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Gen 5 CR500AFX build started on 01.12.2012 - Motor Blown
Posted: July 8th, 2013, 5:53 pm
by fmikhele
So took the bike up north for the long weekend. The bike was previously broken in before the journey north. Initially the bike rode beautifully, on cold starts it seemed to load up with excess fuel a little but quickly cleared itself once riding. I was by no means hard on it and about half hour into the ride it began to feel a bit sluggish. I quickly turned around and headed home but the bike ended up quitting minutes later. The engine did not seize but sounds like the piston is likely damaged.
Bike Specs:
Fuel was 87 octane
Mix ratio was 32:1
Plug is a BR8EG
Carb is a 39.5mm PWK w/ stock setup from carbpartswearhouse
Ignition is a GEN 2 (00-01) CR250
The cylinder was a brand new OEM cylinder and the bridge was relieved
The piston was a Wiseco std bore with lub holes drilled and de-burred
coolant was fresh and full
Decompression head
Really struggling to understand what I missed. Have rebuilt a decent amount of engines and many CR500's, but never had an issue like this.
My initial hunches are the carb's jetting and possibly the plug (I generally run a BR9ES plug). Another possible source may be the decompression head... Is it possible that the valve was not closing properly and drawing in excess air?!?
Thoughts?
Pictures to follow
Posted: July 8th, 2013, 6:24 pm
by AlisoBob
Why run the crappiest pump gas you can get?
Theres tons of info on setting up a PWK for a 500 on here. Why not use it?
Wiesco's suck
Did you check the ring end gap? Butting rings kills more CR500's than anything else.
Posted: July 9th, 2013, 3:43 am
by fmikhele
AlisoBob wrote:
Why run the crappiest pump gas you can get? - You're right, it is crappy gas, but at the same time I've never had a problem running it before...
Theres tons of info on setting up a PWK for a 500 on here. Why not use it? - I did use it... I ordered the carb specifically for the CR500. The jetting (from what I've read) made sense within +/_ a jet size. The bike gave signs of loading up with fuel so I did not feel it was running lean whatsoever.
Wiesco's suck - That is your personal opinion and your entitled to that.
Did you check the ring end gap? Butting rings kills more CR500's than anything else. - Yes, the ring end gap was fine.
Posted: July 9th, 2013, 12:30 pm
by Kuma
fmikhele wrote:AlisoBob wrote:
Why run the crappiest pump gas you can get? - You're right, it is crappy gas, but at the same time I've never had a problem running it before...
Theres tons of info on setting up a PWK for a 500 on here. Why not use it? - I did use it... I ordered the carb specifically for the CR500. The jetting (from what I've read) made sense within +/_ a jet size. The bike gave signs of loading up with fuel so I did not feel it was running lean whatsoever.
Wiesco's suck - That is your personal opinion and your entitled to that.
Did you check the ring end gap? Butting rings kills more CR500's than anything else. - Yes, the ring end gap was fine.
did you drill the oiling holes in the weisco?
Re: Gen 5 CR500AFX build started on 01.12.2012 - Motor Blown
Posted: July 9th, 2013, 2:43 pm
by fmikhele
fmikhele wrote:
Bike Specs:
The piston was a Wiseco std bore with lub holes drilled and de-burred
Posted: July 9th, 2013, 4:29 pm
by AlisoBob
Posted: July 9th, 2013, 4:36 pm
by fmikhele
Understood Bob. Trying to get some free time to tear into it! This weekend is looking promising so I will shoot to have them up then.
Posted: July 9th, 2013, 5:55 pm
by AlisoBob
Posted: July 11th, 2013, 3:45 pm
by fmikhele
Started tearing into the bike tonight. Not looking good so far...
IMG_0040 by
fmikhele, on Flickr
IMG_0039 by
fmikhele, on Flickr
IMG_0041 by
fmikhele, on Flickr
IMG_0042 by
fmikhele, on Flickr
Posted: July 11th, 2013, 3:47 pm
by fmikhele
Jetting Setup
Main: 175
Pilot: 52
Needle "DGH" with clip position Second notch downward (Position 2)
Posted: July 12th, 2013, 9:47 am
by Roostius_Maximus
ring end gap?
Posted: July 13th, 2013, 2:48 pm
by AlisoBob
fmikhele wrote:AlisoBob wrote:
Why run the crappiest pump gas you can get? - You're right, it is crappy gas, but at the same time I've never had a problem running it before...
Theres tons of info on setting up a PWK for a 500 on here. Why not use it? - I did use it... I ordered the carb specifically for the CR500. The jetting (from what I've read) made sense within +/_ a jet size. The bike gave signs of loading up with fuel so I did not feel it was running lean whatsoever.
Did you check the ring end gap? Butting rings kills more CR500's than anything else. - Yes, the ring end gap was fine.
Thats the first thing I thought Roosty....
Posted: September 11th, 2013, 4:59 am
by fmikhele
Update
Motor has been completely rebuilt. Sent the cylinder to Bill
http://www.bannedcr500riders.com/board/ ... wnbillybob
Bored and honed the cylinder for $60... very happy with the results
Bills feed back on the cylinder was piston clearance was to tight... one thing that was noticed when removing the piston was that the piston pin seemed to be nearly seized in the piston. Based on the scoring in the cylinder which was only present on the exhaust side of the cylinder, the seizure of the pin in the piston possibly "caulked" the piston in a tilted fashion to cause the scoring like it did?
Engine Specs (post rebuild)
running 91 octane fuel (instead of 87)
plug is not a BR9ES (cooler then the BR8ES)
In the carb went up one size with the main jet and the pilot 175 --> 180 and 52 --> 55. The needle clip position was returned to the third postion i.e middle.
As for the decompression switch leak that was shown before, I have been making the effort to "lap" the switch a few turns every now and then which appears to be working for the time being.
Bob as always thanks for the feedback
Posted: September 11th, 2013, 5:56 am
by abrracing
wisecos always get blamed but 99.9% of the time it's the guy assembling or machining the cylinder.. how much piston to wall clearance did it have and what was the ring gap???
Wiseco pistons have been used for YEARS by millions of people and pros with success.. we used them in drag racing for years too with nitrous applications.. they're not junk pistons.
Posted: September 11th, 2013, 7:10 am
by Roostius_Maximus
it didnt start at the pin, the shit stuck to the bore tweaked the piston shape as it wedged past it and the pin was tight to come out as a result.
Posted: September 11th, 2013, 9:44 am
by abrracing
Roostius_Maximus wrote:it didnt start at the pin, the shit stuck to the bore tweaked the piston shape as it wedged past it and the pin was tight to come out as a result.
EXACTLY
