Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet Electra & AVL => Topic started by: luoma on October 05, 2007, 10:58:47 pm
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Having a bit of a problem lately with top end. The bike is acting stubborn about getting into the high end of the rpm range. Still runs good when just putting around, but on the rare occasion that I goose it, it struggles to hit 70. This is an Electra with performance kit and larger front sprocket, so it doesn't make sense. Could it be that I am inept at doing the push rod adjustment?
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Although the setting shouldn't change, an overly rich mixture can have this effect.
If it were mine I'd check two throttle positions to eliminate them as possibilities:
1) wide-full-open: if I had one (or two) smaller (leaner) main jet sizes I'd swap those in
2) 1/4 to 3/4 throttle: lower the needle one position (leaner)
I would swap in a new spark plug and eliminate that as a possibility
If my carb is CV, I would check the diaphragm to make sure it is seated properly and isn't ripped/torn or otherwise punctured
As you suggested, I would ensure that the valve clearance is correct - not by the twirl method - but by feeler guage. (see my RE notes link in my signature).
I'd also ensure a clean petcock and even fuel flow.
Good luck!
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Thanks. I've been wondering about the carb. I have the CMW flat slide 30mm. I'm thinking of having my dealer put a sniffer in the tailpipe and dial it in like he does his vintage race bikes. As far as the valves go, I have been using the twirl meathod. I did purchase a feeler gage and will pop the valve coveres off and try to do it the right way.
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Today I took the tank off, and tappet covers, to torque the head. I checked the valves and they apear to be spot on. My dealer, a vintage Brit bike fanatic, said it was probably the main jet. He wants to put it on his dyno and tweak the tuning. I'll probably drop it off there when I go on vacation in December.
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Today I took the tank off, and tappet covers, to torque the head. I checked the valves and they apear to be spot on. My dealer, a vintage Brit bike fanatic, said it was probably the main jet. He wants to put it on his dyno and tweak the tuning. I'll probably drop it off there when I go on vacation in December.
Keep us posted on the results!
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No problem. He's got a tailpipe sniffer on his dyno. Once he gets all the jets and settings right, I'll post them so that everyone with the same performance kit has at least a starting point to work from.
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My dealer, Robert Mclenden at D&D Cycled in Pensacola put my bike on the dyno yesterday. He determined that the main jet needed to be 125 rather than the 140 it came with. He also moved the needle another notch leaner.
I have the CMW kit with the flat-slide carb and drilled out baffle in the classic silencer.
A dyno run CMW sent me before I bought the kit reported 22.3 HP and about 24-25 pounds of torque. I didn't get those results. I guess every RE is a little different. Once tuned correctly, the dyno showed 20-21 HP and 29-30 pounds of torque at the wheel.
Results may have been better if I was better at adjusting the valves. I think that is the problem with my top end problems lately. The bike doesn't run up in the higher rpms quite like it has in the past. It's strong up to about 5000, then struggles. But it gets to 70 real fast. I think with better push rod adjustments I'll get zero to 6000 back again.
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I have the CMW kit with the flat-slide carb and drilled out baffle in the classic silencer.
Results may have been better if I was better at adjusting the valves. I think that is the problem with my top end problems lately. The bike doesn't run up in the higher rpms quite like it has in the past. It's strong up to about 5000, then struggles. But it gets to 70 real fast. I think with better push rod adjustments I'll get zero to 6000 back again.
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luoma, take this for what it's worth but i don't think you are having a valve adjustment problem. besides you already said they were spot on. a question for you...... you said in the past the bike ran fine..... was this before the performance kit was installed ? was this before the new flat slide carb. was installed ? what was the last mod you made before you noticed the problem. see what i'm getting at.... try to isolate the problem. if you were having a valve adjustment problem as in being to tight then you would be having a problem through out the entire rpm range and possably some backfiring through intake or exhaust.
just trying to help you think back to when the problem first occured. all mods should be done one at a time so if something goes wrong you know what it was.
hope this helps you some. let us know.
cyclepath
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Actually, the first mod I made was the carb. The wrong exhaust came with the kit and I had to wait for it. I ran 80 one day just to see what it would do (I usually never ride faster than 60-65). After that, I put the new exhaust on, then later added the 19-tooth sprocket. I hadn't tried a speed run for a long time, then when I did, found out it had a hard time at 75. However, I am also pushing a lot more air with a windsheild and saddle bags, and we have windy conditions here on the coast.
What I was thinking, is that if I had the valves a bit on the snug side, it would run fine, but begin to float the valves earlier than normal. I may be wrong with that assumption.
Otherwise, the bike is runningbetter than ever. I have no real need for speed, except if I want to use a short stretch of interstate as a connecter to better roads. Even then, I usually just find a group of slower traffic to cruise with. Even with a windsheild, anything above 65, the fun stops.
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What I was thinking, is that if I had the valves a bit on the snug side, it would run fine, but begin to float the valves earlier than normal. I may be wrong with that assumption.
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yes i believe this would be the wrong assumption. however it would be easy to loosen them up a tad to check.
it's beginning to sound like you simply don't have enough horse power to pull the taller gearing and push more wind with the bags and shield. 23 horse power is not much. put the other gear back on and see what happens.
i have a small yamaha tw200cc that would run 75 mph top speed and would get there pretty fast for such a small bike. i wanted less rpm at that speed for hiway use so i went with one tooth larger on the engine sprocket and the bike would not pull 75 mph anymore. i had less rpm's then before at 65 but also it was not strong enough to pull the higher gearing. might want to do some testing if it's important to know. i went back to the stock gearing.
cyclepath
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What I was thinking, is that if I had the valves a bit on the snug side, it would run fine, but begin to float the valves earlier than normal. I may be wrong with that assumption.
I don't think a basically stock RE can float the valves. And if it would happen there is absolutely no doubt from the engine sound. And sustained for any length of time, there is a chain of events leading to engine destruction.
The overall cam timing, scavenging parameters of the engine and engine design elements precludes this from happening when the engine is running under load.
Don't focus much on the valve/pushrod clearance as long as the lash is adjusted per factory specs. This for proper valve seating under operating temperatures.
The thing to focus on is final drive ratio, wind (parasitic) resistance and total loaded weight. I'd drop back to the standard front sprocket - a good factory engineered compromise for the engine parameters.
Regards, Foggy
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Thanks. I might go back to the 18-tooth whenever I have to change chain and sprockets (I think about 10,000 miles is recommended). Until then, it runs great so I won't worry too much.
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The bike doesn't run up in the higher rpms quite like it has in the past. It's strong up to about 5000, then struggles. But it gets to 70 real fast. I think with better push rod adjustments I'll get zero to 6000 back again.
I just wonder if you have a Smith tachometer on your bike?
I would not take my Enfield up to 6000 RPM for any reason. The factory HP rating is at 5500 RPM - and held at that RPM the ride would not be nice because of vibration. Plus extra wear and tear on the classic engine design.
The BSA A65L Lightning had a factory RPM rating of 6200 RPM and the Triumph Bonneville had an RPM rating of 6500 RPM. Riders of those two bikes, in reality, never went over 5000 RPM unless hot shifting in a drag race.
My buddies in the 60's who owned these two marques let me ride them - if memory still holds true they shook more than the RE Bullet. They were shifted by feel even though they had tachs. Just like a no tach RE Bullet or Harley today.
Regards, Foggy
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The factory HP rating is at 5500 RPM - and held at that RPM the ride would not be nice because of vibration. Plus extra wear and tear on the classic engine design.
Where did you determine this? I've been trying to obtain the 'official' redline for the LB engines from both AVL and from RE. (As well as posting the question to many sites). So far, I have not seen the official redline from the designers - AVL.
I suspect the AVL LB has a higher redline than the ages-old 5000RPM
Matt
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Hi Thump,
I don't have the lean burn engine. But my Sixty-5 owners manual has 5500 RPM in the tech specs. section. This is the HP graph curve RPM. The max torque is at 3500 RPM. I would say the sweet spot is 4500 RPM.
This classic design engine is no different in stress parameters then the Norton, Triumph and BSA bikes of yore. In the real world, owners of these bikes, with street use, hardly ever would hold sustained RPM over 5000. Plus they'd be going above the speed limits over 5000 RPM.
My Sixty-5 is shifted by feel and rarely does a sustained 65 MPH on the speedo (actual speed 61 MPH).
Regards, Foggy
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Thanks for all the inputguys. I'm not too worried about top end anyway. Only reason for a speed check is curiosity. After remembering back on the days of makeshift mods on old dirt bikes (I'm talking early 70s), I think I know what happened.
I got a dyno run sheet from CMW, taken when they installed their kit on their own bike. By dyno run showed less hp than theirs, but more torque. After shaking loose a few brain cells, I'd be willing to bet the difference in in the fact that I have far less back preasure on my bike. A certain amount of restriction is beneficial.
I remember on my old trail bike, I'd remove the baffle when heading to the hills for a bit more low end power, but put it back in during the week when riding to school and back for better cruising speed.
As ir is, I like the feel of 30 pounds at the rear wheel. HP may be a bit down, but on the flat roads of Florida, who cares.
I might pick up another silencer and swap them to see what the difference is. (I drilled holes in the baffle of mine for better motor music.