RobbieRobot Cafe Racer Project in pictures

Trouble ahead.

 

The camshaft problems were the first indication of a much worse problem. Further investigation today has revealed catastrophic damage to the big-ends (4mm play for one in particular). The decision as to whether or not to change the whole engine has now become an easy one. Engine A is well and truly FU**ED. Tomorrow I hope to service engine B, fit the carb rack from engine A, see how she runs and take it from there.

 

Rather than end the day on a negative note, here is a pic of RobbieRobot Café Racer last week.

 

well done!

CN

 

as a very good friend of mine used to say (and probably still does), "junk is junk, it don't come in grades".

CN

 

Shame to hear about the motor! Good luck with engine B! I've decided to take a few steps back on my project as well and do it the right way like you've done with yours.... in the next few days I'll be taking the whole thing apart, engine out of the frame and polishing, painting, and power coating! Yikes!

 

hey Robbie, I am devastated... dun know what to say!

but keep working on it and reap the rewards later.

kinen1

 

Two days ago I brought the donor bike in from the cold and had a close look at the engine. First off I took the plugs out and discovered that no3 plug hole had been re-bushed and also the threads in no2 were less than perfect but I could tighten a new plug down OK. I had witnessed the engine running on the day I bought the bike a few weeks ago but hadn't started it since. I drained the oil into a clean container then sieved it through a nylon stocking, there had been no oil filter fitted. There was no sign of foreign matter in the sieved oil though. Next thing was to remove the cam cover and a couple of camshaft bearing caps for inspection. There were signs of wear on the camshaft bearing surfaces but only as much as you would expect from a 33 year old engine. The speedo reads 22,000 miles but I have no way of knowing if any of the 15 previous owners ever changed the speedo. On re-torquing the caps down I checked the torque on all of the other caps and found 2 bolts wouldn't tighten. I removed them and found some of the threads clogged with alloy and damaged. Two bolts from engine A did torque down to the required torque though. This situation didn't instil much confidence so far. Next job was to check the valve clearances. I found that the maximum gap wasn't necessarily at 180 degrees to the cam lobe. Some were at their widest point around 90 degrees after closing the valve. I guess this must be further evidence of camshaft wear. Has anybody else found this? Not to be deterred I worked on the assumption that the widest gap would be the reading I would take regardless of the actual position of the cam once it closed the valve. I had to replace 3 of the shims on the inlet side and one of the shims on the exhaust side to get them into spec. Luckily I had the necessary shims from engine A. I then cleaned the mating surfaces and re-fitted the cam cover without a gasket as a temporary measure. I then fitted the carb rack from engine A and refilled the engine with some of the sieved oil. There was about a pint and a half left over with the oil level three quarters of the way up the sight glass which meant the engine had been overfilled in the first place. The oil looked good and didn't smell of fuel so I don't think it had been contaminated, just overfilled. After an auxiliary fresh fuel supply was rigged up the engine started immediately with minimal choke. Have a look at the video in next post.

 

Engine B Running

 

Engine B sliding out of the frame.

 

Engine B out of the frame

 

Engine B on the bench

 

I probably should have stripped the bottom half of the engine as well as just the top half. I think it's more than likely that some foreign matter had got into engine A at some point despite being as careful as possible to prevent this happening. I don't suppose I'll ever know for sure if it was residual blast media or something else such as particles of dirt/paint/metal/gasket. Also having not inspected the bottom half of the engine I don't really know what condition it was in in the first place. I did find a chunk of the lower engine casing just in front of the L/H side cover had been ground away in a crash and had been 'repaired' with filler by the previous owner. Good luck with your polishing, painting and powder coating.

 

Yes, thanks, it was a big disappointment, still, onwards and upwards!

 

Debris found in oil pump strainer from engine B

 

Wowch! that's not nice, still I suppose rather find it in the strainer than in the cam journals...

Speaking of which, the wear on the failed engine did look very like blast media damage, very uniform scratches all the way across the journals and I couldn't see evidence of alloy "pickup" or heat bluing that would suggest lack of oil at all. I suppose if you really wanted to find out, you could dissect the oil filter/reverse flush it through some coffe filter paper & see what's there. If it's blast media there's likely to be a lot of it accumulated in the filter too. Such Is life I guess, at least you've got the right attitude & getting on with the job in hand. Best of luck with the "new" engine. Bike looks good IMO

 

Thanks for the supportive words.
Today I have had chance to look a little further at engine A. I've had the oil pump out and had a close look in the sump. I am almost certain the camshaft damage was secondary because it's very evident that number 2 big end has failed big time. The others are all ok in comparison. There are masses of white bearing debris in the sump and, of course, lots of fine particles, some of which may have been blast media but it would be impossible to identify it as such. The finger nail clipping size flakes of white metal were easily the most obvious and must be the remains of number two big end bearing. This, of course, doesn't exclude the possibility of blast media contributing to the engine failure but now that I've heard engine B running I am not so sure that engine A ever sounded very healthy. One thing for sure is there must have been a massive reduction in oil pressure to the top of the engine given the damage to number 2 big end. It would have been gushing oil out through the gap. I don't think I will ever know for sure but I am a little nervous about taking the head off engine B, but I would like to de-coke it, lap the valves and fit new valve stem seals.

 

There's nothing to be scared of re. taking the head off your "new" engine just make sure you follow the correct procedure/order for loosening the nuts, "safety cord" the camchain so it doesn't run off & hide down the bottom of the tunnel & be careful not to lever and gouge the head surface or damage the fins if it won't lift off easily.

 

After what happened to the first one I think I might just clean it up, paint it and fit it. I did everything meticulously the first time spending many hours and look what happened. You're right though, there's nothing to be scared of.

 

Well yes, I think I might be put off slightly by the experience. I'm 99% the motor was killed by abrasives though so as long as you didn't get any blast media near this it'd be fine.

That said, I suppose there's no real need to pull the head anyway if it was running OK. Engines don't seem to get as coked up with modern fuels & oils & if the compressions good then the valves are likely to be sealing OK. I have heard of people changing stem seals with the head on both by using compressed air to hold the valves shut & by feeding a coil of soft rope through the plug hole & blocking it between piston & valves but to be honest if they really needed doing it'd be a safer bet to remove the head.

If it was mine and compression was good & it didn't smoke, I'd probably leave it at setting the valve clearances & changing the oil/filter for now. Hope to see her back on the road soon whatever you end up doing.