Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet Electra & AVL => Topic started by: Adrian on March 18, 2013, 10:18:04 pm
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No, not the Great White Whale, how about an iron Bullet decompressor retro-fitted to a 500 AVL head? Not possible, so it had to be done.
Pictures first:
(http://img69.imageshack.us/img69/1451/dcv1.jpg) (http://imageshack.us/photo/my-images/69/dcv1.jpg/)
(http://img189.imageshack.us/img189/7834/dcv2.jpg) (http://imageshack.us/photo/my-images/189/dcv2.jpg/)
URL=http://imageshack.us/photo/my-images/209/dcv3.jpg/](http://img209.imageshack.us/img209/8158/dcv3.jpg)[/URL]
URL=http://imageshack.us/photo/my-images/836/dcv4.jpg/](http://img836.imageshack.us/img836/969/dcv4.jpg)[/URL]
Basically you drill and tap for a 14x1.25mm spark plug thread opposite the existing spark plug. Some of the finning between the rocker boxes has to go, but with a milling machine and some careful work (rather than my butchery of an innocent component) you could sacrifice a lot less. I am informed by a UK Bullet specialist that subsequent overheating should not be a problem here in NW Europe as the sheer size of the rocker boxes mean they conduct enough heat away already, not so sure if that holds good for the Southern States of the USA or India, though!
More details if anyone is interested.
Regards,
Adrian
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Oh, now that's cool! Thanks for sharing.
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Well, that should get the attention of the crowd at the local Drive In Restaurant if you use it to kill your engine.
Thump, thump, thump, thump, CHOOF, CHOOF, CHOOF. ;D
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Adrian, I was going to add the Iron Barrel decompressor to my AVL, then got curious as to whether or not the existing valve lifter could be utilized in some manner. I bought an Iron Barrel decompressor lever and hooked the AVL cable to it and it lifts the valve with ease. Is there a down side to that method?
Bob
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Glad to see some one take the plunge and make it happen.....AWESOME !!
There was an AVL twin spark produced for the domestic Indian market so we knew adding a I.B. de-comp was do-able but till now no one I know of had actually done it.
Congrats !
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Looks like a clean job, Adrian.
Should work great.
Thanks for the nice pics too!
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Great job- that's an awesome setup and execution! I'd love to do the same on my uce. Where did you get the parts?
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Standard de comp valve for an Iron Barrel engine. ;)
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Yet another awesomeness!
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Thanks for the encouraging comments, folks. It's a good job those pictures aren't TOO detailed...
If nothing else it has persuaded me to buy a bench drill after I messed up the pilot hole for the 14mm thread, fortunately it all cleaned up OK with an insert kit :-[ You also need a 7/8" drill to counterbore the hole to get the bottom of the decomp valve at the right height (depth?).
The whole point of this was since my AVL project is K/S only and Bullet Whisperer did a good job with the valves, starting could be easier. The original AVL valve lifter also cannot be used with the "S" cams. The only downside apart from extra maintenance is the loss of cooling fins to the head, which can be minimized by careful use of a vertical milling machine. You'd have to decide if it was an acceptable risk or not for your local riding conditions.
Regards,
Adrian
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I still wish the UCEs had the manual decompressor. Would've been so much fun. Not sure if the same thing is possible on a UCE. Drill, manual decomp in. Auto out. :o
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It should be easier with the uce because there's already a spot for one in the casting on the head on the right side. I will probably get a machinist to do it tho- I don't trust myself to get the hole straight.
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It should be easier with the uce because there's already a spot for one in the casting on the head on the right side. I will probably get a machinist to do it tho- I don't trust myself to get the hole straight.
There are easier ways to do a decompressor on the UCE.
A properly located Harley-style decomp is able to be installed unobtrusively, and we have done this with several Iron Barrel heads which were converted to twin-plug ignition.
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Where does the harley style decompresser go? I thought about one of those but the well for the "second spark plug" (for lack of a better description) looks too deep to get your fingers in to reach the release button.
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Will wonders never seize? :o
I always figured Hardly just "holed" their piston to release its compression.
Who knew they might have a device to accomplish the task? :D
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Where does the harley style decompresser go? I thought about one of those but the well for the "second spark plug" (for lack of a better description) looks too deep to get your fingers in to reach the release button.
You have to machine a place for it, just like Adrian did.
The advantage of the Harley-style decompressor is that it is much smaller, and needs a much smaller amount of machining. These decompressors I refer to are aftermarket items, and are installed on various brands of engines, so they are not only Harley decompressors, but they are often seen on high compression modified Harleys. Also seen on chainsaws.
The threaded part is usually about 10mm diameter. Quite compact.
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSOhdlEUk0WJZxf2NlDSxm3QL3D9ZIzGYHV4M5uD72hT4F81loq)
The Iron Barrel decompressor works just as well, and the concept is the same, but there are smaller options, and that is all I was pointing out.
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Very cool, thanks!
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Many of them come from the same place.
http://www.karcoma.com/en/products/overview/valves/valves_description.php (http://www.karcoma.com/en/products/overview/valves/valves_description.php)