Author Topic: Laid down on it's side (Read 5914 times)

hummbug · « **on:** July 21, 2012, 05:42:09 PM »

71 - CB500, all standard except for Dyna ignition and coils. Oh yeah and exhaust is 4-1.

So....this is slightly embarrassing. I was out for a ride and stopped to take a photo of a cow...yep.
When I went to start the bike again, I did so in haste, without checking for neutral. It was in gear and kicked forward, putting me off balance and I laid (not dropped) the bike on its side. The side of the road was quite steep but luckily covered in grass so there was no damage to the bike.

However, after lifting the bike back upright and starting her again, there seems to be the symptoms of vapour lock - the engine, under load, won't rev above 5k rpm.

I did a quick test on the air filter by removing it and riding down the road - no change in symptoms.
After that I limped it home at 4k rpm , drained the float bowls with no change in symptoms.

So, before I go and check my fuel cap vent, drain the petcock and perhaps pull the carbs, does anyone have any ideas for what may have occurred when the bike went down on it's side? My guess is the carb float levels got all messed and/or there was some gunk in there that got mixed up and is blocking something the jets...??

Greggo · « **Reply #1 on:** July 21, 2012, 06:24:48 PM »

If the bike was running, you may want to change the oil, not that that causes vapor lock, but it is a good idea. Gas can get in the oil. Maybe you were close to a change anyway? Just don't kick the starter over to 'empty out the last drops from the motor.'

hummbug · « **Reply #2 on:** July 21, 2012, 06:41:29 PM »

Just did a change about 20 miles before this... thanks though I will put it on the list. It wasn't running when it tipped over, I pressed the starter button while it was in gear.
No kick starter on the bike anymore, but that's another story.

Greggo · « **Reply #3 on:** July 21, 2012, 06:46:12 PM »

Well, just kick it over a bunch with the kill switch 'off' and then run the hell out of it.

Old Scrambler · « **Reply #4 on:** July 21, 2012, 06:53:33 PM »

One or more of the floats may be stuck

.......somehow the chokes are on

.....We've all done something similar

........Regarding the cow....I used to take my uncle (long time dairy farmer) for a drive in the country and he would admire farmer's prize herds in the field.....occasionally he would say "what a bag!" So now you have to post the picture

ekpent · « **Reply #5 on:** July 21, 2012, 06:58:03 PM »

Check the exhaust headpipe temps with a damp rag or something to see which floats may be stuck or which cylinders are not cooperating for starters.

rboe · « **Reply #6 on:** July 21, 2012, 07:00:38 PM »

I've stopped to take pictures of cows, and I have dropped the bike. At a rally in front of forty plus guys. It was fully loaded so I needed about eight guys to pick it up so in that regard I was lucky to have so much help right there. I needed it!

Wrap the carb bowls with a plastic handled screw driver to shake loose the carb floats. And run her.

hummbug · « **Reply #7 on:** July 21, 2012, 07:32:31 PM »

OK, well, it's actually a bull I think, not a cow...you get the gist.

So I've just drained the petcock bowl and have discovered that its not shutting off properly - may have to invest in some new fibre washers I think. No real gunk in there to speak of, perhaps a few specks.

I have taken the fuel cap off given it a clean and its drying at the moment. I have tapped the side of all the carb bowls but might give it another go today.

@rboe - I'm glad you had someone to help you pick it up. My bike wasn't packed at all and to lift it by myself was a bit of a strain on the steep roadside. Woke up a bit tight in the old shoulder this morning. Don't ever want to put it down like that again.

I think it's time to rebuild the carbs again though - those, along with the leaky petcock.... and get it right this time.

hummbug · « **Reply #8 on:** July 21, 2012, 09:50:32 PM »

I went for a ride and saw no difference. I stopped half way and opened the gas cap - no change.

Checked temps on all headers - by feel they are all the same. It runs smooth out to 4k rpm and then starts to falter - like fuel starvation. Seems that perhaps the main jet/s are blocked perhaps. To be honest, I've rebuilt the carbs once before about 12 months ago but they are technically still a bit of a mystery. Maybe that's the problem.

So, my guess is that I need to pull the carbs, check them all out inside, put new washers in the petcock, sync carb and then see what happens.

I needed to do it anyway...now I just HAVE to do it.

rboe · « **Reply #9 on:** July 21, 2012, 09:58:08 PM »

Operate the throttle while staring at the carbs. Sounds like you bent or jammed something preventing full throttle. But that is just a wild ass guess on my part.

hummbug · « **Reply #10 on:** July 21, 2012, 10:12:50 PM »

thanks rboe - checked that but it's all working as it should - something internal I think.

harisuluv · « **Reply #11 on:** July 21, 2012, 11:04:28 PM »

What side did it fall on? If it just was laid down and then suddenly wouldn't run right the carbs wouldn't seem like a likely culprit. Maybe you dropped it on the right side and the points are off a bit?

seanbarney41 · « **Reply #12 on:** July 21, 2012, 11:11:10 PM »

+1 maybe a small dent in the points cover?

dave500 · « **Reply #13 on:** July 21, 2012, 11:21:54 PM »

ill go with some fine debris disturbed,,you might get away with just dropping the bowls and jets,remove the air screws and going for it with the air compressor every which way,,id do that before pulling the carbs off!unless you want to anyway?

trueblue · « **Reply #14 on:** July 22, 2012, 05:05:49 AM »

Quote from: seanbarney41 on July 21, 2012, 11:11:10 PM

+1 maybe a small dent in the points cover?

+2, I would check this before going on a massive search through the carbs, it is a lot easier to check the points then move to the carbs, than to go the other way.

Bailgang · « **Reply #15 on:** July 22, 2012, 05:30:51 AM »

Quote from: seanbarney41 on July 21, 2012, 11:11:10 PM

+1 maybe a small dent in the points cover?

Well he did say it had a dyna ignition rather than points but if there is a ding on the points cover from the fall then I'd be checking it out anyhow.

Steve_K · « **Reply #16 on:** July 22, 2012, 06:23:13 AM »

If it fell on the throttle side the grip may have been pushed against the bar. That can make the throttle turn hard. BTW, that cow could be a steer, an unlucky bull.
Steve

hummbug · « **Reply #17 on:** July 24, 2012, 01:36:49 AM »

thanks for all the answers...

It fell on the left side so no points cover damage - in fact it didn't really fall, I managed to hold onto it as it went and more laid it in the grass. It felt like ages but it probably only stayed there for 30 secs before I managed to heave it up. The hand grip took the brunt of the impact and had a little grass stain on it...
I do have dyna ignition too so points are a moot point.

dave500 - I need to do some work on the carbs anyway so I'll pull 'em. Probably won't bother until I get back from holidays in mid-Sept though.

Bit of a shame, the bike was running nicely until this...
If, after that it's still not back to it's good old self, I'll have to investigate other causes....or push it into a river. It's a 50/50 decision at the moment as I'd prefer to be riding more than I have lately. I mean fixing these things is fun and all but riding is far more interesting.

ChuckG750f1 · « **Reply #18 on:** July 24, 2012, 05:54:48 AM »

This may be stupid, but what about an air restriction? Could something be blocking your airbox intake inside? Just a trying to think what could cause this if fuel wasn't the problem.

hummbug · « **Reply #19 on:** July 24, 2012, 05:58:13 AM »

Good point Chuck I may take another look down there - i did take the air filter out and go for a quick ride to no avail so it's hard to see what else could be restricting the air intake but hey, stranger things have happened... I also have to wait until the weekend to work on the bike - I'll have another look at it on Saturday.
Cheers

ChuckG750f1 · « **Reply #20 on:** July 24, 2012, 07:02:59 AM »

Hummbug- Off topic, I've been to Melbourne twice in the mid/late '80s. I was working but I had a chance to go down to the coast one day (12 Apostles area, I think it was called). I also was up in Brisbane working. There I spent a day hiking in a park (Bina Bura?). 10 days both trips. -Chuck

dave500 · « **Reply #21 on:** July 24, 2012, 01:46:36 PM »

i live close to binna burra,in the hills,great riding.

Sdsbassist · « **Reply #22 on:** July 24, 2012, 02:57:44 PM »

Mooooooo

ChuckG750f1 · « **Reply #23 on:** July 24, 2012, 04:40:28 PM »

Quote from: dave500 on July 24, 2012, 01:46:36 PM

i live close to binna burra,in the hills,great riding.

Dave- Keep a sharp eye out for those Goannas, Koala and Wallabies! -Chuck

hummbug · « **Reply #24 on:** July 25, 2012, 12:44:41 AM »

Love the cow pic.

It's a small world hey Chuck. You probably would have travelled down the Great Ocean Road which is actually great except it's very bumpy and cars are everywhere on weekends - not much good for riding if you want to get a hurry up. There are, however a few great roads leading back up into the hills around that region. It's a beautiful part of the world.

I can't say anything for Binna Burra - never been up there. I'm sure it's great though, except for the banana benders...just kidding Dave, you're actually from down this way aren't you?

dave500 · « **Reply #25 on:** July 25, 2012, 01:07:31 AM »

yeah hummbug ive lived at clayton,glenwayverly,belgrave south,mooroolbark,coldstream,i went to syndal high school,did an apprenticeship with the now defunct MMBW at moorabin(now melbourne water i think?),rode dirt bikes all over,ballarat,castlemaine,worked at springvale,warrandyte,delivered kitchens for three years when mill park was being developed,,maybe even terrys one?worked at dandenongs largest car wreckers in the day,,phew!now im taking it easy on the gold coast,,come up and have a beer,,ill chuck a goanna on the barbie for you i just rode over one its fresh!

Bailgang · « **Reply #26 on:** July 25, 2012, 02:57:19 AM »

Quote from: dave500 on July 25, 2012, 01:07:31 AM

ill chuck a goanna on the barbie for you i just rode over one its fresh!

I like your style Dave.

trueblue · « **Reply #27 on:** July 25, 2012, 03:09:18 AM »

Quote from: Bailgang on July 25, 2012, 02:57:19 AM

Quote from: dave500 on July 25, 2012, 01:07:31 AM
ill chuck a goanna on the barbie for you i just rode over one its fresh!

I like your style Dave.

Better than a chicken too, they got 4 drumsticks on the f#*<ers

ChuckG750f1 · « **Reply #28 on:** July 25, 2012, 09:05:24 AM »

Hummbug- Any chance that the overflow tube is clogged or melted closed? I had a similar problem on a Polaris ATV when the overflow tube sealed shut from touching the exhaust. When I took the tube off the carb, I could not blow air through it! The gas would not flow correctly into the carb until I replaced the hose (I re-routed it away from the exhaust). Just another thought. -Chuck

crazypj · « **Reply #29 on:** July 25, 2012, 09:14:45 AM »

Quote from: ChuckG750f1 on July 25, 2012, 09:05:24 AM

Hummbug- Any chance that the overflow tube is clogged or melted closed? I had a similar problem on a Polaris ATV when the overflow tube sealed shut from touching the exhaust. When I took the tube off the carb, I could not blow air through it! The gas would not flow correctly into the carb until I replaced the hose (I re-routed it away from the exhaust). Just another thought. -Chuck

That's what I would be looking at, oil in air box or plenum connected to carbs. 500 doesn't have drain like 550?
Probably have engine oil in carb air bleed?

harisuluv · « **Reply #30 on:** July 25, 2012, 12:04:23 PM »

I'm really curious as to what happened, any updates?

hummbug · « **Reply #31 on:** July 25, 2012, 07:42:48 PM »

Jaysus Dave you've been everywhere...man. I'll come and eat some lizard with you one day.

No progress as yet - will have to wait until Saturday before I have another look but the overflow tubes is another good lead...I'll have a look at those.

The airbox seemed pretty dry but will go through all the options again to be sure.

harisuluv - I will keep you updated but after looking at your link, I'm keen to see if you do international orders?

hummbug · « **Reply #32 on:** August 03, 2012, 08:50:40 PM »

So I pulled the bike out today to have a proper look, ran it for a while and went for a quick ride to see if the problem remained - it did.
I thought I would drop past a local mechanic to have a chat about the problem. We went over the symptoms and it was still a bit of a mystery. Started it up, gave it a few revs - over 4k, up to 6k, the up to red line (just quickly) and it was revving ok. He was a bit mystified about the problem then and I figured it was mostly because it only became apparent when the engine was under load.
Bit more of a chat and I took it for a ride to show him the problem (riding by) AND, no problem anymore! WTF!?
Went for a longer ride and it no longer hesitates at all - back to it's normal self.
So..it's good news but also bad news because now I don't know what it was. I'm still going to break down my fuel system from fuel tap to carbs and make sure it's all playing nicely - but not until I get back from OS.

Now, off for another ride. Thanks for all the input.

dave500 · « **Reply #33 on:** August 04, 2012, 12:27:10 AM »

strange one alright?the throttle had full travel and a cable hadnt jumped off the pulley?you wouldve felt that though,being right side down maybe the advancer got jammed and no advance?now its re settled itself?

hummbug · « **Reply #34 on:** August 04, 2012, 05:19:39 AM »

yeah - suspected the advance and I'll take the cover off and have another look tomorrow - maybe giving it a good rev unjammed it? Still don't trust that it's fixed so want to find what's wrong...
definitely no problems with the throttle cable or pulley. I checked that this morning before I rode it and it actually fell left side down so the advance was facing up.
weird....

dave500 · « **Reply #35 on:** August 04, 2012, 05:21:17 AM »

just have a beer and forget about it.

ChuckG750f1 · « **Reply #36 on:** August 04, 2012, 05:26:40 AM »

If all else fails, give it a good drop on the right side! That should un-do whatever the first drop did

hummbug · « **Reply #37 on:** August 04, 2012, 05:33:29 AM »

OK, I'll have a few beers and then drop it on the right side - that should fix it yeah? Cheers!

jerry h · « **Reply #38 on:** August 04, 2012, 07:25:20 AM »

Wild guess here.... do you have a fuel filter installed on it? If so, maybe when you laid it down an air bubble entered the filter.... then eventually worked its way out ??

I had some odd intermittent issues like this, (79 cb650) till I took the fuel filter off.

Just a thought.

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Author Topic: Laid down on it's side (Read 5914 times)