Pinging?

[Neil E.]

Finally got out for my second real ride. Only 70 miles, but didn't get started til late in the day. Rode until it was dark and I'm very pleased with how the LED lights illuminate the trail. Mostly single track riding; engine temperature averaging 135*F. Showed 125*F when running on forest roads, 155*F a few times when bushwacking around deadfall.

Originally, the stock jetting was rich so I switched to a JD kit. JD's recommendation is 38/1.5T/Red#4/170. Presently I have 40/1.5T/Red#4,175. I found it hard to get a stable idle, so I set the slide stop for a fast idle. It will do for now. I went rich on the main as I prefer the power to be flat on top.

The engine was pretty oiled up (from the original jetting) and I had to warm the bike up completely before it would take throttle. At first I got some "knacking" from the pipe, but after a run on a forest road, this went away. Throttle response in the single track is OK. My riding is mostly 2nd gear with 1st or 3rd as the trail varies. The other riding is dirt forest roads to connect trails. This is mostly 6th gear riding.

What I am concerned about is the "pinging" sound I was hearing when in 5th and 6th gear. It didn't seem to change based on the amount of throttle. It was most noticeable crusing at 1/3 - 1/2 throttle in 6th. Is this possibly chain noise resonating in the swingarm? I don't think the jetting is excessively lean, but I don't have enough time on the bike to know what it should sound like.

I took a photo of the plug. The insulator was a bit whiter than I expected, but not a real bleached white. This was after a 5th or 6th gear run back to the parking lot with only a few seconds of idle before shutdown. Any advice?

 

[Brian VT]

Is this possibly chain noise resonating in the swingarm?

Yup. We've all been through it. Many posts here about it.
It can happen in any gear. When the chain tension, or lack thereof, is just right it will slap the plastic guard at the front of the swingarm.

 

[Neil E.]

Can anyone describe the sound accurately? This was so much like pinging, I can only think I have a jetting issue. It was a constant light rattle that seemed to come from the engine.

 

[einsteingarage]

The chain is more like a chatter. You could be experiencing a loose pipe at the exhaust port. Do you have exhaust gunk on the front of your motor because of a dented pipe?

 

[stainlesscycle]

pinging sounds like ball bearings bouncing randomly in the expansion chamber. the chain noise is kinda a clatter. like a cluck/cluck/cluck that goes away at higher rpm's...

 

[Neil E.]

The chain is more like a chatter. You could be experiencing a loose pipe at the exhaust port. Do you have exhaust gunk on the front of your motor because of a dented pipe?

I had a bit of gunk on the pipe, but it was from a poor weld overlap. I sealed it up and the pipe is fine.

 

[Neil E.]

pinging sounds like ball bearings bouncing randomly in the expansion chamber

I think it is a lighter sound than this, but I'll richen up the jetting before my next ride.

To me the sound was just like what we used to get on a car engine like a Chrysler 440. A very light pinging that would occur on slight acceleration. (It would go away on hard acceleration because the vacuum would drop off enough to let the distributor plate rotate to retard the timing).

I wonder if the jetting is marginally lean, but not noticeable on single track because of the frequent throttle transitions. Cruising along a fire road is the only time I tend to have a constant throttle opening.

 

[lankydoug]

It is possible to have the jetting right but not have enough octane and jetting richer is only masking the poor fuel by lowering combustion temperature.

 

[CDBiker220]

I had pinging problems with my gasgas300 that I couldnt ever seem to clear up with jetting. Switched to 50/50 mix with race gas and the bike has ran amazing ever since...My buddies yz250 that has never pinged started doing so this year, after running the same mix all his issues were solved. I think gas is getting worse...atleast around where i live

 

[stainlesscycle]

mine has never pinged on 112/93 50:50. it does ping on straight 93 - but that's my own doing (tight squish...)

 

[Neil E.]

I'm using "Esso Supreme" 91 octane. It is not supposed to have ethanol in it. I'm sure when I buy 9L of it, there is 2L of something else in the hose before the supreme shows up.

I haven't heard of any local guys complaining about pinging. My compression test showed 200 psi, so maybe that's higher than most bikes.

 

[lankydoug]

I'm using "Esso Supreme" 91 octane. It is not supposed to have ethanol in it. I'm sure when I buy 9L of it, there is 2L of something else in the hose before the supreme shows up.

I haven't heard of any local guys complaining about pinging. My compression test showed 200 psi, so maybe that's higher than most bikes.

I doubt 91 is good enough. Why not try a batch of 50% race fuel and see if it cures the ping?

 

[Neil E.]

That's a good suggestion, but I don't even have a baseline yet for what the bike should feel like or sound like. I have been using the map switch in Rain mode.

I just removed the flywheel to do a stator modification and there is noticeable play between the key and keyslot (no visible damage, just loose tolerances). I get .015" radial play at the ring gear/flywheel OD of 4.200" dia.

This calculates to .043 degrees. Basically I can back it off almost half a degree just by holding the flywheel retarded while setting the taper. I could also change the stator plate position, but I won't make that timing change until I've got more results from jetting/fuel tests.

I prefer that it run on pump gas, but I will try your suggestion after some other testing.

 

[mikemoto]

Same here for me with the 50/50 race gas. I had pinging at first went to 50/50 and it went away. Last week ran out of race gas and the pinging was back. $100 of race gas is now in my garage.

 

[stainlesscycle]

if you can find race gas in the pump (check around...) - i run sunoco 112 at about $7.50 a gallon. signifcantly cheaper than vp or klotz (in the can). if you buy pump race gas, try to find it NOT from a regular gas station where it just sits.. check with your local drag strip...

 

[CDBiker220]

Ive been using VP110 Octane, from the pump at a gas station right near the local dirt track (so i know other people are buying it up, not just sitting) its 7.99 a gallon. Bike runs and smells awesome with it, will never go back to regular pump gas.

 

[lankydoug]

I buy VP110 for $8 a gallon from a local machine shop that builds automotive race engines. I was buying Sunoco 110 for $9 at a NAPA auto parts store. You just have to ask around but there's always someone out there with a motorhead.

 

[Neil E.]

To update this, it turns out that what I thought was pinging was the heatsinks on the LED lights. They had come undone and were rattling. The cooling fins amplified the noise and it sounded just like pinging.

I am used to the chain slap rattle and can identify it easily now. Only happens at low RPM in 6th gear. I've gotten used to downshifting a bit earlier and rarely ever hear it now.

No problems running on 91 pump gas for simple trail riding.

 

[nokturnal]

I believe Esso has ethanol in all it's gas. Shell V-power is the only non-ethanol pump gas that we can get here in Ontario.

I ran the V-power 50/50 with Profuels 110 Mark II in my RS250 trackbike. I still have some mixed up from last season if you wanted to swing through uxbridge next trip to the ganny. I could toss you a couple of litres to try.

 

[Neil E.]

Correct, I should have added that I switched to the Shell V-power. It seems to work OK. I don't see the need to try any racing fuel, as I'd only be kidding myself. I rarely ever need more than 1/4 throttle for any of the riding I do. It seems I'm mostly doing 2nd gear single track (with some 1st and 3rd) or on the fire roads in 6th).

Let us know how your top end work turns out.