CRF450 Crank and other important parts

bmwm750 · Jan 26, 2004

I have an 02 CRF450, so it now has 2 seasons on it of twice weekly riding on motocross tracks, I am an intermediate rider. I have already done the Kibblewhite SS valves and upgraded springs, which have been wonderful. I have done new pistons twice in the motor, over both previous winters.

Now I am interested in using this for a Motard bike while I use my new 04 CRF in the dirt. So, I'm thinking higher compression piston (Wiseco most likely), perhaps hotter cams, maybe the Power-Now, and anything else you guys can think of.

My real question, though, concerns the lower end of the motor. Should I be concerned about freshening the lower end? How long are these cranks supposed to last? I've seen a few guys throw rods through the cases on these motors, and thats the LAST thing I want to do. Along those lines, may it be time for a replate of the cylinder?

Any recommendations/ advice would be greatly appreciated.

Rich Rohrich · Jan 26, 2004

If the bore is still round, doesn't show signs of taper, and doesn't have damage to the plating you should be OK. Depending on how the bore looks it may be worthwhile to have it diamond honed to ensure good ring sealing.

Two seasons on a crank can be a lot or a little depending on the rider and maintenance schedule. If you are going SuperMoto racing you'll spend alot of time at high rpm, so there is a lot of stress on the crank/rod assembly and any weakness will show up in a hurry.
If you aren't sure it's worthwhile to rebuild or replace the crank and main bearings. Cranks are relatively cheap, and it's good insurance. Even if you don't change the crank you should check the main bearing retainer plate screws. They have a nasty habit of backing out over time.

The higher compression Wiseco is a nice upgrade and it's about 1.5 grams lighter than the OEM piston. Hot Cams has a new cam for the bike but we haven't tested it yet, or had a chance to compare it to the OEM Honda 2004 cam. I'll have some detailson this in the future.

The Thunder Alley exhaust is an inexpensive upgrade and fills in the low to mid portion of the torque curve nicely.

In my opinion there are better ways to spend your money than a PowerNow.

bmwm750 · Jan 26, 2004

Rich-

Thank you for the info. I'm inclined to think that with my maintenance schedule (HP4 w Moly every 2-3 rides) and my not wide open all the time riding style, that if you say that 2 seasons can be a little or a lot of wear, that my 2 seasons are a little. Would diamond honing the cylinder remove its plating? And, who would I have do that service? You mention that a crank is cheap, how cheap is cheap in this case? I'd still hate to not touch it and then throw a rod. By the way, I'm not taking it Supermoto racing, just looking to make it barely legal to ride on the street.

I think Wiseco makes both a 12.5:1 and a 13:1 piston, which would you recommend? Either way, I'm gonna be stuck on race fuel anyway I figure. Do you know what differences the 04 cam has than the 02-03, or for that matter, the Hot Cams?

Thank you again for the help!

Rich Rohrich · Jan 26, 2004

Service Honda has a new crank listed for $190.99 , not much more than a rebuild costs.

Diamond honing won't hurt the plating but it will provide the proper plataeu to the crosshatch and help ring seating and oil sealing. Only the better equipped engine shops with a Sunnen honing machine or similar equipment can do the diamond honing. Worst case a 320 grit ball home can do a decent job of deglazing the cylinder.

Going from the 02 cam to the 03 cam usually helps low end and mid range a bit. Exact specs on the differences escape me right now. I have an 04 cam coming from Service that I'll put on the Cam Doctor equipment and post the results along with the new Hot Cam data so we can all compare them.

The CRF engine likes compression, and can tolerate it really well from an octane stanpoint. A CR of 13:1 is no problem on pump gas unless you slot the cam and advance the cam timing a lot (early IVO = greater trapped CR and higher pressures). The 13:1 piston will be the best bet if the intake close timing is later with the newer camb.

That said, these engines also respond incredibly well to the proper race fuel, so if you can afford it RUN IT. Pump gas is for your TRUCK not your 11,000 rpm race bike. :)

bmwm750 · Jan 26, 2004

Rich-

Thank you again for the wealth of information. The CRF can really do 13:1 on Ultra 94 pump fuel? That REALLY surprises me. $190 for a crank isnt bad, and as you said, is cheap insurance.

Given your worldly knowledge on said subject, what would you recommend I do to this motor, given what I plan to do with it? I will gladly trade a bit of overall performance for reliability, by the way.

Eric Gorr · Jan 26, 2004

Just a side note, if you were motard racing, Falicon now makes a stronger knife-blade connecting rod kit, but they cost $300 installed. I think you'll be fine with a stock Honda crank.

bmwm750 · Jan 27, 2004

Eric-

Good to hear back from you. How are you? Would you recommend I replace the crank as well? Just be curious to hear your suggestions on how to make that a reliable street motor. Thanks again!

Rich Rohrich · Jan 27, 2004

Well you already did the most important thing for long term reliability and performance by going to the Kibblewhite valves and spring kit. Porting can help some but not as much as a proper multi-angle valve job and profiling the new valves to match the seats and throat area when compared on a dollars spent/value basis.

We already discussed the OEM cams and their basic characteristics. The OEM '03 is still a great drop in mod at a good price.
Webcam has a couple of excellent cams for this engine but it takes some work on the guides to install them. The initial feedback I have gotten on the new HotCams piece has all been positive, but due to the weather I have no first hand testing info to share.
You can slot the OEM cam and play with the intake lobe center angle timing if you don't want to pop for a cam. White Brothers sells pre-slotted cams for this purpose. I'll have more info on the new cams and the power characteristics in the near future.

The basic point is what really makes these engines work is the small detail stuff. Honda built a great starting point so careful massaging of the valve shapes and seat area along with a comprression increase and some chamber/piston crown mods can make them really work well with a pretty minimal outlay of cash.

Of course if you just want to go the bolt on route the most fun mod is a 480 kit and at $375 it's a much better value than 90% of the pipes out there. A 480 kit combined with a good exhaust like the Thunder Alley slip on exhaust cannister, the stock headpipe, the stock '02 cam and the Kibblewhite valve package is an insanely fun and reliable package. A 230 pound street bike with ~55hp and super torquey wide range power , is BIG FUN in my book. :yeehaw:

bmwm750 · Jan 27, 2004

Thanks for the input guys. I've considered the 480 kit actually, that comes with new cylinder, piston, and gaskets, and I send you mine and $375, yes?

What seperates the 03 cam from the 02? I had though the motor stayed pretty much the same until 04. I havent ridden my 04 yet (weather issues up here in NY) but am told I'm going to like it ALOT. I can absolutely vouch for the kibblewhite valves though, excellent product. Which actually brings a good question, are new valves needed in the 04 also?

Thanks again.

Rich Rohrich · Jan 29, 2004

So far the 2004s seem to be fairing better then the earlier models in terms of valve life, but we won't really know for sure till guys all over the country put some serious hours on them.

MXW · Jan 29, 2004

I read Rich mentioning the Cam Doctor measuring equipment and was wondering where this or something similar can be purchesed from.

Thanks

Jason

SFO · Jan 29, 2004

Cam Doctor went out of business a while back.

MXW · Jan 29, 2004

Thanks
Do you know any other company that sells cam measuring equipment and software or where I can obtain an old cam doctor kit.

Rich Rohrich · Jan 29, 2004

Audie Technology makes a cam measuring system called Cam Pro Plus that is far superior to the old Cam Doctor.

http://www.audietech.com/cppinfo.htm

MXW · Jan 29, 2004

Thanks very much, this was very helpful

Jason

bmwm750 · Jan 29, 2004

So if I wanted to change cams to the 03 or 04 OEM, or the Hot Cams, where would I obtain said cam and for how much?

bmwm750 · Jan 29, 2004

Rich Rohrich said:
So far the 2004s seem to be fairing better then the earlier models in terms of valve life, but we won't really know for sure till guys all over the country put some serious hours on them.

So if I wanted to go to either the 03 or 04 OEM cam or the Hot Cams, where would I obtain said cam and for how much?

Rich Rohrich · Jan 30, 2004

bmwm750 said:
So if I wanted to go to either the 03 or 04 OEM cam or the Hot Cams, where would I obtain said cam and for how much?

Service Honda can get you the OEM Honda cams , and the HotCams are available from MX-South or Eric Gorr (aka Forward Motion) and a host of other dealers.

Hot Cams has a Stage 1 and Stage 2 cam available for the CRF. The Stage 1 cam is more of a low -mid rpm cam for engines that aren't heavily modified. Stage 2 looks to be the ticket with big bore engines that are ported, and have had seat and valve mods done.

I'll try to have cam graphs comparing the Hot Cams and the OEMs up in the next few weeks. I'm building a new Cam Doctor fixture so it may take a little while. :thumb:

clee5914 · Feb 3, 2004

I rode 2 20 mile loops on my new 2004 450 and it's back at the shop the valves dont sound so good but the good thing is the bike is only 1 month old so honds going to get the bill

tillertracker · Feb 13, 2004

I put a Wiseco 12.5:1 piston in mine and weighed it on my digital scale before installation. It was HEAVIER then stock by (around) 30 grams. The wristpin was heavier also with a .1mm thicker wall. I put it in anyway and noticed no extra vibration. Did you weigh your piston or did Wiseco just say it was lighter? I've also heard the JE piston is lighter. Hard to believe, the stocker is a work of art!

Rich Rohrich · Feb 13, 2004

tillertracker said:
The wristpin was heavier also with a .1mm thicker wall. I put it in anyway and noticed no extra vibration. Did you weigh your piston or did Wiseco just say it was lighter?

I measured the Wiseco 12.5:1 piston, & pin combination at 1.5 grams lighter that the Honda OEM combo. Using the OEM Honda wristpin with the Wiseco piston drops it to ~ 2 grams lighter total. At this point I'm unsure if the OEM pin with the Wiseco piston will cause any reliability issues. I'll keep everyone updated as I know more.

Wiseco is using a newer forging process on the CRF pistons which results in a much lighter piston than the earlier YZF models of similar size.

I haven't measured the JE piston for the CRF so I can't comment.

tillertracker · Feb 15, 2004

I wonder what machining step they missed on my piston? Now I'm going to have to do some research, I hate heavy parts!

Rich Rohrich · Feb 16, 2004

tillertracker said:
I wonder what machining step they missed on my piston? Now I'm going to have to do some research, I hate heavy parts!

When I get a chance I'll post the exact weights I measured.

CRF450 Crank and other important parts

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