Forum

[dre22]

I am restoring (or rather, resuscitating!) a 1987 350 Bullet that I picked up a few months ago. There's a temptation to add or replace all manner of parts, but I'm challenging myself to keep costs down without sacrificing longevity and reliability.
The Bullet stacked up 12k km before being stored for 9 years then sold to me, & I don't think it was de-coked once in its lifetime. So it's a full rebuild for the head, amongst many other things.

There were some rubber valve guide seals that fell apart as soon as I moved them from the old valves. My kneejerk reaction was to find replacements immediately, but it seems to me they may not be essential.

So my question is: what experience/opinions do other Enfield owners have regarding valve guide seals? Are they beneficial, or is it just nice to know they're fitted? I know a fiver each isn't much, but it's a tenner or so that can potentially go towards other parts instead.

Thanks all.

[Bullet Whisperer]

None of my Bullets have them and they don't use oil. I removed the valve guide seals from a 350 I tuned recently - one of them had come off the top of the guide anyway. You can have pretty worn guides on a Bullet and not use much oil. Piston rings are a different matter, though. I would say that you don't need them.

[Les H]

Most classic bike engines do not have oil seals on the valve guide as standard and the Bullet engine didn't either. However, the Bullet engine oiled its rockers after limiting the flow to them with a pressure relief valve. As the Indian models don't have the relief valve, the entire oil flow ends up in the head, and double that if Hi-cap pumps have been fitted. I found that even with oil seals fitted quite a bit of carbon builds up on the back of the inlet valave, so perhaps you should check on your own inlet valve how much carbon has built up after 12K Km. This will be the best indication if your engine requires them or not. As a POI the inlet valve is really the only one that is likely to suck in excessive amounts of oil, the exhaust guide is mainly under pressure and could benefit from having some oil along the very hot valve stem anyway. Having said that, it is not unknown that some engines with a large amount of oil flow to the head can sometimes carbon up the exhaust valve stem which can cause it to stick open, sometimes with nasty consequences!...... It seems many owners including myself find fitting the guides extremely difficult, I'm not sure if the old cast iron guides allow easier fitment. Remember that oil seals are not a cure for worn valve guides, which might need replacing anyway.

[Bullet Whisperer]

That should be taken as you don't need the valve guide seals, of course you need piston rings !

[Alan R]

Hello there dre22}------During last winter overhaul of No1 bike, I tried to get our hosts guide seals to fit onto the new bronze guides that I'd just fitted. For various reasons they didn't go on so my bike has been on the road this year WITHOUT seals and, so far ( approx 650 miles of club riding--- ) all is well. It does use a small amount of oil ---1/4" off the dipstick in approx 200 miles) but I can live with that. My intention was to have a seal on the inlet stem only, for the same reasons that LES H has indicated ie the high vacuum created within the inlet tract on the over-run with the throttle shut. My No2 bike does that in a BIG WAY and especially when stopped at traffic light on idling. However it still returns the same sort of oil consumption on a run----recently from Farnborough(Hants.) to Telford (Shrops.)------as No1 bike does. So that will be getting a top-overhaul and a seal on the inlet only. Remember that the HOTTEST part on your engine is that very area around the exhaust valve stem / guide nose, and it's not receiving a particularly positive means of lubrication. That's why I don't fit a seal on the Exhaust stem at all. Hope that's of some help ???

[Midge]

There is a very interesting interview with R.A. Wilson-Jones the then technical manager of the original 500 Bullet engine at http://www.royal-enfield.net/articles/articles.html which I think many here will enjoy reading. I am sure that the quality of manufacturing and materials used in the Indian Bullets are not as good as was originally intended even though the engines look practically identical. Have a read and see what you think.

[Les H]

Hi Midge. I had read this sometime earlier and it is very interesting. I read through it again. it was interesting to read that the over oiling of the exhaust guide can coke up the valve as I had said. The big end he compares to a cheap crowded roller type but admits a caged roller bearing is as good (read better?) The sintered iron rocker blocks he mentions...I wonder if the Indian ones are sintered iron or are they cast iron? he makes an interesting point that alloy ones will expand more when hot and create more noise! ...so I wonder if the Samrat rocker spindles fit the old iron blocks? Certainly the Indian heads are nowhere near the port finish of the originals which explains the reduced power in comparison, and there has always been a question mark over the valve timing compared to the Redditch model.

[Riggers]

In the 1970s I was the proud owner of two new Triumphs - a 500cc Tiger 100, and a 650cc Trophy Sports. As was the norm in those days these bikes were not fitted with valve guide seals. Interestingly, Triumph seemed happy to accept that oil would find its way into the cylinder because in the owner's manual they recommended snapping shut the throttle now and again to draw oil down into the barrel. Can you imagine doing that today on the crowded M1!!!

[dre22]

Thanks all for your input. Great advice, & I reckon I can live without the guide seals. The tenner I'm saving can go towards a disc brake conversion (the single lead brake on my Bullet scares the crap out of me!) . The carbon build-up on my cylinder head was HUGE; clearly through lack of proper maintenance over the years... & I suspect some ill-judged tinkering too. Fascinating comments by everyone & the Wilson-Jones article has left me a little jealous of English Bullet engineering over Indian, but ultimately reassured by how much intelligence and forethought went into the Bullet design.