| Author | Message | ||
     Stricnine |
I just removed my cylinders to paint them black and noticed that there is some scaring on both pistons. It's only on the inside of both (side facing each other). The outside of each piston looks fine. Does anyone know what might be causing this. They're Wiseco 20 over pistons. | ||
| Jimincalif |
Did you show it the whole "Aliens" series on DVD? Or is it scarring?  | ||
| Stricnine |
My bad. Scarring | ||
| Spiderman |
Can you post a pic? Some small scaring is ok, but massive amounts may mean a bad rod bearing. Check your rods side to side freeplay. Your man. will state the amount of allowed side to side freeplay. also check your bushing tolerance also. | ||
| Patrickh |
are they just dark markings or do they have palpable depressions in them? | ||
| Stricnine |
One has enough scarring for it to grab your fingernail on. You think it could be oil starvation or most likely rod bearings. I'll post pic as soon as I can. (Message edited by stricnine on March 25, 2006) (Message edited by stricnine on March 25, 2006) | ||
| Stricnine |
How hard is it to replace the rod bearings. | ||
| Natexlh1000 |
very hard. The cases have to be split. The lower end has to be pulled apart with special tools. How do the jugs look? perhaps you just inhaled some grit? | ||
| Stricnine |
Jugs appear to be fine. The only place I can see or feel any scarring is on the insides of both pistons. I guess I should be praying its not the rod bearings. | ||
| Spiderman |
If the Jugs are fine then you may not have a problem... Still check your rod's freeplay... | ||
| Stricnine |
Here's everything that happened. I pulled the heads to see the intake valve on the front cylinder hit the piston and the exhaust valve hit the piston on the rear cylinder. I removed the cylinders and saw the scarring of the pistons. Do you think that the valve to piston hit could have caused this issue. I should have stated the full problem from the start. Good thing I was painting the cylinders or I might not of saw this in time. Thanks guys. (Message edited by stricnine on March 28, 2006) | ||
| Leftcoastal |
Have you sorted out the cam timing problem that caused the piston/valve interference? ANY contact between these parts is going to cause damage - i.e. bent valves, cracked or weakened pistons, etc. The scarring may have come from bits of carbon or metal debris released when the contact occurred. You'd better 'bite the bullet' and tear that motor down to the degree needed to find and repair the basic cause of the problem and any resultant damage, instead of trying to fix the symptoms. Just my 50% of a buck Good luck! Hope it turns out to be minor! AL | ||
| Stricnine |
Piston to valve issue is solved. Just curious if that could be why pistons are scarred. | ||
| Stricnine |
Okay guys. I took the whole topend out and did to the best of my knowledge, check the freeplay. The rear rod seemed fine but the front rod (rides in between the bases of the rear)seems loose. If the rod bearings were bad, wouldn't both the front and rear both move. The manual doesn't explain it to clearly. It shows to check the bearings when everything is removed. Does someone know the tolerance and the exact way to check it with them still in the cases. Also, the insides of the pistons, where it scarred, is discolored. I appreciate all the help everyone has offered. (Message edited by stricnine on March 29, 2006) | ||
| Blake |
172689 http://www.badweatherbikers.com/buell/messages/3842/3588.html | ||
| Pammy |
Info on modifications, air filter, mileage. The discoloration on the insides of the pistons is typically an indication of heat. Pictures of pistons and cylinders would be helpful. | ||
| Steveshakeshaft |
If you are sure that both inlet valves have touched the piston crowns, then the fact that the scarring is on the inlet valve side of both the piston skirts on both jugs gives us a clue. Sounds like debris from a valve/piston event has scarred the surface to me. Without debris, you'd expect any minor scarring to be on the piston skirt thrust faces of both jugs. Without viewing the parts it's difficult to say if they are re-usable or not. On the bright side, I've smoothed/polished off minor scarring, honed the jugs and fitted new rings before now. But on the other hand........ You need to check the valves are straight too. | ||
| Blake |
"the intake valve on the front cylinder hit the piston and the exhaust valve hit the piston on the rear cylinder." I think you've probably identified your gremlin. | ||
| Buellistic |
Mechanics check for this kind of stuff !!! Technicians read the BOOK again !!! | ||
| Steveshakeshaft |
I beg your pardon, I partly misread the original post. I withdraw part of what I said above. Sorry. | ||
| Mmmi_grad |
jeeze .........no picture? Why dont you buy new pistons and rings , make sure the jugs get a light hone out for a cross hatch and have the heads checked. as long as you got the side clearance in spec for the rods and you dont feel any up and down movement with the rod then you should be ok. Strait scarring means your rods are strait. | ||
| Stricnine |
The scarring appears to be straight and there's no up and down movement on the front rod and very very slight on the rear rod. Here's a few pics for everyone to see. Maybe they will shed some light on things and someone can tell if they think the rod bearings need replacing. On the front cylinder wall, there's a spot where part of the piston has somehow came off the piston skirt and stuck to the wall.  | ||
| Stricnine |
Rear Cylinder  | ||
| Stricnine |
Pistons  | ||
| Blake |
Those are "scuffed" all to heck. Debris, oil starvation, overheating, poor fit, could be some/all the causes for that. The cylinders may be salvagable, but if it were me, I just go get myself a nice shiny new 1250 kit. Carefully remove the top compression rings and examine/scrutinize them with a magnifying glass; do the same for each piston's top compression ring lands. Notice any evidence of contamination or overheating? | ||
| Denfromphilly |
I agree with Blake, that's pretty bad whatever the cause. Get the 1250 kit, augment it with the race kit, some stage two or three heads and a nice lumpy cam. In the end it's only a few more bucks than making it stock and you will love the performance increase.  | ||
| Pammy |
Tq plate bore and hone to (new)piston specs. That is some harsh scuffing. You will have to have a qualified tech check your bottom end. But, THAT damage was not likely caused from rod bearing issues. While you have it apart, have the heads checked out as well. How long was the motor together after rebuild? Who rebuilt it? How do you ride? Was it properly (dyno) tuned? Looks like it was very lean. You have to start over my friend. Sorry for the bad news but on the bright side, if you were happy with the way it was running before, you will be ecstatic with the bike when it is running properly. (Message edited by pammy on April 03, 2006) | ||
| Jimincalif |
Get a 1250 kit based on the Axtell Nikasil cylinders. NRHS has a nice kit with those and whatever compression/shape of forged race pistons you want. I went with 10.5:1 and domed like a Thunderstorm motor, with '04 heads cut to match. | ||
| Stricnine |
Thanks guys. I was looking at the 1250 kit or going .030 over. Is the new $750 kit from nallin a good one. I already have a brand new set of stage 2 nallin heads. I just don't want to overlook something and this happen all over again. That's why I was wanting to know if it may be the rod bearings. Is it an expensive thing to have the bottom end checked and/or bearings replaced. I already have the motor down. (except the primary)to just the bottom. | ||
| Blake |
That $750 NRHS kit includes iron cylinders I believe, not the plated all-aluminum alloy ones that you are probably wanting. Better yet, support the BadWeB sponsors and purchase your 1250 kit from them. Try Cycle Rama or Revolution Performance. Revolution Performance obviously provides their own lifetime warrantied Revolution components. Cycle Rama can provide either the Revolution Nicasil plated cylinders or the Axtell Nicom plated ones as you wish. You won't go wrong with either one. I am compelled to say that it seems a darn shame that our most loyal and supportive sponsors invest their valuable time and effort to help folks here, offer up their expert advice only to have people suggest that we then take our business elsewhere. Please support the folks who support us and our little community here; they are all top notch. |
