Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: ringoism on March 30, 2019, 07:08:19 pm
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Renewed my bike insurance here in India recently and was surprised to find that any bike over 350cc's has now had the third-party insurance rates tripled. Leading me to get thinking:
I've already got the AVL500 (Machismo), but in researching rebuild options for its crankshaft was reminded that the connecting rod / crankpin are same on the UCE350's as on the 500's / 535's - which suggests that the bottom end is pretty much overkill for a 350, and that it could probably easily handle some significant power enhancements with great reliability / longevity.
For local use here in the hills (at 7,000ft), 350's have seemed a little too tame for me, but with just a few more hp one could probably be nearly as useful as the stock 500, with lower purchase/ running / insurance costs, etc...
So suppose I buy one worn-out and dirt-cheap (running ones can sometimes be had as low as $400 here now), lighten the bike as much as possible, and rebuild the engine to where I might lose a few kmpl in fuel efficiency (45-50 down to 40ish maybe, which is still a fair bit better than the 500, and about as good as my 150cc Honda commuter), and maybe pump up the power from 20hp to perhaps 24ish (20%)... Vs. the AVL, I'd now have quieter hydraulic lifters (much better for my tinnitus), the auto cam backlash / primary chain adjusters, etc... A good daily rider in other words.
Any thoughts on how to achieve this?
(I seem to be hungry for a new project already)
-Eric
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Are you riding the bike ONLY around your 7000 feet elevation, or do you go down to low elevations with it?
I have a good reason for asking this.
Being at 7000 feet elevation with very thin air, your engine is making very low compression. This is an unavoidable by-product of high elevation.
The remedy is to increase your static compression ratio to compensate.
At the very least, you should do the squish mod like we do on the 500. If you can go further and do the BW piston mod to get even more compression, you should do that. If there is a flat top piston available for the 350, then start with that and do the above mods.
If you are going to buy a used engine, then buy a 500 engine and drop it into your 350 frame, and just don't tell anyone so it doesn't affect legality. Then you can do all of the above mods to the 500.
But just for the minimum, you have to increase the compression ratio. That will be a big help at 7000 feet.
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Are you riding the bike ONLY around your 7000 feet elevation, or do you go down to low elevations with it?
I have a good reason for asking this.
Being at 7000 feet elevation with very thin air, your engine is making very low compression. This is an unavoidable by-product of high elevation.
The remedy is to increase your static compression ratio to compensate.
At the very least, you should do the squish mod like we do on the 500. If you can go further and do the BW piston mod to get even more compression, you should do that. If there is a flat top piston available for the 350, then start with that and do the above mods.
If you are going to buy a used engine, then buy a 500 engine and drop it into your 350 frame, and just don't tell anyone so it doesn't affect legality. Then you can do all of the above mods to the 500.
But just for the minimum, you have to increase the compression ratio. That will be a big help at 7000 feet.
Thanks, that's right.
For that reason mainly, I shortened the barrel (by 2.5mm if I recall) and did the squish / corresponding piston crown mod on the 500AVL, (static) compression is a good bit higher than stock, and that's presumably where most of the performance improvement came from. And no detonation (/pinking) on the standard pump fuel here, though I probably never got it down below 6,000ft in 2,000km's after building it.
But in the UCE we have hydraulic tappets with no adjustability, right? So how does that work when shortening the barrel?
I very seldom go below 4,000ft (been as high as 18,300 which is rare, but 11,000+ is not!). Can't rule out an occasional trip down into the plains, but in those cases I guess just would have to go easy on it, use the highest octane fuel available, make sure I'm not getting into detonation.
-Eric
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Thanks, that's right.
For that reason mainly, I shortened the barrel (by 2.5mm if I recall) and did the squish / corresponding piston crown mod on the 500AVL, (static) compression is a good bit higher than stock, and that's presumably where most of the performance improvement came from. And no detonation (/pinking) on the standard pump fuel here, though I probably never got it down below 6,000ft in 2,000km's after building it.
But in the UCE we have hydraulic tappets with no adjustability, right? So how does that work when shortening the barrel?
I very seldom go below 4,000ft (been as high as 18,300 which is rare, but 11,000+ is not!). Can't rule out an occasional trip down into the plains, but in those cases I guess just would have to go easy on it, use the highest octane fuel available, make sure I'm not getting into detonation.
-Eric
Either shorten your pushrods by the same amount that you take off the barrel, or buy new ones of that shorter amount.
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when I had my uce 350 I tried just a sports exhaust for $80 and got very good increase in the power, same too with the 500 $80 on a muffler and the difference is noticed immediately. after that its more work and more $$$
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Sad the REs 350 or Thunderbird is not imported to the USA.????I would buy the Thunderbird 500 X and a 350 Signal in a second if the were.????
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when I had my uce 350 I tried just a sports exhaust for $80 and got very good increase in the power, same too with the 500 $80 on a muffler and the difference is noticed immediately. after that its more work and more $$$
Did you need to re-jet with the new exhaust? Just wondering as I have a stock 350 UCE, and a pipe in the post...
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I think it would be a very good idea especially when you start moving it along at a quicker pace and the motor is working harder