crank seize up

Ok,I need help--the rod seized on the crank. OH MAN! What possible causes? Oil changed regularly and coolant in good condition. Bike used mostly on the street. Less than 3000 miles. Bike has been uncorked and was running great. It appears the piston skirts are scored. Does this mean the nickel sil coating is gone? The cylnder looks good (no scoring. A complete tear down is now in order isn't it?!

Ouch! - too bad. Yes a complete teardown would be my first thought. Cylinder is probably ok. My guess on cause would be no oil. Look at the screen in the tank and pan and see what you find. What was the first clue that something was wrong?

Look for the silver lining - now you can do a Carrilo rod and a 715 kit!

Look for brass shavings in the oil. Sure sign your crank went. Its a common problem for the BRP. Team Honda rebuilds their cranks every 750 race miles. The OEM crank is not rebuildable, but there are a couple companies that offer super tuff and rebuildable cranks for the pig. You are looking at a 1200-$1400 or so rebuild job. Rob Barnum is a good guy to go to for this type of thing...

Where would I find parts for the 715 kit? Is this just stroking or does it require overbore? Would this add to the crank weakness? I really like this scooter; however, in all the information I read about the BRP no one once said the cranks are a weak point. Is this problem going to happen repeatedly? If so the reputation for bullet proof is not deserved!! As said, most of my miles are on the street as a hooligan and all that implies. After repair should I look for a more durable bike?

Baja Designs is reported to mention a 715 kit in their new catalog. Thumper Racing says a 710 kit is in the works. This is all done with the piston bore.

If you do a search of this forum you will see very few mentions of crank failures, (or any problems really). This bike is as bullet proof as any race bike ever made. My guess as to why your crank seized, (your bikes crank :)), is not in a Honda design flaw but a chain of events happening that you may or may not have contributed to, (low or contaminated oil, oil filter put in the wrong way, etc.). Pull the motor apart and I bet it will be clear what went wrong.

Make sure to have the new crank balanced. I know Rob Barnum balances & can also blueprint cranks for XR650R's and other bikes. He also offers an optional cryo treatment for various engine parts including the crank. They also offer an optional aerospace coating the military uses to reduce friction, reduce wear, reduce galling & extend the life of valves, oil pumps, bearings, gears, cylinders, etc. When I went to pick up my suspension from Rob many months back, he showed me various engine & suspension parts that were recently coated for customer bikes he was building and these parts felt very slick as if they were super smooth and slightly wet, but yet they were completely dry.

Rob Barnum has two XR650R engines in his shop right now with seized cranks! Its not 'common'-i shouldnt have used that word in my last post-Dutch is correct, the thing is VERY reliable. But crank seizing is 'known to happen' on the 650-and like tuliping valves, its a 'minor' emerging issue as the bike gets a few miles/years on it...ask any mechanic who works on 650R race bikes-in fact its Rob Barnum who first pointed this out to me!! :)

A 715 kit would DEFINATELY put more strain on the crank. If you have to buy a crank anyway-why not get a tougher one!? Its no accident there are tougher 650R cranks on the aftermarket :D has some info on the biger piston. 710 and 715 kits have been raced in Europe for at least a year- so worth asking them what all they have done to the engine. Lightened? Balanced? Ceramic bearings? Solid film lubricants? I'm thinking of doing some of the same to mine one of these days. Keep us posted if you bore yours out.

Interesting to read the Thumper and BD kits are all bore jobs. Any idea if they went with LA Sleeve or Nikasil? I havent seen the 715 piston offered yet in the catalogues. Must be a 104? Anyone?

Nice to see these posts that get beyond jetting, tire choice, and air filter issues!!



any chance of oil starvation during a long wheelie?

I'd love to buy a stronger crank. Who makes them? Thus far in may teardown I have found brass from the con rod bearing so the crank and con rod need to be replaced. The piston skirt is scored (replacement required). So far it looks as good as can be expected. Tomorrow I split the case--wish me luck. As far as long wheelies, I wish I could do them but you go quicker from corner to corner if it is on the ground.

Just FYI- found this today on the yahoo 650 site!!



From: "John Hermann" <> | This is spam | Add to Address Book

Date: Mon, 21 Jul 2003 09:35:18 -0400

Subject: Re: [XR650R] Bottom end bearing problem?

I am roadracing my 650 for the first time this weekend, and have been told that the bottom end rod bearing is the weak point on the motor. I know that some racers who motard their bikes (using the HRC kit) have had a few problems, but my bike is only uncorked. XR's only sells an upgraded bottom end bearing and Carrillo (sp?) rod kit (which I may look into over the winter). Anyone have any problems with their bottom end rod bearing?

--I guess you arent alone! :D Follow his advice and check out Xr's Only. Their new XR650 HD bearing/crank set up seems to be the way to go. They have info on Carrillo and Hot Rod cranks too. The HRC kit should include a tuff and rebuildable crank!

Ultimate engine:

715 piston

XR's HD crank

Stage 2 cam

SS valves/ HD springs

Ceramic bearings! (not yet available, but I'm working on it!)

Balanced, ported

Bored out (42mm) QS carb/Uni filter/opened airbox, side cover cut out...

Steel (not Ti or ceramic!) hi flow headers

HD clutch

15/45 gearing. 62+hp/277lbs? 112mph top end? 4th gear wheelies!! :)

Rob Barnum can build you this engine!

Any body know how much that after maket crank cost?

Sounds like the thing to do. any idea if there available in long stroke versions.

And I agree with "IRONDUDE" it is nice to hear about the big mods, so keep posting all the performance stuff.



00 BRP cam, piston, pipes, and more, for road racing the BRP! :)

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