Engine sound decel

Jakobi

Jakobi

Super Moderator
Hi everyone,

Just wondering what everyones engines sound like I decel after blipping with idle. The last few rides I have noticed my bike makes a BRRRRRR kind of sound that is in time with the vibrations the bike makes. Is this normal for the Gas Gas range? I can't think of a time that my bike has not done this but I'm not 100% certain.

I rode a friends 2011 and his felt much smother and didn't make the sound. I have noticed the KTM makes the traditional nang nang nang sound which mine doesn't either.

Is this normal?? At 50hrs I'm thinking it might be time for a re-ring

http://www.youtube.com/watch?v=X0iKTObBOuQ Audio to help.
 
I think the sounds the engine makes coincide with the jetting setup. Lean, I get a weak buzz, no ding-ding sound.

Too rich I get a "kack" sound ... ding ding.... KACK!... ding.....

Just right I get a whirr, maybe some dinging at the very bottom end. But by then I am happy and the world is a better place and I get back on the gas hard! :D:D
 
Rings at 50hrs in a 300? :confused: With good oil/filter service that should go over 100 hrs on a complete top end and retain peak performance.

Like swazi says cherck your orings, also check motor mounts, PV adjustment, and otherchassis hardware. Sometimes the pipe springs vibrate enough to contact the header slightly as well.
 
My 2011 300 6-days sounded like that after 45 hours. I just changed piston. Old looked like it was used +100 hours :eek: . Allways had clean filter properly installed. Jetted properly, no signs of lean mixture.

Bad Vertex item I think.

With new piston bike sounds and runs as new. We made reclamation to factory...

I'm not sure if you have the same problem, but If I was you I'll check the piston...
 
GasTimppa said:
My 2011 300 6-days sounded like that after 45 hours. I just changed piston. Old looked like it was used +100 hours :eek: . Allways had clean filter properly installed. Jetted properly, no signs of lean mixture.

Bad Vertex item I think.

With new piston bike sounds and runs as new. We made reclamation to factory...

I'm not sure if you have the same problem, but If I was you I'll check the piston...
Click to expand...

What am I looking for in terms of piston wear? I'll be digging into it to throw some new rings and will replace the piston also if required.

Same deal here. Air filter after every ride always mounted correctly. Air boot always ensured to be sealing. Jetting has always been close. A little too lean at times but always identified and resolved before putting the bike to work. Always 50:1 with GasGas recommended GRO.

Exhaust o-rings replaced as I have also experienced that vibration. Much more tinny sound. Inspected piston through exhaust port. Black coating has worn off piston as expected. No visual signs of scoring exhaust side. No evidence of blow by. Engine mounts are all in spec also. Bike feels it may have lost some of its snap, but by no means feels weak. Still good compression felt through kick starter.

I have noticed the sound does vary somewhat with jetting also. I would consider it the sound bailey speaks of. The WRRRR kind of sound. Only noticable on decel and in idle. So is this just a worn in engine, or is it something worn out? I'll have to dig into it to find the answers.

Whats everyones opinion on cylinder prep? Hone? Scotch Bright?
 
When I think about it, mine started making the noise right after the switch from N1EF to N3EG needle. Could it be jetting related? I need to swap back, see what happens.
 
bergerhag said:
When I think about it, mine started making the noise right after the switch from N1EF to N3EG needle. Could it be jetting related? I need to swap back, see what happens.
Click to expand...

I have made too many jetting changes recently to be bothered making another one. I could always drop the N1EF back in quickly. I also have another theory as I just noticed the kick starter doesn't come 100% back under its own spring. I wonder if it's very lightly still engaged. Will test that today after a wash. If not I'll be doing the rings and possibly piston, and spending up on an S3 head bling.

Quite possible the gasser just sounds different to the other 2 strokes I have listened to. I'm no 2 stroke guru with this being my first one ever.
 
Mate i wouldnt stress. Both my Gasser's have made sounds that have you expecting implosion of the motor. It just normal. They are noisey buggers on decel.

Main thing i would be checking is your pipe and springs.
Most of the noise from mine is the springs vibrating on the bent pipe on decel.


Scotties recomend piston and rings 50 - 60 hours. Theyve been racing them long enough, to know. Im doing mine soon too. Better to do both while your in there mate.
Keg will tell you the same.
 
NSE.ONE said:
Mate i wouldnt stress. Both my Gasser's have made sounds that have you expecting implosion of the motor. It just normal. They are noisey buggers on decel.

Main thing i would be checking is your pipe and springs.
Most of the noise from mine is the springs vibrating on the bent pipe on decel.


Scotties recomend piston and rings 50 - 60 hours. Theyve been racing them long enough, to know. Im doing mine soon too. Better to do both while your in there mate.
Keg will tell you the same.
Click to expand...

Good call. I knew you'd have something valuable to say! I'm sure I'd read elsewhere about your engine sounding like its going to explode. Haha!

I'll make a few more needle changes again today. Want to try the N1EG and the N3EJ again for a back to back comparison. Will take note what difference it makes to the idle.

My friend thought it sounded like ring flutter and having around the 50-60hrs on it I think its time. I haven't been racing and was considering doing a set of rings and then the piston next time but might just take your advice. Its not much added cost. Are you going to do small end bearing too, or just piston and rings?
 
From what im aware it all comes togther,
Small end
Rings
Piston.
Could be wrong.
Ill probably just use a woosner(SPL?) piston kit i think.

Scotty has recomended 3 base gaskets aswell.

Probley 2 more normal rides and then its time for me. I wanna get it done before the next VORC round in 2 months.
 
I'll order one from the keg I think. Sounds like the goods. Did you end up with an 'A' jug?

Any idea why they recommend more base gaskets? Port timing? Head work at the same time? Compression ratios? I was going to stick with the 2 gaskets as it is now. I'm happy with the power delivery. In saying that the 2011s come with only 1.

I'm actually teasing myself with thoughts of an S3 head. Bit more bling!
 
Dont know yet, havnt pulled it down and mic'ed it up.

Yeah 3 for port timing i think. I just really do what they say, they havnt been wrong yet. Im a sucker with them he could sell me anything:D

Ive ridden Dons (Scotties Mech) bike. He normally pulls them down new and does their mods and he has also put on the S3 head with Black insert into his 11' 300.
Very nice and crisp accel, with heaps of bottom. Was doing really sloppy ST so cant comment on top end but it was nice overall.
 
Looks like they have the Wosner piston kits and everything I need in stock and ready to roll. Will be a little while before I find the day to fit it back together. Still waiting to hear if they have the S3 in stock and how much. Feeling pretty keen on it.

The sound I've been worrying about definately isnt the pipe vibing. It could be the sound of the piston through the pipe possibly.

As far as jetting it made no difference to the sound I'm referring to.. I'll check back after I've got the new slug in to give an update.
 
Could be too.. Sticking my finger up the exhaust port there is definate side play in the powervalve that makes a nice sound as it clinks against the side. I imagine this would make some noise when everything vibrating.

Any which way.. I calculated I have about 60-70hrs on it now.. Will get everything together for a top end now so its ready for the near future.
 
Jakobi said:
Could be too.. Sticking my finger up the exhaust port there is definate side play in the powervalve that makes a nice sound as it clinks against the side. I imagine this would make some noise when everything vibrating.

Any which way.. I calculated I have about 60-70hrs on it now.. Will get everything together for a top end now so its ready for the near future.
Click to expand...

Let me know how you go.
There was a good thread on DBW about top end rebuilds by JC Insomniac
 
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