Top End Rebuild
Thread Starter
|
Tourer
Joined: Dec 2007
Posts: 388
Likes: 0
From: West Tennessee
Top End Rebuild
Hi, I'm new to the forum. Just happened to stumble across it. I just bought a 76 XLH the other day. I'm loving every minute of it. Thing leaks quite a bit of oil from the primary case which I am working on fixing, but my main concern is the main problems I'm having with the motor itself. Which is why I am planning on doing a top end rebuild on it. But I have a few questions about it.
I noticed another thread with this same problem but never really a resolution to it. When I pull the throttle hard on my bike at higher speeds around 35-50 the bike will just increase its RPM's really high but it will never increase it's speed. I'm leaning more towards a carb problem but I'm not sure. It could also be a tranny problem. The carb that was on there was a Mikuni carb, but to be honest I am not certain what model as it doesn't look like any of the current carbs on their page. Anyone else had this problem and if so was it actually the carb or worse?
The next question is with the actual rebuild. I realize that the motor will have to come out to open the rocker boxes and the cylinder cases. My question is exactly how heavy is that motor and for you people that have pulled your motors did you have to have a motor lift or did you just have a couple of hands around to lift it out? Stupid question I know.
Thanks from a new member.
I noticed another thread with this same problem but never really a resolution to it. When I pull the throttle hard on my bike at higher speeds around 35-50 the bike will just increase its RPM's really high but it will never increase it's speed. I'm leaning more towards a carb problem but I'm not sure. It could also be a tranny problem. The carb that was on there was a Mikuni carb, but to be honest I am not certain what model as it doesn't look like any of the current carbs on their page. Anyone else had this problem and if so was it actually the carb or worse?
The next question is with the actual rebuild. I realize that the motor will have to come out to open the rocker boxes and the cylinder cases. My question is exactly how heavy is that motor and for you people that have pulled your motors did you have to have a motor lift or did you just have a couple of hands around to lift it out? Stupid question I know.
Thanks from a new member.
Extreme HDF Member
Joined: Sep 2006
Posts: 10,033
Likes: 29
RE: Top End Rebuild
1.) It sounds like you clutch is slipping. Start by adjusting it before doing anything else.
2.) You can do a top end job with the motor in the frame. It does not have to come out. Before doing anything, do a compression test and see if you actually even need to do a top end job.
2.) You can do a top end job with the motor in the frame. It does not have to come out. Before doing anything, do a compression test and see if you actually even need to do a top end job.
Thread Starter
|
Tourer
Joined: Dec 2007
Posts: 388
Likes: 0
From: West Tennessee
RE: Top End Rebuild
You can do the rebuild with the motor in the frame? I can't get a few of the bolts for the rocker boxes out because of clearance of the frame. How did you get around that? The main reason I am doing a top end rebuild is because that the motor is burning oil. I will likely need to re-hone the cylinder cases and new valve seals and also new gaskets.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: Top End Rebuild
supr2nr.......
Your engine/trans weighs 188 lbs. That is the same weight as a fireplug, by the way.
The rear rocker box will not come off the head because of a lack of clearance with the frame member, as you have so said.
The rear head and rocker box is removed as one unit. The same applies when you put the parts back in place. So, remove the pushrods and then the head bolts of the rear head and pull it off.
When you begin to remove the cylinders.......
Be sure to do this: Lift the cylinder off the crankcase just far enough to stuff clean rags all around the rod. The reason for this is the fact you may have some broken piston rings (not likely, but it could happen) and the rags will prevent broken pieces from falling into the lower end. If that were to happen you will have no choice but to remove the engine and totally disassemble it.
If the engine is burning oil, brace yourself with the knowledge that you may be looking at a rebore with new pistons.....not a simple honing of the cylinders.
Worn bores can result in burning oil. Honing the cylinders just makes the worn bores even more 'worn'.
If you are lucky enough to just have worn valve guides and need new rings, then the expense is going to be much less. The wear measurement of the bores will determine what you have to do.
Measure the bottom of the cylinder (where the piston never goes) against the top of the cylinder (where the cylinder wear takes place) and see what the difference is. This tells you if new pistons are needed.........pg
Your engine/trans weighs 188 lbs. That is the same weight as a fireplug, by the way.
The rear rocker box will not come off the head because of a lack of clearance with the frame member, as you have so said.
The rear head and rocker box is removed as one unit. The same applies when you put the parts back in place. So, remove the pushrods and then the head bolts of the rear head and pull it off.
When you begin to remove the cylinders.......
Be sure to do this: Lift the cylinder off the crankcase just far enough to stuff clean rags all around the rod. The reason for this is the fact you may have some broken piston rings (not likely, but it could happen) and the rags will prevent broken pieces from falling into the lower end. If that were to happen you will have no choice but to remove the engine and totally disassemble it.
If the engine is burning oil, brace yourself with the knowledge that you may be looking at a rebore with new pistons.....not a simple honing of the cylinders.
Worn bores can result in burning oil. Honing the cylinders just makes the worn bores even more 'worn'.
If you are lucky enough to just have worn valve guides and need new rings, then the expense is going to be much less. The wear measurement of the bores will determine what you have to do.
Measure the bottom of the cylinder (where the piston never goes) against the top of the cylinder (where the cylinder wear takes place) and see what the difference is. This tells you if new pistons are needed.........pg
Novice
Joined: Dec 2007
Posts: 17
Likes: 0
RE: Top End Rebuild
Yes as stated before you can remove the top end and cylinders in the bike. Most likely it is valve guides that is your oil buring issue.. almost 100% sure its your clutch on the RPM thing.. there are a few tricks.. i dont remember what year you said it was, but if it after 76 you can put some automatic transmission fluid in the tranny to see if it locks up better. If it is 76 or earlier you will need to weld up the crossover valve. Also just checking the clutch ajustment would be easy but it sounds like it may be too far gone for that.
Good luck
Good luck
Road Warrior
Joined: Dec 2007
Posts: 1,854
Likes: 20
From: Eagle River WI
RE: Top End Rebuild
Its pretty scary seeing who has sportsters and the up coming wrenching isn't it!!
Trending Topics
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: Top End Rebuild
ORIGINAL: sqdealgeorge
Its pretty scary seeing who has sportsters and the up coming wrenching isn't it!!
Its pretty scary seeing who has sportsters and the up coming wrenching isn't it!!
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Intermediate
Joined: Dec 2006
Posts: 28
Likes: 0
From:
RE: Top End Rebuild
He's talking about the sportster owners who add ATF when their clutch is "too far gone" to be fixed by a simpleadjustment.
Othersportster owners know that is the time to service the clutch properly.
Granted theATF might work if you're in the middle of no where though.
Othersportster owners know that is the time to service the clutch properly.
Granted theATF might work if you're in the middle of no where though.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: Top End Rebuild
ORIGINAL: jones
He's talking about the sportster owners who add ATF when their clutch is "too far gone" to be fixed by a simpleadjustment.
Othersportster owners know that is the time to service the clutch properly.
Granted theATF might work if you're in the middle of no where though.
He's talking about the sportster owners who add ATF when their clutch is "too far gone" to be fixed by a simpleadjustment.
Othersportster owners know that is the time to service the clutch properly.
Granted theATF might work if you're in the middle of no where though.
Thread
Thread Starter
Forum
Replies
Last Post
