is it true that the 86 350X + 250R engines were detuned?

[3Wheelers4Life]

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.

[pickleweasel_00]

so if the stock 86 beats a stock 85 like you said, it wouldn't be de-tuned :wondering

[ATC-Eric]

Thats what Im thinkin, you just made two different statements..........

[Dirtcrasher]

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"

[SWIGIN]

no detune at all in the 350x

[3Wheelers4Life]

He just screwed up his wording...
yea, sorry guys its fixed now
i meant to say that the 85 250r and 350x will beat the 86's. i heard this somewhere.

[Nick_R_23]

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 :TrikesOwn

[tri-Z ripper]

i say LINE EM UP BOYS and find out for sure!!:lol:

[GPracer2500]

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

[hrc200x]

Isn't it true that the liquid R ATC's had a touch more horse than the TRX R's?

[Nick_R_23]

I'm not aware of any other changes to the engine. They could have had slightly different cylinder porting [shrug].

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??

-Nick :TrikesOwn

[DeePa]

ive heard that the 85 top ends for the r's were faster

[edog]

ive heard that the 85 top ends for the r's were faster

You are correct the 86 cylinder head was detuned.

[Rustytinhorn]

You are correct the 86 cylinder head was detuned.

I'm just curious what they did to detune the head??