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PazyrykTheGreat

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About PazyrykTheGreat

  • Birthday 04/12/1986

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  • Gender
    Male
  • Location
    Phoenix AZ

Previous Fields

  • My Bike(s)
    Dnepr MT16
  • My Story
    Bought a bike from Yuri and it's complete crap.

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Russian Bike Nut

Russian Bike Nut (3/3)

  1. I have a Harley style coil on it and the spark looks good. I want to make sure I order the right rings since there appears to be two different types of pistons. Mine is the kind that doesn't have the second set of scrapers around the skirt of the piston and has two different thickness for the compression rings- 1.5 and 2mm. Also what diameter should I get? 78, 78.2 78.5 or 79mm?
  2. I replaced the coil earlier this spring and the fuel flow looks good and the carb jets are clear. Here's a look at the ring gap. I don't have any gages but I compare it to a ruler and it looks to be about a millimeter which from my understanding is supposed to be 0.25-.05mm.
  3. Well she still won't start. I got fuel puffing out of both exhaust ports, spark to both, but I'm still getting really low compression at 75psi on the left and 60 on the right and there are no leaks from the head gaskets. Since the compression pressure jumps when there is oil in the chamber I really think we've exhausted all other possibilities and that it's the piston rings not doing what they are supposed to be doing. So do I need to get new rings or is there something else that I am missing?
  4. Maybe you're right. I realized that the exhaust port on the right cylinder wasn't puffing out any fuel so I decided to take a look at the carburetor and... blehhh. I gave it a good scrub in the sink to get the gunk out.
  5. I cleaned and polished the inside of the left cylinder till there was no black residue, lightly oiled it, reinstalled and measured the pressure at 85psi. I put some oil in the spark plug hole and the PSI shot up to 135 then went back down to where it was. Engine won't start.
  6. So currently the engine won't start and after a few turns the pressure drops and is currently around 70psi. So I guess that means there's a problem with the rings? Is that all I need to do to confirm that or are there any measurements I should take? I suppose I should get I micrometer. The cylinders where honed in by the mechanic when the pistons were replaced so I am assuming the crosshatching is good.
  7. So I noticed when I turned the engine air was puffing out of the engine vent. So for an experiment I trying the trick of pouring some oil in the spark plug holes and sure enough the chamber pressure jumped up to 125psi on both cylinders. So does that mean my piston rings are bad? I don't know why they would be the pistons and rings are new and only had not even 620 miles on them. I replaced the pistons when I got the motorcycle because I took it to a mechanic and he said they were close to catastrophic failure, But when I got the new pistons they didn't have the rings so the mechanic had to custom order some, so maybe that's the problem since the rings aren't factory?
  8. So I managed to get the surface flattened on the head and it seals where the gasket ring is. I lapped the valves in some more while I had the head off and got both the valves to hold water in the combustion chamber without the springs so I figured them good, but when I installed the head and the cylinder and measured the pressure it only came up to 50psi with is less than it was before. I'm not getting any bubbles from the gasket ring or from the spark plug hole, adjusted the tappets, the piston rings looked good and made sure the gaps were spaced opposite of each other, so how could it be worse? I'm really at a loss here and not sure what I'm doing wrong. Are these heads just bad and need to be replaced? There's some on ebay right now for around $450 for a new pair but I'd rather not make that kind of expense if I can get these damn heads to work. 😢
  9. Okay so here's the possible solution I've come up with- cutting out a disk of sandpaper and gluing it to the cylinder and using that to flatten the mating surface. So hopefully this works.
  10. Thanks for the offer I will keep that in mind. I've been lapping valves in the right cylinder head and got the valves to hold water without the springs so I figured they were good. Reinstall it and got the compression psi at 80 up from 75 with no other visible leaks so not a huge improvement. My over problem is with the left head gasket not sealing. So I took the head and marked the mating surface with a sharpie and then took the cylinder and ground them together. Sure enough it looks like the surface of the head isn't flat. You can see the two black marks near the valves. I think this happened when I got the cylinder head back and first installed it but the gasket ring didn't line up properly and got crimped in at an awkward angle impressing its shape into the surface of the head. So now what? Can this be fixed? Do I need a knew head? I was thinking of taking the cylinder and grinding it into the head to get the mating surfaces flat like lapping valves. Would that work?
  11. I got the compression chamber pressure guage tool and I was able to measure the PSI and it was 71 on the outboard cylinder and 75 on the inboard. My understanding is the PSI should be around 90-110. So I'm still leaking some compression. I guess I need to lap the valves some more?
  12. So after I annealed the gasket ring I managed to get it to start with great effort with the chokes open but died when the chokes were closed. After that the gasket started to leak again. I took the head off and checked the gasket ring, it wasn't blown but had scorch marks near the valves. It wasn't sealing anymore and I wasn't able to get it to seal until I had to stack 3 gasket rings on top of each other and torqued the head to 25lbs, which is weird but it works. I got it to start twice since then with the chokes open only but has been mostly unresponsive. It's got fuel since it ignites with a lighter infront of the exhaust port when I turn the engine, it's got spark, and I guaged the tappets. So I'm suspecting that it's still a compression problem. I'm a bit short on tools and I don't have the equipment to test for leaks. I guess I should get a air compressor or a combustion chamber test guage now?
  13. Well annealing the head gasket appears to work I'm not getting any more bubbles from the head/cylinder gap or from the spark plugs but the thing still ain't starting. I made sure the tappets were adjusted after putting the head back on so I don't know what the problem is tho I suspect that it still might be a compression problem. Is there a way to test the valve seal without taking the head off again?
  14. Okay I have a torch and I will try the annealing process. It's just weird that I've never had to before. I'm pretty sure it's the head gasket that isn't sealing because when I spray soap on it and turn the engine bubbles come out of the gap between the head and the cylinder. Like a lot of bubbles as if the gasket is too thin and not sealing at all. I tested all the valves by pouring gasoline behind them and there wasn't any running thru the valve seats so I'm fairly confident that they are sealing functionally. It would make sense since it's the last thing I changed so I'm confused as this doesn't seem to make sense.
  15. Hello everybody, it's been a while. A bit of an update- I managed to get the final drive assembled back together properly (hopefully). I found out that the valve guides were worn out and the valves stems were bent on the outboard cylinder. So I replaced those and lapped in the new valves and they appear to seal well as well as having the whole head glass beaded in a glove box. But now I have a problem where I'm getting compression leaking from the head gasket. I tried with a new copper gasket ring, sprayed it with the sticky copper gasket sealer goop, torqued it up to 25lbs like I always have, and it's not sealing. I tried with a used gasket ring, but still not sealing. This is the same procedure I've always done and it's always sealed fine so I don't know why it's not holding in compression now. Should I try stacking two gasket rings? Should I get thicker gasket rings? I don't know the thickness of the ones I have since I don't have a micrometer. Should I put more torque pounds on it? I'm afraid to tighten the head on anymore for obvious reasons. The head looks fine and not cracked so I can't figure out what the problem is. The inboard head is torqued to 25lbs and seals fine. Thanks, Pat.
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