Horizons Unlimited - The HUBB

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-   -   Engine noise (https://www.horizonsunlimited.com/hubb/yamaha-tech/engine-noise-36260)

Gawain 1 Jul 2008 11:08

Engine noise
 
Hi guys, long time lurker but 1st time poster.
My 3TB engine (in an SRX400 frame) has a knocking sound from what sounds like the bottom end. Replacing the camchain and putting the chain guide the right way round :censored: after setting the tappets dulled it but its still there. Its primarily noticable at idle, cant hear anything after that coz the pipe a 'bit' noisy. Any obvious things to check? The camshaft looks mint so not likely to be from previous oil starvation, I hope?

As an aside how the hell are you supposed to get the covers off the engine, I mean the ones to turn the crankshaft and see the timing marks? Had to get someone else to do it! any tips?

Thanks!

Gawain 3 Jul 2008 12:51

Probably not my most descriptive paragraph...
The noise occurs equally hot or cold and is only noticable at idle.
Pulling the clutch lever has no effect.

louposteph 3 Jul 2008 21:19

noise
 
Hi ,try this link :http://www.horizonsunlimited.com/hub...ine-gone-6422; "loose nut on the crank shaft ";
It might not be that, but after my scary but in the end lucky experience, bolt on the crankshaft (the one holding the two pinions together) or the one on the balancing shaft would be the first thing i would check if i was ever to hear that banging noise coming from the botom of my 3AJ again.

Regards;

Gawain 8 Jul 2008 09:02

Very interesting! SO how would I go about tightening this nut? How far do I need to dismantle the engine? Im not particularly experienced but willing to learn!

Anyone with a guide how exctly to go about doing this?

XT GIRL 9 Jul 2008 08:00

From the Xperts
 
Hello BANANA BOY! :clap:

With regards to the bolts on the crank case - you can find the settings and sequence of tightening them in the service manual. (if you don't have one - i can send you the bits from our manual, just pm me.)


For some light entertainment, whilst you solve your problem, I can show you, very graphically and visually how NOT to do it... How to Kill Your Engine...

bikerz 9 Jul 2008 08:42

dear god who told you to use a lever to tighten a 6mm bolt....you two certainly do need some mechanical tutoring!:rofl:

robinh44 9 Jul 2008 10:32

Hi,

I find it is worth having two types of torque wrench, a 1/2" drive which will handle larger sockets and torques with a range of 50nm-200nm and a smaller torque wrench with a 3/8" drive for smaller sockets and a range of 10nm-80nm. After a while you get the feel for hand tightening bolts but on things like flywheels always stick to exact torque specs, as I found to my cost on my Morini and had a flywheel come off causing the following damage to my casing and a 2 mile walk home. Experience don't you love it , you get the test then shortly followed by the lesson.

The hole made but the flywheel nut coming off
http://i71.photobucket.com/albums/i1...o/IMG_4453.jpg

However quickly fixed by taping some card on the outside and using some jb weld, very good casing repair. Still holding out after over a year of service

http://i71.photobucket.com/albums/i1...o/IMG_4481.jpg




Regards

Robin

Gawain 6 Sep 2009 08:59

A long overdue update...
 
Quite a few months ago I got my mechanic to have a look at the crank/balancer nuts and they were stil factory and on spec so thats nt the problem.
Yesterday I found a missing bolt which holds the header to a short connector box, cant believe I missed it! Havnt started the bike yet but im hoping thats the cause of the tapping.


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