What is causing this noise?

[Turnersmith]

My blaster is freshly rebuilt and has an odd rattle to it mostly at idle. Runs and drives good but I am worried something could be wrong because of how it sounds.
Any help or opinions would be greatly appreciated!

 

[Turnersmith]

My blasters top end is freshly rebuilt, runs and starts good with good compression but the engine has a rattle to it mostly at idle. While riding or revving the rattle goes away. I need to know if there is a problem or if it could be considered normal? The motor is all stock besides a k&n air filter and the cylinder has had some port work from Ken oconnor, as well as the head has been machined by him as well . Any help or opinions would be greatly appreciated!

 

[Awk08]

blaster engines are notoriously noisy similar to that, but since you just mentioned a rebuild, I have to ask....
who did the bore/hone and did they chamfer the ports ?

 

[Turnersmith]

blaster engines are notoriously noisy similar to that, but since you just mentioned a rebuild, I have to ask....
who did the bore/hone and did they chamfer the ports ?

I sent the cylinder and head away to Ken oconnor and he did all the work so I am pretty confident in the work.

 

[Awk08]

I sent the cylinder and head away to Ken oconnor and he did all the work so I am pretty confident in the work.

yes sir, that work would be 110% correct
like I said, blasters make that noise, but it's hard to tell thru a video if it's excessive or not

 

[Turnersmith]

yes sir, that work would be 110% correct
like I said, blasters make that noise, but it's hard to tell thru a video if it's excessive or not

Okay thank you for your opinion. Another question I have is what the normal operating temp would be at the head? I feel the engine gets hotter then it did before the build and I have even upsized the main jet to a 280. Having port and head work done, could having a stock exhaust cause any of this?
Thank you for your time

 

[Awk08]

no way does a stock exhaust blaster need a 280 main jet, the pipe being the biggest factor in main jetting, closely followed by the intake/filter < there's only so much we can do there. but different pipes flow out differently and require jetting to match each, the stock restrictive pipe requiring the leanest jetting.

essentially, jetting is determined by air in and air out, when either is changed the jetting gets changed to keep the optimal fuel/air ratio.
porting/head mod alone only optimizes flow and burn inside the engine, without changing the pipe or intake/filter, jetting shouldn't have required the change to the 280, as for the heat, fuel is a big factor in cooling also, it should be running cooler due to the fuel, but the increased burn the new modded head created may increase it some.

learn plug chops to get your main jetting correct.....
http://www.blasterforum.com/threads/how-to-plug-chop.53237/

the stock 32.5 pilot with airscrew around 1-1/2 turns out, and the stock needle on the middle clip position will work for your setup

 

[Turnersmith]

no way does a stock exhaust blaster need a 280 main jet, the pipe being the biggest factor in main jetting, closely followed by the intake/filter < there's only so much we can do there. but different pipes flow out differently and require jetting to match each, the stock restrictive pipe requiring the leanest jetting.

essentially, jetting is determined by air in and air out, when either is changed the jetting gets changed to keep the optimal fuel/air ratio.
porting/head mod alone only optimizes flow and burn inside the engine, without changing the pipe or intake/filter, jetting shouldn't have required the change to the 280, as for the heat, fuel is a big factor in cooling also, it should be running cooler due to the fuel, but the increased burn the new modded head created may increase it some.

learn plug chops to get your main jetting correct.....
http://www.blasterforum.com/threads/how-to-plug-chop.53237/

the stock 32.5 pilot with airscrew around 1-1/2 turns out, and the stock needle on the middle clip position will work for your setup

Okay I will try to do the plug chop. Should I be starting at the stock 230 or because I have the k&n filter with no lid should assume it needs more fuel and start with a 240 or 250? Could an air leak cause the noise or the excess heat? Thanks for all the help once again

 

[speedyslyder]

i have a video of mine that sounds simular to yours
not as clanky but videos can be deceiving
what is your compression?
what plug you running?
what octane gas and or pre-mix you running?

 

[Turnersmith]

i have a video of mine that sounds simular to yours
not as clanky but videos can be deceiving
what is your compression?
what plug you running?
what octane gas and or pre-mix you running?

I am pre mixing 32:1 with 90 octane fuel and I am using belray oil. Just tested compression and it is at 130. The plug in using is an ngk br8es.

 

[speedyslyder]

sounds like you did not get the head mod from kor then if compression is at 130psi??
130psi is a average compresion/if you had the head rechambered/modified it would be in the 150psi range,or your gauge is lying?
the rattle could be lower connecting rod bearing or summin stupid like exhaust spring rattling from vibration/or anything rattling on quad loose bolts/anything really haha

every 2-stroke i have owned sounds broken close up to the cylinder on certain days/other days sounds different?
yz250's cr125' blasters' ect

If piston ring end gap is correct and the lower connecting rod bearing is within specs/squish band is set correctly...Then don't worry about it.Of course there is other possibilities but this is the internet can only explain so much haha

 

[Turnersmith]

sounds like you did not get the head mod from kor then if compression is at 130psi??
130psi is a average compresion/if you had the head rechambered/modified it would be in the 150psi range,or your gauge is lying?
the rattle could be lower connecting rod bearing or summin stupid like exhaust spring rattling from vibration/or anything rattling on quad loose bolts/anything really haha

every 2-stroke i have owned sounds broken close up to the cylinder on certain days/other days sounds different?
yz250's cr125' blasters' ect

If piston ring end gap is correct and the lower connecting rod bearing is within specs/squish band is set correctly...Then don't worry about it.Of course there is other possibilities but this is the internet can only explain so much haha

I definatly got the head mod done i seen the head when it got back. Does the engine need to be warm when doing the test? Seems concerning if it is suppose to be around 150 maybe I will give it another try. Thank you for the advice I am hoping the engine is just being noisy and nothing is wrong.