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4rt ~ 250 v 260 Differences?


johnnyboxer
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I found the engine braking a lot less from the 250 to the 260. Engine feels a bit nicer but nothing major. I found the std 260 ligter on the front than a 250 Showa suspend model. The RR is just better again.

Edited by jimmyl
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FYI: The Montesa Repsol and the Standard 4RT are both 258,9 cc.  

The 300RR is a 289cc

"I found the engine braking a lot less from the 250 to the 260"

Where and how did you ride a 250cc Montesa to feel a difference in engine braking as to a 260cc

as there are only two cc sizes 258.9cc & 289cc?

 

 

Edited by billyt
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36 minutes ago, billyt said:

FYI: The Montesa Repsol and the Standard 4RT are both 258,9 cc.  

The 300RR is a 289cc

"I found the engine braking a lot less from the 250 to the 260"

Where and how did you ride a 250cc Montesa to feel a difference in engine braking as to a 260cc

as there are only two cc sizes 258.9cc & 289cc?

 

 

The early 4RT was only 249.1cc and changed to 258.9cc around 2014 with the new fuel tank and rear mudguard design so he is probably talking about the earlier model with the big looking fuel tank and lower tipped up end mudguard.

Edited by oni nou
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Oni Nou     You may be correct about the model years.  

However I doubt he was feeling engine braking from 9cc's of a difference....

More like the changes Montesa made to the engine braking aspect itself thru the model years. :)  

Edited by billyt
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I have an 07 250 4RT, have been on a 2017 260 4RT and have a 2017 300RR.

In short I agree with the above, changes between the older 250 and newer 260 do feel different on the engine braking but also I feel the suspension on my 07 was stiffer than a 2014+ (tell I had it modified) and the power comes on a bit more smooth on the 2014+.  

As for the 300RR, lighter front end, I like the peg position a little more as its a bit rear ward, and of course more power.  

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I recall one of the features of the 260 when it was introduced was reduced engine braking. Might have been the age of my 250 (2007 model) when I swapped it for a 260 (2015 model) but the engine also seemed more balanced; didn’t vibrate as much at high revs. 

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On 1/30/2019 at 2:17 AM, billyt said:

Oni Nou     You may be correct about the model years.  

However I doubt he was feeling engine braking from 9cc's of a difference....

More like the changes Montesa made to the engine braking aspect itself thru the model years. :)  

Yep that’s the point - nearly ended up throuh a fence on a early go on my 15 260 after years on the 250s . Rolled of the throttle on top of a bank and she didn’t slow down as expected ???

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2 hours ago, rollox said:

Sorry, but the vent part no. is the same for 2005->2014

I'm referring to the P.N 90901-NN4-D00, ORIFICE #190. It first showed up in the 2010 Japanese RTL260F and then in the 2014 4RT260.

Are you looking at the reed valve?

The reed valve vents on the downstroke to clear oil from the sump. It's closed on the upstroke, and the ORIFICE #190 relieves some vacuum force on the piston.

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Billy, the reed valve, P.N. 18601-MBW-003, is the same on all 4RT models from the original 2005 to present. The same reed valve is used in CRF***R crankcases. I was thinking that's what Rollox's last post was about.

The new part that appeared in the 2014 4RT260, when Honda advertised reduction of engine braking, is the small vent jet in the left crankcase half. Look at parts list frame E-11 for 2014+ models compared to earlier models. The newer bikes have an Item # 18 "90901-NN4-D00 ORIFICE #190" that earlier models don't have, and different left crankcase half that accepts it.

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