[hpwaco]

A brief description of the differences between Bullets,  AVLs and Electras would be appreciated.  When did the UCE come out?   I had a 02 Bullet ES.  thnx, hp

[ace.cafe]

Bullets have the old British type engine with separate gearbox. 1954 type frame. 4 speed gearbox up to 2004. In 2004 the 5-speed gearbox became available . All have drum brake. Discontinued 2008.

AVL have the newer engine design which has some modifications on the old Bullet crankcase, and a shorter alloy barrel with the AVL head that sort of tried to simulate the old Big Head in appearance. CV carb. Most had disc front brake,  but some like the "Classic" had drum breakes. All had the 5-speed gearbox. In the US it was available 2006-2008.

UCE became aviable in 2009. Transmission was moved into the crankcase in the unit construction form. Frame changed, all geometry changed, almost all parts different, fuel injection introduced. All have disc front brake.

[tooseevee]

A brief description of the differences between Bullets,  AVLs and Electras would be appreciated.  When did the UCE come out?   I had a 02 Bullet ES.  thnx, hp

            A Bullet can be an AVL OR an Electra.

            An Electra IS an AVL.

            Do you mean difference between UCE, AVL and Electra?

            I have an '08 Bullet AVL Classic. It has front drum brake, EI and ES.

            If it had a front DISK brake, it would be an Electra.

            That's put very simplistically and I'm sure I'll be corrected on the details.

           

[Adrian II]

The AVL and the classic or cast iron/iron barrel were produced concurrently during the naughties until the whole shooting match was dumped in favour of the Unit Construction Engine (UCE).

The AVL engine appeared in several different bikes for the Indian home market and two export variants. It was originally developed as a lean burn type engine as a 350cc emissions dodger, which required a few upgrades - a steel con-rod and needle roller bearing big end were needed to cope with the higher compression ratio needed to run under lean burn conditions, as well as high-capacity gear-type oil pumps. The higher temperatures in a lean burn engine needed an all-alloy top end, ace.cafe mentioned the head, which is a huge chunk of alloy for conducting the heat away. It also has a pent-roof combustion chamber instead of the classic hemi-spherical combustion chamber used in the classic Bullet head as well as lots of other old Brit bikes. Early versions were fitted to the 350 Machismo home market model (which was otherwise a classic 4 speed Bullet) and had CDI ignition and on very early models launched in 1999, a 28mm Dell'Orto carb!

The 350 Machismo later got a 5 speed gearbox with left-foot shift and a front disk brake, as well as a CV carb, and was joined in the home market by a factory custom 350 model, the Thunderbird. The export market finally got a look-in in 2004 with the Electra-X model, unlike the Indian models this was a 500, again this was a 5 speed model with a front disk brake, electric start, TCI ignition, and the side panels and tool boxes off the Thunderbird. In the USA only the Electra-X was joined by the AVL Classic, same engine and gearbox but bolted into a classic Bullet rolling chassis with a front drum brake.

Meanwhile back in India the final 350 Machismo and Thunderbird models got an electric start and CDI ignition, and the factory finally released a limited number of 500 Machismo models in 2007.

Export market UCE bikes are usually fitted with electronic fuel injection, Indian market versions however were **mostly** still fitted with CV carbs until very recently, but even India has had to catch up. Latest models also now have rear disk brakes and ABS.

I might be able to post some pictures on the older AVL models.

A.

[gizzo]

Bullets have the old British type engine with separate gearbox. 1954 type frame. 4 speed gearbox up to 2004. In 2004 the 5-speed gearbox became available . All have drum brake. Discontinued 2008.

 

So are you saying only the old iron barrels are real bullets? My CGT has "Bullet" as the make on the compliance plate. No biggie to me, just curious.

[ace.cafe]

So are you saying only the old iron barrels are real bullets? My CGT has "Bullet" as the make on the compliance plate. No biggie to me, just curious.

Just my personal naming convention to keep things straight.

[Chuck D]

And then there are the Fireballs...

[hpwaco]

Thanks for all of the info.  That will help me understand/keep up with various posts.   One more question - was twin spark an export model?

[ace.cafe]

Thanks for all of the info.  That will help me understand/keep up with various posts.   One more question - was twin spark an export model?

As far as I know, twin spark was home market product. The regular heads could be converted, if anyone wanted to.

[Kevin Mahoney]

Twin spark was an Indian only product. It was the result of a marketing war with Bajaj. If I remember TVS put out a similar product and got into a large legal wrangle with Bajaj. The RE version which came a bit later than the TVS model did not attract the ire of Bajaj. Those at the factory tell me that it didn't make a whit of difference other than bragging rights.
Could a second plug make a difference? Who knows but it will make for a great argument and engender lots of theorizing.

[Richard230]

Twin spark was an Indian only product. It was the result of a marketing war with Bajaj. If I remember TVS put out a similar product and got into a large legal wrangle with Bajaj. The RE version which came a bit later than the TVS model did not attract the ire of Bajaj. Those at the factory tell me that it didn't make a whit of difference other than bragging rights.
Could a second plug make a difference? Who knows but it will make for a great argument and engender lots of theorizing.

A second spark plug certainly improved the performance of the air/oil cooled boxer engine used in the BMW R1100/1150 models during the late 1990's and early 2000 years.  During that time the engines were running so lean that they constantly surged when trying to hold a steady speed - which really irritated people like me. Apparently the design of the combustion chamber was not conducive to emission requirements as programmed in BMW's FI computer.  However, around 2004, BMW stuck a second spark plug at the lower edge of the combustion chamber. That change completely cleaned up the lean surging and the bikes ran just fine up until the latest WC version of the boxer engine. 

The new water-cooled boxers have a completely redesigned engine, with just one centrally located (expensive) spark plug and they function about as good as you might expect a lean-burn engine to run.  However, BMW has designed and are currently testing another new engine design, with a slightly larger displacement, using variable valve timing that they apparently feel will be needed to meet Euro 5.