I have search this topic many times and I am unable to find out what my problem is I have a 2004 yamaha blast and I keep blowing my head gasket I bought it uses and it ran fine when I fist got it it has a big bore kit on it and its a 72.5mm gasket I have blown out three because my nuts keep backing off the head studded can anyone point me in the right deriction thanks Dylan
head gasket problems
- Thread starter hotrods64
- Start date
A few questions and suggestions 4 you.
I do not know much about the big bore kit. Is there any mods that needed to be done that were not done ? You might want to read up and inquire in that area. To see if your issue is arising from there.
Is everything flat and level ? on the surfaces that mate up with one another ? There might be a issue there too.
I am surprised your bolts are loosenging up, did you use some thread locker on them ? and are your getting the right torq ?
I know its very hard to get in there with a torq wrench, I cant and I dont have the adde on tool that can get in from the side like that.
But on a regular blaster motor, I just tried them each down by feel. You can take a torq wrench and practice on something esle to that torq and kind of get a feel for what that torq level is, and then go do it on those bolts by feel.
And have you done a compression check, the reason I ask, if you are blowing head gasket and everything is right, there has to be reason.
I just dont deal with the big bore kits, and do nto know if they have to have head work done to them.
Sporty
I do not know much about the big bore kit. Is there any mods that needed to be done that were not done ? You might want to read up and inquire in that area. To see if your issue is arising from there.
Is everything flat and level ? on the surfaces that mate up with one another ? There might be a issue there too.
I am surprised your bolts are loosenging up, did you use some thread locker on them ? and are your getting the right torq ?
I know its very hard to get in there with a torq wrench, I cant and I dont have the adde on tool that can get in from the side like that.
But on a regular blaster motor, I just tried them each down by feel. You can take a torq wrench and practice on something esle to that torq and kind of get a feel for what that torq level is, and then go do it on those bolts by feel.
And have you done a compression check, the reason I ask, if you are blowing head gasket and everything is right, there has to be reason.
I just dont deal with the big bore kits, and do nto know if they have to have head work done to them.
Sporty
I think Sporty pretty much has it covered here, but I'd respectfully suggest that
the cylinder head nuts will not back off if properly torqued and should not need locktite
(even though I am a locktite addict and would probably use it anyway!).
It IS a hard place to get a torque wrench into, so use it on the nuts you can access and go over them and feel how tight they are. NO TIGHTER.
If the nuts are backing off
1) they are too loose to begin with,
2) they or the studs or the threaded holes are stripped,
3) you have serious detonation issues and will likely have other issues soon
4) something is fetching up or relaxing, like dirt on the head/cylinder surface
5) piston is hammering the gasket because you have a 72mm piston hitting a 66mm headgasket?
(I have not ever done a Blaster BBK either, but have done others)
So:
1) assure the head is flat, 100 grit paper on glass should work, do a figure "8" with the head.
2) clean the cylinder, if you have any doubts, pull it off, pull the studs and lap it on the glass and sandpaper too.
3) check that the studs are down tight, locktite them for sure. Clean around them.
4) make sure you have the right big bore headgasket and it is clean, not damaged and on in the right direction.
5) tiny bit of oil on the head studs slide the head on and torque it down in pattern.
That should do it my man.
If the head is true, the gasket is new and tensioned down evenly and diagonally to 20 ft lb it should never give any problems.
Causes for nuts backing off are,
Not being re tensioned after heat cycles.
Re using nuts that have been previously been overtightened and had the threads stretched.
The threads should be dry, no oil or Loctite as torque setting specs are for dry bolts.
Causes for nuts backing off are,
Not being re tensioned after heat cycles.
Re using nuts that have been previously been overtightened and had the threads stretched.
The threads should be dry, no oil or Loctite as torque setting specs are for dry bolts.
