Big end bearings.

[zoro]

I noticed a little amount of play, while riding on the back roads, while the engine was going up through the gears & rev range. This was not felt, on a straight road at fixed revs, this had me thinking the large bearing on the crank behind the fly wheel. Engine stripped, a slight movement was felt, even more with the engine spinning the fly wheel.
With a rigid mounted engine to frame, every little flaw can be felt coming on, as the problem arises.
I showed the big end bearings, to a engine rebuild firm, this morning, the answer was that they where well worn, the copper showing through on a few places, the bearings in the 406 clone where all jap made bearings, of what seems to be a good name, unless these have been cloned too, but all showed a little wear.

Given the low revs & good oil changes, the bearings would have most likely went on for years, as for most engines that are abused on the building sites, with very little problems. I have put up around 16,000 miles on the motor.

This has me thinking, about the Hatz motor, I read some where the sommer build enfields, had a 2 year, unlimted millage warranty, on the engine & bike. I have heard little details about the big end bearings being looked at or checked.
At these low miles, is this a sign of poor materials in the big end bearings, or might the Yanmar or Hatz, have the same wear, but at higher millage, any thoughts from the guys who have experience on these l100 engines

[zoro]

I thought I would double check, the wear & tear on the big end bearings. The salesman at my local Yanmar hire shop, phoned Yanmar UK, to see at what the service limits where on the shell bearings. Was told as long as there where no groves, bad marks or scrapes, in the inner surface, or much in the way of black spots of dirt that has passed through the oil feed to this area, to the bearing faces. I showed the shell bearing to a car engine rebuild, there is a big difference in the engines of a car & a L100 basic diesel engine, these guys said the shell bearings where well worn, yet the yanmar guys after, seeing the bearing faces said that they where well within the service limits & to reuse them again & that they where well within their working limits.

They also said that this was not a problem area & the engines where not noted for this. I think I will take the advice of Yanmar Uk & reuse the bearings. Most likely for peace of mind, this winter I will change them for new ones, as they are easy to replace.

Most likely I have answered my own question to a degree.

[coachgeo]

Recheck with your Yanmar guy's BUT caveat that the engine is NOT used in an industrial manner sitting in a sail boat or tractor both which are constant speed and load. This is the mindset they they operate in when asked questions and that is the mindset they respond too.

Since our application has these engines moving up and down the RPM range way more so than typical use... and they are in frames that get jostled and pounded by road surfaces at highway speeds. Also wheels that the engine turn get applied random changes of torque not constant load of tractors and boats etc. Just wondering if that will change their answer's or not.

[zoro]

When I think back at the miles the engine has covered, the areas & road types, it has took a pounding. Not abused in any way, but it is understandable, at the wear & tear on the fly wheel bearing, spinning at different revs & load. They need to be tough little engines to cope with this. The big end shells & small engine are in the same area, of load stress.
The Yanmar guys, would have worked as you stated, on the experience of a fixed engine, with steady revs. The clone engine, would most likely if run in this manner, given no trouble for a long life.

The engine being a clone, the bearings can be uncertain, at where or what factory they came from. Yes they did have a good bearing name, but a engine coming from china, one has to be suspect, at their thinking & clone skills. I replaced all the bearings with SKF Explorer, some where a tight fit coming out & going back in. It will be interesting to see at how long the fly wheel bearing will last this time, mine has been running unsmooth & with a little noise for a while now, but I have seen a lot worse coming from bike engines. Most likely would have lasted for a while, but with the heavy fly wheel & thump of the engine, it comes to a time when riding the bike, it tells you its time to change.

I will be changing the shell bearings in the winter, so that's 6 months away, this will at least show how smooth the skf bearings are running. You are very correct at the way & state of mind people are in, when you ask a question, that is out side their experience. Even with a Yanmar engine, with better materials ect, the load will be no different, than the load of the clone engine, at the rev band & road conditions.

If I had run the engine to say 20,000 then replaced the bearings , oil seals & shell bearings, this is still a very low price to pay for spares, for the low cost of running the engines. The bearings & oil seals cost £50 all in.(( shell bearings not in this price )) The shell bearings, for the con rod & the one that sits in the outer left hand case, that the crank runs in, are very little money also

With this info, is a Yanmar engine, at maybe 3 times the price of the clone & the running stress & load out on the road, going to be that much better. Only time & road miles will show on this engine