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| Decarbomizing a MR175 (1975) https://vintagedirtbikeforums.alp-sys.com/viewtopic.php?f=21&t=2227 |
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| Author: | OLDDIRTRIDRER [ Sun Apr 05, 2009 6:28 pm ] |
| Post subject: | Decarbomizing a MR175 (1975) |
All, I just got a new gasket kit ordered from Ebay and when it arrives I want to clean up the internals on my 1975 Elsinore MR175 (Green Tank-Silver Fenders) soooooooo........ - Any advise? 1) Any special tools need? 2) Any secrets to make sure it all goes back together correct. ( I have a Clymer Manual is that sufficient?) Note: The engine seems sound right now, 140 compression, just want to do the decarbonizing as prevenative maitnenance. Larry |
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| Author: | rayivers [ Sun Apr 05, 2009 7:59 pm ] |
| Post subject: | Re: Decarbomizing a MR175 (1975) |
Larry, Yeah, it's me again... ;>) I'm glad you asked about pulling apart the MR175 motor, because I've never had an experience quite like it (well, several experiences now). The original cylinder on the bike was probably the hardest to get off. I tried the head bolts and realized that normal amounts of torque weren't going to get them off, so I pointed a space heater at the cylinder and soaked them in PB Blaster for about a day and a half, then used my new 120V impact wrench to get them off. All of them fought hard, but off they came. If I had tried it with a breaker bar, I would have snapped off all four studs in the cases (see below). After the bolts were out (completely rusty inside and out), I gently pried off the head by rocking it front to back and side to side (be careful, there are locator dowels on the sides of the gasket surfaces). If you're careful, the head gasket can be re-used, sometimes over and over (I've used one three times now, it still looks and works great). OK, the easy part is over - now you have to get the cylinder off. It may feel like it's welded to the cases, because it probably is. Heat is your friend. My studs were even rustier than the bolts, and the locator dowel tubes at the cylinder base were rusted to the studs, the cylinder, and the cases :>( - The entire bike could have been lifted by the cylinder. I filled the four stud holes with PB Blaster and let them sit for another day, with the space heater still on. Then I used a small heat gun to heat up the entire gasket surface real hot, a large bearing puller clamped to the top fins with the center pin bearing down on a buffer (I used a large plastic drawer pull) against the piston crown at BDC, and a flywheel puller pushing down against a wood block atop the cases, and up against the underside of the intake manifold. Hey, you asked. :>) Maybe you'll be able to lift yours off with two fingers, but I doubt it. I've got several cylinders here that were removed using the 'eBay seller' method (hammers, crowbars, and dustpans to sweep up the broken fins), but mine didn't even mar the paint. The other original cylinders I pulled off weren't quite as bad, but still absolute bitches to remove - even the cylinders I've replaced the dowels and used new lubricated bolts in, and treated with PB Blaster pre-assembly still can put up a pretty good struggle. One last thing for now - once you have the cylinder off, be sure and measure the ring gap !! Ray |
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