GS1000E Missing and faarting, suggestions?

[terry]

I'm spending a lot of time scratching my head at the moment, I recently built a Suzuki GS1000E out of a couple of wrecks, one had a good frame and the other an engine with a Yoshimura big bore kit and maybe some (slightly) bigger cams, that sat for 5 years in a lady's front yard under a tarp after a messy divorce.

It starts straight away, (and surprisingly, the charging system still works) but it misses and farts under accelleration. I thought it might have been the plugs, (they were at least 5 years old) so I swapped them for new, hotter range NGK plugs but it made no difference, so I swapped the coils, still no good, and I've ordered some new plug caps but they haven't come in yet.

I hadn't adjusted the valve clearances, so I opined that possibly the valve clearances were too tight, and when hot the valves weren't completely closing, so I spent all afternoon yesterday adjusting them. They're much quieter now, the clearances are supposed to be between .001 and .003, but mine ranged from less than .0015 (my smallest feeler guage) to .009, so I re-shimmed them to around .0025 and I'm happy that they're now correct, but it made absolutely no difference to the engines missing and farting problem.

Today I'm going to swap the plug caps from my GS1000S, if they don't fix it I'll do a compression test (which is a pain with CV carbs) in case I've got a burnt valve or two, and lastly, I'll take the cam cover off and check the valve timing. My gut tells me it's ignition, but I'm willing to try anything right about now. Oh well, at least it keeps me out of the pub, ha ha! I can't think of anything else right now, so I'm open to suggestions? Thanks in advance guys, any suggestions will be gratefully received! Cheers, Terry.

[mike_of_bbg]

And what makes you think that the carbs sitting under the tarp with the engine for 5 years do not need a rebuild? Have you checked for vacuum leaks around the intakes? I'd much sooner suspect fuel delivery than ignition.

[terry]

And what makes you think that the carbs sitting under the tarp with the engine for 5 years do not need a rebuild?

Nothing, I checked and cleaned the carbs when I built the bike, they're fine. Cheers, Terry.

[posplayr]

Well, is this a jetting issue? It is not clear that that Yoshi bigblock kit was ever married to the carb settings? Bigger piston and cams would need bigger mains.

[terry]

Thanks mate, it's only a 1085 kit, and maybe slightly bigger cams (although they look to be the same as my "S" cams) so I'm pretty sure it's not a jetting issue.

The PO's former wife and another friend have both said that the mods were done several years before it was "parked", and I doubt that he would have ridden it in this state for so long.

I know who built the engine too, and he wouldn't have let it out of his shop running like this. Cheers, Terry.

[lordcannon88]

maybe an exhaust leak? my 82 1100GL was doing the same thing and i noticed when i started it up once i saw a spurt of smoke from where the header connected to the can and i pulled the clamp off to look and the clamp was fully tightened but not really doing anything to seal the connection...so 5$ and 2 huge industrial strength clamps later the problems disappeared.

[posplayr]

Poping could be an exhaust leak, but not the stubbling under acceleration.

OK Assuming that your compression test is good, and the valve timing is correct, and you have confidence in the carbs, then only two things left.
Ignition and gas.

I have come to find that a 10.25:1 CR needs premimum gas. Try that next.

Also the hotter motor needs good spark so make sure the voltage to the coils is good (orange /white wires to coil (+) provide over 11V).

[slip]

Sounds like my 78 GS1000E. I am beginning to think mine is the low spark of High Heeled Boys. I only have 8 VDC going out to the coils. I am convinced it is either this, in which I will install a relay mod tomorrow. Or at worst, the coils themselves. My compression is good, and with the VM29's, pods, and Supertrapp, I know I have a beast under there, just waiting to be unleashed!

[terry]

Thanks guys, I'm about to go out to the garage and start.

I didn't mention before that it's a 1980 GS1000E, with the big port head, electronic ignition and 34mm CV carbs as standard. It's still running the OEM airbox and filter, and it's running an "as new" aftermarket 4 into 1 pipe. It did have a Yoshimura 4 into 1 when I bought it, but it was so rotten from sitting so long near the sea, that it fell apart, so it went into the trash, in several pieces.

There are no exhaust leaks, and the backfiring, missing and farting happens under accelleration. I'll definitely check the voltage to the coils, and if that doesn't indicate a problem I'll go buy some 98 octane gas. Keep those suggestions coming guys, I really want to fix it today! Cheers, Terry.

[posplayr]

I'll go buy some 98 octane gas

Is that pump gas? In the US High octane is 91 . So putting 87 regular in can be an issue.

[chef1366]

Maybe the rings need to reseat after sitting for so long. A compression check is in order.

[terry]

Serious? Geez mate, over here 91 is standard unleaded, 95 is premium, and we can buy (if we want to spend the extra money) 98 and 100 octane from most gas stations?

Anyway, I've done the tests, the plug caps made no difference, so I cheated with the compression test in that I didn't pull the carbs, I just connected the hoses and figured any major difference in one cylinder would indicate a bad valve, but with the carbs on I was still getting 125-135 psi per cylinder.

Hmmnn, what next? I measured the voltage to the coils and got 11.8 volts, so I figured that was ok, so I checked the spark again, and it seemed pretty weak. I'd already replaced one set of coils, so all that I could think of was the igniter box? I swapped out the one on my GS1000S, reinstalled everything, and VROOM! Much better!

I'm gonna go get a tank full of gas and take it for a ride, and I'll report back on my return. Wish me luck! Cheers, Terry.

[chef1366]

I have extra igniters if you need one. You pay shipping

You can test compression with the carbs on at WOT.

[terry]

[QUOTE=chef1366;1021101]I have extra igniters if you need one. You pay shipping

Woohoo! Thanks mate, I was going to put the word out that I now need one, so I'll take you up on that offer, I gave my spare one away to another forum member a couple of years ago, and I don't know anyone here with a spare, so thanks very much, let me know what I owe you and your Paypal details, my poor old GS1000S won't be going anywhere until I get another one!

So to finish off the story, I didn't leave until 4.30 pm, and being the day before our first official day of winter, it was a tad cool. In my haste to get on the road I didn't think to put on some overpants, so while I was toasty warm from the waist up, my legs were almost frozen stiff by the time I arrived home a couple of hours and 100 miles later.

No matter, the bike went perfectly, the best it's been since I turned two wrecks back into one useable everyday rider, with a dash of Yoshimura muscle. I cruised along at 60-90 MPH, and sneaked it over 100 MPH every now and then, all without incident. I did notice when I got back in the garage that it smelled like it was running rich and I remembered that when I received the wreck with this engine, it was running a (disintegrating)foam "unifilter" with no lid on the airbox, so I'll take my home-made lid off again, and see if that addresses the richness.

Thanks again for all your help guys, as always, I was impressed today at how quickly the suggestions flowed in, where would we be without the internet, and this great forum? Cheers, Terry.

[KEITH KRAUSE]

Glad you got it fixed.
I swear I was going to suggest testing the ignitor.