Buying used and servicing

[Mr. Dazzle]

Plus that really freaking hot gas can erode the seats. Exhuast gas and valves get incredibly hot, I always find it slightly impressive the bits can survive being so hot while simultaneously being hammered together 100 times a second.

[dern]

Yep. These were all standard bikes running standard exhaust. The point was that you can never assume valve clearances don’t need doing and it’s always worth checking in my opinion unless you want to chance it.

[Le_Fromage_Grande]

Yep. These were all standard bikes running standard exhaust. The point was that you can never assume valve clearances don’t need doing and it’s always worth checking in my opinion unless you want to chance it.

Interesting, I've never had Suzuki or Yamaha bucket and shim valves need changing when I've checked them, but I've only done one Suzuki and two Yamahas, my old air cooled 8 valve Kawasaki needs shims changing every time, but the valves get hammered (and the valves were made in 1983)

[Mr. Dazzle]

I've said it before, but its still true.

Rate of wear = random number generator!

[Bigyin]

https://www.ebay.co.uk/itm/334453345120 ... SwmJZijnjV

Thats blue B1H is about 25 miles from me if he does get back to you and you want it looked at

[Numnut]

https://www.ebay.co.uk/itm/334453345120 ... SwmJZijnjV

Thats blue B1H is about 25 miles from me if he does get back to you and you want it looked at

Cool, cheers. I’ll try him on eBay and see if I get a response

[maccecht]

My Burgman 650 has 74k on it and had the exhaust shims changed 5 times. Beancounters TDM2 his favorite one ate a valve head due to lack of clearance checks not something that should be ignored. Many bikes check out OK at the intervals but they should be checked never ignored

[Le_Fromage_Grande]

I'm coming to the conclusion I've been lucky with valve clearances.
The old Suzuki screw and lock nuts needed adjusting every 3000 miles.

[Mr. Dazzle]

The old Suzuki screw and lock nuts needed adjusting every 3000 miles.

Luxury!

[MingtheMerciless]

My 9R E1 needed three valves re shimmed at its first valve service (8K I think). I got moaned at for doing too many track days and also the mechanic thought that the kwacker cams were quite steep/fast opening/closing so that helped hammer them (I've no idea if this is true, it's all mechanical magic as far as I'm concerned).

[Mussels]

I've said it before, but its still true.

Rate of wear = random number generator!

I wonder if apparent rate of wear of shims at first check = competence of the fitter in the factory.

[Mr. Dazzle]

Not necessarily even competence, there's a tolerance on everything and it's perfectly possible a bike just squeezed into the "OK" band. When you consider how many manufacturing steps there are, not just in assembling the engine but also making all the individual bits...

That's why people blueprint engines right?

I don't actually know how they shim engines in the factory, but I doubt it's someone actually checking them with gauges at the end. More likely they just have inspection data for all the bits and a computer programme just spits out which shim you need. Or maybe even they just know that it's always shim X and they've done the stats to know all the other process steps are within acceptable bounds.

[MingtheMerciless]

I remember watching a TV program about car manufacturing. There was the same car produced in America and Japan and the Americans couldn’t initially work out why their transmissions and engines were noisier than the same units produced in Japan. It wasn't until they stripped an American and a Japanese engine/transmission that they found the answer. Both were built correctly and to the tolerances, it was just the Japanese parts were all pretty much in the centre of the tolerance band whereas the American parts were all over the place.

[Le_Fromage_Grande]

I've said it before, but its still true.

Rate of wear = random number generator!

I wonder if apparent rate of wear of shims at first check = competence of the fitter in the factory.

The shims don't wear, the valve clearances tighten up, it's the valve or the valve seat being hammered, on air cooled Kawasakis it's the valves, on race engines the valves come out with knife edges, they look splattered.

[Mr. Dazzle]

I remember watching a TV program about car manufacturing. There was the same car produced in America and Japan and the Americans couldn’t initially work out why their transmissions and engines were noisier than the same units produced in Japan. It wasn't until they stripped an American and a Japanese engine/transmission that they found the answer. Both were built correctly and to the tolerances, it was just the Japanese parts were all pretty much in the centre of the tolerance band whereas the American parts were all over the place.

There are certainly variations between suppliers/OEMs.

I've engineered/supplied loads of stuff to various supercar manufacturers over the years, I now work for one of the really big German OEMs. My current bunch have more people dedicated to quality than the supercar guys have total employees!

Tolerance bands are only the start these days, its all about the stats too. Proving how consistently you hit the middle, how wide the spread is, how you know you're hitting what you think you're hitting etc. Simultaneously interesting and incredibly dull.

The shims don't wear, the valve clearances tighten up, it's the valve or the valve seat being hammered, on air cooled Kawasakis it's the valves, on race engines the valves come out with knife edges, they look splattered.

Tis true...but teeny tiny variations in the valve etc. itself will make a surprisingly big and very hard to predict difference. A fraction of a fraction of a mil off centre, very slightly different seat angles, miniscule differences in surface texture. It all adds up in a really annoying way thats hard to design out.

[Le_Fromage_Grande]

Many years ago I made lawn mower engines, one of my jobs was setting the valve clearances, feeler guage to measure the clearance, grinder to change the length of the valve.

[Mr. Dazzle]

Imagine doing that for a 16v engine!

Possible, but there's gotta be a more efficient way.

[Le_Fromage_Grande]

Imagine doing that for a 16v engine!

Possible, but there's gotta be a more efficient way.

I suspect it's why Suzuki went screw and lock nut when they went to 16 valve engines, much quicker to set up on a production line than bucket and shims. Yamaha must have been confident of their quality control when they went shim under bucket on the 20 valve FZ750.

[Skub]

The C and D models of ZZR1100 had a little rocker arm on a spring,so to change a shim all you did was pull the rocker out of the way and lift out the shim with your magic magnet. No cams out bollox and a gift to work on.

[Mr. Dazzle]

Self adjusting hydraulic tappets FTW.