1976 BMW R90/6 "Jimmy Neutron Wanna Be"
- Thread starter Hurco550
- Start date
Top end put back together with fresh push rod tube seals and gaskets, and the fresh carbs to boot. I didn't do rings at this point as I didn't have the scratch and they were both pushing 145 cold psi per side. If I end up starting to blow smoke, ill do it then, but for now, it'll do. I put er together, clicked the starter and away she went. I'm sure it will need a carb sync, but that will have to wait til tomorrow.
https://youtu.be/GhvVRO5Zc0w
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https://youtu.be/GhvVRO5Zc0w
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Time to start syncing the carbs. One known method on airhead bmws is to short out one side then the other using spark plug short rods and a screw driver to the head, until it runs evenly on both. I'm sure this is nothing new to most of you guys, but I figured I'd share my carb sync short out rods. I didn't have the time to wait on a set to order them, and this method is much cheaper. All told I think I have around $7 in the pair. I used two 4 mm by 60 mm long bolts with the heads cut off, two coupler nuts and four standard nuts (all 4mm) as well as a piece of 3/16 inch inside diameter brass tube cut into two equal lengths around 50mm long. All materials where in the hardware section of Lowe's. The coupler nut is recessed on the threaded rod enough to screw over the spark plug. I also used two old spark plug thread on terminals. The standard nuts just act as lock nuts to keep stuff from coming apart. These do fit on both Bosch and NGK caps.
Also made up a set of Gatorade bottle vacuum sync gauges. Of course as soon as I went to start it the battery was dead. Oh well, one more thing to chase down lol
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Also made up a set of Gatorade bottle vacuum sync gauges. Of course as soon as I went to start it the battery was dead. Oh well, one more thing to chase down lol
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The Gatorade bottles were just a bit too large in volume, so I tried a different route for syncing. I had a set of actual gauges on order, but for the second time this month, for whatever reason, the eBay order got cancelled. Oh well.
Off to harbor freight for a $10 Vacuum gauge (with coupon of course) and a $4 aquarium splitter valve from the big box store. I had to drill out and remove the check valve from the splitter, but other wise it worked well. It would be easier to do with two separate gauges for sure, instead of having to block one off and work back and forth, but oh well, it worked and the job is done I'm pretty sure.
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Off to harbor freight for a $10 Vacuum gauge (with coupon of course) and a $4 aquarium splitter valve from the big box store. I had to drill out and remove the check valve from the splitter, but other wise it worked well. It would be easier to do with two separate gauges for sure, instead of having to block one off and work back and forth, but oh well, it worked and the job is done I'm pretty sure.
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Ha, valves are needed either way to dampen the vacuum pulse, and not buying the second gauge wasn't a $6 issue, it was more that I didn't trust harbor freights Chinese quality control to have a pair of them that were perfectly calibrated to one anothertrek97 said:Dude, rather than spend the $4 on the "aquarium splitter". I woulda loaned you another $6 for the second gauge.
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JustinLonghorn
No Purple Hearts, No Blue Ribbons
She sure is purrdy.
That's what I've done, but I've also gotten shocked doing it too.
Thanks guys.
And sonic, there is a bunch of debate on that. Some claim that anything with points is safe to do just that. Some claim that you shouldn't pull plug caps on anything post /5. I figured for $7 I would just make up some short rods and not risk it.
You definitely don't want to pull caps with most (if not all) electronic ignitions.
John Deere made a snowmobile back in the day called a spitfire that had a unique to it c.d.i. ignition. If you didn't have the cap on the plug and pulled it over ONE TIME it was fried. Now, there are none of those boxes left, so many of those sleds are sitting around in good shape with a fried box that isn't available anymore.
I did light myself up even with the short rods. I grabbed a file instead of a screw driver the first time and it had a wood handle with a metal sheath up a little farther than I had realized lol live and learn.
And sonic, there is a bunch of debate on that. Some claim that anything with points is safe to do just that. Some claim that you shouldn't pull plug caps on anything post /5. I figured for $7 I would just make up some short rods and not risk it.
You definitely don't want to pull caps with most (if not all) electronic ignitions.
John Deere made a snowmobile back in the day called a spitfire that had a unique to it c.d.i. ignition. If you didn't have the cap on the plug and pulled it over ONE TIME it was fried. Now, there are none of those boxes left, so many of those sleds are sitting around in good shape with a fried box that isn't available anymore.
I did light myself up even with the short rods. I grabbed a file instead of a screw driver the first time and it had a wood handle with a metal sheath up a little farther than I had realized lol live and learn.
Well it felt good to finally have a vintage bike that I felt was dependable enough to do the distinguished genltlemans ride. Round trip was about 180 miles, and the ol lass handled it great. About 70% of those miles were 4 lane interstate traveling at 70+ mph and she didn't skip a beat (though interstate riding isn't gonna be what I continue to do for fun lol)
I am very happy with the old girl so far. Its low on thrills, but is by far the most pleasant, well mannered and refined vintage bike I've ridden or owned to date.
The only issue ive had is the need for fairly constant head re torqueing and valve adjustment after having the top end off. Luckily, there is no easier bike to torque the heads and adjust the valves on. 3 nuts and the cover is off. You don't even have to pull the tank. Its great.
A few shots from the weekend.
Where's waldo?
Back home safe and sound
I am very happy with the old girl so far. Its low on thrills, but is by far the most pleasant, well mannered and refined vintage bike I've ridden or owned to date.
The only issue ive had is the need for fairly constant head re torqueing and valve adjustment after having the top end off. Luckily, there is no easier bike to torque the heads and adjust the valves on. 3 nuts and the cover is off. You don't even have to pull the tank. Its great.
A few shots from the weekend.
Where's waldo?
Back home safe and sound
CarbsAndCylinders
Careful With That Axe Eugene
Do you mean that you will adjust the valves more than the factory says you have to?
Mine has a 1976 and I would ride it long distance if it didn't have clip-ons and a Cafe seat. These engines run for ever.
Glad you had a nice ride
Brian
Mine has a 1976 and I would ride it long distance if it didn't have clip-ons and a Cafe seat. These engines run for ever.
Glad you had a nice ride
Brian
I just clocked over 600 miles since my rebuild and last valve adjustment. I re-torqued the heads once after a few heat cycles, though.
I had the top end completely off for push rod tube seals. I have torqued the heads/ adjusted the valves 3 times in the 300ish miles since putting the top end back together. The nuts aren't loose, the studs are just stretching I thinkSONIC. said:
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