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61 mm cylinder block

wvlfonlus

wvlfonlus

New Member
guys i have a question...ive noticed knocking sound out of my engine....more like "tukotok"sound when th engine is idle, mine has a 61mm CMR block almost a year now, no other problem ...just the sound...it has the power...just want to ask other big block user if they experience the same issue...iam gonna make a video so it would be easier t understand...one more thing ...how can i fix this backfiring..i already fixed the muffler, no leaks on the muffler and the elbow...i already opened the air screw 4 turns ...but i cant get rid of the backfire.
 
Rolly

Rolly

Super Veteran
wvlfonlus said:
guys i have a question...ive noticed knocking sound out of my engine....more like "tukotok"sound when th engine is idle, mine has a 61mm CMR block almost a year now, no other problem ...just the sound...it has the power...just want to ask other big block user if they experience the same issue...iam gonna make a video so it would be easier t understand...one more thing ...how can i fix this backfiring..i already fixed the muffler, no leaks on the muffler and the elbow...i already opened the air screw 4 turns ...but i cant get rid of the backfire.
Click to expand...
did you changed your stock camshaft with a racing camshaft without decompression pin? how about your carb jettings? do you still use the stock carb?
 
sniping_area

sniping_area

Super Veteran
wvlfonlus said:
guys i have a question...ive noticed knocking sound out of my engine....more like "tukotok"sound when th engine is idle, mine has a 61mm CMR block almost a year now, no other problem ...just the sound...it has the power...just want to ask other big block user if they experience the same issue...iam gonna make a video so it would be easier t understand...one more thing ...how can i fix this backfiring..i already fixed the muffler, no leaks on the muffler and the elbow...i already opened the air screw 4 turns ...but i cant get rid of the backfire.
Click to expand...
(back fire)try changing the air jet 22.5... ;)... sir admin is the man!
 
sniping_area

sniping_area

Super Veteran
wvlfonlus said:
guys i have a question...ive noticed knocking sound out of my engine....more like "tukotok"sound when th engine is idle, mine has a 61mm CMR block almost a year now, no other problem ...just the sound...it has the power...just want to ask other big block user if they experience the same issue...iam gonna make a video so it would be easier t understand...one more thing ...how can i fix this backfiring..i already fixed the muffler, no leaks on the muffler and the elbow...i already opened the air screw 4 turns ...but i cant get rid of the backfire.
Click to expand...
i used the super stock carb with no air box with 115 main jet, i need 22.5 for the pilot... my pj is 15 right now... maybe its the (con rod) that produce the knocking sound or a fuel knock ... the stock conrod is build for the stock piston... :) i haven't experience that noise yet... i don't over rev in city driving... our bike is modified and the wear n tear of the engine is more shorter than the standard... so much better if you save the over rev.. and used it in a special occasion.. :rolleyes::p;)
 
sniping_area

sniping_area

Super Veteran
romkazoo said:
what do u mean sir? different from stock engine consumption it means the 61mm consume more gas?
Click to expand...
ener in an idle throttle with the 61mm its more tipid than stock bcuz u dont have to exert full throttle to gain your desire speed... get it ;)...the engine has its "muscle":D
 
wvlfonlus

wvlfonlus

New Member
Rolly said:
did you changed your stock camshaft with a racing camshaft without decompression pin? how about your carb jettings? do you still use the stock carb?
Click to expand...
i use a vixion cams with stock bore, my only worry is that my engine did not sound like this before, although ive been using my cmr 61 mm for 8 mons so far no engine trouble except for that nasty "tukotok" sound, BTW, i have resolve the backfire with the help of my yamha mechanic baki, he cleaned the air induction as well as the reed valve, i also disabled the AIS by plugging electrical tape inside the hose.
 
Rolly

Rolly

Super Veteran
wvlfonlus said:
i use a vixion cams with stock bore, my only worry is that my engine did not sound like this before, although ive been using my cmr 61 mm for 8 mons so far no engine trouble except for that nasty "tukotok" sound, BTW, i have resolve the backfire with the help of my yamha mechanic baki, he cleaned the air induction as well as the reed valve, i also disabled the AIS by plugging electrical tape inside the hose.
Click to expand...
have you checked your valve tappet clearance? the clearance might be too much already.
 
wvlfonlus

wvlfonlus

New Member
just recorded the sound of my sniper engine this morning...here it is:

I have a 61mm CMR block, vixion cams , stock valve springs, ported head...

just wanna know if others have the similar sound.
 
sigea2

sigea2

New Member
wvlfonlus said:
just recorded the sound of my sniper engine this morning...here it is:

I have a 61mm CMR block, vixion cams , stock valve springs, ported head...

just wanna know if others have the similar sound.
Click to expand...
Bro, i have a friend who is running on a fully modded sniper, his bore is 58.5. His mechanic did his bike up to a point that it's a race bike thats on the streets. He too has this knocking sound, for 2 years. I guess it's normal.

I am on a 63mm bore, Keihin PE28, hi-cam stage 4, stock cdi, his bike leaves me behind when it comes to straight roads and he gets beyond 180kmh easily.
 
wvlfonlus

wvlfonlus

New Member
sigea2 said:
Bro, i have a friend who is running on a fully modded sniper, his bore is 58.5. His mechanic did his bike up to a point that it's a race bike thats on the streets. He too has this knocking sound, for 2 years. I guess it's normal.

I am on a 63mm bore, Keihin PE28, hi-cam stage 4, stock cdi, his bike leaves me behind when it comes to straight roads and he gets beyond 180kmh easily.
Click to expand...
That's the thing, i don't feel any power loss, if indeed it is the connecting rod, my engine should have been destroyed mons ago, i rode this set up to sagada and back, where i got into an awful accident(but that's a different story)..and yet power still there...its just that annoying noise...
 
wvlfonlus

wvlfonlus

New Member
sounds like a typewritter on steroids...what do you think guys...con rod or not...i am planning to have it overhauled tom.
 
sigea2

sigea2

New Member
If your mechanic finds out what is wrong, do share it here, some of us would like to know too. Thank you.
 
sniping_area

sniping_area

Super Veteran
wvlfonlus said:
just recorded the sound of my sniper engine this morning...here it is:

I have a 61mm CMR block, vixion cams , stock valve springs, ported head...

just wanna know if others have the similar sound.
Click to expand...
so far my bike doesn't sound like that...

i go for the conrod bearing or the loose bore...:)

did you try changing new bore kit??
 
Rolly

Rolly

Super Veteran
wvlfonlus said:
sounds like a typewritter on steroids...what do you think guys...con rod or not...i am planning to have it overhauled tom.
Click to expand...

it seems the noise is coming from the cylinder head. did you removed the lever (see picture) inside the camshaft sprocket which activates the decompression pin through centrifugal action? without the decompression pin it would be free to bounce and create noise. this would not affect the engine performance but would create knocking noise.
 
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