So theoretically if it isn't the float height, what else could it be?? If the float height is inadequate I'm going to end up taking the carburetor apart anyway right? While I'm there I might as well check everything else (jets etc).


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Could be a clogged carb breather tube too.

In regards to the coil dropping out: that has happened to me, but on much older bikes (1968 Honda, 1980 & 1983 Suzuki). Once the coil gets hot it would drop spark until it cooled down - anywhere from 15 to 30 minutes later. Didn't matter how fast the bike was going either. A new coil fixed that along with some high rpm missing as well.

That's interesting about the coil... This bike does have 47k miles on it... I might start it up and just keep it running in the driveway for a bit, rev it up a couple times to see how long it would take to recreate the problem. Is there any way of confirming if it's the coil other than replacing it?


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Checking the impedance with a multimeter. The specs are in the service manual.

I'm not saying let the bike idle in your driveway to test the coil..... but if you do, make sure there's a fan blowing on the engine.

Alright, so I adjusted the idle the other day (when I posted last) and as I said filled the tank up. I put premium gas in. Set the idle to about 1300 and didn't touch it for my short ride, and shut the bike off. Start the bike up today, it's idling in the normal range, but after I throttle up to 5-6k Rpm about 4-5 times the idle was at 3,000rpms and wouldn't go back to the original after waiting or throttling back up. So j reset the idle and it seemed to hold after that.

Would that be indicative of dirty carbs possibly?

Maybe the fresh premium gas is just cleaning them out? Really hoping thats the case here...

Still haven't tested the coil or float bowl levels yet.


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The bike has to be completely up to operating temps before adjusting the idle speed. I'm guessing it was still a little cool when you adjusted it, which would cause it to idle too high once it gets to temp.

It sounds to me like your choke is on... ?   

As funny as that may sound, I stopped by the side of the road last summer for a young guy on an old gixxer. 
He said he bought it from his friend and it overheats.  He could ride it about 10 minutes but then it would die, and he'd have to wait by the side of the road until it cooled down. 
And yeah, his choke lever was all the way back.  He didn't know what it was, or even that it was a movable lever.
Choke lever off, bike started right up and we both rode away.

Choke all the way off, haven't had to mess with it at all since I got the bike.

The issue consistently happens after riding 5-6 miles exactly. On my ride today, I could tell by the engine sounds that it was about to start having the same issue, so I pulled over and watched the engine drop to idle speed, then below idle, then die. Then it wouldn't start, whereas it has before. I tried to roll-start it down a hill, but it only started briefly, then sputtered and died.

Well, I checked the float height in the carbs both before taking it out for the 5-mile ride, and after it started to have the problem again. Looks to be good... just about at where the gasket is.

Really hoping it's the coil now...


Edit: how slow is "slow" for filling the tube for the float test???

Repeat of my other post - sorry about that. Stupid browser/ISP.

The Suzuki standard for valve clearance is .03mm to .08mm. Some riders like to set their exhaust valves higher than that to maximise exhaust valve cooling. I do not, but I can understand the logic for that one. The choice is yours.

As for the special tool recommended, what it effectively does is to compress the valve spring by pressing down on the bucket. This in turn increased the gap between the cam and the shim, which means it can be removed. I find this is a tricky enough operation using the tool: it takes me multiple attempts to get the bucket caught and locked down. The tool costs under $20, and from both a mental health perspective and also time saved is well worth the investment. The only other technique that I have seen is to remove the camshaft supports and get the shims out that way. Seems a lot of work to me.

Good luck.

It should fill immediately. If you have to wait, there's your problem. Another way to confirm this is to replace the fuel hose from the frame petcock to the carbs with a clear hose (make sure it's fuel rated, 1/4'' or 7mm). If, after 5 miles, you have to pull over and watch your fuel fill the line back up, there's your problem.

Alright. This problem has reached the point of truly pissing me off. I bought I multimeter (overpriced IMO) and tested the coils. They seem to be good for the primary at about 5.5-6.0 on the 200ohm setting. The secondary (coil to spark plug wire end) only momentarily displays on my multimeter and then dies. I was seeing ranges anywhere from 12-18 (yes, on the 20k setting) on both sides, but as I said, only momentarily. Is the multimeter a piece of $#*!

Or is it the spark plug wires...

Testing was done without running the bike at all that day.


I'm this close to taking this thing to a mechanic this weekend...


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I'll redo the float test this weekend and see how fast it  fills, but it might have taken a sec...


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Alright, so I redid the float height check and it did take fuel trickling in to get the level right at the gasket of the carb. I might try that trick running the clear line to the carburetor. I called around to some local shops and apparently due to environmental laws in ca, clear fuel rated hose is hard to come by. One guy said I'd be able to get away with a clear non fuel rated line for a short ride if I put the original line back immediately. So I'll try that out tomorrow.


At this point I'm just documenting this here for myself or anyone using Google. Chime ins are always welcome from those experienced of course.

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The cheap clear line will work fine. My bike had that on it for years before I swapped out the lines earlier this year. It might harden and crack over time though.

I too have cheap clear lines... got them in the small engines section at Auto Zone or Advance. I hear what you're sayin' though about perhaps being hard to find in CA.... perhaps online?

Also yes they do tend to get a bit hard over time but I don't mind replacing them.

Wishing you luck !!

They are supposed to be replaced every 4 years.

So it sounds like the problem is definitely fuel starvation because the bowls aren't filling fast enough. Both bowls???
Were you using prime? That eliminates any possibility of a vacuum issue not opening the frame petcock all the way.

You may want to look on ebay (or some such place): you can normally find clear fuel hose sold by the foot. Go ahead and pick some up and replace all the fuel line. It will help with this problem, and may be of help to you in the future.

I used the clear fuel line connecting the frame Petcock to carbs (frame Petcock switched to prime) and it remained full even once the problem started.

Unless I'm wrong, this means the problem is with the carburetors themselves and not with anything in the fuel process before that. If this is true, I'd honestly feel way more comfortable with a mechanic doing the cleaning/rebuild. I might even consider installing a fuel filter to prevent the carbs from getting gunked up again.

The time it takes the problem to occur seems to be reducing as today it took just under 3 miles for it to act up.


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Additional development:

Took the bike for another ride after it had cooled down for about an hour and a half. After 2.5 miles, the bike started to do it again. This time I felt it - mid throttle after shifting to 3rd gear, my body lurched forward a little as the engine lost responsiveness. I pull over, bike dies, start it again, and decide to pull the spark plug wires. First the left, no change to the engine. Put the left back on. No change. Pull the right. Engine dies completely. I repeated this test twice to be sure. The engine was only working on the right cylinder.


Any thoughts on this? I realize the problem could still be fuel related, but I'm kind of hoping that this means the left coil is bad. I'll pop it off and look at the plug wire next time to see if it's sparking or not. Didn't think to do so until I read another post about a similar deal.

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