Boxerworks.com

Want to get more perspectives on the sound of the bike and the look of the exhaust "smoke" (after some reading, I'm unsure if it is smoke or the more common water vapor that get's mentioned throughout the Airhead-themed forums).

In any case, Would greatly appreciate some feedback and more experienced perspectives.

(And yes, I'm well aware the license plate is showing, and frankly, don't really care.)

Ruff as guts.
Start with valve clearances, then timing, then coil/plug connections, then carbs.
One cylinder is not firing intermittently, at idle.

The only conclusion that can be drawn from that video is that it's not running ideally.
Too many possibilities for anyone to even guess at why. Not enough info.
Could be anything from a bad spark plug to a top end overhaul.
Needs a test ride by someone with airhead experience.

How old is the oil?
What grade oil?
How old is the gas?
How is it on the road? if you ride slowly? if you boot it to redline?
How does it idle after a 20 minute ride?
Does it smoke (visibly a lot) once really warmed up if you quickly rev it to 6K in neutral and chop the throttle?
If it smokes a lot when you boot it, it needs rings.
If it smokes a lot on closed throttle deceleration from high rpm, it needs valve guides.

I would proceed in the following order if a road test didn't immediately make the problem obvious to me...which it probably would...

1 - Valve clearance check
Too loose will just clack, on the tight side but with minimal clearance will run great, way too tight (less than 0 clearance) will run crappy.
2 - Compression check.
Remove the carbs (or jam the slides partly open with a popsicle stick) when checking the compression.
Anywhere over 105 psi can be made to run ok, between 120 to 150 psi is preferable.
Under 105 psi means it's time for a top end rebuild.

If compression is over 105 psi...
If your bike has points, check the gap, if they're worn or blue, replace points and condenser.
Does the bike have the correct spark plugs?
Replace the spark plugs if age and mileage are unknown and they don't look pretty new.
Check the timing. Check the air filter.
Does each side stall if you turn the carb mixture screw all the way in?
If not, you have a blocked idle circuit, time for carb work.
If all the above is A-1 and it still runs crappy, you might need a coil and/or HT wires.

that's enough for now

gspd wrote: ↑Thu May 06, 2021 10:19 pm How old is the oil?

If I had to guess, around 3 years old. When I first checked the oil, it resembled perfectly healthy (and relatively new looking) oil. not dark, good consistency. After about 300 miles since then, It's looking quite a bit dirtier. I have no reason to believe it's had an oil change since before it came went into storage ~3 1/2 years ago. This is on my do it ASAP list of tasks.

gspd wrote: ↑Thu May 06, 2021 10:19 pm What grade oil?

Unknown. I plan to replace with 15w50/10w50. I've heard the Motorex Boxer 4T oil name thrown around. Would that be a good oil or is there something else you prefer?

gspd wrote: ↑Thu May 06, 2021 10:19 pm How old is the gas?

New ethanol-free from 2 days ago.

gspd wrote: ↑Thu May 06, 2021 10:19 pm How is it on the road? if you ride slowly? if you boot it to redline?

As this is how it's been since day one of me owning it, I can't really give comparative descriptions, but it doesn't seem bad. Slowly or accelerating quickly, it *feels* like it isn't struggling for power. But then, as I've stated, it's my first ever boxer/airhead, so I have no idea what it *should* feel like.

gspd wrote: ↑Thu May 06, 2021 10:19 pm How does it idle after a 20 minute ride?

like this:

gspd wrote: ↑Thu May 06, 2021 10:19 pm Does it smoke (visibly a lot) once really warmed up if you quickly rev it to 6K in neutral and chop the throttle?

Yes. on a throttle chop, It does smoke quite heavily. Also sounded like it backfired a couple of times. Or, well...Maybe backfired isn't the right phrase. That same kind of sound some performance cars make when you rev them up. Popping in the exhaust. Excess fuel burning off in the pipes, maybe?

gspd wrote: ↑Thu May 06, 2021 10:19 pm If it smokes a lot when you boot it, it needs rings. If it smokes a lot on closed throttle deceleration from high rpm, it needs valve guides.

It didn't necessarily smoke a ton on the way up to redline, although I will have to have my wife record it next time I finish a ride. However, the sudden chop of the throttle made a lot of smoke. This would make me lean towards your "Valve Guide" suggestion. Would you recommend a service shop do that work or would it be relatively straightforward for an enthusiast with a weekend and some tools? I'm not scared of tearing things apart, especially with the comparative simplicity this engine has to basically any other I've ever owned.

gspd wrote: ↑Thu May 06, 2021 10:19 pm 1 - Valve clearance check
Too loose will just clack, on the tight side but with minimal clearance will run great, way too tight (less than 0 clearance) will run
crappy.

I don't specifically hear anything noisy, but my lack of experience with these engines likely means I wouldn't hear anything obvious. Valve clearance

gspd wrote: ↑Thu May 06, 2021 10:19 pm 2 - Compression check.
Remove the carbs (or jam the slides partly open with a popsicle stick) when checking the compression.
Anywhere over 105 psi can be made to run ok, between 120 to 150 psi is preferable.
Under 105 psi means it's time for a top end rebuild.

I'll be able to check the compression the next time I am at my parents'. I'm 90% certain my dad's got a compression tester within his repertoire of tools.

gspd wrote: ↑Thu May 06, 2021 10:19 pm that's enough for now

Wow, thank you! So much better of a response than I imagined I'd get.

The pilot jet is the smallest passage in the carburetor and the first thing to clog with old gas or other crap. It sounds a bit like it's idling on one and then opening up to two when you open the throttle and get the slide/needle/main system in use.

Drop the bowls, pull the pilots, and clean them out. Then try again

ME 109 wrote: ↑Thu May 06, 2021 8:42 pm Ruff as guts.
Start with valve clearances, then timing, then coil/plug connections, then carbs.
One cylinder is not firing intermittently, at idle.

Strange. Alright.

gspd touched on a lot of this, too. Looks like I'll have some work cut out for me this weekend.

melville wrote: ↑Thu May 06, 2021 11:38 pm The pilot jet is the smallest passage in the carburetor and the first thing to clog with old gas or other crap. It sounds a bit like it's idling on one and then opening up to two when you open the throttle and get the slide/needle/main system in use.

Drop the bowls, pull the pilots, and clean them out. Then try again

So you think at least part of the issue described is possibly caused by a clogged jet? The way you describe it seems to make practical sense, even with my relatively limited knowledge of how carburetors work.

Sounds a lot better warmed up. Hard to be definite when I can't twist the loud handle in person.
Does it 'feel' like it runs a lot better to you once warmed up?

Change the oil (and filter) to a brand name 20w50 NON-Synthetic oil RIGHT AWAY.
DO NOT OVERFILL
After that, when the bike is well warmed up, rev the piss out of it in neutral and see if it smokes a lot.

Does your bike have points? or electronic trigger ignition?
One ignition coil or two?

Feel around the exhaust nuts/heads to make sure both sides are firing ON COLD STARTUP ONLY!

https://youtu.be/O2CnaIehh48

Quite the knock on the R65 start.

Kurt in S.A.