Tonkaman's CRF450R build

[Tonkaman]

So its finally time for me to give this old Honda some lovin. The valves are maxed out now and the entire engine probably isn't far behind on wear so i'm tearing it all down this winter to make her better than ever. Were talking about a 2007 CRF450R with all stock internals, I've never even replaced a piston on this thing! I never did buy an hour meter but I bet its got several hundred hours on the engine, nothing high revving but it usually gets pushed.

HEAD
The head is getting a complete overhaul with stainless valves, new seats guides etc. I'm sending off to Ron Hamp Cycle in Michigan to do the work along with a custom port and cam

CYLINDER/PISTON
I definitely plan to do a big bore kit with over sized cylinder but haven't decided on an exact setup yet. Because I only plan to get a kit with a new cylinder I wan to BIG! What is your opinion on compression ratios? Stock the bike is 12.1:1 but i'd like to bump it up. Any reason I wouldn't like 13.5:1?

CRANK
Common sense tells me that with this many hours on the motor I am just asking for a trouble unless I service the whole bottom end as well. After flipping through pricing on parts it seems just as cheep to buy a new assembled crank than the bearing kit plus pay a shop to press the bearings on and off. After further investigation I realized its about the same price to buy a stroker crank instead of just a replacement crank.

I really have my eye set on a kit from ICECUBE its a 523cc big bore/stroker kit using a Billet cylinder with nickasil plating, and it holds more coolant than stock http://www.maxrpms.com/crf523r-ice-cube-big-borestroker/

I would really like to do a big bore stoker kit and turn this bike into my super moto/ sand machine, problem is I don't really know the first thing about stroker engines. Here is where I really need some input, tell me why I would or would not like a stroker crank. Although I feel confident enough in my mechanical abilities I have never split a case open before so its all new territory for me. I have a service manual and it makes the job look easy but I wonder if you have any reasons I might not do it alone?

 

[rholbrook]

We did this for one of my friends.
http://www.thumpertalk.com/topic/686889-new-crf450-cylinder-heads/

Well worth it and you can customize what you want.

 

[Gravy]

my experience is that the more you try to squeeze out of motors the less reliable they are...
but superior parts will get you superior reliability
I think you should just get a rebuilt on the head with stainless valves and whatever you believe you need to do with the crank..

 

[rholbrook]

I'm with Stratton on this.

 

[Deleted member 12904]

I do know that cam choice is super important with a stroker motor. Without the proper cam you can often not net any power gains and sometimes even less.

 

[jeeper]

My opinion..
Step 1: toss honda.
Step 2: buy 2 stroke.
Step 3: keep riding 2 stroke!


Way excited for this build! You are an incredible rider, and it will be even more impossible to follow you now. Good luck!
I'd offer up my knowledge on cams, valves, and such, but we all know I don't have a clue!

 

[anderson750]

One other thing you may need to consider if you are going to do this is how well it will cool and your a ability to run pump gas. Every Honda 4T I have owned runs warmer than most most other 4Ts so you may need to upgrade other parts of your cooling system.

 

[Tonkaman]

One other thing you may need to consider if you are going to do this is how well it will cool and your a ability to run pump gas. Every Honda 4T I have owned runs warmer than most most other 4Ts so you may need to upgrade other parts of your cooling system.

I have noticed this bike runs pretty hot compared to others. I always run engine ice, a high pressure cap and will be upgrading to a boyesen water pump when I do the rebuild. The main reason I like this IceCube kit is the fact it's billet and has big water jackets for extra cooling. If I still need extra cooling I don't mind upgrading radiators

 

[Tonkaman]

Russ - I was going go with them, they have a great product especially at that price! I decided to go with Ron Hamp because of his reputation working with factory honda and his experience building stroker bikes

Stratton- Your absolutely right, and that's why I started this thread. I hear so much controversy over big engine builds that I don't know the TRUTH behind it. I value the opinions of the RME crowd

Brian- I said I want MORE power not less... Ha ha

 

[Tonkaman]

I do know that cam choice is super important with a stroker motor. Without the proper cam you can often not net any power gains and sometimes even less.

Ok good that's why I'm having Ron Hamp do the head and cam it's the most important part of delivering that power. He has custom cams made depending on what I decide to do with the rest of the engine

 

[anderson750]

I have noticed this bike runs pretty hot compared to others. I always run engine ice, a high pressure cap and will be upgrading to a boyesen water pump when I do the rebuild. The main reason I like this IceCube kit is the fact it's billet and has big water jackets for extra cooling. If I still need extra cooling I don't mind upgrading radiators

I used to run engine ice but made the switch to Evans Coolant this year. Neither myself or any of my riding buddies that made the switch have had a boiling over issue since.

http://www.evanscooling.com/products/coolants/

 

[Tonkaman]

Sounds like I'll be switching to Evans then! Thanks for the tip

 

[anderson750]

Here is the link to the actual Evans product for the bikes. I put the wrong link in the previous post.

If you go this route after rebuilding the bike, you will not need to buy any of the prep fluid. Most places only sell it in 4 half gallons, so you may want to find a couple of people to go in with you on it. One thing we learned from doing this on bikes we were replacing coolant on is to do the following procedure:

1. Drain the coolant. Lean the bike over, stand it up and repeat a few times to get as much of the fluid out on its own. If you can, cup your hand around the radiator cap hole and blow into it to force more fluid out.

2. Fill your cooling system with Prestone radiator flush and bring up to temp. As soon as you can open the cap, drain the flush with the same procedure as you did with the coolant.

3. Fill your system with the Evans Prep and bring it up to temp. Do the same drain procedure as above but do not discard the prep, it can be used multiple times.

4. Fill your system with the Evans Coolant.

It is important to get the system completely clean of any traditional coolant since it will contaminate the Evans Coolant.

 

[rholbrook]

KTM 4Ts run the hottest. All the guys I ride with have put fans on them

 

[Tonkaman]

Thanks to Caleb I got the first batch of goodies to get some progress rollin. I didnt actually get much, mostly specialty tools. Luckily I had a fellow grease monkey to help me with stripping the bike down for about an hour.

 

[GAR]

looking good! Did you decide to go with the big bore kit?

 

[Tonkaman]

Yes I did, my original plans for the IceCube kit didn't workout since they have been discontinued. I have managed to round some of the major components but most of them are still in shipping.

Ordered so far:
Cylinder works 100mm (+4) Nikasil cylinder
Carrillo piston kit 13.5:1
Hot Rods +3mm crankshaft welded and trued
Hotrods main bearings and seal kit
Top and bottom end kits
Webcams camshaft
Stainless reusable oil filter

 

[Caleb]

KTM 4Ts run the hottest. All the guys I ride with have put fans on them

My CRF ran hot as hell. Even with Engine Ice my CRF was always 20-30 hotter than Noah's WR. We both had the Trail Tech commuters with sensors in the same location so the measurement was the same on both. My KTM has a fan from the factory, so I can't say how hot it would run without a fan, but I don't think it's anywhere near as hot as my CRF.

 

[Gravy]

Your daughter is the best! Good luck with the build. Let me know when I can come over and help wrench. I've never had a bike motor apart... just the top checking valves.

 

[Tonkaman]

Thanks she is a real gear head already ha ha. Your always welcome to come help out but Leimomi has dibs on all the hammers thats her expertise. I'll let you know once I'm rebuilding it all and we can make a party out of it.


I have boiled the coolant on my bike more times than I could count even with engine ice. I'll definitely make the switch to Evans just to see if it helps