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[rmueller23]

My father and I purchased a 2002 Bullet 500 a couple months ago. It was not running at the time, and had been in storage for a couple years. The engine was hopped up to a 612cc by the original owner, but he had a significant failure. The gentleman we purchased the bike from purportedly had the engine rebuilt to a more standard displacement and configuration by Perry's Sidecars in Texas a year or two before it went in storage.

After cleaning the carb and re-timing I managed to get it running, only to discover it had no oil pressure. Further inspection revealed a failed oil pump spindle. I have since replaced the pump spindle, worm gear, failed distributor base gasket, oil and filter, and installed the filter packing piece and magnet from our hosts. After more tinkering with the Amal 932 I was able to get the bike idling well enough, and it ran sufficiently well to ride it around the block a few times. After it warmed up a bit the engine began making what I would describe as a hollow, metallic clanking sound when revved. No untoward noise at idle, only at higher RPM. I corrected a loose rear fuel tank fixing bolt, ensured the exhaust was secure, generally looked things over to make sure there wasn’t some external source for the noise, and I can’t find one. It sounded to me like it was cylinder/top end related, and to my ear sounds similar to examples of piston slap that I’ve heard on YouTube.

I pulled the head, cylinder, and piston. The engine has eaten some metal per that pump spindle gear failure. I’ve not disassembled and closely inspected the head and rocker arms yet, except for noting that the top half of the exhaust rocker arm bearing set looked like it’s picked up some metal on the race. The cylinder measures pretty close to 3.305” everywhere—front to rear, side to side, top-middle-bottom. The bottom of the piston skirt, 90 deg to the piston pin, measures at 3.302. This would seem to make piston slap an unlikely source of the noise, as my understanding of slap is that it would be the result of loose tolerances.

Here’s a shared gallery including some shots of the cylinder and piston. The cylinder has vertical streaking from metallic debris, though only one or two spots barely catch a fingernail—I would think overall it should just hone out. The piston picked up more damage, and I’d like to seek opinions on that—do you think that could be cleaned up and returned to service, or would be it be prudent to replace it?

https://photos.app.goo.gl/EKW1x8NBAuQe34Xe8

I’m at a loss as to the source of the noise at this point, though I still have to disassemble the cylinder head and check the valves. I wiggled the small end of the connecting rod while referencing a rule, it appears to have about 1/16” play—Snidal’s manual says 3/16” is the limit. It doesn’t seem to have any noticeable “in and out” play. I’m hoping we’re not looking at having to split the case halves, and it ends up being a top end issue….suggestions appreciated. Thanks,
-Ryan

[simon]

I had a similarly frustrating noise with my 350 and it turned out to be the worm drive slipping on the oil pump drive spindle. It seems to happen most when the motor is partially warm. If this is the case with yours then there are a number of potential cures. 1. Use a lighter grade of oil (I was running straight 50 and changed to 20/50) 2. Make sure you have the lighter grade springs hold the pump rotors against the body. There is no oil pressure relief valve in the Indian made motors so lighter springs allow the pumps to lift off the body and hence lower the pressure. 3. Check that the worm is in good condition. If the spindle stripped and you only replaced it and not the worm it might be only partially engaged. Goodness knows why they did away with the pressure relief valve on the Madras motors as the one in the Redditch motors was very simple and effective but they did andmwith a plain big end bearing the pressure can get too high quickly.

[vince]

Hi, how are you measuring the small end play? 1/16inch seems excessive. Vince

[rmueller23]

HI SIMON: The worm gear and spindle were both replaced. I am running 20W-50 motorcycle oil. The noise seemed plenty loud and and direct when I leaned over to the left side of the engine, so I doubt it was coming from the right side only. Thanks

HI VINCE: I laid a rule against one of the cylinder studs and held it at the level of the top of the small end of the rod. I deflected the small end fully in one direction, adjusted the rule so it was at an inch marking, and deflected it fully in the opposite direction. This measured close to 1/16" of travel. Per the Snidal manual, "A small amount of side play at the small end is normal; 3/16", or 4.5-5mm is acceptable." I tried to move the rod up and down along it's vertical axis, and cannot detect any play in that regard.

[Adrian]

A slack primary chain will cause a lot of clatter. A.

[simon]

So not this noise then? https://m.youtube.com/watch?v=EOC1a3zPQ ... e=youtu.be

[another Allan]

Hello Ryan.

Your side-to-side measurement of 1/16" at the small end eye is actually referred to as sideplay in the big-end because it is clearance in the big-end bearing which allows this movement.

You mention that the engine was reduced in capacity from 612cc. Is the crankshaft now a standard 500 cc one with a floating plain bush bearing, or what do you have? The answer to this can have a bearing (sorry!) on how much sideplay at the small end is ok.

[rmueller23]

simon: Not like that noise, no. It sounded more along the lines of the noise in this video, however it didn't occur all the time as it did for this gentleman. With ours the noise was not there at idle--as you can hear from the sound in the video from my shared gallery link in the previous post. It would present itself when revved to a higher RPM while stationary, or at a sustained elevated RPM while under way. To my ear it had the same hollow, metallic clanking noise as demonstrated in the video. The noise is consistent and continuous at elevated RPM, until it drops down to idle and the noise would go away.

https://www.youtube.com/watch?v=meTYSCaXyM0

[rmueller23]

another Allan: Thanks for clarifying the terminology. Unfortunately I do not have the particulars on the rebuild work, I just had the basic information from the seller. I've reached out to the shop that did the work--formerly Perry's Sidecars--but Perry has since passed and it is under new ownership. So far they haven't located their records.