ot - motorcycle problem - pinging.

I have asked others about this, but I can't seem to get a straight answer from anyone who really knows what they are talking about. just a bunch of hoodoo and conjecture.

I have a stock 1983 honda xl600r that pings more often than I would like when under load at mid to high engine rpms. like accelerating from under 45 mph in 5th gear. I know with most bikes you could chalk this up to bad driving technique, but with a big thumper, this shouldn't be a problem from my previous experience. I have ridden KLR 600's from the same time period, and they never gave trouble when doing this. I also have a stock 1985 honda XL350R that does not manifest this problem, even in 6th gear from 35-40 mph.

I read somewhere a while back on the forum that maybe the gasoline composition has changed and does not atomize in carbs as well as it used to? I cleaned the carbs and jets meticulously and put on new gaskets, etc. The jets are of the original factory size in the proper places (dual carb model), so I am guessing this should not be a problem. air filter is new and properly oiled, and all the rubber is still soft on the intake and airbox, and seems to seal up well. is there any way to check for leaks along there?

I want to believe that it is just bad driving technique that is making it ping, but like I mentioned, I have driven other bikes poorly in the past and it didn't affect them like that...

suggestions that I could try out? thanks,

jon

Anchorman...Most pinging is caused by low octane gasoline..try changing brands; also ignition timing. Too far advanced will cause pinging as you describe. Check it against factory specs. with a timing light. This should get you going. Mark in Buffalo

There are a few things I would list to check
first.

1) excessive compression from a modification
or carbon buildup in the chamber/head. Run
a compression check and compare with stock,
if you can. I know my KLR250 has an exhaust
valve lifter auto compression release so
something like that may hamper that test.

2) poor fuel. It's getting worse, of course
you are using the highest octane you can get,
but in my case a half tank of 100 octane cam2
fuel was a definitive test in one of my bmw twins
which said I really had to reduce the compression.

3) ignition timing, and advance curve. Be sure
it is to factory spec for starters, and that
the advance curve as published agrees with what
you see with the light.

4) Carburation. If you are running lean on the
main jet this will give you troubles. Have
you done any work on the jetting, did you try
to do plug chops? If you can try to find
somebody who has an EGO sensor. But be sure
that you have the stock main jet in there for
starters.

If you've pulled a plug out after the bike's
been idling for even a bit, seen some sooty
carbon and said "oh it's running rich" and
began reducing the main jet, you can cause
problems there for sure.

5) intake air leaks. Use the unlit propane
torch, or WD40, to search for an intake leak
that's making you run lean.

Good luck - Jim

no mods on this bike whatsoever, also I don't think there is any way to adjust the timing on it. When I pulled the carbs to clean them, I notcied that the jets were switched so the primary jet was in the secondary carb, and vice versa. The bike ran, but IIRC would ping at low rpms more than high as it does now. For those not familiar with these bikes, honda decided to place two carbs onto one 599cc cylinder. I think mostly because of space issues, but also to make life difficult.


I have to say, after cleaning and re-installing the carbs I only did a rather cursory adjustment of the idle mix (no tacho available) but I might have set it a bit too lean. I'll check this weekend. I think once I got it set where the engine would not increase speed anymore that I opened it an 1/8 of a turn instead of closing it an 1/8 of a turn. got to read that manual again I keep forgetting that opening the screw (turning it counter clockwise) lets in more air. this is after all the idle air adjust screw... maybe it is a matter of error on the side of the mechanic (me) and not on the side of the rider (also me)... can such a little thing as the idle air mix really effect the running when the throttle is close to full open? I probably did as poor a job adjusting the idle air mix on the 350 (which is practically the same engine but smaller) and it never blinked...

it might be time to finish building my little air fuel sensor and gauge...

pinging, more properly known as detenation occurs when the air/fuel misture in the combustion chamber explodes instead of being a controlled burn, low octane fuel, improper ignition timing or fuel mixture are some of the reasons this occurs. Given enough running time it will destroy your engine, first thing that usually happens is burning a hole in the piston crown, but the preceding shock loads to you rod and crankpin have probably done damage there as well. I suggest you stop riding the bike until the problem has been eliminated. And no, there is nothing you can pour down the sparkplug hole that will fix it.

Unless there is some kind of severe leak in the
idle ckt, it is unlikely that is causing a
problem on the main jet.

First off I would pull the mains and inspect
them for any kind of varnish build-up or
restriction, and compare the numbers on them
to what the factory manual says they should be.

Granted the bike has electronic ignition but
there is still an advance curve there and
if you want to cover all the bases, put a
timing light on it and check to see the
trigger coil's in the right place and the
ignition module is doing it's job right.

Jim

If it's a street legal bike, the machine was sold with the jetting on the stupid lean side of things.

Raising the needles half a notch and or going up one size main jet would probally solve the issue.

Got the right plugs? Maybe try a cooler one? (I think, I may have that backwards)

Does it ping immediately after start or only when hot ?

Anchor,
I think that jim nailed the main reasons for pinging. You did not mention the mileage on the bike but regardless, fuel octane and additives were different 25 years ago.

If a good tune-up does not solve the problem, I would look for excessive carbon buildup increasing the effective compression ratio and/or burn characteristics.

Also, fuel had a different formulation back then and the ignition curve may not be appropriate for todays fuels.

You could change the primary drive sprocket to one with 1 or 2 fewer teeth to move the RPM at any given speed further up into the desired powerband.

Perhaps you shouldn't be in 5th gear under 45mph with that particular motor/trans combination; a 600 is not a 350 and comparisons are meaningless.

I agree with Jim, particularly with regard to carbon buildup. Probably it's time to remove the cylinder head and have a look. Also a good ring and valve job at the same time.

It's also possible that the jetting is too lean. That will cause some pinging, especially under heavy load.

Likely, also, you should change to premium fuel.

A frined of mine is an XL600 and XR nut...

A few things to notice: The xl reacts very sensitive to different float bowl levels. Check it on both carbs.
If you had the carb apart, did you pull the needle seats and clean out behind in there?
If not, do so.
Check the link between the two carbs, there are about a million ways to set it the wrong way.

Check the exhaust, just give it a good smack with the flat hand and hear if something is ringing on the inside. Means it is obstructed and needs to be opened and the loose part must be mig welded into place. There is one pipe that will always come loose in there, don´t ask me which one.

The XL is rather choosey with fuels. You´ll get pinging with one and none with the other. Also, the XL is one of the few Honda bikes specified for super fuel over here, means it needs more than 95 octane.
You can even notice a difference with 98 octane super plus, that´s even better.
Before someone starts the story "yeah, this is because of the old valve seats need leaded fuel", it is not! My info is from a Honda dealer. It´s because of high compression ratio and very hot exhaust valves. There are only three honda models that ask for super back from this time, and all honda valve seats can stand unleaded fuel.
Timing can´t go wrong on XLs, the timing mechanism is fixed, the pre ignition is calculated in the CDI box. They don´t miscalculate, they just fail to fire if damaged.
Another thing, if you have an oil cooler, put it on the bike. They run very hot, 160°C oil temperature are found on a regular base.
This leads to another mode of failure, they fry their alternator or ignition windings which are running in the oilbath. Then, you have a very weak spark but the machine won´t start.
This happens after it is cooled down. You set it aside, everything is ok, you try to start a few days later and it won´t fire. Measured cold with a normal meter, the windings will say "good" but it is not. Again, you have a spark in this case, but a very weak one.
In case you pull the head, check for cracks from the spark plug to the exhaust valve seats.

Don´t get me wrong, this is accumulated knowledge from more than one person, found out over 10 years and countless kilometers. It reads bad at first, but the XL is a good and relieable bike! A friend of mine drove more than 100.000km with his.
The RFVC engine is now bored to 650cc but still in use...
There is an excellent manual on all Honda Enduros, Clymers Honda XL/XR 500-650 singles, 79-93 from intertec publishing. Go and buy it, it would still be a steal at twice the price.

Take a look at the engine, there is a line coming out on top of the motor behind the cylinder going into a black plastic box. This box is attached to the airbox via another line. Take off this line, plug the hole in the airbox. Now get the long piece of pipe that goes in this place from a XR 600. It goes under the tank and vents blow by there.
This line would normally vent blow by from the engine back into the airbox and hereby rise the temperature of the mix and preheat it, which can propagate pinging on hot or very hot days.

Cheers,
Johann

I've owned 2 XL600s over the years. One of them is Jon's current bike.

I think that Johann is right on with the premium fuel. I don't remember what it says in the manual, but I ran premium in the '83 and the '86 model XL 600s I used to run. There was a noticeable difference in the pinging with low octane gas vs. high octane gas. But even then, I believe that on a hot day, if you pushed it, it would ping. However, the high octane gas provided acceptable performance for me.

Now I sold my '83 to my cousin. He didn't ride it much, and as a result, had to get the carbs cleaned out due to bad gasoline. He then sold it to Jon. I believe this is why the jets were swapped, someone screwed up at one time.

I'm also inclined to agree with Nerobro, I think that due to emissions regulations, they tend to make them a little on the lean side.

I also feel the engines in those models run hot. You might also try a cooler plug.

Jon does want to put an oil cooler on the bike. I wanted to, but never got around to it. I wanted to make the bike more highway friendly, but after a 4 hour ride on the interstate, I kinda backed off. Vibration on the singles is pretty harsh. Felt like I was running an old chain saw in the hands. I think the bike is up to highway treks, but I wasn't. It certainly has plenty of power.

I really don't think he needs to pull the head. The bike has pretty low miles, and the history is pretty good. I think the guy I purchased it from took good care of it. I was the third owner, I believe it was the guy's dad who was the first owner. Had the factory service manual with it.

I wish I still owned it, sniff, sniff.

Oh well, no regrets, it was a fun bike at the time.

Hy Keith,
I also don´t think he needs to pull the head, I just mentioned it in case the motor is opened anyhow in near or far future. As I said above, these are the accumulated mishapes of a few more riders over 10 years.
I wonder why you don´t rate the XL highway friendly, we used to ride trips with daily distances of 250 miles and more...curvy terrain over here, this drags down your average speed.
A HD sportster will shake far worse, I rode one from Ohio to Milwaukee once, so I know!
We refered to the XL as the electrobike, no vibrations, smooth action gear with short ways and crisp feedback. Just don´t ride it below 3000RPM, the engine is very short stroked and is made ot rev, not to pull.
I know, this sounds odd for a thumper, but that´s the way it is.

Cheers,
Johann

Spot on about the valves and seats. The older
ones don't react well to unleaded fuel but
that won't cause pre-ignition. Basically what
you see is, the valve clearance just "goes away"
bit by bit. The seats and valves wear and
they tighten up.

Kawasakis did that too. They originally
specified softer valves for my KLR250, and
the dominant effect when they tightened up was,
the bike would be hard starting because the
intakes were not closing all the way. Basically
just blowing the charge right back into the
carb.

When I finally realized this and tore down the
top end, I was able to remove the valve keepers
by hand, pushing down on the valves. Yikes.
The motor was ready to grenade.

The parts folks got me the new valves - whoops
what's this? A revised part number for the
intakes. I re-did all of them but the exhausts
were not badly worn. Since I re-did them, I've
not had to adjust them at all - just check now
and again.

In the US the best grade of fuel commercially
available is unleaded 93 octane. Terrible.
Like I said, if he can get a half tankfull of
100 octane fuel (around here there was a place
that sold "cam2" racing fuel) then that will
be a definitive test that it's a fuel issue.

Float level: the easist way to check this is
to slip a section of clear plastic tubing onto
the drain connection of the bowl, bring the
tubing up alongside the bowl, and open the
drain screw.

The fuel level in the tubing will rise up and
indicate exactly where in the bowl the fuel
surface really is. That's an extremely
important setting and I would say, the absolute
*first* test to do on the carb.

Jim

Johann,
Well, if you're going to compare it to an HD, then you're right, it would be a smooth running engine.

I guess it is a fine bike for highway use, maybe not interstate use. The grip required to hang on at 70-80mph combined with the vibration left me not wanting to spend much time on the interstate. Of course, riding a bike on the interstate is boring anyway, it's too straight.

Maybe I just have gurly hands.

I think it is a fine ride at 55-60mph. Much higher and I get fatigued. It is a street legal dirt bike, not a street machine.

Love the torque those bikes have. Just open the throttle in first gear and it will pop up on you.
(I haven't ridden a lot of street bikes, nor the two stroke dirt bikes, so I'm sure someone will chime in on how their 750 crotch rocket will do the same in second gear!)

I was a farm boy who got his MC license @ 14, so the dual sports were popular in the family. Ride in the dirt, or go ride into town, with one bike.

Not a farm boy anymore, but I really want Jon's XL350. I always felt the 250 was a little underpowered on the street, but the 600 was a little heavy in the dirt.

I can't help on the XL, but maybe what happened on a CB650 I gave my son to keep on base while in the Marines will help! It's an 83 IIRC and it sat for 17 yrs with a few thousand miles on it! Aftre completly "going" through it thourghly it pinged and ran rough at 40-50 mph. Drove me crazy, but I cured it by resetting the air-gap in the ignition, both sides, use brass feeler gage and brush out "oxidation" which will be plenty after all these years. Also I took a thin shipping tag wire and pushed it throhgh all the air bleeds on the carbs followed by gum cutter and air. you can tell by the stream of solvent matching each carb which one is worse off. my carbs had a lot of dried crap that had to be pushed out with the wire! I believe the ping is coming in the transition stage where the carb is not working smoothly. I hope this little bit helps, it's 2 wheel time. Good luck.

Steve

DId you recently change spark plugs? Macona's idea above is correct if you have the wrong heat range in there
Jim

Hy Keith,
Before you get a xl 350 and pay another 500 bucks to mod it to your specs, try out one of the newer 400cc Suzuki DR or a Yamaha WR or an xr400.
A friend went this way a few years ago. You can do unbelieveable stunts with these, he rode on trails I couldn´t follow with my old but heavily modified XL /XR500 mix...we switched bikes, he couldn´t follow me. By the way, he is a far better rider than I am. It´s just suspension, engines and bodywork changed so much on dirtbikes the last 10 years it´s unbelieveable.

@Jim I check for intake leaks with brake cleaner...

Also, I used this as starter spray on certain occasions. It will ignite readily but stays in the intake far longer and is cheap. I found out about it when a label on a starter spray can came loose showing the original product label beneath.
Another good tip is to seal everything with an elastic silicon after you had it apart if it´s the intake and use the stock hose clamps . There are differences between those and the ones from lowes or from cars.
On twostroke engines (I have a few RDs), I even leaktest with small overpressure and soapy water. It´s a blast, I found a leak well hidden on a small engine that gave the owner problems for ages. I guess MacDizzy.com was where I read first about it.

Cheers,
Johann

[ 04-12-2007, 01:34 PM: Message edited by: Johann Ohnesorg ]

I had a Honda XR650L, which was a newer improved version of this engine. All these bikes run lean from the factory but I dont think this is your issue, when this bike runs lean you will get a very subtle popping or backfiring during deceleration at slow speeds, which is easily corrected with jetting changes. I think your problem is either an issue with poor gas if this only happens once and a while, or years of carbon built up in the top end raising your compression. The pinging you here is the engine firing before the piston gets to the correct position. Engine heat can be a real issue for these air cooled thumpers as well, which will only make this happen easier. Also check to be sure you are running the correct temperature spark plug.