[Paul W]

My 350 Bullet Electra IB engine likes to rev since I’ve tweaked it a little. The top end is now limited by valve bounce so I have learned to be careful with it, especially since it now has a Meteor Minor domed piston.

Hitchcock’s produce a “lightweight” valve kit for the 350 engine (#200130) so that would be the next logical step if I wanted to spend almost £200 for one.

Has anyone here fitted this kit? If so, is it worth the expense?

[stinkwheel]

I had one snap through the weld on my 350 iron barrel and drop the valve head into the combustion chamber.

I suspect it was due to slight flexing of the valve against a lump of carbon on the valve seat. Difficult to tell because everything was hammered to death but there was definate blue-ing on the snapped end of the valve stem suggesting a fatigue fracture.





A LOT of elbow grease later and i was in a position to get the valve seat re-cut and fit a new one (which has been fine).:

[stinkwheel]

Realised i didn't answer your initial question. It runs fine. I don't think mine is in a sufficiently high state of tune to notice much difference (I also have a meteor minor piston) and I'm trialing that bike now so it's not really about revs. It does pick up off the throttle very smartly though. Fitting lightweight rockers probably made the most difference to the top-end which probably wont come as much of a surprise to anyone whose seen the original iron barrel ones. I fitted them because my original head lunched itself (dropped the valve seat) and I decided to splurge on the complete tuned head.

They should allow more valve opening before becoming coilbound if you wanted to start playing with cams some time down the road.

[Paul W]

Thanks for the reply. Very worrying to see the damage from what is supposed to be an improved part!

The rocker arms on mine looked like they were made by Fred Flintstone in the early Iron Age but I’ve reduced their weight using grinding wheels, files and abrasive cloth and they now look like the Samrat ones.

I doubt I’ll be going down the modified cams route; all I’m trying to do is get the best top end performance out of what I’ve already got.

[ace.cafe]

Just make sure that they are stainless steel one piece valves and you should be fine. 350 valves are already small and lighter than the 500 valves.
If you are concerned about valve control, get the improved valve spring kit.

[Paul W]

Just make sure that they are stainless steel one piece valves and you should be fine. 350 valves are already small and lighter than the 500 valves.
If you are concerned about valve control, get the improved valve spring kit.

Ace, thanks for your input. My bike is a 350 and some time ago I fitted a H’s stainless exhaust valve, rather than the original Indian factory one it came with (which was damaged, as was the valve seat).

I’m interested in the practical benefits of the complete competition valve kit that H’s sell, including bronze guides, valves with slimmer stems, springs with ally spring keepers etc.

The improved valve springs also offered (#VS420) are stated as not being the same as the type included in that kit. They might do the job for far less money, especially bearing in mind, as you say, that they are also recommended for the heavier 500 valves.

[ace.cafe]

Ace, thanks for your input. My bike is a 350 and some time ago I fitted a H’s stainless exhaust valve, rather than the original Indian factory one it came with (which was damaged, as was the valve seat).

I’m interested in the practical benefits of the complete competition valve kit that H’s sell, including bronze guides, valves with slimmer stems, springs with ally spring keepers etc.

The improved valve springs also offered (#VS420) are stated as not being the same as the type included in that kit. They might do the job for far less money, especially bearing in mind, as you say, that they are also recommended for the heavier 500 valves.

Stock valve gear is expected to be okay up to about 5300-5400 rpm in normal operating conditions.

The key factors for revving higher reliably are one piece stainless valves and stronger springs. How deep you need to get into it depends on how high you want to rev.

The standard Enfield valve train design is quaint and antique, so if you prefer a more modern valve train gear in the head, the whole "competition" package is certainly a convenient way to get that. We used our version of such a package in our Ace heads.

If you want to stay on a budget and might be happy with a 6000 rpm redline or thereabouts, I think just the springs alone and one piece stainless valves would do.

[Paul W]

My engine is certainly capable of a fair bit higher than stock rpm and I do sometimes go there, hence this question being asked. Bearing in mind it still has the standard bottom end I may just go for the stronger springs and H’s ally spring caps and see how it gets on.

Especially seeing the damage photos above!

[stinkwheel]

Don't get me wrong, I'm pretty sure something was making that valve flex in use. Perhaps it was slightly bent or perhaps there was something obstructing it meeting the valve seat square. However, it did happen.

What was interesting was working out what the hell had happened because I was riding along at a steady 60mph on the flat and it just lost power like someone had pulled the decompressor. Tried to restart it and had no compression. My first thought was a tappet had tightened up and sure enough, when I checked the tappet was tight. Only it was still tight when I'd backed the adjuster off all the way. Then I checked the plug and it had aluminium swaft all over it which is when I called for recovery. As dropped valves go, I got away fairly lightly.

[AzCal Retred]

These pushrods are stronger and reduce reciprocating mass. Less mass will directly affect the stresses on the springs by lowering the net forces being resolved. If ACE recommends stronger springs and stainless valves, that's the way to go. Better pushrods can't hurt.

https://accessories.hitchcocksmotorcycles.com/11404?cont_page=accessory-shop/crankcase&page=2
PART No. 90131; PUSHROD SET (350cc), ALL ALLOY INC. ADJUSTERS (2 RODS); £105.00
This is an all-alloy pushrod suitable for 350cc Bullets. They offer a weight saving of nearly 50% over the standard rods. All-alloy pushrods have been available for decades but the specification on these rods is vastly improved to give better strength and durability. They are produced in the USA from 6064-T6 aluminium for the tube and the tops are 7075-T651 aluminium. The adjusters are a massive 3/8" diameter with a fine thread for precise adjustment with no risk of breaking. SOLD IN PAIRS

[Paul W]

AzCal, thanks.

At the end of the day I’m not after a racing engine so I think the best way forward at least expense is the uprated springs and ally valve caps.

Since fitting the stainless exhaust valve some five years / 19,000 miles ago I’ve never had any trouble with it and the tappet clearances never need adjusting. With the OE factory one the clearance closed up completely every 50-100 miles.

[ace.cafe]

AzCal, thanks.

At the end of the day I’m not after a racing engine so I think the best way forward at least expense is the uprated springs and ally valve caps.

Since fitting the stainless exhaust valve some five years / 19,000 miles ago I’ve never had any trouble with it and the tappet clearances never need adjusting. With the OE factory one the clearance closed up completely every 50-100 miles.

Alloy upper valve spring retainers will save a significant amount of moving mass in that system.

[Paul W]

I think that’s the best compromise for this bike. I can’t imagine that I’ll want to rev the engine much more than I do already but occasionally I have briefly detected the onset of valve bounce just as I was about to change up a gear. 

[Guaire]

Just make sure that they are stainless steel one piece valves and you should be fine. 350 valves are already small and lighter than the 500 valves.
If you are concerned about valve control, get the improved valve spring kit.

ACE - His 350 valves don't cross over to the Iron Barrel and the UCE valves?

[Paul W]

I’m not sure what you mean. This IS an iron barrel engine.