Unofficial Royal Enfield Community Forum

Royal Enfield Motorcycles => Bullet Iron Barrel => Topic started by: Seipgam on March 14, 2021, 09:30:07 am

Title: Iron Barrel 350 project
Post by: Seipgam 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
Title: Re: Iron Barrel 350 project
Post by: Bullet Whisperer on March 14, 2021, 09:43:35 am: Standard Indian 350 vs standard Indian 500? Subtract about 5 - 10 mph for the 350.
B.W.
Title: Re: Iron Barrel 350 project
Post by: Paul W 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
Title: Re: Iron Barrel 350 project
Post by: cyrusb on March 14, 2021, 12:44:30 pm: So just how fast were you traveling ? The action cam makes it look like 80
Title: Re: Iron Barrel 350 project
Post by: Adrian II on March 14, 2021, 12:59:40 pm: Quote from: Paul W 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.

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.

A.
Title: Re: Iron Barrel 350 project
Post by: cyrusb on March 14, 2021, 01:13:44 pm: Yeah, I guess pulling a hill is where the extra 40% in displacement comes in handy.
Title: Re: Iron Barrel 350 project
Post by: Paul W on March 14, 2021, 01:38:45 pm: Quote from: cyrusb on March 14, 2021, 12:44:30 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.
Title: Re: Iron Barrel 350 project
Post by: Paul W 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.
Title: Re: Iron Barrel 350 project
Post by: cyrusb 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.
Title: Re: Iron Barrel 350 project
Post by: Paul W 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.
Title: Re: Iron Barrel 350 project
Post by: cyrusb 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.
Title: Re: Iron Barrel 350 project
Post by: Seipgam 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.
Title: Re: Iron Barrel 350 project
Post by: Paul W on March 14, 2021, 03:56:20 pm: Quote from: cyrusb 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.

If you measure the rolling radius of the rear wheel and know the front and rear sprocket details you can work it out.
Title: Re: Iron Barrel 350 project
Post by: ace.cafe on March 14, 2021, 04:20:04 pm: Quote from: cyrusb 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.

As a rough guide, the 500 with stock gearing gives about 16 mph per 1000 rpm in top gear.
Title: Re: Iron Barrel 350 project
Post by: Paul W 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
Title: Re: Iron Barrel 350 project
Post by: Bilgemaster on March 14, 2021, 08:01:01 pm: Like Paul our "Bullet Whisperer" said, all things being more or less stock, about 5 or 10 mph (about 8 to 10 kmh) less top speed compared to a comparably standard 500 Bullet might be expected, along with a little less "Oomph!". But there's still plenty of fun to have with a 350 out there on those nice little "B", "C" and other roads out there all around Ballarat, where it wouldn't need to struggle (See: https://www.travelvictoria.com.au/victoria/roads/).

By the way, there's also a town named Ballarat in California, named by one of your countryman. All but a ghost town now, it was once a fair-sized center for mining in the area. It's had a peculiar history, including the Manson Family shacking up there for a bit.

(https://upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Ballarat_California.jpg/250px-Ballarat_California.jpg)
Rush Hour in Ballarat
Title: Re: Iron Barrel 350 project
Post by: AzCal Retred on March 15, 2021, 04:52:53 am: Paul W's Bullet sounded pretty crisp to me, the 5 speed really was working well to keep him "on the cam". You can hustle along smartly on 23-25 HP with proper ratios. My old bone-stock 1978? XT250 Yamaha ran 65-70 pretty reliably on flat ground, no headwind. The big gap between 3rd & 4th on the 4 speed drops my 500 I.B. noticeably "off the cam". The 5 speed has better ratios to work with. These engines seem capable of 6000 RPM, maybe not as a steady diet, but Paul W had room for more. For max speed the gearing needs put the max HP where it can balance the drag. Many have gone 100 MPH on 30 HP, proper gearing & rider blended into the paint.

My speedometer is temperature dependent - at under 55F keeping up with local traffic I show 60-65 MPH. A bit later in the day at 65F, the same traffic is 50-55 MPH...Obviously I am much speedier in the AM! Or the grease dragging the magnetic cup around in the speedo is grippier when cold... ;D ;D ;D In any event, the Bullet speedo is more entertaining than informative.
Title: Re: Iron Barrel 350 project
Post by: Paul W on March 15, 2021, 08:14:54 am: My normal cruising speed on the 350 is about 55 max, mainly because I enjoy that speed and I don’t often ride on the motorway. I use the bike mainly for backroad exploration, occasionally with some off tarmac stuff. I’ve no desire to get any more speed out of it. I’ve already found the natural rev limit; it needs stronger valve springs....but I doubt I’ll get round to that anytime soon. It does the job as it is.

If I want a faster run I’ll use my 1991 CB750 Nighthawk, although since I bought the Bullet the Honda has has very little use...the battery for that sits on my workbench.
Title: Re: Iron Barrel 350 project
Post by: viczena on March 15, 2021, 08:19:13 am: Quote from: Bullet Whisperer on March 14, 2021, 09:43:35 am
Standard Indian 350 vs standard Indian 500? Subtract about 5 - 10 mph for the 350.
B.W.

The 350 and the 500 have the same cams . So no wonder why the 500 does not produce more.
Title: Re: Iron Barrel 350 project
Post by: Seipgam on March 15, 2021, 09:28:23 am: Bilgemaster,
You have way too much time on your hands.

Geoff.
Title: Re: Iron Barrel 350 project
Post by: Adrian II on March 15, 2021, 12:43:24 pm: Quote from: viczena on March 15, 2021, 08:19:13 am
The 350 and the 500 have the same cams . So no wonder why the 500 does not produce more.

Nothing to do with the original 500 iron barrel Bullet being a mid 1950's upgrade of a late 1940s design, then? I think the best preforming Redditch 500 singles (apart from the competition models) were the Big Head Bullets from 1959-61 which claimed 27BHP. That was using the "S" cams, which were the same as the 350 Bullet used, and why not ON A TOURING BIKE? For scrambles and racing use they had the "R" cams. Indian iron barrel cams are similar to the "S" as the engine is just a continuation of the Redditch design.

Hitchcocks' used to offer different performance cams of their own for the 350 and 500, maybe they still do!

Getting back to the use of stock Bullets under Australian conditions, Winifred Wells managed to cross Australia from West to East and back on her 350 seventy years ago, and both bike and rider managed perfectly well.

A.
Title: Re: Iron Barrel 350 project
Post by: ace.cafe on March 15, 2021, 01:33:02 pm: Quote from: viczena on March 15, 2021, 08:19:13 am
The 350 and the 500 have the same cams . So no wonder why the 500 does not produce more.

But the 500 has larger inlet and exhaust tracts, and larger valves that the 350. This means that even though both 350 and 500 have the same cam specs, the 500 has more air flow in/out of the engine during the time that the valves are open.
The cams may be the same, but the engine breathing is certainly not the same.

Cams are only part of the equation.
And BTW, those cams have 280° duration, which is not a short cam duration by any definition. They have plenty of duration.
Title: Re: Iron Barrel 350 project
Post by: Paul W on March 15, 2021, 04:38:09 pm: I've read various discussions about 'S' and 'R' cams, here and elsewhere.

Does 'S' stand for standard and 'R' for racing? If so, are there any other factory cams?
Title: Re: Iron Barrel 350 project
Post by: Karl Fenn on March 27, 2021, 04:03:55 pm: I have been toying with the idea of a 350 for the odd Sumer day out plotting the county lanes, l don't expect it to be any faster than a C15 but l will only ride it at 45, l had iron barrels in the 70s they never cooked up, never had it happen, just a trip in the past where not much traffic goes these days.
Title: Re: Iron Barrel 350 project
Post by: ddavidv on March 28, 2021, 12:17:52 pm: Having had both 500 and 350 versions in my garage, I can say the 350 is a nice, cheeky around town bike. Where it fails is out in the country. Where I live we have quite a few steep hills that will slow a 500. The 350 really didn't like them. Not that it can't climb them, it just requires a lot more throttle, noise and downshifting. Kind of reminded me of my dad's old Honda CT90. ;D

If you live where things are mostly level or nicely undulating, no real problem.
Title: Re: Iron Barrel 350 project
Post by: Paul W on March 28, 2021, 01:11:40 pm: The "rideability" of my 350 was transformed by fitting a 5 speed gearbox. No more big gaps in gear ratios means it will go up hills very well. I'm now often held up by traffic ahead rather than holding up traffic behind.
Title: Re: Iron Barrel 350 project
Post by: AzCal Retred on March 28, 2021, 06:00:27 pm: " l had iron barrels in the 70s they never cooked up, never had it happen " - Karl -

The cooling delta between the iron barrel & alloy barrels is large. The Iron Barrel stays cool for a couple minutes before beginning to warm, long after the head is warm. Quite a thermal lag. The good news is that it retains heat on a cool day and requires less or no choke to restart. If air temp is less than 75F it probably won't ever matter much. Here at 110F it's a lifesaver.
Title: Re: Iron Barrel 350 project
Post by: Amlousdad on June 12, 2021, 05:26:51 pm: It’s a lot of work but converting the 350 to 441 makes quite a difference.
Title: Re: Iron Barrel 350 project
Post by: AzCal Retred on June 12, 2021, 11:41:32 pm: How did you t to 441? Crank? Big Bore? Where did you source parts? Any Pics?
Title: Re: Iron Barrel 350 project
Post by: Adrian II on June 12, 2021, 11:54:20 pm: https://forum.classicmotorworks.com/index.php?topic=31039.0

A.
Title: Re: Iron Barrel 350 project
Post by: Amlousdad on June 13, 2021, 02:15:36 pm: Using a custom made liner and a bsa B44 piston,crankcase and barrel machined to suit.
Title: Re: Iron Barrel 350 project
Post by: ace.cafe on June 14, 2021, 12:59:37 pm: You know, RE actually makes a 500.
Maybe look into it?
Title: Re: Iron Barrel 350 project
Post by: AzCal Retred on June 14, 2021, 05:28:05 pm: +1 --- Very "true 'dat".