Engine Clunk When Starting on Cold Days

[USMC CWO]

I've noticed that when starting my bike when it is cold out, and I have 20W40 in the crankcase, that I get a random clunk from the engine until it warms up. It only happens when temps are around 35 or below. During my last oil change I tried 15W40 and the problem went away. This leads me to believe that 20W50 will only make this symptom more pronounced. Has anyone else experienced this?

 

[twowheelnut]

No, but I have an answer for you: Don't start your engine on cold days. Problem solved. Next?

Seriously, I've been using 20/50 since day one and even when I've started it in the cold (yes, Mildred, even below 350 on a few rare occasions), I never get clunkage.

 

[exskibum]

For the cold weather start, expect the "20" part of the designation to be the important one, not the "40" or "50". At cold temperature, it's going to act like the 20 W oil it's based upon, nevermind its additives that make it behave like a 40 or 50 at high temperatures. As you've already discovered, using an oil with a lower initial designation (15 vis 20) is what counts in the cold.

 

[Charlie Hoss]

Castrol makes a 5W50 synthetic which seems to be just the thing for cold weather starts and high rpm protection. I use it in my snowblower here in Maine. Not what we FjR owners would think of as high RPM but full throttle in a Briggs engine for 1 1/2 hours might qualify.

20W50 synth stays in the FJR all year with no strange sounds.

 

[JimLor]

Nope. I run the 15/40 Deltex or rotella and have never had that happen. Now, I will sometimes clunk when starting on cold days, but not ole Maxine! 'Course you have one of those new fangled fancy FJRs...

 

[Bounce]

i run mobile 1 15w50 and have never had this problem.

 

[Violione]

USMC CWO,

Hello from Virginia Beach - I have used the Mobile 1 15W/50 for the first three changes, mostly summer months, but on the last oil change tried the Shell Rotella T Synthetic 5W/40. Put it in just before the EOM rally in September and just changed a week ago. During this past 3500 miles I have really been riding hard and going up and down the mountains with some long stretches of high speed super slabbing, so this oil has been working hard! Here are the two things I noticed with the Rotella T Synthetic 1) clutch warm up is much quicker and predictable with less chattering than with Mobile 15W/50 in all weather temperatures and 2) the engine and trany seem to run smoother and more efficiently (slightly better fuel mileage) and shifting noise has not been a issue. I have been photo documenting the oil changes and the Rotella T has been cleaner looking that the Mobile 1 . Yes, I have been using the same type oil filter (Puralator One 14610) new at each oil change, so that is consistent as well as cleaning the K & N air filter at the same time. So I am planning to run the Rotella T Synthetic 5W/40 through September of 2008 or equivalent mileage as with the Mobile One to get an good base to compare with.

Being formally from up-state New York, I can tell you that you defiantly want lighter weight oil on cold winter day start ups! And with synthetic oil you get a much greater viscosity range that with Dino Juice, which is a good thing in my book. It's not the brand of oil, but the grade (quality) and viscosity that really count.

I hope that my $.02 helped.

 

[jestal]

I've noticed that when starting my bike when it is cold out, and I have 20W40 in the crankcase, that I get a random clunk from the engine until it warms up. It only happens when temps are around 35 or below. During my last oil change I tried 15W40 and the problem went away. This leads me to believe that 20W50 will only make this symptom more pronounced. Has anyone else experienced this?

Do you mean that the engine "clunks" on it's own after cold starting or that you get the clunk you are questioning when you first put the transmission into gear after a cold start?

The second would be pretty normal I would say. To help with that hold in the clutch, tap the trans into first gear and THEN crank the engine. Let the starter break the clutch plates loose instead of doing it when you shift into gear the first time and get the loud clunk. Even if you want to start the engine to warm it up before riding, let it warm up and hit the kill switch, put it into first gear and crank/restart holding the clutch disnegaged. Totally eliminates any morning sickness type of clunk from the trans on the first into-gear shift.

 

[USMC CWO]

The "clunk" I refer to is definitely coming from the engine and not the xmsn. It is a random, almost misfire, sound. There is no backfire. The sound is mechanical in nature and sounds similar to what you hear when you first engage the xmsn. On a cold day this will happen about 3-4 times within 5 min of start-up. It is hard for me to further troubleshoot the problem because I have switched to a 15W40 oil, which has eliminated the problem. I'm about due for my 8k mile oil change. Maybe, I'll experiment by putting the 20W40 in and try to pinpoint the source of the sound. I'm just not sure if I want to go through the hassle, especially if there is the possibility of causing engine damage in the process.

 

[Violione]

USMC CWO,

Where did you buy the bike? Casey Cycle City? Tomorrow I will record my bike at a cold start. I think what your hearing is not the trany at all but the ECU, Ox sensor and spark plugs (what I call) syncing up. It is almost like a miss fire but is just a momentary bump? My has done that since new and a little worse since I switched to the Auto Lite Iridium spark plugs. But as soon as it gets one/two bars on the temp gage (about two minutes of warm up) or idle it at 2K, it smooths out. Yea, let me see if I can get a good sound bite of mine and see if that is what your hearing.

P.S. see you changed your avatar - nice shot!

 

[jeremybhm]

Mine does the single clunk when starting sometimes. It's usually in neutral on the center stand and after it has sat all night(or longer). I guess I thought it was the clutch plate disengaging or sticking. One time after I let it sit a few weeks while I was out of town, it turned over pretty hard a few times before it cranked, but that only happened once.

I use the Shell Rotella T 15W40 FWIW...

 

[dean]

yep, mine does it, too. i can't say for certain that it's exclusive to cold weather, but i'd like to think so. and we're not talking about the initial clunk of dropping it from neutral into first, we're talking when the bike is idling with the clutch pulled in. just sounds like every once in a while there's a big hammer in there. i may switch to diff oil, i'm running mobil 1 red cap (bought cases of it before it disappeared).

side note: if your fjr is clunking from the tranny from the initial neutral to 1st gear gear change, try this: leave bike in 1st gear when parked; in the a.m., before even starting the bike, pull clutch in, and "rock" it out of first, into neutral. if you're intent on leaving it parked in neutral, in the a.m., before even starting, pull in clutch, drop into 1st, [edited as was wrong when i first typed, is now correct] keep clutch pulled in, rock back and forth gently, then put back in neutral.

hth.

 

[vabrzn]

Mine has a muted thump on occasion while warming up. I think it is the ECU changing the fuel mixture as the engine temp increases.

 

[S76]

My bike does the same thing. The colder the day the more it does it. I don't believe it has anything to do with the oil. It is just a lean missfire before the cylinders come up to temp. Kinda sounds like it coughs a time or two. It will do that 2/4 times depending on the temp.

No big deal.

 

[Wicked Webby]

My bike does the same thing. The colder the day the more it does it. I don't believe it has anything to do with the oil. It is just a lean missfire before the cylinders come up to temp. Kinda sounds like it coughs a time or two. It will do that 2/4 times depending on the temp.
No big deal.

My 07 too! I have heard this referred to as a lean misfire also..... Actually numerous times on this board..... I wonder if the new ECU corrects it?? Some have reported that the new ECU runs a bit richer mix??? Anyone............

WW