was that with the stroker crank the quench ended up around .042". The stroker crank is +3mm, or about .120". I'm no expert on motorcycle engines, but I have quite a bit of experience with car engines. In a performance car engine build we always try to keep the quench are around .039". Doing so promotes better combustion and reduces the chance of detonation. The quench area on the stock engine must have been around .160"!!! Maybe there is something different about motorcycle engines, but I honestly can't imagine that being the case. In my mind, even though I'm adding compression with the increased stroke I'm getting the quench area closer to where it should have been all along. Thoughts?

P.S. Got the engine back in the frame over the weekend. Still have to reconnect all of the electrical connections, install radiator, etc... Hoping to get it fired up this coming weekend. Will keep everyone posted.

I wish I could offer some opinion on the quench question but it's out of my league. My degree is in chassis and suspension, I've pretty much exhausted what I've learned building motors and hanging out with the power train guys.

For me, as long as the valves and the pistons don't occupy the same space at the same time, the rest can be handled with tuning :)