Engine gets tight

2006 450yzf,

Changed oil and filter (engine was run for about five min. after oil change), a good cleaning and put to bed for about six weeks

Started bike up to get ready to go riding, it run for about 30 seconds got tight and quit.

Checked oil (it was ok) started again and got tight and quit again, kick starter was hard to move. Let it set for about five min. and it turns over normal. Drained oil checked filters all are good. I am thinking maybe cam bearings??

Any ideas..

I had kind of a wierd thing happen to me too. Same thing, didnt start it for like three weeks, tried to kick it over and it acted like it had a bad bearing. kept trying and got more and more easy to kick, finally started. Now I start it once a weekend and have had no problems. Maybe from oil draining to the bottom of the engine and not lubed up?

What kind of oil filter are you using? If the bike has the Ready Racing oil filter cover, the filter can be installed backward, cutting off the oil flowing to the engine.

If that's the case, you'll need to inspect the cams and the cylinder wall/piston.

Might also be wise to look at the coolant.

No, filter is installed correctly, it has the factory oil filter cover.

Gray not sure who you responded to, but my oil filter was installed correctly and coolant looks good.

thmperpower, I tried running it three times and it did the something each time. I would start it and let it run just above an idle after about 15 sec. it would start to slow down and then quit. When I tried to restart it would not turn over, after about two min. it would start to turn over but fell tight then after about five min. it would turn over normal.

Sorry, I have no idea. doesn't sound like the same problem I had.

When I tried to restart it would not turn over, after about two min. it would start to turn over but fell tight then after about five min. it would turn over normal.
I think you're going to need an exploratory tear down here.

Well I finally got some free time to tear this thing down, found a bad main rod bearing.

While it's apart any updates or anything special I need to do when I have the cases apart.

Do I need any special tools to split the cases?

Should I have the crank rebuilt if so who does good work( I live in Vegas) or get a replacement.

It’s a 2006 yz450f

Thanks

Well I finally got some free time to tear this thing down, found a bad main rod bearing.

While it's apart any updates or anything special I need to do when I have the cases apart.

Do I need any special tools to split the cases?

Should I have the crank rebuilt if so who does good work( I live in Vegas) or get a replacement.

It’s a 2006 yz450f

Thanks

I was able to install my rebuilt crank with a freezer. I suggest replacing the case bearings since you are in there, they are pretty easy to inspect and just as easy to replace. I dropped the new bearings into my freezer for an overnight chill after popping the old bearings out, pressed in the new bearings while the crank went for a little nap in the freezer, and then dropped the frozen crank in after everything in the cases got up to room temperature. I did put a little heat to the cases before pressing the bearings in, but I don't think that it was that necessary.

I used "Mr. Crankshaft" to rebuild my crank in September, $189.95, including all parts and return shipping. I stuffed my bad crank into a USPS flat rate box and shipped it for ~$13, including $500 insurance (replacement cost). Basically, right around $200 for a rebuilt crank door-to-door, plus a couple hundred in new bearings all around (and gaskets as needed, etc), I think that I was finished for less than $500. Oh, I put some WR400 gears in while I had it open, quite the transformation for a woods bike. Check your wrist pin, too. Replacing that is cheap insurance.

Thanks for the info, I will look into Mr crankshaft.

Did it take any special tools to split the cases. I lent out my manual and am waiting for it to return(should have it tomorrow) that is way I am asking about the tools.

Thanks for the info, I will look into Mr crankshaft.

Did it take any special tools to split the cases. I lent out my manual and am waiting for it to return(should have it tomorrow) that is way I am asking about the tools.

The manual says yes, I say no. I did use my 6" vise and a couple of large deep sockets to press the bearings in, so for the bearings it may require some ingenuity. But the crank was easy to pull/install with the application of heat and cold as required.

I did use my 6" vise and a couple of large deep sockets to press the bearings in, ...
Heating each case in an oven at 250 ℉ and pre-chilling the bearings in a freezer make this a good deal easier. Know that the bearings will almost instantly "grab" in their bores unless you drop them perfectly straight in, but it's OK to use a brass punch on the OUTER race to drive them in to the bottom of their pockets. If you can find a large piece of steel tube that fits the race, that works even better.

This applies to all of the case bearings. One thing that will probably be needed is a blind bearing remover for the left hand main shaft bearing. I have had some luck heating the case and slapping it inside face down on a bench to do this, but it's a little risky using uncontrolled heat, and it doesn't always work.

Always let the cases air cool naturally.

The crank itself requires more than just a press to replace the rod/bearing/pin. There are jigs involved, and a truing process to be executed.

Heating each case in an oven at 250 ℉ and pre-chilling the bearings in a freezer make this a good deal easier.

Yep. You can also use a wood stove, radiant heater, sunshine (depending on season and location), hair dryer, etc. Another method is to degrease the case, put it in the dishwasher on hot wash, hot rinse, and hot dry. A little bit of dishwashing liquid in the cup and you are set. It will be nice and toasty, as well as clean and dry. Nothing like having a clean engine ready to assemble and install!

going to be putting it back together this weekend(if the crank comes in), what is a good sealent/gasket maker to put onto the case halfs before I put them together??

going to be putting it back together this weekend(if the crank comes in), what is a good sealent/gasket maker to put onto the case halfs before I put them together??

Anything non-hardening. I currently use Yamabond 3 or 4 (can't remember exactly), or Permatex makes a motorcycle specific non-hardening sealant. I don't recommend silicone, because it is harder to remove and leaves a residue that may affect future sealants. Plus silicone is a bit harder to clean up, in my opinion.

I really recommend a practice run or two before you apply the sealant and assemble the halves. If you can get it all together twice in a row without getting it stuck or crooked, then you have a high chance of success upon final assembly. There is not much worse than having to pull case halves apart and then removing and reapplying sealant after you smeared it over half of your shop and both cases. Not that I would know anything about that...

Good luck, and keep us updated.

Yamabond is the specific sealant called out for this, but any sealer designed to seal machined joints without gaskets will work. Most ordinary RTV silicon sealants are not suitable for this because they don't cure well in the absence of air, and also don't resist being squeezed out of a machined joint altogether very well. Furthermore, they are not the least bit tolerant of oil residue on the joint.

Permatex makes a retail product that functionally duplicates the special RTV formulation used by GM professionals that is as superior to common silicon sealers as a Mercedes is to a Yugo. It's called "The Right Stuff", and a good auto parts store will have it.

Question? How many hours on engine And what kind of oil are you using?

2006 450yzf,

Changed oil and filter (engine was run for about five min. after oil change), a good cleaning and put to bed for about six weeks

Started bike up to get ready to go riding, it run for about 30 seconds got tight and quit.

Checked oil (it was ok) started again and got tight and quit again, kick starter was hard to move. Let it set for about five min. and it turns over normal. Drained oil checked filters all are good. I am thinking maybe cam bearings??

Any ideas..

Question? How many hours on engine And what kind of oil are you using?

Not sure on how many hours we got it used, but my son has been riding it for about a year before the problem and we do not use hour meters.

Oil we use in all of our bikes (2007 KTM 250sxf, 2005 Husky TC 250 and the Yamaha) has been since they were new after break in is Shell Rottla T syntetic.5-40. Oil is change after about two hours of riding and filters every third oil change.

After tear down and inspection the only thing wrong with the engine was the main rod bearing. All of our other bikes have been running fine with no problems. We have been riding almost every weekend up until the little break during last summer. We ride and race mostly moto with some desert gp racing about once every 2-3 months. The KTM is the most used bike of the three it is my son’s favorite.

This will most likely open a can of worms about oil, but use what WORKS FOR YOU. My experience with this oil in our motorcycles (I am an aircraft mechanic) has been nothing but positive.

You being an A&E tech, you might be intrigued at the results you would get back from a used oil analysis of your Rotella. Look in particular at the SUS or cSt viscosity at 212 ℉ (100 ℃) after the two hours you run it. The results may startle you, and your 250SXF may be even harder on the oil than your 450

You being an A&E tech, you might be intrigued at the results you would get back from a used oil analysis of your Rotella. Look in particular at the SUS or cSt viscosity at 212 ℉ (100 ℃) after the two hours you run it. The results may startle you, and your 250SXF may be even harder on the oil than your 450

Gray you would be surprised at what pro team uses shell oil, I have been to a shop that does some of the R&D work on their motors. They have been using shell T for at least the last 5 years. I am not saying that the shell oil did not cause our problem with the Yamaha, but with the other two bikes ZERO problems using this oil since break in, and these bikes do not putt around they are raced and raced hard. On practice days they are ridding even harder and longer.

About 3 months ago an engine builder(KTM) that I have been talking to knew what oil we use, he said he wanted to look at our KTM motor( would do all work free just pay for parts and shipping). It needed a set of rings and piston anyway so I removed the motor and sent it to him. He said all parts were well within specs and just keep doing what you are doing. The only engine parts that have been replaced on the KTM (2007 sxf 250) is two pistons and two sets of rings.

Like I said the oil subject ALLWAYS gets alot of attention, I truly believe that you should use what works for you and your maintenance schedule. I am not trying to convince anybody to switch oils just telling people about my experience with this oil.

The sealant that you said to use does it come in a pressurized can but come out in a bead instead of spread like paint??

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now