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Ryengoth

1982 XJ550 Maxim Project

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I'm in the process of re-birthing an 82 xj550 and will be posting some updates along the way. I've started a picture thread in the gallery as well but will keep the technical discussion over here. Can anyone confirm that the crank case and trans are the same between the 550 and 650? I've been debating doing a parts swap on the case I have to upgrade it. If it's too much modification then I'll just redo the bike with the original bottom-end. The original head is in the spare parts bin with a heavily scored exhaust cam cap on #1. I have a decent used head on the way and will hopefully get another 30 years out of this re-build. I found a cam set from a bike with 1000 miles and will be sending them off to WPC for micro-peening. That should give the cams and caps a lifetime of friction freedom for cheap. Electrical is a mess. No ignition switch, fuse box rotted into oblivion and the gauges don't do anything at all. Horn works, starter works and it fired over on starter spray. The taillight, signals and indicator cluster lights work but I'm having to rebuild the signal flasher relay. The capacitor inside is worn out. No headlight power still. Lots of work to do!

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Sounds like you have a handle on this. I can’t help with the cases as I thought the 600 was directly related to the 550, whereas the 650 is different 

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Thanks for chiming in! I'll take any input I can on this model as it's my first bike rebuild. I've done 2-smoke and 4-stroke varying from chainsaws to the boosted v6 GDi engine on my Genesis Coupe 3.8T project so I have a wide range of fundamental knowledge and skills. I just need guidance on what's common between models and series as well as where to get engine parts (besides eBay). Most of the online "Yamaha Parts" stores I've found have the same generic bolt and gasket selection with no real OE parts. Example, the small allen-head knurled screw for the chain tensioner housing. The long knurled nut came off easy, the bolt had to be forced out since someone cross-threaded it. 😡

 

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Well I have a 650 head now since I wasn't paying attention to my eBay wish list selection and bought the wrong one. Anyone need some cleaned XJ650 valves? 

The 1000mile cams are on the way to WPC for Izumi to mico-peen them. The lobes and journals should last a lifetime on a bike like this. At the very least, the heat build-up from air-cooling should not affect lubrication as much on the bearing surfaces. I'd love to do the crank journals too but I'm not tearing that far into it unless I crack a piston or start getting ring blow-by. Based on my initial compression tests 180psi leads to be believe it's fine.

New ignition switch and used cover fit well. I still have to find a sumitomo 250 connector for the harness end. Someone took the cutters to it and didn't put the connector in the glove box.

New voltage regulator is on the way, I was getting 10v from the regulator while the AGM battery it was connected to was pushing out about 13.5V. I believe the turn signal issues will go away once voltage is above 12v. Still unsure about the charging system and won't know until the bike is running again. Also not sure what's up with the headlight wiring. No light but the lamp is fine.

Master cylinder and lever have been replaced, as well as the clutch control. Someone broke a drill bit off in one of the cap cover screws and I had no choice but to try to drill it out and ended up ruining the cap. The handle and housing was beat to death so just ordered a new matching set of lever controls.

New clutch cable is in along with a new old-stock Maxim 550 emblem for the side panel, once paint is done.

Engine block, head and cylinder crown polishing are in progress. I plan on starting on the rear wheel soon. New sprockets and chain are on order since these are worn so I'll get all the wheel cleaning and painting done before the new sprocket goes on.

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Lots of work is done and still to be done. The head and valves have been cleaned, new stem seals installed and valves lapped in. Cams will be here tomorrow and I'll finish the head rebuild. Engine has been cleaned about 50% and will be reassembled soon. The frame has been disassembled completely and is ready for sanding and paint. Someone broke the idle tube off for carb #4 so gotta find a replacement body and another idle jet. The other 3 have been cleaned and waiting for #4 before a carb kit is installed. I started on the gas tank with the stud dent gun and ended up chasing a hole with the TIG until I gave up. Too much rust causing burn-through so I'm working on a parts order for a bunch of parts including an undented tank, full harness, headlight trim, full lock set and various other stuff.

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what's with the micro peening, does it just case harden the steel?

 

 

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It does help some with surface tension but mainly it reduces the surface area of the metal without changing the physical geometry. It also helps with friction reduction by providing better oil layer tension, but alone it reduces surface friction by at least 50%. It's cheap insurance for raw bearing surfaces, especially when dissimilar metals are in contact.

 

 

 

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wow, 50%, must try that next

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It really is an amazing and cheap treatment for bearing surfaces. The racing and motorsports industries have been using them for over 10 years to gain an edge in performance. I learned about them from researching how to increase the valve train rev limit from 6500 to 7500 on my 2013 Genesis Coupe 3.8 GDi turbo build project. With the OEM flat-tappet lifter design there was an inherent rotational limit due to friction heat as well as lifter slop at higher revs. I never finalized my head testing but based on the engineering specs; the Ferrea valve springs (40+ lbs each over stock), high-zinc synthetic oil and WPC treated cam surfaces I would be able to hit 7500 without issue even under 25psi boost. 🤩

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I'm having a hard time locating all of the cylinder/head studs for the xj550 engine. It seems that half of them are discontinued and I've already pulled all but the weird bevel-bottom one on #2, without marking them. ARGH! Is it possible to locate them in the UK? All of the distributors in the US have at least 2 if not 3 of the 5 part numbers unavailable.

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Found this in Nth Dakota? seems to have all the bolts https://www.ebay.com/itm/1981-Yamaha-XJ-550-Maxim-engine-cases-block-crankcase/172256816248?hash=item281b4e6c78:g:UAQAAMXQWzNSc7uZ

As to them being available in the UK new I could not find them, seems that they are "discontinued" here as well, not surprising really it's a long way back, you might find a man with a shed who has some on a shelf that he never used but between you and me I think your flogging a dead horse on "NEW".

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Thanks. I may end up making my own from all-thread and cutting the mid-shaft threading off with a lathe. I found one of the inner cylinder plastic-sleeved ones on CMS in NL. Those are nearly impossible to find new (NOS). Shipping those will be expensive, though and they don't have all of the studs either. I guess I may have to piece this engine back together over the course of several months since one stud # could end up costing me $50-80USD to ship it here. ☹️ That eBay block would be a bit cheaper than the few studs I can find online provided those studs actually come out of the block. I'm going to check the threading and diameter of the ones I've removed and see if I can get away with all-thread. Hoping it's M6x1.25, which is readily available by the meter.

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Well that's a good idea, all threaded rod might work all depends on the tensile strength of the original steel used in them. As to the old block on ebay I sent you, my idea was to just chop the old cases away from the studs and scrap it, after all you only need the studs! Plus a lot less time and money spent faffing around with lathes and postage from far flung lands. Good luck anyway mate.

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