Retightening after rebuild?

[StreetLegalEX]

Sorry guys, for starting another topic, but this is very important to me since I have allready blown 2 gaskets.

I have everything rebuilt, but do I NEED TO RETIGHTEN the 4 nuts of the cilinder studs?
I use OEM Honda gaskets and bolts.

I have run the engine for a while so it has warmed up etc. After I have let it cool down overnight, should I retighten the nuts or not, some people tell me to do this other say don't.
Opinions?

[Steve-o 400EX]

What work did you do to your motor??

I have a Hotcams Stage 2 with a 416 kit and i did not have to retighten anything.

Did you torque them to the correct specefications??

If you did then they should not have to be retightened, the should never come loose.

[skemp]

With Cometic gaskets, it isn't unusual to lose 10-15 ft/lbs of torque on the head studs due to flexion/seating of the fiber gasket after running a bit after a rebuild. With OEM gaskets, you might lose 2 or 3 ft/lbs. I usually just leave them and haven't had many problems yet.

[StreetLegalEX]

Everything is still stock, I had to tear it down because of a blown head gasket. I had the cilinder and head flattened (or how you call that), new studs, new OEM gaskets, and new bolts all over.

I tightened them down to the torque specified in the manual (33lbs ft) so I should be ok?

[YZROOSTINYA]

I never touched mine after the intial install.

No probs here after over a couple hundred hours

[dariusld]

I rode mine after rebuild for an hour, checked them, they were fine. Five hours of riding, checked them again, little loose, some looser than others. I have the cosmetic head gasket.

[stupid driver]

i use the flex steel gaskets and ive never had to do nothing to them after the initial build:macho

[StreetLegalEX]

Hmm seems to be pretty common to just leave them bolts sit tight :)

Might be that mine just got loose because the head wasn't flat enough.

[Chanman420q]

i would just check them after every hour... after 10 hours id say ur good to go

[hondafox440]

Originally posted by skemp
With Cometic gaskets, it isn't unusual to lose 10-15 ft/lbs of torque on the head studs due to flexion/seating of the fiber gasket after running a bit after a rebuild. With OEM gaskets, you might lose 2 or 3 ft/lbs. I usually just leave them and haven't had many problems yet.

I can't imagine losing almost half the torque on a nut after break in. I didn't retorque the studs on either my 440 or my 125 and have had no problems.

[StreetLegalEX]

Originally posted by Chanman420q
i would just check them after every hour... after 10 hours id say ur good to go

Hehe, you have to remove valve cover AND camshaft to check them....like I am going to do that 10 times.....neh... :)

[Chanman420q]

Originally posted by StreetLegalEX
Hehe, you have to remove valve cover AND camshaft to check them....like I am going to do that 10 times.....neh... :)

oh ive never had to do it so i dunno:devil:


my friend kept blowing head gaskets so he let it warm up, idle for how ever long then took it all apart retourged then it was fine. Thats what im gunna do.

[StreetLegalEX]

Since it's my exhaust bolt that got loose last time, I can check that by just removing the valve-head. (only 2 out of 4 bolts are below the camshaft)

Hope it'll be fine.

[StreetLegalEX]

Well, I've had different posts on me and blowing my head gaskets.

Last time I thoroughly fixed my quad. (all bolts/nuts new, new studs etc, new gaskets, flattened head and cilinder, all torqued to spec)
It ran fine until now. Have blown my head gasket AGAIN.

This is the third time and I am getting sick of it.

It holds for about 1month or so, and the gasket always goes bad after long rides. I check my oil level all the time and it's ok. Jetting is also in order.

My quad is completely stock, besides aftermarket silencer and jetting.

What the hell can be the cause of all my trouble??

[BBW]

Sounds like your about ready to blow your own gasket.
Bolts should not, "come loose"! Is your torque wrench calibrated? Are you using lok-tight?
Many engines now have stretch studs that are not designed to be retorqued and in fact should be replaced each time which it sounds like perhaps you did this last time? I'm not sure what EX you have or what year it is, but it would be something to inquire about. Maybe it doesn't take stretch studs but that's what they gave you. Different gaskets also have different requirements. Depending on what you have, retorquing could cause the problem. I would highly recommend asking a professional what the correct procedure is. I think you can get a factory repair manual for around $15.00 which isn't a bad thing to have if your going to do your own work.

[StreetLegalEX]

It's a 2000 Ex, I have a manual, I replaced the studs and torqued everything down to spec.
Last time I also used locktite and the bolts didn't come loose but the gasket itself blew....
I use only OEM Honda gaskets and parts.

[shamisc]

Sounds to me like your mating surfaces are not flush. You could have a warped head or cylinder!:( I'm assuming that you did back off of your cam chain tensioner when you replaced everything, right? Where is the gasket blowing? Is it in the same place every time?

[StreetLegalEX]

Cilinder and head have been flattened so there wont be any warpage left there.

And yes it blows in exact the same spot every time.
(the left corner of the head on the exhaust side)

Yes I took the tensioner apart, checked if it worked ok and then screwed it back holding it with a screwdriver, and releasing it thereafter to take the slack out of the chain.

I followed the manual and guidelines on this forum very carefully, double checking everything.

Is there anything down the engine that can cause this?

[BIGRED400]

I had only 40 hours on my 400 before I installed the 416 kit, took the head with me to the machine shop ,told him to check it for being square if it was out re-surface it to make it square again...........it was uneven , he re-surfaced for me...........kinda surpizing but very possible ,this might be why so many people have problems with head gasket's.........JMO.......take care

[StreetLegalEX]

No I had it checked just before I put it back together. Problem must be elsewhere.

[BBW]

Sounds to me like the only thing it can be is the surfaces are not mating. They may both be flat but something is causing them to not mate. Don't know if you've ever used bluing but you can rub it on one mating surface and apply the other mating surface. The idea is the bluing will come off on the applied surface showing you any high or low spots. I haven't used it in years and there may be something better now but I'll bet your local shop can give you some direction. If the gasket blows in the same spot every time I don't see how it could be anything else.
PS If you use the bluing apply only a VERY thin coat and watch out as that crap gets everywhere and it has to wear off your skin.
If you ever figure this out I hope you will let us know. Good luck!

[StreetLegalEX]

Well, yesterday evening I decided to tear my engine apart once again, to check if all bolts were tight.
After I got the cam out I set my torque wrench to spec and gave them a rip. It popped at 2 out of 4. Surprisingly, the bolts that were loose were at the side where the head leaked air.
I tightened them all, put it back together and fired it up.
After warming it up I put some load on the engine, and my problem seems to be solved. Today I am going to take it for a spin on the track, hopefully it will stick together.

The question that remains is the following; did my head just need to be retightened after placing the new OEM gasket, or is there some other cause for the bolts to go loose?

[cals400ex]

it is very possible the nuts backed off using the stock gaskets. if you used the cosmetic gaskets the problem should have not happened or should not have been as bad. however, with oem gaskets you are suppose to tighten the nuts after riding the bike for a while.

[BIGRED400]

Is your head going down easy or does it bind on the dowels check to make sure it slides over your dowel pins , 1 might be holding it back just a tad.........

[jgfarmsracer]

you need to do a 4- stroke-tech tip split a three layer head gasket and then paint that head gasket it works

i blew three gaskets before i did this not one since!!!

[StreetLegalEX]

Well I didn't actually blow the gaskets, its just that the headnuts get loose causing the head to move upwards so it blows between gasket and head.

But can you explain the 4stroke tech tip?
You split the gasket but what do you mean by painting it?

[howboutchaw]

I would have to guess its not the nuts on top of the head studs coming loose, and it is not the bolts stretching. It is the threads in the cylinder that are pulling after she gets hot. If it blows again just put the bigger studs in, that way you can drill and retap the threads in the cylinder.

[howboutchaw]

I forgot to mention

I haven't retighten the head on my 416 and it is great so far.
;)

I did mic the exposed lenth of the head studs before removeing them just to make sure nothing had moved. the specs are in the service manual.

[jgfarmsracer]

Ya when you split a stock or cometic 3 layer steel head gasket you paint it with b-b-q grill paint and then put it together

i take a file and grind the rivots out split it then use the top or bottom so far i've had no prob's

i have two motors i don't think i have had a stud come lose

when i rebuilt my first one i put new studs in it and have only trashed one gasket

the second motor has been down three times with the studs pull out each time and have never been lose when i took them back apart

Are you sure you havn't pulled a thread in the jug?

[foleyit]

If you torque all of the bolt correctly you shouldn't have to worry about it. I'm using Honda oem gaskets and haven't had any problems with my gaskets.

[cals400ex]

street legal, the paint on the one layered gasket helps the single gasket seal properly so it has less chances of leaking.