So Close!...
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@MadGyver
Cheers geez, it’s all good to know. I didn’t think it was absolutely necessary, but there you go. No two situations are exactly the same...@anyone
I’ve gotten myself a new piece of plate glass (6mm was thickest I can get locally) and loads of fresh w&d from 80grit on through to 600. I’m gonna have one last go and give the head (especially) and barrel a good lapping. If it fails after this I’m gonna get a good 3mb head cnc grooved for orings (is it one or two on a standard head? I still want to know why it’s good for about a 1000 miles before it fails. I would imagine it’d fail sooner if it was poor finishing of the mating surfaces? But, hey ho! One problem at a time! I will get both surfaces skimmed if I can find a good local engineer that hasn’t lost practice cause of Covid
I still want to build another bottom end when I can afford genuine seals and bearings all through. I’ll never buy non genuine fleabay again, that’s for sure. I prefer my Crap Shoots to happen in a Casino!
...Good luck to the people’s with problems, love to all else!
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Just took of the head and the gasket failed at the back of the head, passing pressure to the big coolant opening on the gasket (the others are just 4mm holes) at the mounting point. It’s failed there a few times. I don’t have an original bolt at the front engine mount point, just an Allen bolt. I’m wondering if it’s putting stress on the head mount. Or if it’s just the easy/biggest target?...
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Whacked on another Vertex I had laying about. It was a reject to start cause of very slight creasing, but beggars are not the choosiest!
I did give the barrel a good clean/lap. The head I gave extra attention with 150 grit...Did a 70 mile run in test, nothing over 6k rpm. Temp right on the 60degC thermostat ‘just opening’ spot on the temp gauge. During the hot weather it was up on the 80degC ‘wide open’ spot. It was like trying to cool the radiator with a hairdryer!!...
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10 days and about 700 miles later the radiator level is starting to drop, expansion tank over spilling. This is like fucking clockwork. I just can’t get my head around it!
I’m going to have to get a head professionally skimmed, as well as a barrel...
I also need to find out how much someone like PJME charge for an o~ring conversion...I’ve only recently found out that you can still get Yamaha DTR125 genuine head gaskets!? I read somewhere that they are thick ‘rubber coated’? I just assumed that they had the same thin black coating that Vertex or Athena head gaskets have and you payed a premium for the Yamaha name? Has anyone seen/used a £40 genuine gasket and can give comparison with Athena or Vertex, similar, gaskets?...
It would be a big help
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@SpookDog said in So Close!...:
10 days and about 700 miles later the radiator level is starting to drop, expansion tank over spilling. This is like fucking clockwork. I just can’t get my head around it!
I’m going to have to get a head professionally skimmed, as well as a barrel...
I also need to find out how much someone like PJME charge for an o~ring conversion...I’ve only recently found out that you can still get Yamaha DTR125 genuine head gaskets!? I read somewhere that they are thick ‘rubber coated’? I just assumed that they had the same thin black coating that Vertex or Athena head gaskets have and you payed a premium for the Yamaha name? Has anyone seen/used a £40 genuine gasket and can give comparison with Athena or Vertex, similar, gaskets?...
It would be a big help
...Have you used custom copper gasket with copper gasket spray,they used it for high compression and performance engines,you can anneal the gasket to become softer and sit even better.
You probably burn slowly coolant and venting pressure in the cooling system.
I only use yamaha or custom copper head gaskets+copper spray. -
I’ve got a copper gasket in my room being used as an ornament. Pay for the postage and buy yourself the magic spray and it’s yours
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Email me your address and I’ll post you a stamped addressed suitable envelope
boonierat13@gmail.comI just brought a can of Permatex spray on copper sealant. ...
@ Madgyver
Are the Yamaha ones coated really thick with rubber like stuff?...
Didn’t have any luck with the last one I tried. Mainly cause I muffed up the annealing as well as using sealant from a tube...Cheers Guys...
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Anyone had any experience with ‘exhaust banging’ or engine knocking at low rev coasting? The best description I’ve read of it is that it sounds like someone hitting your engine with a ball peen hammer sharply. It’s basically misfires which happens to be one of the biggest head gasket killers...
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Ah!!.... So simular to Athena, ect? Not wildly different? Cheers bud, I really need to know this stuff. I can always trial & error it but at £45-50 for a genuine gasket I’d rather be told!
I am not a wealthy person, only job I have is getting out of bed in the afternoon... -
@SpookDog I guess you could make a TZR pipe fit but is there a reason you want to?
Also the TZR (2RK) engine is very different to the DTR; much lower compression (I can remember blagging a go on a mate's TZR and thinking it'd blown up when I kicked it over) and the CDI unit is different as well as a few other bits.
Not wishing to shoot down your idea, a lot of lads in Portugal build DTRs with underslung pipes, I'm just curious
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Not for any long term reason. My ‘big one’ is falling apart. I’m looking for reasons that would cause poor scavenging of exhaust gasses (Ive been getting bad knocking/misfires for a while when coasting @ low throttle) I really just want to substitute another pipe for testing. I have a 94 TZR pipe laying around...
On a simular subject I just checked my reed valve and it is not fully closing (on 1 side petal) when ‘relaxed’ out of the bike. I don’t know much about them other than they are a one way valve, not sure if they should be sprung closed, or forced closed by the piston pressure when it goes down, or both!...
If it’s not holding the mixture in the crank case it could maybe really fuck it up and cause misfires, which in turn murder head gaskets...I wish I was a bit smarter! 🤪
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@HOTSHOT-III I run underslung, wheelie machine
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Hmmmm?! I just checked the Haynes manual and found out the ‘stopper height’ for the reed valve on the DTR125 is supposed to be 6.8mm, TZR 8.3. Mine is 11mm! I might just of found at least part of the cause of my ‘pipe banging’ which in turn could be the cause of my gasket problem...
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Just found a good working replacement reed valve with good neoprene rubber seals and flat petals, also with correct stopper heights! Just remeasured the one that was fitted and it is 11mm one side and 13mm the other! A far cry from 6.8!!...
I really am hoping that this was causing the misfires, exhaust banging and in turn the misfires was causing the head gaskets to fail...
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Coming to this conversation a bit later, but I thought I would add my two penny's worth.
Get the head and barrel skimmed professionally, using glass isn't the best option. I know a lot of people will say 'I do it all the time and never get an issue' (I have done it myself, when I can't get to use my milling machine). I know, If you do if correctly then it can do, but it will never be as good as in a proper machine shop. It's not just about having a flat surface, its about having a slight rough finish for the head gasket to grip to.
Check the squish band measurement, if it less than 1mm then this could be the issue, although I doubt this is the issue as lots of different heads and barrels have been used.
If you don't have the carb heating pipes connected to the carb, then they should be at least connected from one banjo to the other. so they is always a flow of water from the head to above the thermostat, ie bypassing the thermostat, to bleed air.
Check the timing is correct?
As stated before replace the rad cap. I would change the thermostat as well.
If the reed valves are not sealing/ closing, then replace them. If you are using standard reed valves then use the stock 6.8mm gap. If you have changed them for Boysen reeds or other after market, then you can open up the stops to give better performance, but they must still seal when closed. If you hold then up them up to the light and can see day light then either the reed block is damaged, or the reeds are knackered.
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I’m actually having a really hard time finding an engineer. Most have disappeared during COVID and half those left are cowboys. The only one I’ve found was not good. The local bike shop managed to fuck up a helicoil. I think I’ve managed to find one localish. Then again I’ve got a good barrel that needs a rebore, so I might just send it and a 3mb head of to PJME who I know do good work that can be trusted. It’s just having the cash and dealing with a 2-3 week turnaround...
I’ve got the reeds covered now. I’d love to work out the surface area of a 28mm circle, then do the area of the reed valve when fully open. The reeds don’t need to be any bigger than the carp at fully open. I’m mathematically challenged tho’
The timing isn’t supposed to be adjustable, but that doesn’t mean a previous owner hasn’t drilled/slotted out the stator mounting holes. It’s something I’ve been meaning to check but not gotten round to...
Any any all advice/ideas are welcome, cause I’ve been twisting my melon over this one!
Cheers bud!...
