# Noise after cold start



## bruteforce_ttu (Jul 5, 2012)

So I've been hearing this noise lately. I'll do my best to describe it.

It's only when the engine is cold and at idle. It's more a "clank" than a knock. I don't think it's coming from the clutch side. Sounds like it's from the engine.

I'll start it up, let it idle, it'll start clanking, then it'll die.

But if I start it, then pull the choke, there is no clanking sound.

Or if I start it, rev it up for about 20-30 seconds, then there will be no clanking.

Once the engine has warmed up for about 30 seconds, there is no clanking and rides perfectly. 

Anybody have any ideas?


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## NMKawierider (Apr 11, 2009)

Most times its just the shoes in the primary. As they wear, they kick back and forth mostly at idle and make a sound that sounds like a rod. Mostly goes away when warmed up. A manual and set of feeler gauges will tell you for sure. Here's avid of when mine were bad. All better now.

BF750 Clutch noise2 - YouTube


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## bruteforce_ttu (Jul 5, 2012)

I watched that vid. Mine is more of a higher pitched sound. I'm thinking it has something to do with the fuel being injected, since there is no noise if I start with choke pulled and leave it pulled.


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## NMKawierider (Apr 11, 2009)

bruteforce_ttu said:


> I watched that vid. Mine is more of a higher pitched sound. I'm thinking it has something to do with the fuel being injected, since there is no noise if I start with choke pulled and leave it pulled.


 
???There's no choke on a fuel injected machine...at least the old ones don't.


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## bruteforce_ttu (Jul 5, 2012)

nmkawierider said:


> ???There's no choke on a fuel injected machine...at least the old ones don't.


I'm on a 650.


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## Waddaman (Oct 3, 2010)

Valve lash really loose. Needs extra fuel to run when its cold but once it warms up the tapets/valves expand minimizing the gap and making it able to run but, you should still here a slight "tick" all the time just not as loud.


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## bruteforce_ttu (Jul 5, 2012)

Waddaman said:


> Valve lash really loose. Needs extra fuel to run when its cold but once it warms up the tapets/valves expand minimizing the gap and making it able to run but, you should still here a slight "tick" all the time just not as loud.


How easy is it to adjust the valve lash? Is this something I need to take to get done? And more importantly, how would I have caused the valve lash to be incorrect?


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## Waddaman (Oct 3, 2010)

They wear over time, causing loss in power, hard starts, etc. How fast is the noise you are hearing? if the noise is coming from the top end and the noise is really fast then that's definitely what it is.

You have to remove air box, battery, FI/carbs, and other various small things to get to rocker cover. Once you have clear access to the top of the engine you use feeler gauges to check the clearances of the little screws on the end of the rocker arms. Adjust them to the proper width using the feeler gauges and re assemble. Not hard, but very important that it is done correctly. If the valves are set too tight then it can cause serious damage.


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## NMKawierider (Apr 11, 2009)

bruteforce_ttu said:


> I'm on a 650.


Oh..Ok, well when you talked about fuel being injected...I assumed...


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## bruteforce_ttu (Jul 5, 2012)

The noise is pretty fast, about 1-2 "clanks" per second. And sounds like it's coming from the carb/engine area.

What damage am I looking at for loose valves? As I've been running it like this for a little while now. Is this an immediate concern?


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## Waddaman (Oct 3, 2010)

No damage, just loss in performance. You can always take a video and post it up here and we can tell you for sure what it is.


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## NMKawierider (Apr 11, 2009)

You know...I have heard of the upper chain gear bolts coming loose on some Brutes. As they back out they click on the edge of the head as it rotates. Don't usually stop when warmed up though.


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## bruteforce_ttu (Jul 5, 2012)

Appreciate the help y'all. I'll get a vid up later this evening.


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## 5.3vortec (Feb 21, 2012)

i have heard that if the idle is really low on start up the decompression arms rattle around until u give it a quick shot of gas to fling them all the way out them mine does the same thing once in a blue moon


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## bruteforce_ttu (Jul 5, 2012)

Mine happens every time.

How do I upload a video?


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## bruteforce_ttu (Jul 5, 2012)

Here is a link to a youtube video of the noise.

video 2013 02 25 18 20 12 - YouTube


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## Waddaman (Oct 3, 2010)

That is wierd dude, that isn't fast enough to be valve noise.. At first I thought it was a rod bearing but when you warm it up it goes away completely..Thats strange lol. Im stumped on that..how could something be that loud and obvious yet go away so fast..only so many things in the engine expand that can cause noise when cold and go away when hot... but to me it sounds like as soon as you hit the throttle it went away not so much when it got hot, there was nothing gradual about that as soon is you blipped the throttle it went from full knock to gone.

To me it doesn't sound like your clutch but I would take it off start it cold let it idle and see if the noise continues. If the noise is still there it is definately engine noise. This isn't something I would ignore and drive because that just doesn't sound good, what ever it is.

---------- Post added at 10:28 PM ---------- Previous post was at 10:25 PM ----------

When I keep listening to it it kinda sounds like a really really bad piston slap, just by the intervals its hitting and the distinct noise. But even with heat you should still hear something after its warm..this is going to bother me now until I find an answer...


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## bruteforce_ttu (Jul 5, 2012)

When it's cold, I can hit the throttle, the noise will go away until it's back at idle.

But once it's warmed up, whether it's idle, 1/4 throttle, or whatever the noise never comes back unless the bike sits for 20-30 minutes.

---------- Post added at 08:37 PM ---------- Previous post was at 08:34 PM ----------

This noise really started after I did the snorkel and rejet. I didn't ride it much after that. Just too hot outside and busy.

I rode on it like this all hunting season, and it hasn't gotten any worse. It's been the same since it started. Maybe put 15-20 hrs on it since the noise began.

---------- Post added at 08:42 PM ---------- Previous post was at 08:37 PM ----------

I normally just rev it up some till the engine is warmed up before I ride it.


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## NMKawierider (Apr 11, 2009)

That sounds like to me either a sticking valve, one that the adjuster has backed off a tad too much or one of the comp releases has an issue. My money is on the sticking/binding valve because dumping fuel on the stem with the choke helps.. but the questions is...why is it binding in the guide? Usualy takes a bent stem for that.


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## bruteforce_ttu (Jul 5, 2012)

So I took the bike to the shop. They checked everything out and said that I don't have any damage to the engine or anywhere else.

They said that my bike was just idled down too low. They adjusted the idle on the opposite side of the clutch. The noise is completely gone now.

I took the bike out this weekend and rode it pretty hard. The noise didn't come up once.


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## SinisterV (Mar 20, 2013)

Seen this before lol if the motor is cold and idles too low the advance weights for the decompression pins in the cams don't swing out to stop the decomp cycle and that's the sound you get turning the choke on richens the mix enough to increase the idle and advance the cam weights. Some harm can come to the cam side of the rocker arm if this happens for an extended period of time but in your case I wouldn't worry


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## bruteforce_ttu (Jul 5, 2012)

Thanks for the help and input guys. I'm just incredibly relieved that it wasn't anything serious. :goodnews:artay::banana::chewbacca:

So I took the money I was thinking I was going to have to spend on repairs, and finally got myself some respectable tires, wheels, and lift!!! :headbang:

Hopefully have everything delivered & installed for this weekend's ride!!!


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## SinisterV (Mar 20, 2013)

Well pics lets see it lol


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## bruteforce_ttu (Jul 5, 2012)

As the girlfriend likes to say....BOOM!!!


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## parkerexpress (Sep 7, 2009)

Nice ride. That noise would have scared me too. Glad it wasn't anything serious.


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## vSpoiler (Apr 4, 2014)

Dude I have the same exact noise on my Brute also....were did he adjust the idle???? and your is Fuel injected right??


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## bruteforce_ttu (Jul 5, 2012)

No. Mine is carbed. It's the 650.

You'll have to adjust your idle one of two places. There is an idle adjustment knob down on the left hand side of your bike, near the engine. This is the only place I had to adjust.

The other adjustment would be your air/fuel mixture screw. Not sure if the FI bikes have this or not.


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