Got The Holeshot
Arm chair racerJust too addicted
i have heard somewhere, that in 1986 honda detuned the ATC250R and ATC350X engines for less power? and if you race a stock 85 350X and stock 86 350X the 85 will win, and same if you race a 85 and 86 250R. Is this true? did it happen with other models or manufactures? thanks.
Last edited by 3Wheelers4Life; 01-17-2008 at 08:27 PM.
My Rides
1983 ATC200 - U-Haul edition - great mudder - SOLD
1984 ATC200X - sucked a valve - frame up resto & engine rebuild with performance parts in the works
1987 Suzuki DR200
199? Go-ped Sport
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Arm chair racerJust too addicted
so if the stock 86 beats a stock 85 like you said, it wouldn't be de-tuned
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Thats what Im thinkin, you just made two different statements..........
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Power User
Catch me if you can
He just screwed up his wording...
I believ at least for the 350X that the bore and stroke and valves are the same, there were some jetting changes but I'm not sure how it was "detuned". Sounds like we need "mythbusters"
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4 Wheels? Huh?
no detune at all in the 350x
80s......185 atc, Yamaha tri-moto 200, 85 200x with tons of work
90s......89 Suzuki quad racer 250 (raced 250 A class for 6 years, late 90s.. custom framed 250x with long travel shocks and a built 350x motor.... built Honda 110
00s...... chomeoly framed 350 RX with all the goodies (thanks to my bro)
2012.....Replaced the 350x motor for a 444cc YZ426
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Got The Holeshot
Arm chair racerJust too addicted
yea, sorry guys its fixed nowOriginally Posted by Dirtcrasher
i meant to say that the 85 250r and 350x will beat the 86's. i heard this somewhere.
My Rides
1983 ATC200 - U-Haul edition - great mudder - SOLD
1984 ATC200X - sucked a valve - frame up resto & engine rebuild with performance parts in the works
1987 Suzuki DR200
199? Go-ped Sport
Power User
Roostin Away
I have heard something similar with the 250R motors, but it wasnt really that they were detuned, just tuned differently. If I remember right, I think the 1985 was tuned for more top end and the 86 had more low end. Im not 100% sure on this, its just what I heard a while ago.
-Nick
1988 Chevy Silverado 5.9L Cummins : 1986 ATC250R : 2012 Polaris RZR 570 :
98% of Americans say 'OH $#!T!!' before going into a ditch on an icy road. The other 2% are Alaskans, and they say 'Here, hold my beer and watch this!!'
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i say LINE EM UP BOYS and find out for sure!!
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2- 85 250SX's
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3-ATC 70's
2- 85 tri-zinger's who needs some parts
First Time Rider
Arm chair racerNew to the board
ATC250R Detuned? Never heard of that. The '86 250r had a better carb (PJ vs. PE). I'm not aware of any other changes to the engine. They could have had slightly different cylinder porting [shrug]. But that's not a factor I'd consider very hard. Between any two particular examples of ATC250R, there's a few dozen other factors that I'd expect would overshadow any OEM sourced differences. Regardless, I consider the '86 the "superior" machine (I have an '85) because it shares more with the TRX and therefor is easier to source parts for (mostly I'm thinking rear suspension stuff).
Maybe this idea stems from the differences between the '86 ATC250R and the '86 TRX250R? The TRX did have a little lower compression and was hence "detuned". But again, these bikes all are 20+ years old. Any present day examples we may be comparing are likely to have been through so much over the years that I wouldn't consider it fair to call one faster than another based on year alone.
$0.02
Got The Holeshot
Arm chair racerJust too addicted
Isn't it true that the liquid R ATC's had a touch more horse than the TRX R's?
Power User
Roostin Away
You know, now that you mention it, it seemed like the 85R motor had slightly different porting, just the way it was shaped or something??? Idk, I read this years ago so who knows?? Anyone have an 85 and an 86 cylinder to compare,, or at least post some pics of the ports??I'm not aware of any other changes to the engine. They could have had slightly different cylinder porting [shrug].
-Nick
1988 Chevy Silverado 5.9L Cummins : 1986 ATC250R : 2012 Polaris RZR 570 :
98% of Americans say 'OH $#!T!!' before going into a ditch on an icy road. The other 2% are Alaskans, and they say 'Here, hold my beer and watch this!!'
Power User
Got the holeshot
ive heard that the 85 top ends for the r's were faster
1986 Tri-z
1985 250r
1985 200s
1985 70[/SIZE]
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The day begins with 3WW
You are correct the 86 cylinder head was detuned.
My old 1985 250R http://www.flickr.com/photos/24898661@N07/show/
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Arm chair racerJust too addicted
I'm just curious what they did to detune the head??
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