www.CVOHARLEY.com
CVO Technical => Twin Cam => Topic started by: Lance0964 on April 02, 2019, 01:36:38 AM
-
Hi everyone,
First post here.
I got a 17 Slim S with around 5000 km(3000miles) on it. I bolted SE585 cam in and 2-1 exhaust around 4000km. But didn’t like the loss of low end power. So, I pulled the head off and sent out for head work. Meanwhile, I took the cylinder off and putting SE 10.5:1 pistons in.
However, I found out the cylinder wall have some light scoring. Then I took off the pistons. The skirt of pistons are worn. Pistons are covered by the carbon build up on the top. The most unbelievable thing is the piston rings are out of orientation. The gap of the top and second ring are close to each other (please see attached pic).
I’m planing to bore and hone the cylinder, then put a set of +.010 pistons in.
Question that I can’t figure out. What caused the damage on cylinder wall and piston skirt? How can I avoid it happens again after rebuild?
Thanks
-
Pic
-
Pic1
-
Pic2
-
Pic3
-
I can't see how the head work is going to help low end. The tune is likely off and scoring from excessive heat. The tune helps the loss of low end and also the heat.
-
Head work (with a bump in compression) will help build more TQ all over the curve.
A better valve job (than stock) will improve cylinder fill, which will pick up some TQ
all over too. JMO
But yeah, heat did this one in.
-
Hi everyone,
First post here.
I got a 17 Slim S with around 5000 km(3000miles) on it. I bolted SE585 cam in and 2-1 exhaust around 4000km. But didn’t like the loss of low end power. So, I pulled the head off and sent out for head work. Meanwhile, I took the cylinder off and putting SE 10.5:1 pistons in.
However, I found out the cylinder wall have some light scoring. Then I took off the pistons. The skirt of pistons are worn. Pistons are covered by the carbon build up on the top. The most unbelievable thing is the piston rings are out of orientation. The gap of the top and second ring are close to each other (please see attached pic).
I’m planing to bore and hone the cylinder, then put a set of +.010 pistons in.
Question that I can’t figure out. What caused the damage on cylinder wall and piston skirt? How can I avoid it happens again after rebuild?
Thanks
Why is it unbelievable that the piston rings are out of orientation ? Rings will rotate due to the crosshatch. ;)
John
-
Why is it unbelievable that the piston rings are out of orientation ? Rings will rotate due to the crosshatch. ;)
John
Thank you for pointing that out. I thought they are out of orientation from the factory.
-
I can't see how the head work is going to help low end. The tune is likely off and scoring from excessive heat. The tune helps the loss of low end and also the heat.
Thank you for the comment. I will check with local shop to get my bike dyno tuned.
-
Head work (with a bump in compression) will help build more TQ all over the curve.
A better valve job (than stock) will improve cylinder fill, which will pick up some TQ
all over too. JMO
But yeah, heat did this one in.
I will look into it. Thank you.
-
Looks like you're from Ontario somewhere. There is a real lack of quality dyno-tuners here. Most shops simply use a downloaded map, which can lead to this.
What fuel tuner (SE, PC, Thundermax, TTS) do you have on the bike?
-
Looks like you're from Ontario somewhere. There is a real lack of quality dyno-tuners here. Most shops simply use a downloaded map, which can lead to this.
What fuel tuner (SE, PC, Thundermax, TTS) do you have on the bike?
I'm from Rocky mountain of Alberta side. To be honest, I haven't tried any dyno shop yet and the closet Harley dealer is doing dyno run with TMax. I bought a Power Vision from Fuelmoto last year and did a few auto tunes(basic) with pre-load map since I just did cams and exhaust. But I can feel that dyno tune is really needed. And I'm definitely gonna bring my bike to the dyno after changing the pistons.
-
The compression addition is the torque plus. The pipe is far more influence on the shape and torque production throughout the curve.
-
In regard to the Carbon build up on the piston crowns, thats due to the breather system in operation from the factory, fit an external breather/catch can and that will reduce it.
-
The compression addition is the torque plus. The pipe is far more influence on the shape and torque production throughout the curve.
I got a Bassani Road Rage B1 2-1 Exhuast on my bike. It seems better than stock, but I’ve no comparison with other pipes.
-
In regard to the Carbon build up on the piston crowns, thats due to the breather system in operation from the factory, fit an external breather/catch can and that will reduce it.
That’s a good idea. I did see engine oil in the throttle body. Maybe I should try that. Thanks
-
Truth be told your pictures don't look that bad. There is evidence of being hot however. A little of the coating off the skirts is normal, the carbon is not excessive, a few minor scratches you can not likely even feel. Blowby is bad ring seal and that is the root cause of issues along with the tune. The venting to the outside is a band aide. Taking the cylinders and having them properly honed in torque plates square and true to proper size and hone pattern seals them right up. Then a tune that isn't on the bleeding edge of lean or too much timing and all the issues go away and these motors can lead a long life as long as the lifters are changed as a maintenance item.
-
Truth be told your pictures don't look that bad. There is evidence of being hot however. A little of the coating off the skirts is normal, the carbon is not excessive, a few minor scratches you can not likely even feel. Blowby is bad ring seal and that is the root cause of issues along with the tune. The venting to the outside is a band aide. Taking the cylinders and having them properly honed in torque plates square and true to proper size and hone pattern seals them right up. Then a tune that isn't on the bleeding edge of lean or too much timing and all the issues go away and these motors can lead a long life as long as the lifters are changed as a maintenance item.
Thank you for the input. I didn’t realize the cylinders are bad until I brought them to a local shop for measuring in order to fit the 10.5:1 pistons. The guy told me better to get .010 over size pistons which I did. I’m now waiting for the cylinders to be bored and honed. S&S lifters are on the list for sure.
Can I use a can map from fuelmoto to start the bike after bolt everything back, then ride it to the shop for dyno tune?
-
Very seldom are standard pistons going to work well. The bores distort due to design, overheating and other issues. This is not wear. I would start it. Check for leaks and noises. Then straight to a tuner that understands how to break them in and control heat. This is not wailing on them right away. There is a lot of low speed tuning and starts and stops. The process breaks them in fast if the bore and hone are right.
-
Very seldom are standard pistons going to work well. The bores distort due to design, overheating and other issues. This is not wear. I would start it. Check for leaks and noises. Then straight to a tuner that understands how to break them in and control heat. This is not wailing on them right away. There is a lot of low speed tuning and starts and stops. The process breaks them in fast if the bore and hone are right.
Appreciate your advice. I will do so when I get my cylinders back.
-
.005 over pistons usually are enough to get rid of the imperfections and make them straight
and round. You can hone .005" out fairly easily. I generally don't even put them on a boring
machine unless I'm taking out .010 or more.
It's a PITA no matter how you slice it. I have Two boring machines (Quik-way FN and an FWS).
FWS for small cylinders and the FN for large bores.
I still hate boring cylinders but it's a necessary evil. People want a one-stop shop for machine
work, so I'm stuck doing them.
-
Happy to take any bore and hone job. Even the lower volume stuff. I have a CV616 Sunnen, their gauging, and a Kwikway bar. I make plates for any job I don't already have them for and have a good selection already. My base plate was set up to accommodate from small bore 883 all the way up to M8 big bores. I use drop in adapters to accomplish that. Here is an example, M8 on my buddies CK10.
-
Have all ya want. It's a mindless task, I only offer it as a service to my
cylinder head customers as a courtesy. I don't waste my time doing them
otherwise.
-
Finally got my bike dyno tuned in local dealer. Here is the chart.
The max torque is OK to me, but the curve is not that flat like the similar build I saw on this forum. Not sure if I need a larger TB or try out some pipes in other brand...
-
That tune has a long way to go to be even close. Seek out a real tuner.
-
That tune is horrible, sorry but truth. There is no way anyone can tune one of these things in only 6 runs.
-
Sorry that you have to endure this,
The Wide open pull is the easiest of the tuning and this sheet doesn’t even show a flat fuel line. You may also have wheel slippage and/or clutch slippage
That graph should me smooth not choppy - if this is what you got back ask for your money back as you didn’t get what you paid for.
I’d be scared to let them have another go at this - you are fairly lean in the mid range RPMs for a wide open pull vs 13.0 or 12.8
This is the basics that they didn’t get right
-
Thank you guys for the comments.
Unfortunately, this is the only local place that able to tune with PV.
I may have to travel a couple hundreds miles to get it done properly...
-
Thank you guys for the comments.
Unfortunately, this is the only local place that able to tune with PV.
I may have to travel a couple hundreds miles to get it done properly...
Spend the money to take it that couple hundred miles. That money will only be a drop in the bucket compared to what you just spent to rebuild a top end