Author Topic: Iron Barrel 350 project  (Read 467 times)

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Seipgam

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on: March 14, 2021, 09:30:07 am
Looking at a 350 iron barrel project.  Had an Indian "refurbishment" before it came to Australia, so could be mechanically ok, could be not.
Has been rather neglected since it came here 6 years ago so needs a good cosmetic tidy up.
If all goes to plan I will have an inspection next weekend and then decide if I take it or not.
Not a fan of the cosmic blue colour (might end up army green) or the seat, but they are minor issues.

My question is - What sort of cruising speed can I expect from a reasonably healthy 350, compared to my 500 iron barrel which will sit on a genuine 90kmh (110 by the speedo) all day but feels a little pushed if I go beyond that for too long
Not expecting anything outstanding but would like to have an idea of what's realistic.

Cheers, Geoff

« Last Edit: March 14, 2021, 09:34:22 am by Seipgam »
1954 Francis Barnett, Kestrel 66 122cc
1995 Royal Enfield Bullet 500
2014 Suzuki S40 Boulevard (LS650)


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Reply #1 on: March 14, 2021, 09:43:35 am
Standard Indian 350 vs standard Indian 500? Subtract about 5 - 10 mph for the 350.
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Paul W

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Reply #2 on: March 14, 2021, 10:46:02 am
With a bit of gas flowing, a decent free flowing exhaust and a good air filter, a 350 can be made to match a 500.

Here's a bit of footage of mine on the M1 Motorway: https://www.youtube.com/watch?v=If47Pnkgfrs
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cyrusb

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Reply #3 on: March 14, 2021, 12:44:30 pm
So just how fast were you traveling ? The action cam makes it look like 80
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Adrian II

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Reply #4 on: March 14, 2021, 12:59:40 pm
With a bit of gas flowing, a decent free flowing exhaust and a good air filter, a 350 can be made to match a 500.

On the flat, at least!  ;D

For this sort of thing down under, an alloy barrel might be a good investment. Henry Price over here sells new con-rods with needle roller big-ends for the iron barrel models, for sustained cruising on a 350 that would be somewhere near the top of my upgrades list.

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cyrusb

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Reply #5 on: March 14, 2021, 01:13:44 pm
Yeah, I guess pulling a hill is where the extra 40% in displacement comes in handy.
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Paul W

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Reply #6 on: March 14, 2021, 01:38:45 pm
So just how fast were you traveling ? The action cam makes it look like 80

I measured the motorway distance travelled accurately using the "path" facility on Google Earth Pro and the time between two points on my GoPro camera (passing two roadside features). The average speed over 6.12 motorway miles took 5.23 minutes, so just over 70 mph (just on the UK motorway speed limit). I did actually slow down a few times on the motorway stretch....twice for overhead speed cameras and a few times for traffic, including two "middle lane hogs". The speedometer on the bike over-reads by between 5-10%.

I do have a 5 speed box on the bike. It doesn't affect top speed because I've arranged the overall gearing to be as close to standard 350 as possible (standard sprockets are 16/38. My bike has 18/42). The bike is an Electra so it has no distributor and no drive pinions for one so might be slightly advantaged over a bike with points ignition due to less engine drag..I don't know.

Without entering a willy waving contest, I can say that a 350 can be made to keep up with traffic - not that I ride it regularly at those speeds; I don't really like motorway riding anyway.
« Last Edit: March 14, 2021, 01:51:22 pm by Paul W »
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Paul W

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Reply #7 on: March 14, 2021, 01:58:31 pm
I have considered an alloy barrel for my 350 (don't they look nice!). If I ever have need to rebore/replace the iron one, I think I'll probably do it "just because". There seems little chance of overheating the engine of a 350 in UK, at least not for most of the year.
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cyrusb

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Reply #8 on: March 14, 2021, 02:03:33 pm
I have found the best measure of speed is either pacing a car or pocket gps. Time over distance can have a lot of slop in it particularly if the rider is also doing the timing. If your final drive is close to stock what could the engine RPM be at 70mph? My 500 after all the standard upgrades was no faster until I bumped up the drive sprocket to 19. Before that even with the extra power, the bikes top speed was limited to the stock math.
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Paul W

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Reply #9 on: March 14, 2021, 02:09:02 pm
OK then, I was only doing 55 mph, Officer.  ::)

But I wasn't doing the timing myself, read the post....it was an average speed distance/time and didn't involve using the bike's speedometer.

GPS on a road vehicle does also have its limitations, btw.
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cyrusb

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Reply #10 on: March 14, 2021, 03:12:43 pm
Not doubting anything. Like I said, my 500's top speed was really limited by the stock final drive. Regardless of my power upgrades that mill can only spin so fast. Anyone have a tach? I would like to know rpm at a known speed with stock gearing. Could be interesting.
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Seipgam

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Reply #11 on: March 14, 2021, 03:18:29 pm
Thanks for the input guys.
Yes, I was talking stock 500 v stock 350.
Won’t be doing any performance upgrades if I get it though, will just be working with what I get.

Geoff.
1954 Francis Barnett, Kestrel 66 122cc
1995 Royal Enfield Bullet 500
2014 Suzuki S40 Boulevard (LS650)


Paul W

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Reply #12 on: March 14, 2021, 03:56:20 pm
Not doubting anything. Like I said, my 500's top speed was really limited by the stock final drive. Regardless of my power upgrades that mill can only spin so fast. Anyone have a tach? I would like to know rpm at a known speed with stock gearing. Could be interesting.

If you measure the rolling radius of the rear wheel and know the front and rear sprocket details you can work it out.
« Last Edit: March 14, 2021, 04:39:59 pm by Paul W »
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Reply #13 on: March 14, 2021, 04:20:04 pm
Not doubting anything. Like I said, my 500's top speed was really limited by the stock final drive. Regardless of my power upgrades that mill can only spin so fast. Anyone have a tach? I would like to know rpm at a known speed with stock gearing. Could be interesting.

As a rough guide, the 500 with stock gearing gives about 16 mph per 1000 rpm in top gear.
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Paul W

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Reply #14 on: March 14, 2021, 04:39:20 pm
You need to know the crankshaft sprocket teeth and the clutch drive teeth (25/56 on both 350 and 500). That gives a reduction ratio of 2.24 as far as the gearbox, same for both engine sizes.
The final drive sprocket teeth (16 on a 350, 17 on a 500) and the rear wheel sprocket (38 on both 350 and 500) gives chain drive ratios of 38/16 = 2.375 for a 350 and 38/17 = 2.235 for a 500.

Overall drive ratios:
350 = 2.24 x 2.375 = 5.32
500 = 2.24 x 2.235 = 5.01

Assuming the rear tyre of a 19" rim is 26" in effective diameter as it sits on the road (i.e. rolling radius x 2):
A standard 350 is doing 4127 rpm in top at 60 mph.
A standard 500 is doing 3886 rpm in top at 60 mph.

(My 350 is slightly different again due to non standard rear sprocket sizes; I reckon it's doing 4,054 rpm at 60 mph).

If you would like to experiment a bit, use this calculator: https://www.omnicalculator.com/everyday-life/rpm

 
« Last Edit: March 14, 2021, 05:22:39 pm by Paul W »
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