crf motor

[duke416ex]

Just wondering what differences in power there would be from a crf 450 motor to a trx 450 motor and if they are a bolt in replacement or what modifications would have to be done for the crf motor to fit into the trx frame. I don't mean just a motor swap, I mean the motor, carb, and cdi.

[dunebuggie66]

why don't you just mod your trx motor to make it the same as the crf. put the cam in, use the crf carb, ignition, cdi etc. you could make it have just about the same power characteristics as the crf.

[Hondacrf15]

There is a tremendous difference between the crf and the trx. The crf has a lot of bottom end and is really snappy. It pulls really hard and in top end, keeps pulling. the trx has a really mellow power delivery and has no bottom end compared to the crf. The top end is a little different. It would be cheaper, probably, to just build the trx motor than to buy and maybe modify the mounts and carb boot. You need a cam, high-compression piston, 41mm FCR carb, high performance race pipe, and aftermarket air filter. There are also some minor things like gas.

[R3Concepts]

You dont modify the carb boot..You have to run an adapter on the CRF carb when you use it on a TRX. Get a pipe, piston, cam, CRF carb and CRF ignition, and viola, CRF motor.

[duke416ex]

Would you not need a different crank also since the crf has a different stroke?

[chad502ex]

well, i'd like to point out that the crf stroke is smaller than the trx, so, the trx makes more bottom end power than the crf (if your just comparing the crank and not the cam or carb). It's the crf camshaft that makes the crf snappier than the trx; that's why ppl rush out and purchased either a 02' crf camshaft or a Hot cams camshaft (with smaller overlap). when you compare the crf engine and the trx engine with the same crf camshaft- the trx, because of increased stroke, will out tq the crf.

I'd also like to point out that the crf tranny was not designed for as much sneaker traction as the trx tranny was designed for. In other words, the trx tranny gears is a bit more beafier than the crf tranny because there is a bigger tire footprint on the ground. The bigger tire footprint the harder the load on the tranny. If I were to install a crf engine in a trx frame, i'd remove the tranny and immediately send it out for hardening so to make them hold up to the increased load.

chad502ex

[mxracer00]

why put a crf motor in the R? The 450R motor is built to handle the weight of the fourwheeler. The tranny is beefier to handle the added weight.

[TWISTED]

Originally posted by chad502ex
well, i'd like to point out that the crf stroke is smaller than the trx, so, the trx makes more bottom end power than the crf (if your just comparing the crank and not the cam or carb). It's the crf camshaft that makes the crf snappier than the trx; that's why ppl rush out and purchased either a 02' crf camshaft or a Hot cams camshaft (with smaller overlap). when you compare the crf engine and the trx engine with the same crf camshaft- the trx, because of increased stroke, will out tq the crf.

I'd also like to point out that the crf tranny was not designed for as much sneaker traction as the trx tranny was designed for. In other words, the trx tranny gears is a bit more beafier than the crf tranny because there is a bigger tire footprint on the ground. The bigger tire footprint the harder the load on the tranny. If I were to install a crf engine in a trx frame, i'd remove the tranny and immediately send it out for hardening so to make them hold up to the increased load.

chad502ex
You seem to have done alot of research so I'll ask you. What difference will I notice going from the HRC cam to the '02 crf cam? Willit be enough of a difference to justify switching cams?

[chad502ex]

Originally posted by TWISTED
You seem to have done alot of research so I'll ask you. What difference will I notice going from the HRC cam to the '02 crf cam? Willit be enough of a difference to justify switching cams?

no stick with what you have- the cam change would not be worth the money spent for the small gain. Now, if you were to ask HC to HRC, then i'd say "Go for it!"

hope this helps.

chad502ex.com

[CdaleXtreme]

My biggest problem with my TRX, is getting it to pickup off the bottom, on slow sections, I always havbe to blip the clutch a little to get the R's up. It just seems hesitant to pick up Revs.

I have thought about going with Ti-valves but dont think I would like the extra maintenince.

I have stage 2 hot cam, FCR, Boyesen quick shot, etc...

[chad502ex]

Originally posted by CdaleXtreme
My biggest problem with my TRX, is getting it to pickup off the bottom, on slow sections, I always havbe to blip the clutch a little to get the R's up. It just seems hesitant to pick up Revs.

I have thought about going with Ti-valves but dont think I would like the extra maintenince.

I have stage 2 hot cam, FCR, Boyesen quick shot, etc...

what gearing and tire size>?

[jgfarmsracer]

Originally posted by CdaleXtreme
My biggest problem with my TRX, is getting it to pickup off the bottom, on slow sections, I always havbe to blip the clutch a little to get the R's up. It just seems hesitant to pick up Revs.

I have thought about going with Ti-valves but dont think I would like the extra maintenince.

I have stage 2 hot cam, FCR, Boyesen quick shot, etc...

Get rid of the quick shot!!

[CdaleXtreme]

13/38 18inch

---

Why do you think I should get rid of the quick shot?

[44oEX]

if you put the crf ingnition, flywheel..... can you still run lights? I would think not...right or wrong?

[jgfarmsracer]

no lights, unless you buy the trail tech stator



the quick shot gives too much gas and can stall or flood the motor out, the fcr carb that comes on the bike has just enough and possibly a little too much of a shot

I have the 04 crf carb on my trx450 and I can flood it out off of a start if I just stand on the gas instead of easing into it

[R3Concepts]

Originally posted by jgfarmsracer
no lights, unless you buy the trail tech stator



the quick shot gives too much gas and can stall or flood the motor out, the fcr carb that comes on the bike has just enough and possibly a little too much of a shot

I have the 04 crf carb on my trx450 and I can flood it out off of a start if I just stand on the gas instead of easing into it

You have to buy the whole TT CRF ignition just to get the lights. The adapter plates arent the same to mix and match..If that FCR is not picking up right off, then the pilots to fat or the air screw is off..Thats the whole point of going to an FCR, no bog throttle response.