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**Buro** · 10-31-2013, 11:27 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by gyan_recl350 View Post

Hmmm... Actually the biggest factor for thump is massive torque at relatively very very less RPM. I never heard about valve seating and ignition timing for that, can you throw some more light on how does these two affect the thump?

Btw: which Bullet you own now?

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Firstly I was referring solely to the 350 Cast Iron Bullet which you rightly pointed out, does produce "massive torque at relatively very very less RPM" thus the thump.
But the sound we actually hear depends heavily on the other factors I mentioned. To me the silencer is the biggest factor for thump. As for your other queries,
when the valves close there should be a good seal, due to tappet sounds some people would tighten the push rods to reduce play and chatter. These adjustments were some times over done, and would thus lead to valves not closing fully, this led to diminished thump.
The old Bullets had Points instead of today's Electronic ignition. The points system was customizable to a riders riding style. On a points system Bullet, retarding the ignition increases thump.

My 1970 Bullet.

**gyan_recl350** · 10-31-2013, 11:49 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by Buro View Post

Firstly I was referring solely to the 350 Cast Iron Bullet which you rightly pointed out, does produce "massive torque at relatively very very less RPM" thus the thump.
But the sound we actually hear depends heavily on the other factors I mentioned. To me the silencer is the biggest factor for thump. As for your other queries,
when the valves close there should be a good seal, due to tappet sounds some people would tighten the push rods to reduce play and chatter. These adjustments were some times over done, and would thus lead to valves not closing fully, this led to diminished thump.
The old Bullets had Points instead of today's Electronic ignition. The points system was customizable to a riders riding style. On a points system Bullet, retarding the ignition increases thump.

[ATTACH=CONFIG]123176[/ATTACH]

My 1970 Bullet.

Hmm.. Now the tappets are hydraulic, they adjust automatically based upon oil pressure. Even I have heard retarding the ignition increases thump but how?

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**Buro** · 11-01-2013, 12:08 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

In layman terms(Me being the layman) when you retard the ignition timing, the spark occurs late. This results in combustion when the exhaust valve has already opened.

**gyan_recl350** · 11-01-2013, 12:18 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by Buro View Post

In layman terms(Me being the layman) when you retard the ignition timing, the spark occurs late. This results in combustion when the exhaust valve has already opened.

Hmm sounds logical but it would definitely lead to bad power and mileage as some of the charge would escape without getting burnt.

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**gyan_recl350** · 11-01-2013, 12:20 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Btw your bull looks gorgeous

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**Buro** · 11-01-2013, 12:55 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Thank you for the complement.

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**simao** · 11-04-2013, 02:22 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by Buro View Post

Firstly I was referring solely to the 350 Cast Iron Bullet which you rightly pointed out, does produce "massive torque at relatively very very less RPM" thus the thump.
But the sound we actually hear depends heavily on the other factors I mentioned. To me the silencer is the biggest factor for thump. As for your other queries,
when the valves close there should be a good seal, due to tappet sounds some people would tighten the push rods to reduce play and chatter. These adjustments were some times over done, and would thus lead to valves not closing fully, this led to diminished thump.
The old Bullets had Points instead of today's Electronic ignition. The points system was customizable to a riders riding style. On a points system Bullet, retarding the ignition increases thump.

[ATTACH=CONFIG]123176[/ATTACH]

[ATTACH=CONFIG]123177[/ATTACH]

My 1970 Bullet.

Lovely bullet....nicely done up. From the picture its looks to be a G2 engine. These were different from the later cast irons. The metal, the crank case, the crank etc. Does it have the amal carb? And is it still having the dynamo and advance/retard lever?

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**simao** · 11-04-2013, 02:34 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Anybody still in search of the majestic thump?

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**Buro** · 11-04-2013, 01:21 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

The last lot of G2 engined Bulls I have seen were 1968 registered ones. Mine being a 70's model was made India and has EI stamped on the engine number(Enfield India) The G2 engined ones have GB (Great Briton) stamped on the engine.

**simao** · 11-09-2013, 12:51 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Your right about the stamping friend. But with regards to the date of the g2 I think it was 1979, correct me if I am wrong. They were made in England but assembled in India. They were all heavy cranks. You can make out on the crankcase itself. You must be knowing

But I really haven't seen the GB stamped on the casings of any royal enfield. Yet to come across one.

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**simao** · 11-10-2013, 01:27 AM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Came across this engine rebuild of the uce 500. Don't know the reason and mechanic was unwilling to tell. Saw the crank lying there.

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**gyan_recl350** · 11-10-2013, 01:42 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by simao View Post

Came across this engine rebuild of the uce 500. Don't know the reason and mechanic was unwilling to tell. Saw the crank lying there.

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Was it a crankshaft mod or something else?

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**simao** · 11-10-2013, 04:25 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by gyan_recl350 View Post

Was it a crankshaft mod or something else?

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Looks to be. Because there was a crank already fitted in the crankcase and this one was out. And it had one hole each on either of the weights. But the crank was heavy, around 10 or 11 kilos. The mechanic was unwilling to shed some light.

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**gyan_recl350** · 11-10-2013, 04:31 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by simao View Post

Looks to be. Because there was a crank already fitted in the crankcase and this one was out. And it had one hole each on either of the weights. But the crank was heavy, around 10 or 11 kilos. The mechanic was unwilling to shed some light.

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Hmm.. Yes UCE engine cranks are already of good weight and not all time low. 500cc crank is around 11 kgs and 350cc around 9.5, but in 350cc Standard's crank is same as of 500cc, 11 kgs.

**Buro** · 11-10-2013, 06:17 PM

Re: Can crankshaft be changed to heavier one in the Royal Enfield UCE Bullet

Originally posted by simao View Post

Your right about the stamping friend. But with regards to the date of the g2 I think it was 1979, correct me if I am wrong. They were made in England but assembled in India. They were all heavy cranks. You can make out on the crankcase itself. You must be knowing

But I really haven't seen the GB stamped on the casings of any royal enfield. Yet to come across one.

Sent from my GT-I9082 using xBhp Connect mobile app

The Royal Enfield Company which was in Redditch England closed in 1967 and Enfield India(Madras) bought the tooling and continued to manufacture with Indian metals.
You will not find GB together. There should be two numbers one should start G2/***** and the other B/*****.

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