Timing Chain & Guides

[bh2285]

I thought the noise that I was hearing was valve train noise so I changed back to my old cam and adjusted the lash and started it up and the noise was still there. This noise is to loud to be valve train noise so me and my buddy(very good mechanic) have decided that it is the timing chain and guides. While trying to set the timing chain/cam at TDC we relized that you cant get it exactly lined up every where its slighty retarded or advanced. He told me this is due to slop in the chain and guides. This is why he says its makeing the noise. SO im going to replace the chain and guides...What are all the parts I should replace while doing this and which brands should I use? Has anyone had this noise in there quad?


Here is my setup:

j&e 12:1 piston,ported and polished head,white bros valve springs,xr 400cam,the head and cylinder have been decked .025,the head studs are9/16 in diameter instead of 10mm and they are 1in. longer than stock. Carb has the choke removed and is tuned to this motor.

[440ex309]

yeh same here i want to replace my timing chain and guides because my quad is doing the same thing...but i dont know what i should get can someone help us out?

[ride_red666]

is it like a loud ticking noise?

[bh2285]

Yes you could decribe it like that...It almost sounds like an exhaust leak but is not...Its only for a spit sec right when you let off throttle. I guess the chain get loose right then and rattles..I guess..

[bh2285]

Bump what kind of chain should I buy? Should I replace any thing besides the guides and chain?

[lafinrat]

if your head and or cylinder are 'decked' as you say, the marks will never line up. you need to buy an adjustable cam sprocket and degree wheel, and degree the cam. but the marks will never again line up. if you're 'decked' 0.050" as you say, your cam is about 6 degrees retarded.

your noise is probably a defective tensioner. i've seen some mugged up ex motors and never had to put sliders in them.

btw. you can use a 400ex chain, or crf450 chain. they both work. some say the bike chain is necessary, some don't. my 400 has one with no probs, and original sliders, and that motor was wasted when i got it.

[bh2285]

Wow...I never thought about that...I bought the motor built like it is. When I first got it with the XR400 cam in it it ran great I changed the cam to the hotcam stage 2 and it started to make this noise. I never thought about the timing and decking..So I take it your telling me I have to advance the timing? What does the noise sound like when the chain tensioner is out? Do you have AOL or some other way I could talk to you quicker I need help and you sound like you know.

[bh2285]

Ok does the tensioner screw thats in the middle hold the part that pushs on the slider? or is that thing that pushs on the slider sprung all they way out?

[lafinrat]

i recommend you take the tensioner off the cylinder, and turn the screw in and out so you can see how it works. the gasket might tear so have a new one ready.

[bh2285]

ok, So I changed the tensioner that was in my stock motor into the other motor and the noise is still there(so that rules out the tensioner)...So you say if my engine has been decked on the head and cylinder that it will be retarded. And you say that it will be retarded 6 degrees. Could this cause the noise im hearing...How would know how to advance it 6 degrees with a stock cam gear? Also how would I tell if my chain and guides are bad?

Btw that tensioner was is in way better shape then the other one...I could tell the spring was stronger. Does the tensioner normally run all the way out or is it only half way out on your motors?

[lafinrat]

it would be hard to conceive that cam position would create a noise. the only possible way, is if you had piston-to-valve contact. 6 degrees is an estimation based on my experiences with milled motors. however, the cam WILL retard as the sprockets get closer to each other (think about it). how much is fairly consistent based on crank gear diameter. anyway.........

did you clay your motor to check p-v clearance? if not, you need to. remember as you retard the cam, the exhaust valves get closer and the intake get further away. visa versa when you advance the cam. and.....................

if you have access to a CNC Bridgeport, you can make your own adjustable cam sprocket--thats what i always do. i've seen people 'dremel them out', but they are hardened steel and will eat up stones and dull carbides. or, you can buy one from Falicon or Web or somewhere like that. and.............

degree the cam--there is plenty of info around on this. if you don't want to buy a degree wheel, i can tell you another way to check cam position. i don't know how familiar you are with cam timing, so i might lose you. but i'll try if you want. so.............

disassmeble the motor and check for any interference--piston to head, piston to valve, etc. and clay the motor and check for p-v clearance. you need .050" on the intake and .100" on the exhaust to account for piston rock at TDC, thermal expansion, and valve float. yes, they all float. also remember, lift has little to no effect on p-v clearance. its all duration and position. the intake valve chases the piston as it opens, and the piston chases the exhaust valve as it closes. contact usually occurs a few degrees from tdc when valve position is low in relation to max lift. thats why some cam companies provide a tdc lift number (Megacycle does I believe).

let me know if you wanna know the backyard way of degree'n a cam.

good luck. check your pm's and call me if you need to.

[bh2285]

Wow I have no idea what this noise is...

I bought the motor as it sits with everything done...The guy I bought it from said that he did have the piston hitting the valves so he added another base gasket and that made for enough clearance. They guy I bought this from knew his stuff...But when I got the motor it had the XR400 cam in it and it ran great with no noises...Then I changed the cam to hotcam stage 2 and it made the noise. So I adjusted the valves agian and agian and it still made the noise so i decided to put my other cam back in (xr400) and I adjusted valves and it still made the noise...Now I have not rode it much at all since I very first changed the cam so I find it hard to belive that the chain and guides are bad because it was fine before I change the cam...Is there anyway to tell if they are bad? I dont know what to do about this I took videos so someone could hear it maybe but its hard to make out but here they are.

www.putfile.com/bh2285


Thanks Alot I might just call you later to make this quicker.

[lafinrat]

i can't get those videos to work. you can email them to lafinrat@hotmail.com.

[bh2285]

OK now they are e-mailed

[kjr]

Iv got that same damn problem, and it's only happened since i rebuilt my motor and put a new wiseco 11:1 piston in it. Im taking it apart today to check for contact on the piston from the exhaust valves because the noise is comming from the front, and what iv read on here seems to say the same thing.If worse comes to worse i guess i could stack gaskets like someone posted earlier. I hope everyone else ends up fixing the problem.

[bh2285]

My problem is my **** has been decked there for bringing the cam closer to the motor causing slop in the timing chain. How can I fix this with out pulling the motor all apart?