Help me figure out how to start my bike.

[koolaid_kid]

Also, it is not a bad idea to unplug the headlight while doing this work. Just remove it and set it aside until you are done.

[StubbornDutchman]

Also, it is not a bad idea to unplug the headlight while doing this work. Just remove it and set it aside until you are done.

I'll take this advice. But may I question why?

Also. I assume these bikes fire two cylinders at a time and not 4 separate times. So if it was a misaligned camshaft shouldn't I have bad compression in two cylinders?

It would seem most likely then to be a missing shim or a bent valve. Or a bunch of other things. But the ticking would lead me to think these two are most likely.

Service history is totally unknown because I didn't buy this bike off anyone. It was found buried under garbage in the back of a barn. Maybe I'll pull it open on Saturday when it's not -30C with the windchill here.

[Steve]

Also, it is not a bad idea to unplug the headlight while doing this work. Just remove it and set it aside until you are done.

I'll take this advice. But may I question why?

Yes, you may question "why?". The quick answer is that you will not be loading down the battery and electrical system while you are doing other testing or trying to start the bike. Until you are ready to hit the road, you really don't need the light.

If you don't feel like opening the headlight bucket to pull the plug, just remove the LIGHTS fuse from the fuse block.

Also. I assume these bikes fire two cylinders at a time and not 4 separate times. So if it was a misaligned camshaft shouldn't I have bad compression in two cylinders?

Not sure what your thinking is there, but you are correct, each coil fires two cylinders at a time, every time the crank comes around.

Not sure how that would affect compression on a compression check, though. Your spark plugs should all be removed. There is NO spark or combustion involved, why would compression change?

The spark is triggered by sensors on the end of the crank, not the camshaft, so they will always be timed correctly, regardless of whether the cams have slipped a tooth or three.

Slipping a camshaft would affect ALL the cylinders, not just one or two.

.

[tom203]

Nope, the cylinders fire one at a time. The piston position in cylinder is same for 1 and 4 and same for 2 and 3 but while one (like #1) is compressing,the other is exhausting (like #4). The piston to valve clearance is really small at top of stroke-any cam to crank timing error might let piston bump valve and cause tick (or worse).
Yeah, it's cold here too!

I think koolaid-kid was refering to charging tests -i.e unplug headlight or pull its fuse

[Steve]

Nope, the cylinders fire one at a time.

Technically true, but don't confuse him, Tom.

Yes, there is only combustion in one cylinder at a time, but there is SPARK in two at a time.
(I think that was the basis of his question.)

At the top of the exhaust stroke for #4, #1 is at the top of compression. When the spark happens, #1 will fire and burn the gas mixture.
The spark in #4 does virtually nothing, but it still happens.

.

[StubbornDutchman]

Slipping a camshaft would affect ALL the cylinders, not just one or two.

.

This is what I figured. So I doubt I slipped a tooth because I only have bad compression in 1 cyl. I guess I'll have to find out the hard way.

Also. Does anyone know the compression spec allowances from factory? I would think 125-130 would be within a good range for an engine like this.

And does anyone know the best place to get shims? I've been doing most of my ordering through CycleReCycle.

[Steve]

I think the factory recommended a minimum of about 100, but general practice says that the lowest and the highest should only be 10-20% apart. A 20% drop from your reported 125-130 would put you right at 100, but you said you had only 65.

Personally, I would add a bit of oil (a teaspoon or two) to all the cylinders and try a compression test again. If it goes up (especially on the low one), your rings are where the compression is getting lost, not the valves. That is actually not all that uncommon in an engine that has not been run for a few years.

.

[StubbornDutchman]

I think the factory recommended a minimum of about 100, but general practice says that the lowest and the highest should only be 10-20% apart. A 20% drop from your reported 125-130 would put you right at 100, but you said you had only 65.

Personally, I would add a bit of oil (a teaspoon or two) to all the cylinders and try a compression test again. If it goes up (especially on the low one), your rings are where the compression is getting lost, not the valves. That is actually not all that uncommon in an engine that has not been run for a few years.

.

Great idea! I'll do that as soon as it's warm enough for me to care.

[eil]

Also, a cold compression reading often doesn't mean much, especially if the bike has been sitting for a long time. Three cylinders should be enough to at least start and run on. After you've put a couple of miles on it, then pull the plugs and do a compression test while the engine is hot. That will give you a better idea of what's going on compression-wise.

[tkent02]

If the bike has sat it may have zero compression, after it has run it may come up. I have a 550 engine which had zero compression in cylinder #2 when I got it. It had been sitting for years, I don't know how many years or how many miles are on it. Tested compression cold and got something like 80 - 0 - 70 - 90.

All of these numbers are lower than standard because I am testing it at nearly 6,000 ft elevation. All engines compression tests read low around here.

After riding it around the block a few times it tested at 100 - 40 - 90 - 100.

After an hour long ride around town it was up to 98 - 93 - 102 - 102. Now after several hundred miles (maybe close to 1000) it reads 102 - 100 - 105 - 108. Plenty close enough to run just fine.