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View Full Version : CRF280X vs Wr290F


hamish
19-03-2010, 11:11 PM
As most know, I put a big bore kit in Wandas WR250F a while ago, and have just finished doing the same with Rebeccas CRF250X

Both engine has new valves and a seat job, new spring, new piston/rings and a new crank, so comparisons can be made without too many variables

I rode both bikes back to back last weekend, and the Honda felt ok off the bottom with a good mid and not much top, where the Yamaha felt horrible off the bottom, getting better the more you revved it (std Yamnaha really)

Funny think is the seat of the pants told me that the Honda had heaps more midrange than the Yamaha, but the Dyno never lies!

Even though both bikes are geared about the same (127-130km/h max rpm 4th gear) , the Honda is geared lower in the lower gears giving it the feeling of more power, not to mention its is much lighter and handles much better, which also effects the seat of the pants feeling

Here are a few dyno runs

For the CRF, 'OLD MOTOR' was a fresh 12.5:1 wiseco piston with a hotcams stage 2 camshaft

'New Motor' is the 280 kit with a stock x camshaft

Its also worth noting that improvments in jetting were made on the Yammy and Honda before these Dyno runs were recorded

07400E
19-03-2010, 11:21 PM
Interesting results

The WR graph looks a lot better.
Totally opposite to how they feel to ride as 250's

The CRF wasnt getting wheelspin was it ?

robo67
19-03-2010, 11:24 PM
you like your dyno stuff you may find this interesting Hamish...

i heard so much hype about the kato i found it interesting...

http://www.motorcycle-usa.com/PhotoGallerys/xlarge/63402170281662519710_250mxhp.jpg

hamish
19-03-2010, 11:31 PM
Interesting results

The WR graph looks a lot better.
Totally opposite to how they feel to ride as 250's

The CRF wasnt getting wheelspin was it ?

nah, hooked up well..
after all its how they feel on the track that matters. I mainly give the bikes to him because I am too lazy to jet them, and the Hondas carby is *@#&*@#&*@#&*@#&ing impossible to work on...

I kid you not, it took me the same amount of time to install the barrel, head and cam as it did to get the *@#&*@#&*@#&*@#&ing carby back in :vomit-smi

Robo, looking at your graph the honda eats them all by a mile! But thats what I have heard anyway

Pete40
19-03-2010, 11:31 PM
So you actually have less horse power with the big bore kit in the Honda - is that expected? (Am I reading that right?)

07400E
19-03-2010, 11:36 PM
Do any of the dyno runs have an AFR plot overlayed ?

hamish
19-03-2010, 11:38 PM
So you actually have less horse power with the big bore kit in the Honda - is that expected? (Am I reading that right?)

yes it was expected Pete.
But the 'old engine' was with a massive cam and 12.5:1 compression. See the way the old engine pulled through the midrange? heaps of fun but not very trail friendly.

Also going big bore on a 250X head only make the small exhaust valves even more inadequate than they are on a 250

A s1 cam and some 250R exhaust valves and it would be intresting, but this is more than enought for a 12 year old girl at the moment :laughing-.

Also remember both these engines were built for the girls where lugability and midrange torque was the main goal

hamish
19-03-2010, 11:46 PM
Do any of the dyno runs have an AFR plot overlayed ?

no, but I do have it in text form. AFR of about 10.5-11.5 for the CRF280, 11.5-12.8 for the WR290 and 12-13 for the 'OLD' CRF

The needle in the CRF probably isnt ideal (R spec, can't remember exact numbers) but I have NFI what I did with my X needle, and the blue JD neeedle was hopeless, and the red JD needle is in the yammy

07400E
19-03-2010, 11:51 PM
no, but I do have it in text form. AFR of about 10.5-11.5 for the CRF280, 11.5-12.8 for the WR290 and 12-13 for the 'OLD' CRF

The needle in the CRF probably isnt ideal (R spec, can't remember exact numbers) but I have NFI what I did with my X needle, and the blue JD neeedle was hopeless, and the red JD needle is in the yammy

Mine feels ALOT better at 12.8-13.2 than 10.5-11.5
I'm using the JD red

rabskyline
20-03-2010, 12:33 AM
mines due back this week hamish with the bb it on it and jd jetting so what were your carby settings ? may assist with setting mine up !

Bluerex
20-03-2010, 12:35 AM
Hamish i had great gains on the dyno, after installing a Athena 290 kit GYR version from the States.
250fw 34.88hp
290fw 38.14hp

But the increase in torque to 22.33Ft-lbs up from 18.56Ft-lb
Is what makes a better ride.

rabskyline
20-03-2010, 12:45 AM
thats what i hope to see, some decent grunt ! the bike hadnt been touched since new and on original everythign so it was probably a time for refresher ! post up the jetting settings hamish !