#96786
jawa-enfield wrote:
Sun May 16, 2021 8:16 am
'Morning to all..
With a 18T sprocket, what is a 'safe' cruising speed?
It is very established in my memory that a Dutch enfield dealer warned not to cruise over 80km/h, or the bullet will self destruct.

Although i understand slugging of the engine (low oil pressure, high strain) is bad, but physics told me that with the rpm the force on the conrod increases in square with the velocity?
And so, the conrod and big end and piston assy -especially on a long stroke bike- is strained very much?

Am i too scared for revving the bike?
A bit of history from my point of view.
I don't have a car and a bike has always been my method of getting about on so anything problematic and unreliable gets the heave pronto. Getting an Enfield set up properly is the secret for long term reliability. The principles of getting it right on a Bullet are no different to any other British single. Running the motor where it doesn't vibrate like a shaker is important, so a bit of time on the crank is worthwhile, and I've always left it with the standard big end and rod. Next, get it breathing better (head, cams, exhaust etc) and then get rid of as much superfluous weight as possible. I've always used the standard oil pumps, and made a point of checking the drive spindle at regular intervals. Let them warm up from cold, and learn to ride them smoothly (smooth does not mean slow), and service them regularly. If Bullets were really as bad as some people would have you belive, I hardly think they would have been in continuous production for such a record amount of years. Speed ? I suppose 60-70 mph is what mine would be travelling at in daily traffic.
#96787
jawa-enfield wrote:
Sun May 16, 2021 8:16 am
It is very established in my memory that a Dutch enfield dealer warned not to cruise over 80km/h, or the bullet will self destruct.
I think this could be true of the nasty mid 90's 500 pistons which split through the oil control lands for fun. The ones you no longer have.
Am i too scared for revving the bike?
Yes, I think so. Putting it a dutch way, It's like riding a pushbike uphill in too high a gear, you have to stand on the pedals and put an excessive load on the pedal cranks and chain in doing so. If you change down and spin the pedals more, it's easier and puts a more uniform load on the drivetrain (it will be the same overall load if you are doing the same speed). Also easier on your legs (engine).
#96788
The tap in question has a push-pull slide for main supply and a pivoting lever above that to activate reserve, ¼ BSPP thread at both ends, and is chrome plated.

You should be able to do a lot better than 80 kph, though that's quite a decent if somewhat relaxed cruising speed. What you need to avoid is the extremes of stress on the con-rod in either form. Giving the engine an absolute thrashing can be destructive in a different way, lugging the engine is bad for the big-end, while constant high revs will risk con-rod failure. Remember it's having to deal with a heavier piston than the 350 Bullet has. This was a known issue on the English built 500 Bullets and the Indian made alloy con-rods are no tougher. The guy who gave you the advice probably had that in mind, con-rod failure often destroys the crankcases. However, the engine should still be able to take a bit of stick now and again. If fragility really bothers you, fit one of our hosts' fancy crankshafts with the steel con-rod and needle roller big-end.

18T could still be over-geared, they were standard on the Electra-X with a higher compression engine than yours, but even so mine could struggle in top despite a good carb and exhaust, fitting a 17T made the bike much moor fun to ride with no loss of top speed.

A.
#96789
Yes i understand fully the uphill/bike comparison, but the mass tim svelocity in square on the conrod 'worries'me more..

As soon as the 18T arrives i will mount it.
It occurs to me i have to do a LOT in 3rd in normal traffic.. 4th gear is for open B-roads but in my area are a lot of elderly folks and women driving unnessecarily slow and/or unpredictable.
And on the hightway 90km/h is a tad too slow..

With a 18T sprcket i thinbk i should forget about 90km/h but maybe less drining in 3rd and less shifting back/forth..
#96790
I have an 18t sprocket on my 500, I live in a hilly, built up area full of old drivers and holiday makers getting in the way.
Riding around here is hard work with a 17t fitted, constantly changing between 3rd and 4th, but with an 18t fitted, third gear is perfect, easily over 40mph before changing into 4th. There is no 'slugging' anywhere, even on the steepest hills.
In my opinion, 18t seems ideal for me, I ride on real life roads, some with grass in the middle, held up by doddering traffic or running down the bypass that has a 50mph average limit imposed, so 'top end' doesn't really come into it.
I found a 17t gave an unnecessarily low 1st gear, I am not going up the Himalayas, or loading up with massive panniers and two passengers.
I'm sure you will find an 18 tooth sprocket satisfactory.
Just my two pennyworth!
#96795
Thanks for reply!
I was told, and hoping for a cruising speed of 100 kph with the 19 sprocket, and yes the bike now runs very well but with strong (Dutch) wind ahead there migght be a struggle.

Still on the market for a good petcock with reserve & enough flow.
@ Adrian the puish-pull ones, A dutch bike part dealer told me he doesn't sell them because they are leaky?
#96797
I think i worry because i had the problem with my jawa 638, under full load the engine stalled.. not fun, especially on a 2 stroke.
I drilled out the holes of the fuel tap and it was better, but not cured fully.
It was solved mounting a BMW fuel tap, connected via 2 clamps and a piece of fuel resistant rubber hose..

Is a too-restrctive fuel tap a happening thing/common problem on a enfield? The carb is a total different one then on a jawa, also the fuel use is less..
#96808
I'm afraid that the Indian fuel taps for the old Bullet were never designed to supply a performance carburettor. So long as the little dribble they could manage was enough for a VM24 Mikarb main jet, they were usually happy. Trying to give one of these poor things the equivalent of a prostatectomy is not the answer, JUST FIT A DECENT TAP! Plenty of choice out there.

A.

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