Author Topic: Heart transplant - vintage twin in a modern Bullet  (Read 7044 times)

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DNash

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Well, I think the title more or less explains it, but I'll elaborate.

At some point, I ran across a passing comment that all of the older twins - the 500, 700, and even the Interceptor twins - will drop right into the modern Indian Bullet frame. I'm hesitant to believe that it's as simple as unbolting one and bolting in the other, so how much trouble would this be?

Also, would, say, a 700 twin mate up to the modern five-speed gearbox, or is that a recipe for disaster?


ace.cafe

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Reply #1 on: July 15, 2009, 04:42:46 am
You have to use the gearbox that was made for the twins.
The width of the engine required a different gearbox shaft to line up with the primary.
So, that means you need the Albion 4-speed gearbox made for the twin.
If you can get the engine and gearbox together with the primary and everything, that would make the best arrangement.

The 5-speed will not work with it, nor will the Bullet 4-speed gearbox.
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rotorwrench

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Reply #2 on: July 18, 2009, 03:50:16 pm
I've thought about going this route with an old 700cc twin motor that I've had for years. The frames on the twins & singes were very similar in 1955. The engine plates for the twins would be a necessity to mount it to the frame. The swing arm may also be the same but I haven't checked that yet. I know they used about the same rear wheel and front end too. It would be easier to find a late type bullet frame than it would be to find an original 500 or 700 twin frame thats for sure.


DNash

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Reply #3 on: August 13, 2009, 05:14:10 pm
Well, I'm looking at selling my '09 AVL Classic and picking up an older, cheaper, modern Bullet to ride for a bit while I collect the parts for a 700 or 750 twin motor & gearbox.

Is there a particular twin that would be especially undesireable for this? Would the Interceptor's twin fit, or do I need to look for Meteor motors?

And, maybe the biggest question: Has anyone actually done this? :)


ace.cafe

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Reply #4 on: August 13, 2009, 05:50:28 pm
Well, I'm looking at selling my '09 AVL Classic and picking up an older, cheaper, modern Bullet to ride for a bit while I collect the parts for a 700 or 750 twin motor & gearbox.

Is there a particular twin that would be especially undesireable for this? Would the Interceptor's twin fit, or do I need to look for Meteor motors?

And, maybe the biggest question: Has anyone actually done this? :)

They will all fit, AFAIK. The only one I'm not sure about is the Series 2 Interceptor, since it has quite a different engine with a wet sump, but it may fit also. I just don't know about that one.

The Interceptors are the most powerful ones, and have all the later improvements included. The early twins are the lowest powered ones, and they got their improvements as time went by, so the early ones lack some of the upgrades that happened over time.

If you are happy with a 500, but just want a twin, the Meteor 500 twin is a dandy machine, and is very good all around, with about 25hp.
It doesn't have all the later upgrades, but it is well within its design limits, and quite reliable and smooth.
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rotorwrench

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Reply #5 on: August 13, 2009, 07:35:17 pm
I agree with ace.cafe on the 500 twin idea. The Interceptor is a much more powerful engine and I'm not sure the old 1955 style frame would hold up to that much power. Any of the 500 twins from the old "500 Twin" of the early through the mid 50s or the later Meteor Minor or Meteor Minor Sport models (all 500cc) would be the easiest to fit in the old style frame. The 500s aren't as fast as the 700 or 750 but they have lot more torque than the Bullet and they are probably the most reliable of all the twins. Most came with a lucas distibutor ignition that is easier to care for than the magneto ignitions of the big twins. An alternative would be one of the older 700cc twins with the single carb. The Meteor motor up through 1955 will fit right in but the 56 & later Super Meteor/Indian Trailblazer heads were different. The only thing with them and the 750 Interceptors is that the motor is taller by a little bit and I'm not sure if it will bolt right in without modifications to the mounting plates.


DNash

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Reply #6 on: August 13, 2009, 11:03:07 pm
Man, asking you guys a question is like trying to get a sip from a fire hydrant. Awesome.  ;D

The 700 Meteor has particularly piqued my interest. I'm not sure why, I think it just sounds cool. "Seven-hundred Meteor". I'd like more power - power enough for the interstate. I tripped over an article via Google that indicated that the 700 Meteor would happily cruise at 70 - is there any truth to that?
« Last Edit: August 13, 2009, 11:09:09 pm by DNash »


Kevin Mahoney

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Reply #7 on: December 30, 2009, 03:44:20 pm
I have seen this done before. One of our old dealers put an Interceptor engine into a Bullet frame. It really worked good and it was an easy conversion.,
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t120rbullet

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Reply #8 on: December 30, 2009, 08:08:50 pm
Series 2 Interceptor in Bullet frame.

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bullethead63

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Reply #9 on: January 28, 2010, 03:46:37 am
Hmmmm...I see a sudden,unexpected run on 700 Interceptor engines,parts and components on eBay...I'm no psychic,but if it's that easy...why throw a fortune at a modern 500 Bullet single engine...throw the same money at a Interceptor engine,and have something UNIQUE...too cool... ;)
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ace.cafe

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Reply #10 on: January 28, 2010, 01:15:06 pm
Hmmmm...I see a sudden,unexpected run on 700 Interceptor engines,parts and components on eBay...I'm no psychic,but if it's that easy...why throw a fortune at a modern 500 Bullet single engine...throw the same money at a Interceptor engine,and have something UNIQUE...too cool... ;)

It's because if you throw alot of money at a Bullet  535 or 612 single, you get very close to the hp of an Interceptor, and still get the 100+ pound  lower weight advantage of the single.

While some claims were made for a high-13's quarter mile for the Interceptor, most averaged in the mid-14's for the quarter mile.
There have already been Bullets that have posted in the high 14's for the quarter mile, and it may be possible to get to the mid 14's, which would put it on par with a typical Interceptor. In any case, it could get very close, and be lighter and nimbler.

Also, if you read most Interceptor road tests of the old days, the company "claimed" 115mph top speed, but most tests showed maybe 103mph-106mph as what they actually could do.
There are modified Bullets that have done 103-106mph or more out there right now.

Add to that the fact that it costs more to build an Interceptor engine because there's 2 of everything to buy, and the vintage parts aren't cheap, and  you end up with reasons why people hot-rod Bullets.
You get comparable power and speed, in a lighter package, and the cost is comparable too.

In fact, the Interceptor is the most powerful version of the big Royal Enfield twins, and the 700 Super Meteor and Constellation have lower power, and they can be virtually equaled by a hot modified Bullet for power.

Plus, I personally think the Bullet engine is a better looking engine, anyway. The vertical twins are too "fat" looking for my taste.

The thing that's better about the twins is that they are bigger, so that they will produce their power loafing along, but you have to push a modified Bullet to do the same results. So,  it will be easier on the engine for the big twin.

A cheaper way out is to drop a Yamaha XS650 engine into a Bullet frame, and get alot of power for only a few hundred bucks. But then it's a Yamaha, not a Royal Enfield anymore.

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bullethead63

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Reply #11 on: January 28, 2010, 10:14:57 pm
All valid points...I can see how building an Interceptor/Bullet could run into a lot of money in a hurry...unless you just HAPPEN to have an Interceptor engine and tranny laying around...and lots of spare parts... :D...I hear that they have a tendancy to throw a rod,as well...sure looks cool,though...
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GeorgeE

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Reply #12 on: January 29, 2010, 03:14:35 pm
I think maybe some of the big REs reputation for coming apart is based on the fact that with the advent of the Constellation they were sold as hotrods. And who is gonna buy a hotrod. The guy that wants to flog his bike.Ton Up guys etc. So if you constantly push something to it's limits it's going to have a tendency to show up any weakness.  Actually the US market got the hotrod a little earlier. My understanding is that the later Indian badged models 58-9 were built to the same specs as the Connie. I will say that my Trailblazer can whip my Connie anytime.
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bullethead63

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Reply #13 on: January 24, 2011, 12:31:49 am
I have found a series one Interceptor engine...this may be a VERY hot thread in the near future!
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carlo

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Reply #14 on: January 24, 2011, 05:32:26 pm
Funny running into this thread right after I expressed doubt about this concept in another thread.  I stand  corrected.

However, my concerns are still worth consideration re: engine mounting for a big twin in a 1955 style frame built for a single.
My 500 twin lacks the head steady and the large aluminum block connected to the swingarm plate at the back, so obviously, it wasn't considered necessary to mount the short-stroke engine solidly. The cylinder heads on it do have undrilled bosses, which could be drilled and tapped for the head steady, so it's likely that the longer-stroke 700 did use them.
The Interceptor engine definatley has head steadies as well as the solid rear mounting. They surely didn't do this if it wasn't needed.
I have a spare 700 engine, . I can look at the  heads to see if it has the bosses drilled and tapped for a head steady.

The other issue I raised -chain aligment- should still be considered. I don't know if the sprocket location for a Bullet is the same as a twin, but the twins have the rear wheel spoked with a slight offset (about 1/2 inch, I think) to center the wheel in the frame. 
If the Bullets have the same offset, then there's nothing to worry about.