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Steve, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 6980
Experience:  30+ yrs. experience, MMI, HD technician, HD early, engine rebuild/performance, bike builder, kit bike program manager, CCI 2001-2004
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I recently installed a 1200 upgrade kit and new cams on a 98

Customer Question

I recently installed a 1200 upgrade kit and new cams on a 98 Harley sportster. After the bike had 250 miles on it (since the upgrade) my friend claims he rechecked all the critical fasteners After 800 miles on it he calls me saying my #1 headbolt keeps coming loose . He said he tightened it again and again it came loose. So I began the process of tearing down the #1 jug. While doing so I found that headbolts 2,3 & 4 were loose also. I know he did not check those two headbolts hidden under the rocker box. The gasket I installed were still in place and nothing had been disturbed. After getting the boxes off and the head I found the gasket was blown out the back near the #1 plug where the bolt comes thru the cylinder. So I need in help in resolving why this happened. All of my work was done according to factory manual and also parts manufacturer.
Submitted: 1 year ago.
Category: Motorcycle
Expert:  kwiggins29059 replied 1 year ago.

Hello, did you install new head bolts?

Customer: replied 1 year ago.
No I did not. Nothing appeared to be wrong with them. They were snug and held well with the old jugs. Based upon my experience I saw no need to do that.
Expert:  kwiggins29059 replied 1 year ago.

Thanks, ***** ***** torque to yield bolts, meaning they stretch and should not be reused. I would suggest buying new bolts, using a thread chase to make sure the holes are clean and when installing them coat the threads and underside of bolt head with engine oil to ensure an accurate torque reading. Also follow the steps below when torquing.

1. Tighten each bolt to 7-9 foot pounds of torque.

2, Tighten each bolt to 12-14 foot pounds of torque.

3. Mark each head bolt and head with aligning marks. Tighten each bolt 1/4 turn (90 degrees).

Customer: replied 1 year ago.
Well I did all the steps you spoke of except the new internal threaded screws as Harley likes to call them. The thing is I asked the dealership when I picked up the gaskets about the screws, if they could look that year up to tell if they used one time screws and they said re-use what you have. I have three bikes sitting in my garage with UG kits installed and no loose bolts etc. After many miles still holding true. The guy who owns this bike is a hard driver. Before 800 miles was on it and he was taking to 90 miles plus at a blink and he has bragging rights about outrunning this wide glide with a 107 kit on it. If they were one time only screws seems too me they would have failed before he put 800 miles on it.
Expert:  kwiggins29059 replied 1 year ago.

Thanks, ***** ***** habits may have had a lot to do with the failure. Him running it that hard will defintely cause more of an expansion/contraction of the heads allowing the bolts to back off. The bolts having some stretch in them already would contribute some as well.

I'm sorry the dealer led you down the wrong road on replacement. Reusing the bolts will hold up under most conditions but with it being ran extremly hard the expansion is going to ocntribute a lot more to the failure.

The article below covers this really well concerning the expansion of the heads.

Click here

Customer: replied 1 year ago.
May I ask your background and are you working at a HD dealership?
Customer: replied 1 year ago.
The dealer says HD uses conventional you say they use TTY that is why I ask. Can you provide with info that says HD uses conventional or TTY headbolts?
Expert:  Steve replied 1 year ago.


there are a few possible reasons for loose head bolts, but having found them is actually a problem for me.

you NEVER check head bolt torque on a Harley EVO. you torque them per the sequence and you never touch them again. I don't even know if you have a problem. typically, if you find a blow out head gasket, you'll find loose head bolts during the disassembly.

so, from there you are I would do this:

- plan to rebuild the top end with a COMETIC top end gasket kit. use other brands at your own risk, although most are perfectly fine. your call.

- check to ensure you are not pulling studs out of the cases and that there are no cracks around where the studs fix in the cases. (if you find this, your crankcases are no good)

- remove the heads and cylinders and rebuild with COMETIC gaskets.

- you may apply oil to the head bold threads and underside of the head, but I use a small amount of never seize. you're call, they both work.

- assemble and torque per manual.

- resist the temptation to check the head bolt torque.

let me know if you need more help.


Customer: replied 1 year ago.
Hi Steve I used James Gaskets on this build so I WILL USE the Cometic as you suggest. Can you think of why it happened after riding 800 miles on the rebuild, 786 miles to be exact. The guy is hard on his Sportster. After he raced that Wide Glide the problems began. From the way he describes his riding style it sounds like he red-lining every time. I am also trying to understand thru all of this was it my fault the motor failed or his because his abusive riding.
Expert:  Steve replied 1 year ago.

I don't think anything happened......unless you see evidence of pulling head studs or crankcase cracks at he head studs?

also, if the bolts were not properly lubricated, they will not achieve full torque. that's why I use never seize instead of oil.

the issue here is......someone tried to check the torque on the head bolts. not only is that not possible, it's not supposed to be attempted, due to the torque method.

I can't tell you what the torque on the head bolts looks like after a break-in period because I have never touched the head bolts after I torque them. if you are going to follow the manufacturers instructions, follow ALL the manufacturers instructions.


Expert:  Steve replied 1 year ago.

let me know if you need more help.

if not, please leave a POSITIVE RATING.

thank you,