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Author Topic: Harris Scrambler gets 'S' cams  (Read 2493 times)

Bill Harris

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Harris Scrambler gets 'S' cams
« on: March 27, 2013, 07:56:38 PM »
Installed 'S' cams into the Harris Scrambler.  The head is stock and as with many stock AVL heads the valve seats are not flush with the combustion chamber.  I had intake valve to piston interference because of the seat not being flush.  To remedy this without machining the seat flush, I timed the exhaust cam to the timing marks and the intake cam one gear tooth retarded.  The bike runs very good.  I'm getting more RPMs out of the engine, don't know just how many, I don't have a tachometer, but I can make 75 mph in forth gear and 80 mph in fifth with the cycle as you see it.  Not only am I able to get more RPMs and a little more top speed, I also have very good low speed throttle response.  The only performance modifications to the engine are:  'S' cams, 30mm PWK flat-slide carburetor with K&N pancake air filter, and a free flowing, upswept exhaust with the Indian made classic short silencer.  The bike is also running stock gearing with a 18" rear wheel.  I'm very pleased.             
« Last Edit: April 16, 2013, 10:42:32 AM by Bill Harris »

Ice

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Re: Harris Scrambler gets 'S' cams
« Reply #1 on: March 27, 2013, 08:23:06 PM »
Oh great...........
Keeping up with him was tough enough before......now I need some ACME rockets.

I can break it better,,,,at night, in the rain, on the trail,, 20 miles from nowhere.

REA #136

"TIMEX", the '06 Iron Barrel Military...it takes me everywhere I want to go... and some places I shouldn't.

boggy

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Re: Harris Scrambler gets 'S' cams
« Reply #2 on: March 27, 2013, 08:27:38 PM »
Wow Bill, that is some noticeable power... really good to hear.  Sounds like 70-75 mph in 5th will be a bit more relaxed.  You went back to the stock TCi, correct?

The Harris Scrambler looks good as always.
« Last Edit: March 29, 2013, 10:44:32 AM by boggy »
2007 AVL
2006 DRZ400SM

Bullet Whisperer

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Re: Harris Scrambler gets 'S' cams
« Reply #3 on: March 28, 2013, 04:58:46 AM »
Thanks for sharing that, Bill. I am glad it worked out ok. So far as I know, all the other 'S' cam modified AVL machines ran ok 'on the dots', but retarding the inlet cam one tooth to avoid the piston isn't as drastic as the numbers [degrees] would have you believe. It will also take you further away from any likelihood of pinking [pinging] and aid top end performance a little, too.
 Good news indeed and I hope you continue to enjoy your machine !
 B.W.

ace.cafe

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Re: Harris Scrambler gets 'S' cams
« Reply #4 on: March 28, 2013, 06:49:18 AM »
Congratulations on another nice mod to your Harris Scrambler, Bill.
I'm glad you like it.
Bullet Whisperer has done all the leading research for this stuff, and he's really at the top of it.
« Last Edit: March 28, 2013, 06:51:46 AM by ace.cafe »
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Adrian

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Re: Harris Scrambler gets 'S' cams
« Reply #5 on: March 28, 2013, 07:50:38 AM »
Bill,

when you get those valve seats sorted, putting the timing back according to the stock timing marks will make you see exactly why you wanted those cams.  ;D   Lots more fun still to be had!

Regards,

A.

EnfieldJake

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Re: Harris Scrambler gets 'S' cams
« Reply #6 on: March 28, 2013, 10:01:44 AM »
Bill, glad to hear about your experience with the "S" cams. I just received my cams from BW as well. How did you go about checking for clearance? I have yet to turn my engine over as I'm waiting for my new pushrod adjusters to come in since I accidentally broke one during the install. Also, did you have to do any machining of your case or cover? I found that my cover would not fit with the "S" cams and I had to use a dremel with a grinding stone on the timing cover to get it to fit flush again. I probably removed around 3-4mm.

Bill Harris

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Re: Harris Scrambler gets 'S' cams
« Reply #7 on: March 28, 2013, 03:49:52 PM »
Bill, glad to hear about your experience with the "S" cams. I just received my cams from BW as well. How did you go about checking for clearance? I have yet to turn my engine over as I'm waiting for my new pushrod adjusters to come in since I accidentally broke one during the install. Also, did you have to do any machining of your case or cover? I found that my cover would not fit with the "S" cams and I had to use a dremel with a grinding stone on the timing cover to get it to fit flush again. I probably removed around 3-4mm.


Enfield Jack,

To check for valve to piston interference, take out the spark plug, put the transmission into neutral and turnover the engine very slowly by hand with the kickstarter.  If the engine sticks or just makes a metallic tapping sound from the head, you may have interference.  If this did not take place.  turnover the engine very fast by hand with the kickstarter.  If the engine just makes a metallic tapping sound from the head, you very well may have interference.  If the engine sticks, back off the pushrod adjusters, one at a time until you can turn the engine over freely.  Start with the intake adjuster first.  The intake valve is most likely the one with interference.  If either valve has interference with the piston, you can have the valve seats machined flush with the combustion chamber.  If you are not ready to do a valve job at this time you can probably get by with just retarding the intake valve and or advancing the exhaust one cam gear tooth.  To retard the intake valve, turn that cam one tooth counterclockwise from the mark.  To advance the exhaust valve, turn that cam one tooth counterclockwise from the two timing marks.  Recheck for valve to piston interference.  If no interference, you should be good to go.  As for the timing chest cover not fitting after installing the 'S' cams is a mystery to me.  My 'S' cams were .003 of an inch shorter than the stock cams from the outside to the inside at the spindle hole and the cam lobes had good clearance.  I just installed the 'S' cams using the same shims in the same place, one shim on the gear side of each cam, as was on my stock cams.  Everything fit and is working just fine.  With that said, every Royal Enfield is a little different.  I hope this helps.

Cheers,
Bill                   
« Last Edit: March 29, 2013, 09:10:47 PM by Bill Harris »

DanB

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Re: Harris Scrambler gets 'S' cams
« Reply #8 on: March 28, 2013, 11:02:40 PM »
thanks for sharing Bill and BW.  This is great stuff.  I kick myself for not finding a way to get those cams when they were available.

Bill, do you use any decomp at all? If so, what did you end up doing (Adrian's mod comes to mind)
Suppose I were an idiot, and suppose I were a member of Congress; but I repeat myself. ... Mark Twain
2006 AVL Electra

Bill Harris

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Re: Harris Scrambler gets 'S' cams
« Reply #9 on: March 29, 2013, 12:50:11 AM »
thanks for sharing Bill and BW.  This is great stuff.  I kick myself for not finding a way to get those cams when they were available.

Bill, do you use any decomp at all? If so, what did you end up doing (Adrian's mod comes to mind)

DanB,

I got rid of the decompression stuff a long time ago.  I just didn't use it, so why have it.  We are only talking 8.5:1 compression ratio and it's not hard to get over TDC with the  kickstarter and kick start the engine.  I almost always kick start.

Cheers,
Bill       

Bill Harris

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Re: Harris Scrambler gets 'S' cams
« Reply #10 on: March 29, 2013, 01:14:01 AM »
Wow Bill, that is some noticeable power... really good to hear.  Sounds like 70-75 mph in 5th will be a bit more relaxed.  You went back to the stock ECU, correct?

The Harris Scrambler looks good as always.

Boggy,

I installed the performance TCI unit a while back.  The Harris Scrambler didn't like it.  It would kickback when starting and I feared for the sprag.  I reinstalled the stock green TCI and that's what I'm running in it now.

Cheers,
Bill   
« Last Edit: March 29, 2013, 12:29:40 PM by Bill Harris »

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Re: Harris Scrambler gets 'S' cams
« Reply #11 on: March 29, 2013, 08:40:33 AM »
That TCI [CDI] might have been faulty, Bill. The performance CDI boxes as on the machine I tuned should give 4 degrees more retard at starting and low RPM's and 4 degrees more advance at high RPM's, for a bit more top end go. Certainly, any tendancies to kickback on this testbed machine were eliminated by the new CDI box.
 Back to the 'S' cams, there are a number of plain 'Iron' and some 'Asbo' iron engine Bullets now using these cams and showing improvements as a result, as well as the AVL types they were mainly intended for.
 B.W.
 P.S. - very important - if any interference is noted between the exhaust valve and piston, the timing for this valve should be ADVANCED [move cam anticlockwise] to close it sooner and make more room over the piston going over TDC on the 'overlap'. Please, do not retard this valve's timing by mistake, or damage will probably result as a consequence.
 Retarding the inlet timing by turning this cam anticlockwise opens this valve later and will increase the space between piston and valve going over TDC on the 'overlap'.
« Last Edit: March 29, 2013, 01:25:38 PM by Bullet Whisperer »

Bill Harris

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Re: Harris Scrambler gets 'S' cams
« Reply #12 on: March 29, 2013, 09:46:57 PM »
 
That TCI [CDI] might have been faulty, Bill. The performance CDI boxes as on the machine I tuned should give 4 degrees more retard at starting and low RPM's and 4 degrees more advance at high RPM's, for a bit more top end go. Certainly, any tendancies to kickback on this testbed machine were eliminated by the new CDI box.
 Back to the 'S' cams, there are a number of plain 'Iron' and some 'Asbo' iron engine Bullets now using these cams and showing improvements as a result, as well as the AVL types they were mainly intended for.
 B.W.
 P.S. - very important - if any interference is noted between the exhaust valve and piston, the timing for this valve should be ADVANCED [move cam anticlockwise] to close it sooner and make more room over the piston going over TDC on the 'overlap'. Please, do not retard this valve's timing by mistake, or damage will probably result as a consequence.
 Retarding the inlet timing by turning this cam anticlockwise opens this valve later and will increase the space between piston and valve going over TDC on the 'overlap'.

Thanks B.W.

That's right, advance the exhaust valve.  I revised my post to Enfield Jack.  Thanks for the correction.  You know about us old people, we don't know if we're coming or going.   :-[

Cheers,
Bill   
« Last Edit: March 29, 2013, 11:57:08 PM by Bill Harris »

Adrian

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Re: Harris Scrambler gets 'S' cams
« Reply #13 on: March 30, 2013, 04:13:32 AM »
My senior moments seem to be running into each other, the gaps in between are getting shorter, what forum was this?

Adrian (just let me check...)

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Re: Harris Scrambler gets 'S' cams
« Reply #14 on: April 02, 2013, 05:10:49 PM »
I got a chance to install the cams this past weekend. No valve/ piston clearance issues but the cams did require a richer fuel mixture. Now waiting on larger jets to arrive. I have a 2006 Electra with the CMW Performance Kit. Free flowing downpipe with baffled shorty silencer (drilled 6, 3/8" holes into front and rear baffles), 30mm PWK with #35 pilot, 130# main jet and K&N Pancake Air Filter. I can't wait to try it on the road with proper jetting. To be continued...
Jake