Engine Power Rebuild

[mumur]

I've got a 2019 CRF450R and after 2 years of constant oil changes I apparently dropped my brain on the floor and installed my steel oil filter backwards during my last oil change. Engine is totally ****ed, cylinder is cracked, looking at a complete rebuild. Keeping positive about it though, this is opportunity to make more power! When looking at parts I noticed some of the aftermarket stuff is significantly cheaper than OEM (Cylinder Works Big Bore kit w/cylinder and piston is cheaper than an OEM cylinder for ex).

Any recommendation of what I should do in this rebuild to get more out of the new engine? Big bore kit, stage 2 cam, upgraded valves and springs? I've been reading a few folks threads where they're making 70HP+ reliably... would be sweet to get to if possible. Any tips on what I should look for? This is a dedicated snowbike.

 

[G-Force]

Cylinder works has a pretty decent rep, in the dirt world, at least. Yup, all like you listed, big bore, cams, ported head, high comp piston, exhaust, and appropriate tune. Will it crack 70? hard to say, but definitely be more than stock!

 

[Toy4rnr]

I threw a GYTR ported head on my YZF. Yes not a CRF, but between the cams and that head the bike pulls pretty dang good! Should have went high comp and got a header while I was at it lol.

 

[eric82930]

I can't remember hearing any thing about guaranteed 70hp mods for the Honda but I was fairly impressed with the bike stock and I'm a hard core ktm guy. If you just do a high comp piston it would be a nobrainer improvement for sure and might not even have to tune it. Cams, big bores,porting etc won't be guaranteed and may run like poo if you don't have a good matching tune and the right combo of parts.

 

[G-Force]

I can't remember hearing any thing about guaranteed 70hp mods for the Honda but I was fairly impressed with the bike stock and I'm a hard core ktm guy. If you just do a high comp piston it would be a nobrainer improvement for sure and might not even have to tune it. Cams, big bores,porting etc won't be guaranteed and may run like poo if you don't have a good matching tune and the right combo of parts.

If a known builder / tuner like Jamie at Twisted Development did the build, it would run like a banshee.. but to get a head from A, a piston from B, maybe C does the throttle body etc, turns into a science experiment. I'd recommend finding a shop that can tick off all, or as many boxes for what you want.

 

[Mendomotox]

You will be playing with fire trying to run 70hp through a 450. it will be a ticking time bomb if it's even possible. If you want reliable big hp, I'd be shopping for a 2 stroke. The Panthera 550cc is trx based and *may* be an easy install in a crf. Sébastien says it can make 102hp, so even if that's a bit of an inflated number it should be at least 70hp. Last I checked its about $4500 for a panthera 550 plus the cost of exhaust. I doubt it will be much cheaper to make 70hp with a 450 thumber though.

Or as previously stated you could just do a mild pump gas rebuild with a little more compression and be happy with 55hp.

 

[wwillf01]

I can tell you this no experience with Honda but I have both a Panthera and a 70hp regular bore 450 ktm… this is my take … my 450 is rock solid 100 hour top ends and is a blast. Panthera is a blast , uses twice the gas and is 20 hour top ends or the pistons shatter… it was very hard to jam in a 530 ktm frame with a lot of fab… the engine is giant..( the manual says 10 under race conditions) the key is finding a good tuner for the Honda and trusting them to give advice on what to build you for reliability. This is what I did…. Believe it or not you can get more than the 70 but then you are trading reliability more than I wanted. It has to be dyno tuned with all the right parts. That’s my 2 cents.


Sent from my iPhone using Tapatalk

 

[byeatts]

the 450 with the high Rev DCR cam and RP exhaust and airforce intake is a different animal. it hits rev limited in 3rd climbing, huge track speeds with all the reliability.

 

[braapbraap.]

the 450 with the high Rev DCR cam and RP exhaust and airforce intake is a different animal. it hits rev limited in 3rd climbing, huge track speeds with all the reliability.

Is that with a high compression piston or stock, super curious.

 

[byeatts]

Is that with a high compression piston or stock, super curious.

stock factory bike. However they have a higher compression piston on some years