Push rod fail

Out for a lively 30km or so Sunday ride around the island on the red 750 with the Maney engine, crank and FCRs. The bike loves to rev with this set up.

About 2kms from home the bike just stopped and would contemplate a restart. I’m used to Nortons quitting but the symptom this time was new and like nothing I’ve experienced before.

Got a tow home and went through the usual process of confirming spark, fuel and compression.

I thought I’d check valve gaps as part of the process. The outlet rocker arm was not moving at all.

Through the right valve cover, I spotted the outlet pushrod.

Pulled the head, and found that the right outlet pushrod had destroyed itself with the left one also out of shape.

I’ve been riding this bike pretty hard lately, so assume that is the cause.

I had not long ago service the bike including setting the valve gaps to 6" inlet and 8" outlet. The gaps on the other valves where in spec when I checked them recently, and now before I removed the head from the cylinders.

Non-OEM pushrods?

Check the rocker arm ball engagement to the recess in the pushrod, including at an angle as the push is not always perpendicular, on some pattern pushrods the recess is too deep and the rocker touches the top edge of the pushrod. If its done it on the exhaust then the inlet will be the same.

freefly103 said:

Out for a lively 30km or so Sunday ride around the island on the red 750 with the Maney engine, crank and FCRs. The bike loves to rev with this set up.

About 2kms from home the bike just stopped and would contemplate a restart. I’m used to Nortons quitting but the symptom this time was new and like nothing I’ve experienced before.

Got a tow home and went through the usual process of confirming spark, fuel and compression.

I thought I’d check valve gaps as part of the process. The outlet rocker arm was not moving at all.

Through the right valve cover, I spotted the outlet pushrod.

Pulled the head, and found that the right outlet pushrod had destroyed itself with the left one also out of shape.

I’ve been riding this bike pretty hard lately, so assume that is the cause.

I had not long ago service the bike including setting the valve gaps to 6" inlet and 8" outlet. The gaps on the other valves where in spec when I checked them recently, and now before I removed the head from the cylinders.

Click to expand...

Nasty - what brand pushrods?

Check the oil hole orientation in the rocker ball end. If it's turned the wrong way no oil will get through to lube the pushrod end. I made that mistake once, similar result

The 2nd one is ready to soil the sheets as well......

A quick look at the underside of the rocker arm will show contact hits? Leo Geoff told me stock pushrods are the things to use.

Why use 0.006" and 0.008" as clearance? The 0.006" and 0.008" is OK with a standard set up, but it isn't correct for pretty much any non-standard cam, with standard aluminium pushrods and iron barrels.

Do you know the full spec for this engine?

Maney specifies different valve clearances depending on which parts are in use. If you have his just his steel pushrods, he recommends you halve the valve clearance, if you also have his alloy barrels he recommends you close it to 0. Yes, 0, because the alloy barrels expand a lot more than cast iron ones.

Maney's cam is close to a 3S Norton cam, I'm not sure of specs, but with standard pushrods and iron barrels you would use around 0.011" inlet and exhaust. (This is the figure for the 4S and PW3 with standard pushrods, followers and iron barrel.)

If you just have his pushrods and his cam then set both at 0.0055", not the 0.011" in the cam spec. Typically, I would round that to 0.006" inlet and exhaust. So your figure may be OK.

But not if you have Steve Maney alloy barrels, because it will be opening up a lot when the barrels get warm.

You are going to have to measure the length of the pushrods in any case, typically with a performance cam and skimmed head Steve would supply pushrods 0.090" shorter than standard.

Carl H said:

A quick look at the underside of the rocker arm will show contact hits? Leo Geoff told me stock pushrods are the things to use.

Click to expand...

There is very little wrong with standard pushrods if they are of the correct length for the motor!

Steve Maney supplied his push rods in any length you require, which will vary based on the milling of the head face!

kommando said:

Check the rocker arm ball engagement to the recess in the pushrod, including at an angle as the push is not always perpendicular, on some pattern pushrods the recess is too deep and the rocker touches the top edge of the pushrod. If its done it on the exhaust then the inlet will be the same.

Click to expand...

He says it's a Maney engine and these look like Maney pushrods, which are very good quality chromoly steel.

SteveA said:

Maney specifies different valve clearances depending on which parts are in use. If you have his just his steel pushrods, he recommends you halve the valve clearance, if you also have his alloy barrels he recommends you close it to 0. Yes, 0, because the alloy barrels expand a lot more than cast iron ones.

Click to expand...

This is a very good point. I always wondered why Norton kept the same clearances when they changed from steel to aluminium alloy pushrods , but I never bothered to investigate. I shall now do so and report in a new thread.

hybridracer said:

This is a very good point. I always wondered why Norton kept the same clearances when they changed from steel to aluminium alloy pushrods , but I never bothered to investigate. I shall now do so and report in a new thread.

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Interesting question. When did Norton make the change? I know all the Commandos had aluminum push rods, but I'm not so familiar with earlier models.

Ken

Yep, they are Maney pushrods. Steve built the engine circa 2016 for me. I hadn't put many miles on the bike until recently when I changed the bars and seat for a more comfortable ride. Since doing that, it's become my daily rider, and have been enjoying the engine set up, particularly how it builds power above 4,000 rpm.

Hybridracer, you are correct. I recall now that Steve specified a much smaller valve clearance for the set up I have i.e. zero gap. I think I must have forgotten about the specs over the years and resorted to the standard clearance settings. My bad.

Steve also refurb'd a Combat head for me with 3mm oversize inlet valves. That head has been sitting in my garage for years so maybe now is a good time to install it. I've reached out to Steve for some advice so will post again with how I plan to go forward from here.

Expensive lesson learned.

Unfortunately, I have a large number of expensive lessons chalked up. You are not alone.

Andy Molnar said he's glad he doesn't have time to get on the internet when I asked him if I should reduce the tappet clearance from spec for his alloy barrels and a set of alloy pushrods with a performance cam. I'm just the messenger. Yeah I know different parts but maybe his mindset is like that of Norton since they did not reduce the tappet clearances for alloy pushrods

Any suggestions for Combat head, stock barrels, std (not-Combat) cam, and Maney titanium pushrods?

freefly103 said:

Yep, they are Maney pushrods. Steve built the engine circa 2016 for me. I hadn't put many miles on the bike until recently when I changed the bars and seat for a more comfortable ride. Since doing that, it's become my daily rider, and have been enjoying the engine set up, particularly how it builds power above 4,000 rpm.

Hybridracer, you are correct. I recall now that Steve specified a much smaller valve clearance for the set up I have i.e. zero gap. I think I must have forgotten about the specs over the years and resorted to the standard clearance settings. My bad.

Steve also refurb'd a Combat head for me with 3mm oversize inlet valves. That head has been sitting in my garage for years so maybe now is a good time to install it. I've reached out to Steve for some advice so will post again with how I plan to go forward from here.

Expensive lesson learned.

Click to expand...

Hmmm? I went and typed all that stuff about Steve Maney kit for you and it's Hybridracer who is correct?

Carl H said:

A quick look at the underside of the rocker arm will show contact hits? Leo Geoff told me stock pushrods are the things to use.

Click to expand...

Unless you have a combat Or other shaved head.

ILLF8ED said:

Unless you have a combat Or other shaved head.

Click to expand...

I use stock length in my bikes, but I remove the ball end and thin the underside of the rocker arm by whatever I need and reinsert it. You save a whisker of weight that way. And it saves screwing up good push rods.

I think everybody is correct.

Just for fun I did an experiment to test the alloy barrel alloy pushrod expansion theory. I went for a short ride in 80F degree weather and ran mostly in 2nd gear under 40 miles per hour in traffic. Purpose was to get the motor hot. When I returned from the ride, I removed the exhaust rocker covers and adjusted the timing side tappet clearance to .006 when hot. I then let the motor cool for 3 hours and checked that clearance again. It was .0021. So yeah the deck height increases when the valves, alloy push rods and alloy barrels are hot and recedes when cooled. I've been setting the tappet clearance all the way around at .008 cold.

I don't worry about it much even with JSM pushrods, which are similar to what Maney is/was selling, but my rockers are all reshaped to accommodate slightly aggressive geometry and lighten them up a little.

Below is a quote from the notes that come with the JSM JS2 smooth ramp cam. Different parts, different approach. It is relevant to the heat expansion discussion IMO.

"Use .006" intake and exhaust tappet hot running clearance (.008" on SJ3 cams). Then measure when cold and keep records so you can check them when cold."

Will I start setting my tappet clearances at .0021? Probably not, but I might try .005 and see if I break anything.

Interesting post albeit an unfortunate lesson for the OP.