Head problems
Head problems
hey everyone, I posted over in the new guy section but haven't really had any suggestions yet so I'm trying in here. this is a copy and past from the other section...
I got a great deal ( well I think so anyways) on a 2004 Sportster 1200 custom.
reason I got it cheap was because it lost compression in the rear cyl.
i figured if nothing else i could part it out..
so today I tore the top end down and found that the reason it lost comp. was because the exhaust valve seat dropped out a bit. At first i thought it
missed the piston but after looking closer I see that it did tap it just a tad I will try to load a pic to show. so I know that I will have both heads rebuilt
but my question is should I go a head and replace the piston due to the contact?
and is the one head even serviceable?
Sorry for such a long post.
Any advice is welcomed..
Oh and the bike has right at 30K miles
shiny part on the right is where it touched
and of course you can see where the valve seat dropped
I got a great deal ( well I think so anyways) on a 2004 Sportster 1200 custom.
reason I got it cheap was because it lost compression in the rear cyl.
i figured if nothing else i could part it out..
so today I tore the top end down and found that the reason it lost comp. was because the exhaust valve seat dropped out a bit. At first i thought it
missed the piston but after looking closer I see that it did tap it just a tad I will try to load a pic to show. so I know that I will have both heads rebuilt
but my question is should I go a head and replace the piston due to the contact?
and is the one head even serviceable?
Sorry for such a long post.
Any advice is welcomed..
Oh and the bike has right at 30K miles
shiny part on the right is where it touched
and of course you can see where the valve seat dropped
Tourer
Joined: Mar 2014
Posts: 304
Likes: 24
From: Black Hills SD
Depends on your budget. It has hit close to the ring lands and there is not much mass there, it may have distorted the piston dome or ring land. I would replace it. Having said that, I have had to run pistons like these when at the drags. If you are on the road, with no spares, you try to run it.
So I decided to go ahead and pull the jugs and pistons. Everything looks fine but might as well have everything inspected at the shop while its apart. Machine shop said that at 30K it's time to have the cyls. checked and possibly bored (I can still see the cross hair pattern on the cyl walls from when it was originally put together) does that sound about right? I have no clue if was ever tore down before..
Also what top end gasket set should I use? the HD dealer of course said to use all HD stuff
Also what top end gasket set should I use? the HD dealer of course said to use all HD stuff
Cruiser
Joined: Sep 2012
Posts: 203
Likes: 0
From: Livingston, La.
With the miles on the bike and you having already pulled the jugs it would be smart to do a top end at this time. My answer is based on you having the funds to do such work as it is not cheap to the every day working guy who has a wife and kids. If you plan on keeping the bike and not selling or trading it in the near future, a new top end will give the bike new life. If the funds are available then why not do the heads so that you get more out of that motor. I mean to send them off to a head porter like BIGboyz. Again it all goes to the funds in hand. Harleys are just like all other motors. They may be made to go as fast as your wallet allows. Have fun riding and be safe. Fairshake
yeah i plan on keeping the bike but i'm not sure about doing major work on the top end (unless I really need it done), i'm thinking more for reliability i will just stay mostly with stock parts. if i start putting bigger pistons and having the heads ported then i will have to redo the carbs and what ever else right? I have a CBR 1000RR for going fast the Harley is just to have fun and be comfortable while doing it.
What do you all think it will run to do everything, if I can stay under $1000 i will be happy..
What do you all think it will run to do everything, if I can stay under $1000 i will be happy..
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Banned
Joined: Jul 2010
Posts: 853
Likes: 19
From: Melbourne
- Inspect the cylinder bore...if you can still see the crosshatch marks then leave them alone. If they are faded and not visable then your in for a hone and new rings (thats all I did to my 50k Evo)
- Replace the buggered piston and piston pin. No need to do both pistons and so long as the new one weight's the same as the old you will be fine.
- Get an oversized valve seat installed. I would also be replacing the valve as well, as if its touched the piston at all then it could be bent or weakened.
- Thats about it....replace the gaskets (HD, James or Cometic are all good brands). I like the MLS type for the heads as they seal better.
- Then ride the pants off it...And do not forget to wind up the rpm once in a while...lol
- Replace the buggered piston and piston pin. No need to do both pistons and so long as the new one weight's the same as the old you will be fine.
- Get an oversized valve seat installed. I would also be replacing the valve as well, as if its touched the piston at all then it could be bent or weakened.
- Thats about it....replace the gaskets (HD, James or Cometic are all good brands). I like the MLS type for the heads as they seal better.
- Then ride the pants off it...And do not forget to wind up the rpm once in a while...lol
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HDF Community Team
Joined: Jun 2006
Posts: 12,774
Likes: 2,606
From: san antonio
No disagreement with previous posts; however, you can fly cut the valve relief in that piston and run it. It is common practice to fly cut intake valve reliefs with OEM pistons when larger intake valves are installed. If you do fly cut the valve relief on the damaged piston, have the other one cut as well to maintain equal chamber volumes.
Bead blast the pistons, have the fitment measured in torque plates and if within specs, new ringsk, light hone to break the glaze and put her back together. Have heads worked by BigBoyz or your porter of choice and have the valve issue addressed as part of that package. Some gaskets and oil and you are back on the road. JMHO.
Bead blast the pistons, have the fitment measured in torque plates and if within specs, new ringsk, light hone to break the glaze and put her back together. Have heads worked by BigBoyz or your porter of choice and have the valve issue addressed as part of that package. Some gaskets and oil and you are back on the road. JMHO.
I'm checking on two places in my town tomorrow that was recommended by a few people. I called one online shop but he was trying to talk me into doing all sorts of performance upgrades, for the fun of it i let him talk and before i knew it he had the price just shy of $1000...
I will call BigBoyz tomorrow also to check there prices.
All im looking for is a good job and not to have the fastest Harley in town..
here is the picture of the cylinder, absolutely no scratches or grooves. on the right side of the pic. is just oil on the side wall that looks funny..
.
I will call BigBoyz tomorrow also to check there prices.
All im looking for is a good job and not to have the fastest Harley in town..
here is the picture of the cylinder, absolutely no scratches or grooves. on the right side of the pic. is just oil on the side wall that looks funny..
.