Author Topic: Changed plugs now no power (Read 3834 times)

Bahumut · « **on:** July 04, 2011, 10:26:13 AM »

I've searched for a while today on the forums but couldn't find an answer (or simply missed it) for the issue I'm having today...

I had NGK D8 plugs in my 77 550 until it started running weird yesterday. I pulled the plugs and they looked a little dark in cylinders 1 and 4, so I bought D7s and did a carb tune (no adjustment needed) and now the bike pulls harder than it did in low RPMs, but has NO POWER at higher RPMs under load. I jumped on the highway and it wouldn't go above 70!

any ideas?

Deltarider · « **Reply #1 on:** July 04, 2011, 10:32:54 AM »

Odd. You didn't set the gap too wide, did you?

Fritz · « **Reply #2 on:** July 04, 2011, 10:47:40 AM »

Sometimes plugs are shot before they fire a single spark.
You should use D7ES (not DR7ES which is spark plug recommended by NGK).
But maybe it's something different that is not really related to your changing the spark plug type, like the spark plug sockets or brittle hight tension wires.

Cheers
Carsten

Psychonaut · « **Reply #3 on:** July 04, 2011, 11:01:48 AM »

Plug gap? Too much gap can cause a miss under load, usually peak torque and above at WOT.

Bahumut · « **Reply #4 on:** July 04, 2011, 11:13:04 AM »

ahh.. I honestly didn't even look at the gap. what should it be set at?

Bahumut · « **Reply #5 on:** July 04, 2011, 11:17:04 AM »

Quote from: Bahumut on July 04, 2011, 11:13:04 AM

ahh.. I honestly didn't even look at the gap. what should it be set at?

nvm, many results for proper gap in search.

thep1pe · « **Reply #6 on:** July 04, 2011, 11:23:09 AM »

24 to 28 thou

Bahumut · « **Reply #7 on:** July 04, 2011, 03:07:22 PM »

.. well, I checked the gap, it, except for one plug, was within spec. Still won't give me power at higher RPM. I can't figure it out. It's been a 1-step forward, 3-step back kinda day. I think I'm going to leave it alone for a while

Spanner 1 · « **Reply #8 on:** July 04, 2011, 03:29:45 PM »

Doest thou have an electronic ignition perhaps ??

Bahumut · « **Reply #9 on:** July 04, 2011, 03:41:46 PM »

Quote from: Spanner 1 on July 04, 2011, 03:29:45 PM

Doest thou have an electronic ignition perhaps ??

nah, I have the standard points and condensers.

Gearheadgreg · « **Reply #10 on:** July 04, 2011, 04:57:24 PM »

Dirty Air filter

Bahumut · « **Reply #11 on:** July 04, 2011, 05:16:26 PM »

Quote from: Gearheadgreg on July 04, 2011, 04:57:24 PM

Dirty Air filter

all four air pods are clean as chemicals and a rinse can get them.

sick_seven_fifty · « **Reply #12 on:** July 04, 2011, 05:38:11 PM »

Since you were having a problem with cylinders 1 & 4, could it possibly be that your advance for those cylinders is off? And going to a hotter plug worsened the condition? That would explain the power loss in the higher rpm range...

Veterans, throw in your two cents if I'm out of line...I don't want to lead you in the wrong direction...just giving some ideas.

Bahumut · « **Reply #13 on:** July 04, 2011, 05:52:33 PM »

Well, I definitely appreciate the idea. I've never jacked with the ignition timing and gap before, so I'll have to check that. I'm too faced on Jack D and anime on Hulu to mess with it for the rest of the night, but since it's my daily, I'll hit it hard in the morning

TwoTired · « **Reply #14 on:** July 04, 2011, 05:55:36 PM »

Did the power loss come along with the "pods" cleaning. What brand/style pods do you have?
Do you still lose power with the pods removed?
What to the plug deposits tell you?

Bahumut · « **Reply #15 on:** July 05, 2011, 05:18:42 AM »

Quote from: TwoTired on July 04, 2011, 05:55:36 PM

Did the power loss come along with the "pods" cleaning. What brand/style pods do you have?
Do you still lose power with the pods removed?
What to the plug deposits tell you?

Morning everybody. The new plugs are telling me the bike is running fine if not slightly lean. They're tan but cylinder 4 is a tinge whitish. The pods are the K&N style chromie types. I cleaned them after the power loss because I thought that might have been the problem. I'm too afraid to run the bike without some type of filter on the carbs; we have turkey vultures out here... If I suck one of those bad boys into the engine....

Bahumut · « **Reply #16 on:** July 05, 2011, 05:24:10 AM »

I have the same pods that this bike is using: http://www.bikeexif.com/honda-cb750-6

sick_seven_fifty · « **Reply #17 on:** July 05, 2011, 05:52:56 AM »

You put a timing light on it yet?

Bahumut · « **Reply #18 on:** July 05, 2011, 06:23:06 AM »

That's what a local guy said last night too. Building up this bike has been part patience, part buying tools. I don't have that tool yet. I guess I know where my lunch money for the week is going...

chickenman_26 · « **Reply #19 on:** July 05, 2011, 07:00:21 AM »

Quote from: Bahumut on July 04, 2011, 05:52:33 PM

I've never jacked with the ignition timing and gap before,...

Then you've not jacked with the most likely cause of both #1 and 4 acting up at the same time. When 1 set of points, 1 condenser, and 1 coil control the 2 cylinders that are acting up, wouldn't it make more sense to examine the ignition circuit before fiddling with the fueling? It's not likely that #1 and 4 carbs or pods suddenly both developed problems.

Stu

Bahumut · « **Reply #20 on:** July 05, 2011, 07:17:37 AM »

Quote from: chickenman_26 on July 05, 2011, 07:00:21 AM

Quote from: Bahumut on July 04, 2011, 05:52:33 PM
I've never jacked with the ignition timing and gap before,...
Then you've not jacked with the most likely cause of both #1 and 4 acting up at the same time. When 1 set of points, 1 condenser, and 1 coil control the 2 cylinders that are acting up, wouldn't it make more sense to examine the ignition circuit before fiddling with the fueling? It's not likely that #1 and 4 carbs or pods suddenly both developed problems.

Stu

I agree. The shop that did some of the work for me said they handled the points for me and I believed them because, up until this weekend, the bike ran great. I'll have to buy a timing light, learn how to check gap and tackle that this week.

sick_seven_fifty · « **Reply #21 on:** July 05, 2011, 08:02:31 AM »

I've never done it on these bikes, but timing is a piece of cake...You can get a light fairly cheap these days too.

Duke McDukiedook · « **Reply #22 on:** July 05, 2011, 08:52:02 AM »

You will want to pick up a dwell meter and timing light if you don't have them already.
If your condensers have not been chenged in a while you will probably want to change them.

How long have you been running with podz on this bike? Did you rejet to compensate for extra air intake?

Sounds like you could be possibly having some carb issues too- when was the last time your carbs were fully cleaned?

Bahumut · « **Reply #23 on:** July 05, 2011, 06:47:31 PM »

Quote from: Industrial-sized Dukiedook on July 05, 2011, 08:52:02 AM

You will want to pick up a dwell meter and timing light if you don't have them already.
If your condensers have not been chenged in a while you will probably want to change them.

How long have you been running with podz on this bike? Did you rejet to compensate for extra air intake?

Sounds like you could be possibly having some carb issues too- when was the last time your carbs were fully cleaned?

I was told the condensers were new. They look it but that doesn't mean much.
Pods since the rebuild began and ever since I've been running the bike (it didn't come with an airbox)
I rejetted.. It had 98 mains.. went to 130s. Fouled plugs. 125s: rich 120s: still rich but it ran nice. Pulling the carbs is easy.. putting those bastards back on is such a #$%*, but it can't hurt to take a look

Thanks for the tip on the meter and light. putting stuff down on my weekend shopping list:
-dwell meter
-timing light
-tin foil hat
-electronic ignition...

Duke McDukiedook · « **Reply #24 on:** July 05, 2011, 10:03:39 PM »

Points should work fine as long as the mechanism is lubed and the points are not worn down (and the condensers are not bad). Just make sure the dwell is set properly.

TwoTired · « **Reply #25 on:** July 05, 2011, 11:34:56 PM »

You don't really need a dwell meter. All it is used for is to set the point gap, which you can do with a thickness gauge.

Cheers,

Bahumut · « **Reply #26 on:** July 06, 2011, 07:30:01 PM »

Well, I'm on broke-mode, so I went to harbor freight, bought a timing light and got to work. And man did I learn a lot today playing with that light!

I spun the timing plate counter clockwise a little bit to get the F mark to line up with the casing mark and went to work. After rechecking the gap I screwed everything down and back together went on a test run and not only did it run better, my tach actually swept past 4K for some reason. The bike still seems to stutter at 3/4 to WOT though, which it DIDN'T do last week, and the sound from the intakes sounds like it's drowning or something. The bike will pull (eventually) past 80 which is as brave as I'm to take it.

So, power is back, but something is still up...

Spanner 1 · « **Reply #27 on:** July 06, 2011, 08:16:44 PM »

So the timing light showed both points opening at their respective F marks @ idle ( 1100 rpm, no more) but did you check for max. advance @ 2,500-3,000 rpm with your strobe light showing the // marks in the 'window' ??

Bahumut · « **Reply #28 on:** July 07, 2011, 05:36:41 AM »

yeah, the F1.4 (2.3) would rotate counter clockwise and stop at the ]] marks to the right of the numbers under revving. I didn't purposely check that, I just noticed that it did that and was consistent across all four plugs with the timing light. One thing to note however is that it takes a while for the revs to come back down on their own. On my fuel-injected bikes, you hit the throttle and it revs up but goes back pretty quickly. This CB seems to take a lot longer than a split second to come down after shutting off the throttle.

I'm gonna pull the carb bank off tonight and re clean them, just in case I have some crap in there or something.

Bahumut · « **Reply #29 on:** July 07, 2011, 05:48:30 AM »

You know what.. I'm thinking I advanced the timing a little tooo far. I'm going to go back to there and adjust it once more. I'll let you know how the bike behaves after all this rain stops...

Spanner 1 · « **Reply #30 on:** July 07, 2011, 11:24:32 AM »

Be careful with the strobe as anything above idle rpms will show advanced timing as the advancer may be already turning the cam ( which would be normal )

dave500 · « **Reply #31 on:** July 07, 2011, 12:52:37 PM »

ignition sorted,,now play with pods and jetting.

Bahumut · « **Reply #32 on:** August 09, 2011, 01:48:55 PM »

It's been a month, I figured I'd fill y'all in.

First off, thanks to everyone for helping me sort out my issues (with the bike, my personal ones are a whole 'nother thing).

It ended up being a combination of problems that was keeping my bike from running right. The timing was off for sure but when I took the carbs apart, one of the main jets was sitting in the bottom of the float bowl!

Now i have another problem, but I'll do a search first and start a new thread if I need to.

Thanks again everybody!

Bankerdanny · « **Reply #33 on:** August 09, 2011, 01:58:00 PM »

That heppened to me right as I was getting my bike on the road, I pulled a float bowl and found a jet sitting at the bottom.

dtmmil · « **Reply #34 on:** August 09, 2011, 02:31:24 PM »

Did you get your 1-4 trouble fixed? Sometimes with the pods the airflow from the sides will kinda rob the air from those carbs with pods. If you didn't, next time your out try moving your legs around to deflect the air at those carbs, or cover the outsides of the pods with some tape or something and try again.

dave500 · « **Reply #35 on:** August 09, 2011, 02:57:15 PM »

I don't have that tool yet. I guess I know where my lunch money for the week is going...

ive eaten cold boiled potatoes and those corn disc styrofoam things for lunch at work for a fortnight to save for things before!

Bahumut · « **Reply #36 on:** August 09, 2011, 03:20:59 PM »

Quote from: dave500 on August 09, 2011, 02:57:15 PM

I don't have that tool yet. I guess I know where my lunch money for the week is going...

ive eaten cold boiled potatoes and those corn disc styrofoam things for lunch at work for a fortnight to save for things before!

wha----?

News:

Author Topic: Changed plugs now no power (Read 3834 times)