engine knock after replacing head gaskets???

10748 Views 29 Replies 14 Participants Last post by rdm531, Jun 1, 2016

wicked04

Discussion Starter · Feb 6, 2010

I just got done with the head gasket job. when i started it up there was a loud knock and the a back fire out of the front carb. i let it sit and started it up again and it was knocking and smoking(white smoke) pretty back. i killed it relaxed and then started it again and let it idle and the smoke stoped. now it idles fine and doesnt smoke but 5 secs or so after giving it a little throttle it starts knocking and get worse the more throttle you give it.

i bought a manual and did it step by step of the manual except for rolling the motor to TDC before removing the rocker boxes. i didnt roll the motor over or move the cam chain. i marked the cam chain to the cam gear with a paint marker and lined the marks right back up when i went together. i installed everything correctly per the procedure(cam tensioner, rocker box, head, etc....) except rolling the motor like it said cause i didnt see it.

I dont think i changed the timing by installing the chain exactly back where it was but do yall think it might have jumped time before the tensioner pushed the chain tight. i dont think its a bent valve cuase i think it would do it at idle as well but........

PLEASE HELP!!!!!!!!

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Hunterworks

· #2 · Feb 6, 2010

Your going to have to take the rocker covers off and rotate the engine clockwise using the bolt head on the end of the crank on the magneto side.

Align TR up with mark in hole then look at the alignment marks on the rear cam, then rotate engine clockwise 270 and line up TF and check that cam.

T_Dilley

· #3 · Feb 6, 2010

Sounds like a crank bearing..louder it gets with more throttle.

wicked04

Discussion Starter · #4 · Feb 6, 2010

Hunterworks said:
Your going to have to take the rocker covers off and rotate the engine clockwise using the bolt head on the end of the crank on the magneto side.

Align TR up with mark in hole then look at the alignment marks on the rear cam, then rotate engine clockwise 270 and line up TF and check that cam.

If all that checks out ok then its prob. coming from the bottom end huh. it never made an ounce of knocking before i parked it to do the head gasket. does all the info i gave you sound right cause i am trying to think if i have told you what all i have done and thought of. if you need anymore information let me know

Hunterworks

· #5 · Feb 6, 2010

You can what if it to death but check the cams first. The lobes should be pointed down too.

hndlbarmonkey

· #6 · Feb 6, 2010

white smoke is coolant

you're gonna have to pull the heads back off

got something messed up

wicked04

Discussion Starter · #7 · Feb 6, 2010

Hunterworks said:
You can what if it to death but check the cams first. The lobes should be pointed down too.

i hope your not saying both cams right, which cyclinder should be pointed down

hndlbarmonkey

· #8 · Feb 6, 2010

put you flywheel on TR, yank the rear cover off, the cam sprocket arrow should be pointed up and the two hash marks parallel with the head, rotate the crank 270* and put it on TF, yank the front cover off and now that arrow should be pointing up and hash marks parallel with the head

Camo Joe

· #9 · Feb 6, 2010

???

It must be in time..................being out of time will cause a knock or
(pinging clatter) because of the back pull .........some sounds are normal and some are not............hopefully not a sticking valve..............and hopefully not bent now..............is the engine missing? Did you adjust the valves or leave them as they were?......... Don't run it any more until you correct the problem.........$$$$$$$$$$$$$$$

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wicked04

Discussion Starter · #10 · Feb 6, 2010 (Edited)

it is idleing alittle rough, and i didnt adjust or touch anything valve wise. what are you calling pull back? i gonna look into it a little further in the morning, thanks guys for all the info. hopefully i find out some good news and its a cheap or easy fix.....

hndlbarmonkey

· #11 · Feb 6, 2010

did you leave much coolant sitting in the cylinders when you pulled the heads off?

most forget to pull out the 2 8mm bolts on the sides of the cylinders....drains the coolant sitting in the heads and cylinders

wicked04

Discussion Starter · #12 · Feb 6, 2010

does anybody run maual cam chain tensioners. a friend of my said his went out on his suziki and it was making the same nosie cause the cam chain is streched out and the tensioner wont extend enough to tighten it up and i am hearing the cam chain slap around. does this make any sense to anybody?????

Camo

· #13 · Feb 6, 2010

Yes, but that's why we change our chains.

I wonder if you have a chain guide out of place? Did you have the cylinders off at all?

Camo Joe

· #14 · Feb 6, 2010

...........

wicked04 said:
it is idleing alittle rough, and i didnt adjust or touch anything valve wise. what are you calling pull back? i gonna look into it a little further in the morning, thanks guys for all the info. hopefully i find out some good news and its a cheap or easy fix.....

The back pull as I call it in layman terms.............is like if you use cheap low grade fuel (low octane) in an engine............and you hear clattering, pinging, knocking sounds...........its because of the fuel ............its not firing "on time". So if an engine is not in time it can do the same thing. The clearance or slack in all the fitted parts.........bearings, bushings, guides, etc. in the engine are not a constant one way like a normal running engine............its back and forth ...back and forth fighting against itself................then you hear all kinds of abnormal sounds..........

GoatMan

· #15 · Feb 6, 2010 (Edited)

Spun a rod bearing...

Did you pull the cyl's and check for slack in either of the rods while you were down there?

White smoke when you first cranked it up could be from moisture still in the pipe... You'd have to run it a little bit to be sure that its still got a blown head gasket.

Though obviously if it blew a head gasket it had gotten hot and it must of got hot enough to get the rod.

cowboy316911

· #16 · Feb 7, 2010

have you doubled checked the cam for timing? you said you used a paint marker as ref. but that could still mean your out which will give you white smoke and knocking from valves being out of time.?.? I know this from my own experince.

05-BF-750

· #17 · Feb 7, 2010

Sounds to me your cam timing isn't right.

wicked04

Discussion Starter · #18 · Feb 14, 2010

ok well i just had time to work on it again. i checked the cam timing just like everyone told me to do and it is in time. the cam chains are tight, the chain guides are in place. all of the stuff that i touched is fine. what else could it be because im puzzled now. i would think that a rod bearing would start to knock as soon as i give it gas and knock a little bit at idle. it doesnt start to knock until about 5 to 10 secs after i am giving it some gas. its seems to me that something loosens up after i give it some gas. the little weights or what ever they are called on the cam gear that move in and out are not touching anything when i push them out. what should the valve clearance be. i am not sure what size cam is in it but on my paper work it says it is a stage 1 arc cat 650. would there be a certin clearance for this. i just hope someone here can help before i end up having to take it to someone and get charged an arm and a leg!!!!!!!!

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Wild650

· #19 · Feb 14, 2010

Just throwing some ideas out there, but someone have a bad knock a few years ago they thought was in the engine but actually something in the clutch. Would only make noise when given gas nothing at idle

wicked04

Discussion Starter · #20 · Feb 16, 2010

Well after all the time and money spent on the POS i now have a rod knocking and am pretty sure thats what the knocking noise i heard right after i did the head gaskets. i took a doctor hearing device and its definitly coming from the bottom end but the wierd thing is it didnt make a sound for about ten minutes after i put everything back together and idled it up. it was like a light switch that it just started knocking all the sudden.

has anyone else every heard of this?????

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