Vander's 3YF 660 engine overhaul

[xtzrick]

I'm not sure about this wear Vander

It looks quite deep, but then it is a close up photo.

Might be worth taking the whole bottom end to get an expert opinion.

Rick

[ActionManMelb]

Err....Houston, we have a problem.

The wear on the small end of the connecting rod may be a deal breaker. Better get your engine checking guy to have a look at that.

If you can't polish away the marks, then you may have to split the cases to repair. This will be complicated by the fact that not many shops can rebuild the crankshaft.

However, Actionman has a cunning solution.
If you get desperate, have piston pin hard chromed oversize by about 0.1mm. Ream the small end 0.08mm oversize, the pin is now a press fit in the rod. Ream the piston pin hole (in the piston) 0.1 oversize and hand lap the now oversize pin to suit the piston.

You will now have a floating piston and a fixed pin. This method is used in many automotive applications as it gives twice the bearing surface. That is, the pin is sliding in the piston boss rather than the connecting rod.

[vander]

Well, touching it doesnt felt that bad.

All was going too well I guess.


I like your cunning solution ActionMel!! I dont loose much by trying that. A lot better than open the whole case.

[Mezo]

Use your fingernail Vando, push it through & if it stops its fucked.

Mezo.

[xtzrick]

The other option is to rebuild the spare head (lap the valves & replace the valve seals ) & swap the barrel, piston & head with the ones on the engine in your bike, providing your original bottom end is ok.(or just use the barrel & piston with least wear )

You should be able to buy a new piston pin, if not, try the one in your original engine if that is ok. Always use NEW circlips in the piston.

Rick

[vander]

I dont think the other engine will be better to use than this. It has been run low in oil and a clear "clakclakclak" can be heard, wich I think comes from the rod/crankshaft. I've read this is recurrent in the 5valve teneres.

I will post a video with the sound tomorrow.

Im fed up with engine noises. My CB also has the typical Honda clutch noise due to faulty springs.

[vander]

My 3YF's bel canto. Remember this is not the engine that I am rebuilding in this post. ...but it could be the engine I open next and maybe mate with it.

This was this afternoon.

[youtube]eDzmwpsDsRg[/youtube]

[xtzrick]

I dont think the other engine will be better to use than this. It has been run low in oil and a clear "clakclakclak" can be heard, wich I think comes from the rod/crankshaft. I've read this is recurrent in the 5valve teneres.

I will post a video with the sound tomorrow.

Im fed up with engine noises.

The recurrent problem on 5valve 660s comes from the balance shaft drive gear rattling against its' 'key on the right hand end of the crank.

Problem is caused by these 2 washers grinding each other down, which has the same effect as loosening the nut.

My bike sounded very similar to yours before I changed my washers.
The good news is Yamaha appear to have corrected the problem themselves.
New parts are harder & properly machined.

It's about 40euros in bits including gaskets, washers, keys & lock washers. And it only takes 1-2hours to fix, engine in frame.

Rick

[vander]

Ok, I spoke with the honer. The cylinder was oval, so I said lets go. cylinder honing is 60€.

But until next week he is off. His wife will bring a kid to this world tomorrow morning.


Now with the piston, I'm a bit confused. You have all advised me not to change it, but is it really possible to keep it if the cylinder is honed? There's no bigger rings, only bigger pistons, right?



What you think of the high compression pistons? Wiseco's are cheaper than Yamaha ones... but I dont need more power if I loose reliability.

[Cucumber]

I dont think the other engine will be better to use than this. It has been run low in oil and a clear "clakclakclak" can be heard, wich I think comes from the rod/crankshaft. I've read this is recurrent in the 5valve teneres.

I will post a video with the sound tomorrow.

Im fed up with engine noises.

The recurrent problem on 5valve 660s comes from the balance shaft drive gear rattling against its' 'key on the right hand end of the crank.

Yup, sounds like that. I just bolted the nut with a little higher torque, together with loctite.

I never heard about changing the washers. Isn't the wear on those washers a result of a losening nut, instead of being the problem?

Vander, my honer hones the cilinder with the measurements of a new piston. Because it's oval I don't think that you'll get away with the old piston.