250r engine question 85 vs 86

[denn]

Is there a difference between the 85 and 86 250r motors? Did they change anything? Any info will help.

Thanks denn

[250r'en +TCB]

I know the carbs were changed.
Go to servicehonda.com, go to genuine parts finder and look at the differences between the two.

[Jason Hall]

I believe the only difference is the weight of the flywheel & the color of the paint, 85 was black & 86 was grey.

[deathman53]

every year had a different weight flywheel and difference cylinder head, don't know the reason for the change, the 88/89 flywheel is advanced 2 degrees. from is visual look the 85-87 heads have a smaller dome, 88 is alittle less and 89 is the least.

[BigRedRunner]

What are you looking to know exactly? Do you have a pile of parts you want to put together, or just swapping engines?

[denn]

I'm building an 86 250R from nothing. I am going to need an engine. I was just wondering if an 86 engine was improved over an 85. I would like to try and keep the bike all 86 but if I can come across an 85 engine I could just change whatever the differences are between the 2 years. I really don't know much about the honda's. I have been strictly a TRI-Z guy for 15 years. I got one when I was 13 and never rode anything else.


Thanks Denn

[BigRedRunner]

Yeah, I've been there. 85-86 are essentially the same thing. Its when you hit '87 that you get into different gearing, long rod engines, clutch setups, blah blah blah. However, they'll all fit in your chassis.

[Blown 331]

Trikes don't kill people. I kill people. Now that is awesome!

[firefirefire90]

i thought the ATC 250R was already a long rod?

[X2guy]

I think it was in 87 that they went to the long rod crank. I'm currently building an 86 with a long rod crank. I will need a piston for a 87+ to compensate for the increased rod length. The long rod is 5mm longer so the piston pin is set 5mm higher in the piston.

[Blown 331]

I think it was in 87 that they went to the long rod crank. I'm currently building an 86 with a long rod crank. I will need a piston for a 87+ to compensate for the increased rod length. The long rod is 5mm longer so the piston pin is set 5mm higher in the piston.

You can acutally run a long rod with the 86 piston, you just have to get a 5mm spacer plate under the jug. I think spark plug to frame clearance is pretty tight if you do this on a 3-wheeler.

[deathman53]

Its not too bad, I use spacer plate motors, don't even try it if you are gonna use a cool head though, or any aftermarket head. the spark plug is so hard to get to,

[sandrooster]

Trikes don't kill people. I kill people.
Blown, you're a cop?

[movistargixxer]

someone told me that the early 85's were 5spd

[Red Rider]

someone told me that the early 85's were 5spdSomeone didn't know what they were talking about. :rolleyes:

[movistargixxer]

well i didnt doubt them i had 2 85 both had 6spd
they must have just had a 85 with a messed up 6 gear lol