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[Al Crusader]

Following fitting a new Mikcarb and having overhauled the ignition system ( to fix bad staring from cold problem) the 350 bullet was flying it. Going like a bullet in fact. Seduced by this performance and frustrated by the lock down I admit to giving the old girl a lot of ungentlemanly full throttle, just to see how how far the needle would swing to the right. Bullet and rider were happy until we got home and I noticed a lot more tapping coming from the cam followers. Inspection in the morning was the same, and the bullet refused to start. Compression was down and it barely fired once. Tappet settings perfect, no bent push rods or such like obvious stuff, so I took the head off. Without the pressure of valve springs the tappets were silent, of course. Exhaust valve pretty badly coked but intact. Inlet not so hot either so time for all that business . I took the barrel off while at it to check piston and bore. Both perfect.
Question one: Any ideas for the cam noise--a distinct "clack, clack" as the cam meets the follower and rides over the hump.
Question two: How much side play on the con rod/big end floating bush is right. I can detect nil up and down movement on the big end by grabbing the rod and tugging up and down. The small end of the con rod "appears" to rock from side to side in conjunction with the visible side play at the crank end. But no up and down movement.
The bottom end was rebuilt 5000 miles ago .
It is a 1990 350 bullet, Indian home market model.
I have checked the oil flow everywhere, and is good.
I can deal with the head overhaul etc but not with the head paranoia!!!

[stinkwheel]

I ring my 350s neck everywhere it goes, no need to appologise for doing so.

Have you checked the piston rings are free to rotate in the lands? Enthusiastic riding can cause crowns to collapse and grip the rings.

I've had a 350 head drop the exhaust valve seat. you wouldn't see that until you took the valve out and bashed it on the tabletop because the spring would be holding it up.

Cam noise is probably just backlash. Which you can put up with or fit adjustable cam spindles. May be worth checking the end-float too?

My understanding is lateral play on a big end is no big deal providing there is no vertical play. In fairness, I'd expect a white metal floating bush to either be totally OK or completely FUBAR. There wont be much of an intermediate stage, it is either floating on oil and therefore fine or it is touching metal and destroying itself.

[Al Crusader]

thank you stinkwell. all good stuff. I will work on it and let you know.

[stinkwheel]

Another thing worth considering is if it was running unexpectedly well, the ignition might be too far advanced? Which would also make it a PITA to start.

[vince]

Check if there is any play in the cam followers. Vince

[Al Crusader]

Couple of things Stinkwell... if it is too far advanced, wouldn't that give a lot of kick-back when starting....?

I am intrigued by the eccentric cam spindle deal. Not heard of these critters before. looked them up on our hosts window and read the pdf fitting instructions but still don't get it. I suppose unless actually doing the job doesn't make sense.
Can you explain in what circumstances they would be needed, and how and where they actually fit and work?

Secondly, regarding the exhaust valve seating possibly dropping, I can get a finger nail against he edge of it proud of the the combustion chamber. Will give it good thump today and see if it moves any more. If it does come lose and drop, then re-fitted, pressed in presumably, what stops it dropping out again.
Despite my many years living and working on this Bullet i am amazed how much is still possible to learn about a basically simple design engine. It is this simplicity and tradition that makes them maddeningly attractive!
Thanks for your ideas. Hope you can enlighten me a tad more, Al

[stinkwheel]

Yes, would usually kick back if too far advanced, just a thought was all.

There are a lot of youtube videos on cam backlash showing the eccentric spindles and how they work, mostly in India where I presume some of the models came with them as standard.

Basically, standard ones are just a straight pin located centrally in the hole in the crankcase, no adjustment. The eccentric ones don't land up exactly centered in the middle of the hole they fit in and have a locknut that allows them to be loosened and rotated. If you rotate them it will very slightly move the position of the exhaust cam gear in relation to the timing pinnion and the inlet cam in relation to the exhaust cam. So if there is any play in that system, it is taken up.

It's not necessarily an issue or THE issue but it is a known cause of a rattling noises coming from the timing chest on bullets.

This guy seems to explain it pretty well and demos it on the bike.
https://youtu.be/TIL-fTzpqHU

The main question I'd ask is is this actually a problem that needs to be solved or simply a feature of the bike? I don't know the answer to that one. Maybe one for Bullet Whisperer?

If the valve seat is loose, it would probably need a new, slightly oversize valve seat fitting and re-cutting to suit the valve. It's esoteric work. My local light engineering guy does such things and I remember him showing me his set of tools for cutting valve seats and the recess they sit into. It was in a mahogany box and looks like it came from the 1930's (I suspect it actually did). He also had a huge box of randomly assorted valve seat blanks because he said he's got into the habit of ordering a spare one every time he orders a set. As such, he can usually find a slight oversize if one is needed.

My head was not the best, he's fitted a seat but the alloy under it was in a very bad state of repair, a combination of a casting flaw and chronic gas leakage round the old seat.

Again, this is probably not the issue but is easy to check if he bike is dismantled this far. It could also cause an intermittant near total loss of compression. When it happened on mine, I started getting a lot of popping and banging on the overrun. I didn't realise it was a problem until I'd taken the valves out to re-lap them and put the head down on the table with the valves out. I heard a "dink" noise and when I picked the head up, there was a metal ring sitting on the table. It took me a while to work out what it was.

[Al Crusader]

All is now clear. The power of video, tells a thousand words. So thank you again for sharing your experience and knowledge. I agree, this is not THE problem, only one of many small ones that accumulate with these older designs. A bit like my growing older body with aches and pains in places I didn't know I had. Typical of the Indian mechanics to be so ingenious and improvising. Our hosts sell these alternative spindles, but not available is the little yoke needed to grip and extract the existing spindles.
I will sort every else first and get her running and see how we go. If it annoys me enough I might venture into experimenting with the anal job of eccentric spindles. Just to be able to pass it on to other users. But nearly all my Enfield mates have aspired to EFIs.
Good luck to yourself.

[stinkwheel]

A slide hammer with a jacobs chuck would probably make short work of removing the spindles if you needed to. Or welding a bolt (hex head down) to the end of them and winding them out with a nut and a bit of pipe. (destructively removing them isn't too much of an issue, what with them being a tenner each).

As I say, I'm not convinced there's an actual need to. I considered fitting a set of adjustable ones when I built my 612. It would have been very easy because the original ones were already removed to machine out the casings to accept the high performance cams. I decided that on balance, something that can be loosened and adjusted can also potentially loosen itself and go out of adjustment.

Excessive end-float on the cams could be another source of noise, something that's easily fixed by fitting inexpensive shims and presents an excuse to legitimately use plastiguage, something I'll admit I was unreasonably excited about.

[Adrian]

Don't waste your time with adjustable spindles. The end nuts can come loose while the engine is running, and there goes your careful adjustment at the very least. There's an example on the US forum at the moment. There's always going to be some clearance around the timing gears, and if you do manage to tighten it up between the cam gears you just put extra slop between them and the idler gears for the ignition.

I think the Electra-X was the first version of the Bullet to have them as standard, but my Electra-X hybrid engines have had SOLID cam spindles retro-fitted. Sod the rattle, it's one thing LESS to go wrong. Loud gears save clearances, or something!

If you really, absolutely INSIST on having them, remember to heat up the crankcase before trying to drag the old ones out or you risk destroying the interference fit, and while oversize plain spindles are a thing, I don't know if you can get oversize adjustables.

A.