long rod/short rod

Wheelie-Gene · Post by **Wheelie-Gene** » May 19th, 2009, 7:49 pm

I have an 86 and an 87 engine. Both have long rods.
Which years had the long rod?

fastkart · Post by **fastkart** » May 19th, 2009, 8:02 pm

84-86 had short rods according to roostius's diagrams.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 20th, 2009, 5:51 am

check the case, in this pic the only 86 case is the 2nd one, see how later ones have a very noticable edge above the curved part

Here is an 87 case on an 86

Wheelie-Gene · Post by **Wheelie-Gene** » May 20th, 2009, 6:15 pm

Ahhhhhh, I see.
So the difference in length is taken up by the thickness in the case deck.
I need to look at what was supposed to be an 86 engine, which had a long rod crank in it. Maybe it just had an older clutch and side cover swapped in at one point.

That truly answers my question.
Thanks for the pics.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 20th, 2009, 6:31 pm

No problem
One thing that could have been done is a thick spacer made by cometic on the case to allow an 87+ rod to be used on the crank

100hp honda · Post by **100hp honda** » May 20th, 2009, 8:04 pm

if you didnt have a spacer, the piston would hit the head with 144mm rod. maybe both your bottom ends are '87. honda did the same thing on the 250r with 5mm longer rod, but the difference was made in the wrist pin height rather than deck height of the cases.

Wheelie-Gene · Post by **Wheelie-Gene** » May 21st, 2009, 6:25 pm

I have always run 400 (Chevy) small blocks in all of my personal hot rods/street cars. For years I've heard all the controversies of running a long rod vs short rod. I never wind my engines up to drastic RPMs, so I always preferred a short rod engine. A short rod brings the power in sooner and the quicker piston acceleration away from TDC gives the cylinders a deeper breath (so to speak). The disadvantage is side loading of the skirts.
The differences in rod lengths is taken up in wrist pin locations (duh...).

So, does a short rod 500 perform any differently than one w/a long rod? I realize that port timing, chamber design, timing advance/retard, etc....plays a role in power delivery, but is the hard hit of the early engines due to the short rod?????

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 21st, 2009, 7:57 pm

Wheelie-Gene · Post by **Wheelie-Gene** » May 21st, 2009, 8:13 pm

Hmmmmmmm.

Exnav · Post by **Exnav** » May 21st, 2009, 8:29 pm

My 85' definitely had a harsh hit, where the 97' in my Gen1 is more linear. The 85' could flat get away from a guy if he wasn't paying attention and really, my Gen1 doesn't scare me at all.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 22nd, 2009, 6:11 am

i love that 86 engine in my 88. Its got no bridge, carbontec reed and the big fmf gold series pipe. that engine comes on to power after its only pipe shutter/vibration/shock spring dance that it has within what feels like 1000rpm off idle, then pulls unreal hard and revs way past my other bikes.
I'll have to take some video

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 22nd, 2009, 6:42 am

Wheelie-Gene wrote:...I never wind my engines up to drastic RPMs, so I always preferred a short rod engine...

I've never been one that concerned themselves with what rev i got to, only that the engine had enough vavle spring to get there and live. My daily driver before this gm 6.0 heap was a 350 carbureted in an 89 1/2ton that i turned to atleast 7200rpm everyday on my way to work, and 7800 with 175hp nitrous under it on weekends in truck pulls. STOCK VORTEC RODS with arp bolts in it too. That engine was victim to me for 5 years and got a head gasket treatment only once cuz i was already there when i tuliped a delwest stainless valve and broke a spring. The kid that got it sold it and that kid is still driving it, i sold it 4 years ago this fall.
The 500's mooved in to try and sooth that wound

nmdesertrider · Post by **nmdesertrider** » May 22nd, 2009, 7:35 am

The long rod motors feel pretty tame compared to my 85.

Wheelie-Gene · Post by **Wheelie-Gene** » May 22nd, 2009, 10:38 am

I put too much time into my personal builds to take them out and give 'em a good thrashing. I like to have fun and thrill the power, I'm just cautious.

I had an '81 CR450 a long time ago......that thing had a throw-a-person-to-the-ground kind of hit. I loved the bike. I was its 3rd owner. It practically mamed all those that owned it before and after me. A good friend of mine experienced the thing, he came back shaking and as white as a ghost.

I was really cautious the first few times I rode my 480. Maybe it's the aftermarket pipe that it has, but it's tame compared to the 450. Lots of low end grunt and a linear powerband with no hint of a hit.

I've never had the honor of riding a 500.....I can't wait to get mine fired up when it's finally done.

I'd love to see a vid. Post one up some time.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 22nd, 2009, 11:59 am

my fmf gold series is deffinately an up top pipe, i modded that DG more lastnight and got the 87 tuned, its dammn near upside down as t comes off the stop, and lame up top. I really want to get my 450 engine in a chassis too

Wheelie-Gene · Post by **Wheelie-Gene** » May 23rd, 2009, 1:52 pm

Checked out your 'tube vids. Looks like a cool place to ride.
The bike sounds strong.....friends to ride with....what else could you ask for.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » May 23rd, 2009, 3:52 pm

Thanks! I'm going to do some runs with the 87-88-03 tommorrow and load them monday (boonie internet is too slow)
That place is an hour or more from home and sandy, I've got clay and dirt with valleys here. Its always a blast wherever we go

I am considering fattening the pilot and changing the needle so that i've got a lil more fuel mid-range.

BannedCR500Riders.com

long rod/short rod

long rod/short rod