RECENT POSTS



honda cr250f???

May 17, 2000
37
0
#1
i have only seen about 1" of magazine space about this,,, should i expect it in feb.??????? any ideas at all are greatly appreciated...im waiting somewhat patiently!!!! cw
 

Humai

Lifetime Sponsor
Feb 6, 2000
199
0
#2
- Alloy frame based on '01 CR125 frame
- 212lb claimed dry weight
- 77mm bore/ 54mm stroke
- Electrically contolled double VTEC variable cam timing
- Four valve (non RFVC) DOHC head design with titanium valves.
- claimed power (at crank): 44ps at 11,000 rpm
- rev limit: 14,000rpm
- Keihin 37mm FlatCR carburetor

How's that for ideas? Reality may change specifications without notice ;)
 
Jun 1, 2001
17
0
#3
Is this CR250F stuff reality or are you guys just dreaming.
If I was in charge of the CR250F designing, I would do this.

3rd generationCR125 frame
CRF450 unicam design
4 titanium valves
at least 40 hp
rev limit at 13-14000RPM's
as light as a 02CR125 and faster
and some type of 2barol carb would be nice imagine the power band hit it would have!
and a off road CR250F would be very nice
 



Rich Rohrich

Moderator / BioHazard
Jul 27, 1999
22,769
566
Chicago
#4
Originally posted by honda bob
and some type of 2barol carb would be nice imagine the power band hit it would have!

Say what????????????
 



Aug 3, 2001
10
0
#7
I think they should turn the head around so the exhaust comes out the back, that way the header pipe lenth will be way too short to tune correctly and the exhaust will bake the shock. ;) Oh yeah someone already did that. :scream:
 

BadgerMan

Mi. Trail Riders
Jan 1, 2001
2,479
8
#9
Honda has already "been there, done that" with regard to the "two-barrel" pipe dream. Remember the '85 XR250R? It did produce more HP than the '86 "single carb" model. I wonder why they did not continue to refine their idea?
 



dirt bike dave

Sponsoring Member
May 3, 2000
5,349
3
#10
Honda used twin carbs on many of their single cylinder XRs in the early '80s, including the 200R, 250, 350 and 500. IMO the extra cost and complication of the twin carbs was why they stopped using it.

Seems like the factories and tuners have figured out how to use single carbs, so I expect the next step is fuel injection, and there will be no return to dual carbs.
 
Dec 10, 2000
1,490
1
#11
Originally posted by honda bob
Is this CR250F stuff reality or are you guys just dreaming.
If I was in charge of the CR250F designing, I would do this.

3rd generationCR125 frame
CRF450 unicam design
4 titanium valves
at least 40 hp
rev limit at 13-14000RPM's
as light as a 02CR125 and faster
and some type of 2barol carb would be nice imagine the power band hit it would have!
and a off road CR250F would be very nice
How about these little tidbits?

fuel injection (for perfect jetting and ease of tuning)
Continuously Variable Transmission (so you are always in the powerband)
Variable compression (like Saab)

Or we could just hope it will start decently...:p
 

Jon K.

Subscriber
Mar 26, 2001
1,354
4
#12
Yamaha had a twin-carb setup that was superior to anything else that I have seen. On their TT600 (and others?) circa 1983 Yamaha used a conventional carb on the left valve and a vacuum operated carb on the right valve. The right carb drew fuel from the left bowl (so did not use a float of it's own) and consisted of a single main jet. So simple! Very effective! The linkage was mechanical; at a certain throttle opening the right side butterfly would open.
I think this system might still be used on some of their overseas models, but don't really know.
Maybe this system could be revived for better starting of the new hot-rod four strokes.
 



Dec 13, 2000
262
0
#13
I have rode both the 84 and 85 XR 350's, the 85 with the single carb was a better bike with more low end and much easier to fiddle with.
 

Jon K.

Subscriber
Mar 26, 2001
1,354
4
#15
Honda never did get the dual carbs quite right. I had a 1983 XR350; bought it brand new, and just like teton says those dual carbs just were not up to standards.
I still have the 1983 TT600 with the abovementioned carb and a half. Works great, so it can be done!
But then, it's a Yamaha!:p
Hey Honda Bob; why do you want a Unicam?
Oh, and IDkTm you are too late! The Rokon used a variable belt drive in the 70s. Actually worked (sorta)! In fact the Rokon Trailbreaker still uses it (me thinks)!
 
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