So Close!...
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@SpookDog
IIRC:
Since I put a new barrel & piston & head on with new gasket (last August) it lasted 7 months until the head gasket went in March. I blame road salt corrosion on the head studs for that one.
This one lasted a month with new gasket, relapped head & barrel and Yamaha dome nuts and washers. I’m hoping that this time was either gasket fault or my fault fitting. I even lifted the engine out so I could get to it with the torque wrench nice and evenly. Cleaned and degreased all surfaces with Wurth degreasant. So I’m gonna have to be extra surgical next time
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@SpookDog WTF - There has GOT to be something wrong with your engine. There just has to be!
I've never had any problems with head gaskets except the cheap white ones you get off of fleabay. I've had some horrible engines in my time too and they were absolutely fine.
So this is very odd.
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I know, I don’t even ride aggressively. This is a new barrel and head since my ‘old’ problems. The first gasket on this top end lasted 7 months and rust got into the studs and nuts, so that’s acceptable. This one has lasted 6 weeks. I’m hoping it was a bad gasket (I’ve had a scratched one before) or ahem user error
We’ll see when I can be bothered to strip the top end again...I don’t seem to have much luck though, that and a painfully slow learning curve are working out worse than a Gypsy Curse!
I will get there thought. I’ve got a 93 4HW TZR project to get my teeth into yet. Can’t find any info on that thing...
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@SpookDog Definitely not putting the gasket on upside down?
You're torquing the head up evenly in a star pattern up to around 22nm? Are you using grease in the bolts as this will impact the reading you get from the torque. Greased bolts torque higher than ungreased?
Sorry if this is very basic but I'm literally baffled!
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@SpookDog did you take them head off for any reason within them 6 weeks as once you’ve tightened the head once you cant take it off again without needing a new gasket or it doesn’t seal properly, only other thing is check the torque of the bolt again once the engines heated
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Up side up,
Using a 1/4 inch drive torque wrench (and lifting the engine up to get at all the nuts evenly and unobstructed)
Studs dry and wire brushed clean.
I clean the top of the barrel and the head by gently lapping them with (180 grit I think) wet & dry on glass, then look for any high or low points with a steel rule.
I clean everything down with solvent, except the gasket which I use straight out of the plastic wrap.I seriously don’t take offence. It’s a mystery to me what I’m doing wrong, but I’ll get there eventually! It only took me 18 months to work out the jetting!
I haven’t loosened or removed the head at all. I haven’t thought about retorquing the head after running just because it’s such a pain in the ass to get at the nuts ‘in frame’
I might have to consider it though. Does anyone else re-torque after first run?... -
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@SpookDog I mean with expansion sometimes things can work loose, people heat things up when they can’t get it loose, I will probably recheck mine. I’m pretty sure when I changed my sump gasket on my landrover the other month it said on the guide check the torque of the bolts once the engines warmed up
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After I took the top end off I managed to break a head stud off level with the barrel while removing them to clean/lap the barrel! FML, eh?! I get all the luck it seems.
So I put the 3MBp00 barrel, piston & head on that I brought recently. Just for the time being. When I first rode it I thought I’d broke the power valve servo wires or such. It was so lacking the usual low down torque. Once I’d established that the servo was working I took it for a ride, it took me a while to get used to the bike feeling so very different, but man that 1mm difference rocks! It really makes the power band noticeable!
I need to take some pics of the 3mb head, piston and gasket that I took off. Once I get camera working!
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@SpookDog Your previous barrel must of been worn out and lack
of power if think 3MB00P has more power as so mildly ported, the
P stamped parts had slighty more power as had different carbs etc. The P stamped head is standard 3MB head just without the casting numbers on top.. -
@theportingmaster I personally didn't like the P barrel. It might have been great on the TZR, but for the DTR it didn't suit the riding position/style.
I will still keep it to one side nevertheless.
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I wouldn’t mean to say power per se, it’s more the way it comes on. It just feels like a totally different animal. It reminds me of an old rd125lc I rode years ago. My old barrel had loads of usable torque in comparison...
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@SpookDog I felt it shifted the power which would be useful tucked in behind a wind shield and what not, but my DT is a town/city rider and doesn't go faster than ~60mph
When I got it 12 years ago the clocks read out 85MPH. So all those "mods" I've done have made it a lot slower lol.
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Head gasket blown again! Second time in two months. I’ve had problems with 3 different barrel and head combinations. The only common factor is me and the antifreeze/coolant I’ve used. I’m gonna guess it’s not the coolant
Weird thing is every single time it’s failed on the top/head side of the gasket. Between the head and gasket surfaces. Never between the gasket and the barrel...
This is the first time this combo has failed (3mbP head & barrel) and I never removed the studs to clean the top of the barrel (because I had a stud shear off on my last barrel) It’ll be interesting to see which side of the gasket failed this time...
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@SpookDog And it's definitely the head that's causing the problem and not some other underlying problem.
For example, I am merely hypothesising here, what if the coolant expansion spring on the radiator cap has failed and the coolant is expanding, adding pressure to the coolant system and eventually so much so that the only place the coolant can go is through the gasket?
This is really not a hard job and I simply can't see you doing anything wrong here (other than putting the gasket on the wrong way up).
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Agree with Calum, you really can't be this un lucky with head gaskets. My own dt had head gasket symptoms, pushing water out the expansion bottle. Turned out to be a slight bit of damage on the radiator filler. Where the cap seal, seals against. It was just allowing water past as the coolant expanded as it warmed up. Also coolant will boil at a lower temperature, if isn't under pressure. I say it's well worth looking at this from a different angle.
