A Royal Enfield forum for the people

[Street_Kleaver]

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Curiosity got to me and I tried compression test again. This time I did a rolling compression test as well as kicking it over. Needle settled at 125psi/9.6ish Bar.

Kicking it over with these cams mustn't give a accurate reading, I could only get it to 110psi by kicking it. Although with the R cams, kicking and rolling gives the same and looking at my last photos. Compression was 165psi where it finally settled after bedding the rings in with the R cams.

170psi was with the stock Indian cams. I got my numbers mixed up after checking my notes. My mistake sorry.

So that's better test than before. How much do you think advancing 3dgs will get? Along with shifting a little to the bottom of course.

Also speaking of "the ton". Early this crisp winter morning she got up to 90mph and I chickened out. I was running our of smooth road! Haha
I haven't deep dived into jetting this properly yet. I've jetted it baseline on the rich side looking at the plug from a test this morning. I think the ton would easily achieved. Once I get this compression and vacuum behaving better at lower rpm. It will be booked in for a dyno tune with the fuel sniffer up the exhaust.

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[Ace.cafe]

Early on with the Fireball, we used to recommend 130+ psi. I think you will get over that no problem with the advanced cams.
As we went on, we found that the system could handle more with decent petrol and 140-155 psi was a lot snappier. You octane availability may be different than ours, so your results may vary. It is all fuel related because the hemi chamber has no squish, and the compression tolerance is totally dependent on octane.
So, to sum up, I think anything above 130 psi is acceptable, and the higher the better, up until about 150 psi or so on premium grade fuel.

[Street_Kleaver]

The fuel ratings here are different.
Correct me if I'm wrong, I'm scratching memory from when I went through all this when I built my own 2 stroke MX race engines.

We have RON ratings in Australia which is measure about 3 or 4 points higher than the US MON ratings.

Our Premium unleaded fuel is 95 and 98 RON. 98 is basically 95 with cleaning/decarbon agents and toluene additives to bump it up to 98 and for modern efi car engines.

I couldn't run 98 on any of my 2 stroke race engines because the additives would foul plugs and burn "wet". Premium 95, absolutely no issues at all. And I had a 16:1 compression YZ144 (big bore 125cc) that revved most of its life at 10,000/11,000rpm. The ingition did have to be retarded a smidge to stop high speed detonation. Premium 98 would foul plugs both in my YZ144 and Husqvarna 250 2 strokes.

So our 95 is your 91. Using 98 is virtually useless in a older engine that's not efi.

[Ace.cafe]

Okay, then do the 95 and keep the compression under 140 or around there.

Be careful with your ignition timing.
Typically I recommend "ping timing" to customize the ignition timing to your specific engine needs.
If you would like an instructional post on how to do it, just tell me and I will be glad to oblige.
I just don't want to assume you don't already know it.
It is very important to get it right because piston failure is a big issue in Bullets with higher compression pistons in them. I have seen a LOT of it, and it is almost always ignition timing related.

Plug looks basically okay. If you can run a projected nose plug like a Champion N9Y without touching the piston over TDC, it will give a better burn. Gap at .025".

[Street_Kleaver]

All good. Appreciate your input.

I had to do ping timing with the Indian and R cams. They were retarded a decent amount. I got it to a point where it behaved but you had to be mindful and not labour it or short shift or the good ol "clickle clackle" would happen. It was generally right off the bottom.

At present they are at the stock setting. I'm using Pazon Electronic Ignition. They are a good step ahead of Boyer. Can run on very low voltages without advancing and their overall setup is a lot more user friendly for tuning.

The backing plate has 2dg increments. I've got some reference marks on the housing for 10dg advance and the stock base timing set point as a guide for tuning.

Not even close to a hint of detonation at all at the moment.

When I first got this bike. The sounds of this engines valve train used to throw me. There's a tick/tick/tick at a certain happy spot of the rpm regardless the gear or load in the valve train that I initially thought it was detonation. I soon learned its just whirl of the primary chain, the clatter of tappets, cam gears,idlers doing its thing. Haha

[Street_Kleaver]

Plug looks basically okay. If you can run a projected nose plug like a Champion N9Y without touching the piston over TDC, it will give a better burn. Gap at .025".

The N9Y is equal to a NGK BP6ES?
Which is a lot hotter than the standard B8ES?
The projected NGK is a BP8ES.

But I can check for TDC clearance with my TDC tool.

I can't get Champion Plugs locally. I'd have to order them in.

[Ace.cafe]

BP8ES is fine as long as it clears the piston, which I expect it will.

[Street_Kleaver]

BP8ES is fine as long as it clears the piston, which I expect it will.

I'll grab one today. But won't do anything more till the 3-way pinion arrives.
I also got the blanking plug for the de-compressor. I don't use it with the compression as it is. One less thing to leak, which it has done in the past. I'm thinking of making a cable up to use the de-comp lever as a choke. Since the choke location now is not very fun to get to! Haha

[Street_Kleaver]

BP8ES is fine as long as it clears the piston, which I expect it will.

The BP8ES fitted fine with miles of clearance!
Started easier too. Still waiting for my H delivery.

[Street_Kleaver]

Here's some snaps from our ride over the weekend. One of the gentlemen is a talented RE fanatic photographer. Sorry for the blokes who don't run a high resolution monitor or screen.

Just prior to these snaps she hit 90mph with a rich tune and igintion at the stock setting. I ran out of smooth road and chickened out! haha
So there's definitely a beast in there!