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Bad gas story

Mat

Mat

Forum Apprentice
Just spent a good part of the day trying to figure out why my bike did suddenly run so crappy (lots of forum reading about valves clearance, carb cleaning and checking various hoses and seals).

Turns out the problem was the gas. Just the gas.:beaten:

At least I can ride tomorow:cool:
 
Run it all you want without gas, it won't hurt a thing, just be real sure the oil is ok.
 
I was returning home from work friday night and there was heavy wind gusts and at first I tought "wow the wind is really shaking my bike like never before":eek: but the bike was really randomly stutering. At some point I lost power so much I could barely maintain the legal limit. Kept and eye on that red light to come on and stopped asap to check oil level and smell (I once let the bike on PRI thinking it meant primary ha ha ah flooded the carter)

Turns out the gas I put that friday morning wasn't premium at all. Will stay away from that station from now on.​
 
Mat said:
I was returning home from work friday night and there was heavy wind gusts and at first I tought "wow the wind is really shaking my bike like never before":eek: but the bike was really randomly stutering. At some point I lost power so much I could barely maintain the legal limit. Kept and eye on that red light to come on and stopped asap to check oil level and smell (I once let the bike on PRI thinking it meant primary ha ha ah flooded the carter)

Turns out the gas I put that friday morning wasn't premium at all. Will stay away from that station from now on.​
Click to expand...

Must have been really rubbish fuel, as the GSs generally can run reasonably well on cheap stuff. Better is better, of course.
 
I hoped you drained the tank. I would go the extra mile and remove the petcock and check the strainer. Mind you in 40ish years the adhesive seems to go bad and shrink allowing fine bits o'crap to pass into the carbs. Some carbs use a dome filter over the float valves which can catch things and eventually be blocked off.

I once bought gas for the k1300 and apparently the gas trck dude forgot to add the hi test additive package. Bike ran horribly due to its electronics retarding timing and otheer fancy stuff. This is a luxury a normally aspirated old bike does not have.

You say it was windy. Harsh side winds have on more than one occasion reduced powere output on my 550. Its disturbing that it happens in spite of using a stock filter and airbox. An el cheapo cone filter is far more susceptible to this.

How many inline filters specced for a low fuel volume lawn mower are attached?
 
Well turns out it wasn't the gas after all...:mad:

Just tried to do a longer ride and the problem returned as soon as I hit the trottle to get on the highway.

It seems the bike rans fine from cold even if I trottle aggressive and once hot it just bogs down and stutters randomly likely 80% of the time.
 
Last summer I replaced the stator and installed the SH775 reg/rectifier, the battery is a NOCO lithium so I'm confident in the charging system. I will still check that because it's not time consuming but I am really worried it might be the valves clearance that needs service...

Time is the constraint for me (I'm a mechanic noob and father of two;)) so I wish to pinpoint the problem asap. I don't feel it's a something's clogged issue because the problem would not manifest only when hot, right? but once hot the valves would behave different than cold, right? as would some ignition parts maybe?

I replaced the spark plugs last summer. I checked and replaced the air hose between the carb and petcock yesterday.

I'm in for quick-check ideas/methods before I leave family to the valve clearance path
 
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Regardless of bike, and you really should tell us specifically what bike this is, valve clearance is not a big job. It’s just that opening up an engine can be a daunting task when you haven’t done it before. I won’t get more into it because I don’t know if you have a 8 valve or 16 valve engine. There is plenty of info in your service manual, on this site and BikeCliffs Website to walk you through it. If you don’t know who, or when your valve clearances were checked, you need to do it now anyway.

Please create a signature and put your bike info there.

I hope you have a vacuum hose and not an air hose between your carbs and petcock.

I think I have read of coils failing upon getting the bike up to temp, you’ll have to do some searching.
 
You are right, that's a GS400E TSCC so that's a 16 EDIT: 8 valves I guess. I'm struggling to find how to edit my signature:o EDIT: FOUND IT

I have all the tools and gaskets to do it, have read many guides but am still a bit uncomfortable as I have had some difficulties with gaskets before on the stator.

About the hoses, both I tried were 1/4 I.D., one being labeled for gas line use and the other being an "uncollapsable" refrigeration hose I had laying around with the same inner diameter and a tighter fit.

One coil failing would seem highly probable to me. The power the bike make when it it struggling is likely half of what it normally output, and when I'm in first and power is restored while I'm at full trottle this makes for a nice backward head bang:eek: Will look into how to check for coils.

Btw nice little Bike logo you have in your signature
 
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Might be worth checking the coil supply plug. It can hide a lot of corrosion inside and I had that issue with the 850. Only happened well into a ride.
 
I understand there will be no practical way to test my coils if the problem manifest itself after a few miles only.

I have spade connectors on them and some were not super tight so I corrected that. The bike starts and idle so well from cold start I'm going to look into valves.

Any problem starting disassembling the covers while the bike is not dead cold then waiting for tomorow for measurements?

I Plan to follow gs850valve_adjust.pdf from BikeCliff website, this is an entertaining read
 
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Looking inside, the 4V per cyl. engine is totally different from the 850 2V. For me, the narrowest feeler gauge I could find was a big help (if you have a wide one, easy enough to trim to fit), a pretty tight spot where the gauge slides in, totally different from the 2V 850
 
rphillips said:
Looking inside, the 4V per cyl. engine is totally different from the 850 2V. For me, the narrowest feeler gauge I could find was a big help (if you have a wide one, easy enough to trim to fit), a pretty tight spot where the gauge slides in, totally different from the 2V 850
Click to expand...

I have the correct gauge for the 400 tough I do not remember where I got the info :rolleyes-new: That was a job I had planned to do during the winter but other priorities showed up:eek:

I'll use the guide but with the proper specs fit for my bike and cross-check with clymers and other manuals I got. Gotta check if I really have the cover gasket and those half-moon still somewhere...

Will do the chain and sprocket job that was planned already while the engine gets cold. At least a week of sun and hot weather in Quebec City:D
 
If I thought a filter was the problem, I'd check the one in the tank... I never was fond of those add on filters, though others swear by them... Also any filter probably wouldn't care if bike was warmed up or completely cold.
 
Agree but since I have the tank at hands I will probably inspect petcock if I can source O-rings.

I quickly checked for valve clearance even it is too early to call it a cold engine, out of 4 there seems to be 3 with no clearance at all (I cannot fit the 0,02 mm gauge when the lobe point upwards).

I think I'll have to double-check my method.

Also I don't understand how to use the motion pro tool to reveal the shims... Pictures in clymer's manual are so blurry I cannot figure
 
You can easily push those valves down with your finger. The adjusting tool can too. Make sure they aren't, or you don't over tighten them, or they won't close. The cam follower is a very easy adjustment, as you can see the bottom of the cams and where to adjust. Adjust each valve separately. I check mine every 3000 miles. The bike ('83 GS750ES) has 40K on it now and the valves are seated. It could use valve steams, but smokes so lightly, and only when it starts up. I over tightened them once, and could not get the bike over 4000 rpm's after it warmed up. Learned my lesson quick. :)
 
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