A Royal Enfield forum for the people

[Ace.cafe]

Our billet GT head has an oval chamber, but the advantages are not much with the stock 26° valve angles. Chamber too deep. We designed 20° valve angles for a shallower chamber and better combustion. Unfortunately that isn't possible with a stock head.
Regarding dyno results, different dynos read differently, so a few hp/tq differences are not consequential. That sort of ballpark numbers are very good.
For real world riding, a nice fat midrange is the most enjoyable, and a steady tickover for around town is nice.

[Street_Kleaver]

Finally fitted the DID 530 VX3 chain and got her out on the shakedown run tonight. Everything seems fine. No oil leaks, no weird noises.
Had to duck home and slacken the chain off a little. By the manual on the center stand calls for 20-25mm, But when seated on the bike its still a little too tight for my liking so I set it to 30mm slack.

The tune is just the Hitchcocks tune for the cams, valves and piston. But not the other work done. It seems to be fine to run it in but it will need a Dyno tune when everything is bedded. But definitely not where it needs to be. When I came home it was idling a little nicer.
Power wise, it feels normal, yet a little stronger than it was stock 3500rpm, Then it wants to take off like a slapped race horse!
It's still running a short-ish (53mm from the airbox wall) velocity stack which helped the stock cams have a little more legs after 3000rpm when they gave up. I'll order some stainless this week and fab a few different lengths up.
I feel it will need a longer stack like Taurim mentioned in his build thread to sort that bottom and midrange out a little more.

So far so good! Loving it!

Tomorrow I'll give it a compression test to see how its going and take it for another run.

[Street_Kleaver]

Materials arrived to make velocity stacks.
Once again like my Bullet airbox. The stack is made out of a 304 stainless steel donut. So the radius of the bellmouth is the radius of the 1 3/4 pipe.
I've been tacking them together to trial different lengths. Then once happy I'll fully weld one and dress it up.





First test was with the existing Velocity stack. But modified so its a 2 piece setup with a carburetor boot joining the two. For easier changes. This measure 100mm from the airbox wall.





On the test ride it did everything that Taurim had reported with his with the longer stack. Smoothed out the transition up to 3500rpm when these cams come on song. Instead of a abrupt hit. Felt like it gained a little bottom end.

Although the standard boot from the airbox to the throttle body isn't quite straight and has a bit of a off center bend to it.
You can see in the next image what I'm talking about with the exposed edge of the throttle body. So I decided to improve this.



A rough diagram showing how I aim to improve the boot from the airbox to the throttle body and also how to mount the velocity stack. A 3 clamp setup. One on the throttle body, one on the airbox and one securing the pipe for the velocity stack.



Can see the end result here. Its just a silicone hose reducer. 51mmx44.5mm or 2" x 1-3/4". Worked a treat. Secures the first section of the stack and the tract is aligned the best it can be. The Carburetor boot in the foreground for the 2 piece velocity stack setup.





Pictured above is a stack length 90mm from the airbox wall. 10mm shorter from the longest length. Which brought back the known 3500rpm hit these cams do. Which feels no different to the original 70mm stack length I had in there.
Next I'll try 95mm. See if that gets it a happy medium.

I've been making phone calls on various different Dyno tuners. All are over a 4hr drive away for me so I decided to order a Power Commander Auto Tuner and tackle the task myself.
My local dyno tuner who is semi retired and is no longer running his Dyno due to health issues swears by these devices and recommends it for a DIY guy like myself.
Also he'll give me the run down and tips and tricks on how to get the best out of it since he's not running the Dyno.
I have the gist of it, but always open to learn more. Should arrive in a week or so then I can really start testing different stack lengths.

But for now I just wanted to get the mounting of it all a better, sturdier setup.

Cheers

Ben

[Street_Kleaver]

RDO today so I did some odd jobs that have been waiting to be done.
I had a 2nd set of Clubman bars. The set on the bike are a little too far forward.
So this set I cut them up and re-set them a bar width higher and closer to me. Also a little more pull back to get my hands in a nicer position. Tailored to where I exactly want them.
All tig welded up and I'll post them off to be re-chromed.





Also fully welded the new 95mm long velocity stack I made and polished it up.
Auto-tuner might hopefully arrive by Friday.

[Street_Kleaver]

This place is pretty quiet and lack of interest. But I'll keep posting.

Finally the Auto Tuner arrived.
Wiring it up was a little tricky. Since this bike doesn't have auto lights on. I wired it into a switched power coming from one of the relays. The side stand relay with the orange wire. Which the relay is redundant now since I've removed the side stand switch. Which was actually faulty! I had re-routed some cables and it wouldn't start. So off that came, even the Allen socket cap screws were loose! The Autotune module is mounted on top of the airbox. One of the seat hook ribs needed a little shaving but everything is a neat fit.

O2 sensor is tucked in a good spot out of the way of the brake pedal (Pictures make it look like it's not) But rest assured it is. Which I also have new plans for the brake pedal. I don't like the rubber pad on it. Takes away feel, it's also not inline with the foot peg. It feels I have to somewhat do a Pidgeon toed action inward towards the engine to apply the rear brake. So that will be dealt with this week.

Welded a little loom bar tab to the frame for the cable to be zip tied out of harms way. Also Fabbed up a little bracket that bolts to the front airbox mount so the 02 sensor plug mounts via the "X-mas tree" clip.





One of my pet hates on these bikes is how messy the looms are. They tend to just shove it anywhere. Mush it all together and throw a lid on it. This is 10x better than what it was.



Another requirement was since the exhaust system is a lot lighter (1.6mm wall thickness stainless steel) even with the mid mounting point still used. The silencer would get a fair old harmonic wobble up at certain rpms. So I made up another little "Z" stay out of angle. So its like as we call in ship building a "bulb bar" steel section. Keeps its strength since the top edge is a "Bulb" compared to a piece of flat bar. Everything feels nice and secure now.



So far today I've replace the spark plug from a NGK BPR6ES to a colder NGK BPR7ES. Since the compression ratio is improved and now we're onto getting it tuned correctly.
With the laptop plugged in I've just had it idling, setting parameters in the auto tune Target AFR. So far it's cleaned up the idle which was very rich and it's idling a lot smoother with better throttle response.
Taking it for a spin this afternoon to see what the Autotune does. I have a feeling it's going to be rich across the board since the plug that came out of it was black.

[Ace.cafe]

I still check in from time to time.
Bill has been needing some time off with personal matters.
I will comment if I see something necessary.
For now, just watching the progress

[Street_Kleaver]

So she hit "The Ton" tonight on my stretch of road I usually go for it on.

100mph/160kmh at 5500rpm.
It gets to 93mph/150kmh easy, just that last little bit it creeps up but it got there and I held it for about 5 seconds.
So that's good enough for me!

I found that a target of 13 seems to feel the nicest through the bottom and mid range. Unsure on the top end, but its richer to be on the safe side.



What the map looks like after that last target table. Some of the cells need a tidy up with those spiked values. I assume they are from backing off the throttle from higher rpm to the 5% & 10% area.



Below is the original H map for the cams.



Interesting to compare the two since the original map doesn't have the velocity stack setup. Just the venturi plate and DNA standard filter.

[Ace.cafe]

Congrats!
Thanks for posting the map values. It will be useful info for future molders.
Cheers!

[Street_Kleaver]

Congrats!
Thanks for posting the map values. It will be useful info for future molders.
Cheers!

No worries. Shared knowledge is always helpful.

The cells do need a tidy up. The rich spikes I'm guessing are from possibly rolling back and overrun from higher rpm to the 5% and 10% columns. A habit how I ride at a guess.

A question for you though Ace. Its running a taller skinnier 110/80 rear tyre, which acts like slightly taller gearing. With the standard 18/38, gearing. Cruising highway speed is 62mpm at 3250-3350rpm. Just before the cams are "on" which is after 3500rpm. But needs to be slotted down to 4th and wound out to overtake.

The gap between 4th and 5th is quite large. Ideal shifting 4th to 5th has to wound out to about 60mph. Rest of the gears feel nicely spaced for this gearing/tyre.

I'm not sure the rev limiter is on the bike. But it didn't seem like it wanted to get past 5500rpm but did sit there fine at 160mph.

I do have a 17 tooth sprocket on hand. At cruising speeds the cam would be just taking affect.

Try the 17 or leave it at the 18?
Our roads are long, straight and all 62 and 68 on highway speed limits.

Cheers.

Ben

[Ace.cafe]

My general rule of thumb is that the gearing is correct for top speed if you can hit redline rpm in top gear.
However, for comfort purposes, some prefer other gearing.
It sounds to me like the 18 is good for your bike. I always downshift for overtaking anyway.