[krza]

Hey all!

Looking for some expertise on oil use in my 2006 CRF450x. Sorry for the long post.

This bike has history as a Baja machine, built by Precision Concepts originally. I purchased in 2019 as a pre-runner. Blew up the motor in 2019 near San Felipe, ran it out of oil and seized the exhaust rocker arm.

This year, I rebuilt the motor bottom to top. New:
- Crank
- Cylinder
- Piston/rings
- Cam chain
- All bearings replaced
- All gaskets/seals replaced
- 2008 450r cam and head
- KPMI Stainless valves, guides, seats ground

I wanted the motor to just be done, top to bottom and not worry about it. Intent was to use it as a pre-runner for the 2020 Baja 1000. My team mate with the race bike dropped out due to COVID, and me and my other team mate had to make a game time decision to race my 2006 because it was prepped. It has great bones: AHM suspension, JD jet kit, case saver, Enduro Engineering parts, steering stabilizer, Excel rims, JD steel sprockets, DID x-ring chain, BD re-wound stator and XL Pro spot/driving combo race light, Firepower li-ion battery, electrical mods for GPS and STELLA, 3.2 IMS with dry break, tires/mousse. Honestly, had no qualms about racing it, and the bike did really great in the end. The motor had about 12 hours on it as of race day.

The motor didn't use oil prior to race. Our crew chief Kirk was checking oil at every hand off and monitoring it closely. About half way through the race, we started to see notable oil use. Usually it was about 3/4 on the dipstick at each rider hand off (every 70 - 125 mi generally, depending on the leg). We added oil as needed.

In the post-race forensics, I did a leak down test. At 60psi, the motor was losing about 3% compression. Air was very clearly coming out the bottom end, I could hear oil bubbling in the bottom end through the oil fill hole. No air escaping from carb, exhaust, or valve cover breather.

My question is: How much oil use is normal in 450x motors?

I'm not too concerned with the 3% leak down, this seems totally fine. The oil consumption did seem like it's a bit much for low hours.

I plan to pick up a newer 450x and race prep it for next year's 1000, and use the 2006 as a pre-runner. Even with the current oil use and compression I'd be happy to pre-run it, but I want to understand normal oil use nonetheless. I also plan to get graduated squeeze bottles to track the number of CCs of oil the bike is using under pre-run conditions.



Final note: The one thing this bike lacked to be race ready this year was swing arm/chain guide gusseting and reenforcement. I totally over looked that mod. Sure enough, our 3rd rider Cort from Vegas hit a toaster sized rock in Matomi wash around midnight and destroyed the chain guide and rear sprocket. We had to send another rider in with a pre-runner and tools/parts to rescue him. We lost a ton of time and barely finished. You can read Kirk's race report at ADV Rider forum, if you're so inclined.

https://advrider.com/f/threads/2020-baj ... x.1479228/

[JimDirt]

Usually oil usage is related to rings , are you breaking them in correctly ??? , if you run Synthetic right away , they will never seat , if you are using petroleum , then I would again say it is ring break in and they are getting glazed due to running it hard right away , and not heat cycling them ........

My suggestion would be to change your break in procedure , and you won't be burning any oil ...... but yea , a fresh engine will burn some , and what your burning seems about right for that , basically it sounds like you are running on non seated rings , or glazed rings , if you break it in right , come race day , there will be minimum to no oil usage compared to what you are currently having ...

[Back2-2]

Hello Mr. Krza.
I believe what you are asking is - Do any of use see oil usage on our 450X's?
The answer for me on my 2006 450X would be no. Zero usage between oil changes. That said, I do not run high RPM for extended periods of time or miles at or near full throttle. When I used my 450 for hard desert riding it was far more high RPM then I do now with tight single track and I had zero oil usage then also. That was even before I did a new top end and my rings where on the maximum wear limit point.

What you are doing with your bike puts engines to the very limits and some oil usage would be expected. How much ? I do not know.
My friend that races Baja in the trucks category I know requires oil during the Baja race.

You certainly sound like you know what you are doing so the only thing I would look for if it were me checking this out would be the following items.
Piston rings and especially the oil ring.
Valve stem seals
Crank case venting.

Not sure that offers much that you probably don't already know. Good luck. Interesting to hear what you find.

[krza]

Usually oil usage is related to rings , are you breaking them in correctly ??? , if you run Synthetic right away , they will never seat , if you are using petroleum , then I would again say it is ring break in and they are getting glazed due to running it hard right away , and not heat cycling them ........

My suggestion would be to change your break in procedure , and you won't be burning any oil ...... but yea , a fresh engine will burn some , and what your burning seems about right for that , basically it sounds like you are running on non seated rings , or glazed rings , if you break it in right , come race day , there will be minimum to no oil usage compared to what you are currently having ...

Thanks for the reply! My break in procedure was informed by Frank Lyons at Lyon's Technical Machining in Beaverton. He knows 450x motors, and motors in general.

Per Frank, I ran a heat cycle for 15 mins at idle to ensure there were no leaks. Then I ran a heat cycles riding a couple of short short duration rides. Short bursts of acceleration followed by engine braking, not revving the engine high or lugging it excessively during break in. After that, normal riding, with slow increase in the max revs. I did a solid 100 miles/3 hours riding like this. I only run Honda GN4 10W30 oil.

For the first rides, there was no oil use. I did a few oil changes, including one after the 100 or so miles. We ran about 50 miles in Ensenada, and I did another change. Not too much metal in the oil on the second change.

Let me know your thoughts on my ring break-in. I'm not a pro, and to be clear I'm super happy our motor finished the race.

[Back2-2]

That sounds like a true by the book break-in and exactly the way I have always done new build break-ins.

I do not think that is the reason for the oil consumption.

[JimDirt]

Yea , it sounds like a pretty good break in procedure , , I did my 2020 450R with a short 5 lap moto , no revving , basically like a sight lap , then let it sit for 15 , then did another 5 lapper but running thru 3rd in the 5,000 to 7,000 rpm range , let it sit for 15 , not holding it on at one RPM for any length of time , did 1.5 hours of that , then changed oil and rode it like normal , I average 9,000 - 10,000 rpm now in 3rd , have 32.6 hours on it with no oil burning .... I average 30 minute moto's ......... , granted that is not doing Baja , but the break in I would think would work for either , but heat cycling is your friend ....

[krza]

Thanks Back 2-2 and JimDirt for the replies.

I feel like I broke the motor in correctly, and oil use was zero prior to the race itself. Maybe the race conditions just caused it to use oil. It was a 900 mile race with the bike going hard for nearly 40 hours.

My plan is to finish up some post-race inspection, and take it out for some long days, like 100+ miles in the desert. I picked up some 240mL squeeze bottles and will start using those to track how much I'm actually adding, and at how many miles.

I'll report back findings here for sure!

[Back2-2]

One other thing -
Were you noticing any blue smoke on starts or while running hard? Of coarse that indicates your engine is exhausting the oil losses. What about oil in the air box ? That would mean you are venting it out of the engine via the case vent.
If you do not have any indications of the oil burning then you may want to consider a case vent modification to vent the oil mist from the extended high RPM back to the engine.
Neither of those conditions should not be happening on a good fresh rebuild but is some thoughts for you to consider.

[krza]

One other thing -
Were you noticing any blue smoke on starts or while running hard? Of coarse that indicates your engine is exhausting the oil losses. What about oil in the air box ? That would mean you are venting it out of the engine via the case vent.
If you do not have any indications of the oil burning then you may want to consider a case vent modification to vent the oil mist from the extended high RPM back to the engine.
Neither of those conditions should not be happening on a good fresh rebuild but is some thoughts for you to consider.

Both good thoughts. I've had plenty of smoking bikes in my time (including my current 2016 350 XC-F that smokes bad on start up haha). This 450x isn't smoking, and I'll have to look at the vent breather hose and the airbox to see if there is any excessive oil.

I am inclined to say the oil use is related to the riding conditions. With the 15-48 gearing on the bike and the 450r cam, the bike tended to bog down easily in the sandy San Felipe washes and deep silt beds. It meant that in a lot of stuff on the East side of the peninsula, we were running wide open in 2nd gear for sustained amounts of time. I know for sure my 100 mile San Felipe leg was probably 70% 2nd gear high RPMs to keep the bike from bogging in the sand. Key learning here is to gear the rear bigger, maybe 50t or even a 14t front, to get more use out of 3rd gear in that stuff. It's not like we're spending lots of time at 100 mph anyway.