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Old 20th August 2011, 21:10   #31
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Default Re: Got the BULL! And some queries

Hi,
I got the ECU remapped sometime back. Its just fantastic, Iam not sure about the tech aspect, but, Iam sure the torque has increased about 15 to 20% and the top speed has also improved. The best change I liked was the irritating engine knock while we accelerate is reduced more than 80%, I can only hear them faintly. Overall its a wonderful change.
As its discussed under many topics, I feel a definite wobble at 105 - 110 kmph. Its not a mild one, its really a scarry one as if the tire has got punctured, after that speed it settles a bit but not soo much to inspire confidence. I know its been discussed about, but, can someone in plain and simple language guide me through the process of reducing it a little bit? Thanks.
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Old 21st August 2011, 04:19   #32
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Default Re: Got the BULL! And some queries

I don't know if it applies to your motorcycle but several riders in the U.S. have noticed wobbles in that speed range and higher due to their tire pressure.
Their bikes were equipped with Avon tires (tyres?) which seem to have very stiff sidewalls.

After reducing their front tire pressure to 18 psi (1.241 bar) and the rear tire to 25 psi (1.724 bar) most if not all of the wobbles went away.

Apparently the bushings in the swing arm pivots on some Royal Enfields could also cause this problem.
Between the swing arm and the frame a small area of the bushings head (enlarged area) is exposed and the ones that seemed to be causing a problem appear to be made of white nylon. RE revised this material and installed a black colored bushing on my 2011 model.

Before pursuing something as drastic as a bushing replacement be sure to try adjusting the air pressure in your tyres either down or up. It may be the solution.
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Old 24th August 2011, 14:00   #33
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Default Re: Got the BULL! And some queries

Thanks a lot Jim, my tire pressure in the front is 22psi, will reduce and check.
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Old 25th August 2011, 00:42   #34
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Default Re: Got the BULL! And some queries

Quote:
Originally Posted by ArizonaJim View Post
Their bikes were equipped with Avon tires (tyres?) which seem to have very stiff sidewalls.
Just noticing the differences in US and UK English, are we?
I'll wait for when you type ' aluminum ' and not ' aluminium ' .
Cheers!
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Old 25th August 2011, 01:56   #35
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Default Re: Got the BULL! And some queries

There are a couple of other things some of the US riders have tried with varying success.

They all require a bit of work but some have found it worth it.

1. Loosen, but do not remove the front axle. Also loosen but do not remove the 4 larger mudguard bolts holding it to the front forks along with the two bolts which hold the forks into the fork "steering stem" (fork clamp).

With the front brake locked, bounce the motorcycle compressing and decompressing the front fork. Repeat this bouncing several times to allow the parts to adjust themselves to the best fit.

Re-tighten the axle. (50-70 N/m)
Re-tighten the axle pinch bolt (3 N/m)
Re-tighten the mudguard bolts. (30 N/m)
Re-tighten the fork clamp bolts (33 N/m)

2. The "rear frame" which holds the rear mudguard on some of the RE's can produce a "loading" or "twisting" on the rest of the motorcycles frame.
Loosening the bolts that attach it and allowing it to "spring" to a more relaxed position will reduce this loading effect.
In at least one case the owner found that he had to elongate the holes with a round file in the rear frame attachment locations to allow it to be assembled easily without binding.

3. With the front wheel of the motorcycle raised off of the ground by using a screw type car jack and someone steadying the motorcycle, try moving the fork forward and aft and side to side. There should be no movement in any direction.
If movement caused by a looseness is found the steering head bearings are loose. These should be adjusted by a competent Royal Enfield shop mechanic.

A great many of the owners in the US have found that they can ride their bikes at speeds of over 120 km/hr (75 mph) without wobbles or shakes.
Hopefully these suggestions will help you achieve similar results.

Last edited by ArizonaJim : 25th August 2011 at 01:59.
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Old 25th August 2011, 04:05   #36
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Default Re: Got the BULL! And some queries

I knew I would forget something.

Something many take for granted is proper wheel alignment.
If the wheels are not aligned the rear wheel will be trying to push the bike to the right or left while the front tyre will be fighting to correct for the error.

I've read the method of using string to check this but I feel a string is too flimsy to use easily so I looked around for something that might be better.

I found that I had some straight aluminum (aluminium?) tent poles that were about 6 ft. (1,830 mm) long.

With the motorcycle resting on the center stand and the front wheel pointed straight ahead, placing the pole against the side of the rear tyre at the front and rear side will establish the direction the tyre is pointed.
I found that the pole could pass thru the center stand without interference and the forward end of it would be next to the front tyre where it rested on the ground.

Because the rear tyre is slightly wider than the front tyre the pole should not interfere with it. Rather, it should clear the side of the front tyre by about 2.5mm.

To be certain that a mistake has not been made, after making this test on one side of the motorcycle, repeat it on the other side.
If the rear tyre is aligned properly the clearance at the front tyre should be about equal.
I say "about" because a very small error in pressing the pole against the sides of the rear tyre will be multiplied greatly over the length of the pole and will change the clearance to the side of the front tyre.

If confusing clearances are found between the pole and tyre, check to make sure the front wheel on the motorcycle is pointed straight ahead.

What one does NOT want to see is a significant clearance when testing on one side of the motorcycle and a significant interference when testing on the other side.

If this clearance/interference condition exists, the rear wheel is out of alignment and this must be corrected by loosening the rear wheels nuts and adjusting it so that it is pointing straight ahead towards the front wheel.

I mentioned my using a tent pole but any straight, small size tube or board would work as long as it is long enough to rest against both the front and rear sides of the rear tyre and still reach the place where the front tyre rests on the ground. I cannot overemphasize the need for the pole or board to be absolutely straight and it must be ridged enough so that it does not flex if a force is applied to its sides.

Last edited by ArizonaJim : 25th August 2011 at 04:09.
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Old 28th August 2011, 13:21   #37
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Default Re: Got the BULL! And some queries

Thanks a lot Jim for such a detailed explanation, Iam sure if I get it done its gonna be fine. Just an opinion, yesterday when I took my wife along with me it was stable like a rock at even 120 kmph, does the weight of the pillion have such an effect? Or the Bull is scared of my wife ? ;-)
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Old 28th August 2011, 13:40   #38
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Default Re: Got the BULL! And some queries

Quote:
Originally Posted by drjones View Post
Thanks a lot Jim for such a detailed explanation, Iam sure if I get it done its gonna be fine. Just an opinion, yesterday when I took my wife along with me it was stable like a rock at even 120 kmph, does the weight of the pillion have such an effect? Or the Bull is scared of my wife ? ;-)
Yes weight does play an important role. My bike with the same set up and tyre pressure was ridden with a pillion for 15-20 minutes at 110-120 continuously without any wobble. Then I changed it with my fellow riders. The one who weighed the least experienced the wobble soon after 110, while the other who was the same weight like me and my pillion took it upto 130 plus without reporting any issues............so it does make a difference.
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