Angle head over intake

MacZulu · Dec 11, 2015

so I put the head on originally with the plug over the exhaust, because I read about the direction of the intake shot into cylinder so put the plug in its path. then someone told me that the whole point of the angle head was to separate the heat of the exhaust port and the spark ignition, that the plug was meant to be over the intake. so I spun mine around and went for 20 mile run, I'm at the tail end of breaking in my engine but she ran very well. best inclines I've done yet, and good idling. I think it took longer to warm up to it happy idle state as well, a good sign to me. so I like it, and will keep it this way.

bairdco · Dec 12, 2015

The main purpose of the angle head is for clearance. It really doesn't matter which way it faces.

maniac57 · Dec 13, 2015

I agree with Bairdco. Any difference is tiny and probably in the mind of whoever is looking

Motakitty · Dec 13, 2015

How far should the spark plug be going into the head on the angle head? My plugs tip is still in the head. Shouldn't the electrode be in the combustion chamber?

crassius · Dec 13, 2015

not a lot of room in there, but a projected tip plug usually works

MacZulu · Dec 13, 2015

the only difference that I would expect, is better heat distribution by separating the spark and the exhaust. It does seem to take longer to get warmed up, and I think it looks better on my set up as well.

sbest · Dec 14, 2015

I was just experimenting with this with my Grubee Skyhawk today. Works much better with plug to the rear. Plug got hotter when to the front (white insulator) and failed the hillclimb test (local steep 1km hill). Got so hot it spark-knocked and would not shut off on the kill switch due to auto-ignition from the hot electrode. To the rear it did the hillclimb just fine.

Steve

Chaz · Dec 14, 2015

This is interesting. After I get my expansion chamber on I'm going to try it and see if my engine prefers one way or the other. Thanks for sharing your research guys.

crassius · Dec 14, 2015

sbest said:
I was just experimenting with this with my Grubee Skyhawk today. Works much better with plug to the rear. Plug got hotter when to the front (white insulator) and failed the hillclimb test (local steep 1km hill). Got so hot it spark-knocked and would not shut off on the kill switch due to auto-ignition from the hot electrode. To the rear it did the hillclimb just fine.

Steve

I would suspect a gasket leak happened during the turning process, or some other cause, as these motors usually aren't that picky about small changes.

bairdco · Dec 14, 2015

I've run both, and always found the angle heads to be slower, a lot hotter, and generally worse all around compared to a straght plug head.

Actual performance angle heads have a totally different combustion chamber design to maximize burning, hp, etc.

The stock angle heads just have less "metal" on one side and a crooked plug.

When they first came out from china, they were advertised as being for tight clearances. Some time after that the were suddenly called "performance" heads, which was from people duped into believing they were faster and better, like a car muffler guaranteeing you 15% more horsepower.

But if it works, or you think it works, for you, go for it.

sbest · Dec 14, 2015

crassius said:
I would suspect a gasket leak happened during the turning process, or some other cause, as these motors usually aren't that picky about small changes.

No gasket leak. That would show up very easily with the nice shiny aluminum head gaskets, and believe me, I know a gasket leak. Seen plenty over the years.

Was doing a day of tuning with a hillclimb as a hp test. Early on the Chinese 3 pronged spark plug failed from fouling. Engine is 2 tanks from new and the 20:1 oil and rich mixture finally killed the plug within 2 km of turning the head around. I dropped in a new NGK BPR6HS if that might be a factor? Any suggestions?

Distinctly ran hot (white) as if it was too hot in the forward direction, ran fine (tan) in the rear direction. There was also some 4 stroking issues in the forward direction at low speeds also.

Steve

Chaz · Dec 14, 2015

A mix of 32:1 is commonly recommended by the experts here. I broke my new engine with such a mix and it broke in fine. I ran the first ten or so tanks with dino oil to seat the rings and then switched to synthetic at about 50:1

I think the NGK BPR6HS is a good plug from my own experience and also from what I've read here on this forum.

hope you're having as much fun winter riding as I am, it's bloody monsoon season here on the wet coast.

crassius · Dec 15, 2015

perhaps during the run in period, those changes might have happened either way - test would be to change back again & see if diff is still there

Chaz · Dec 15, 2015

Crassius is definitely correct. Things change during the break in process. Mostly, performance and manners improve.

Chain will also stretch a fair bit so keep an eye on that. And the tensioner likes to creep into your spokes so watch that also.

sbest · Dec 15, 2015

I got a few breaks in the rain. Spun the head around again and it absolutely works better with the plug to the rear. I don't really know why but there is no doubt. I read about the cooling fins to the front, but it is 10c and raining here today. Cooling is not an issue. Plug to the front I get loping and 4-stroking, lots of rev on downhills but less torque on hills and over heating, turning the plug white. I suspect the torque on hills and overheating is a pre-ignition problem. I can hear death rattle as it heats up (I back off the throttle). Plug to the rear I get steady power, tan plug and good torque on hills.

This is only the 3rd tank of gas in this engine. The 20:1 did sound very rich, I'm used to 50:1 in my KTM but hey, follow the book, right. Next tank I'll try 32:1. This plug seems a bit hot, and maybe the exhaust side of the head runs just hot enough to put it over the limit?

This is the beauty of these engines, 5 minutes to spin the head around. Awesome! So simple to work on and experiment with. I bought a spare $30 cylinder so I can experiment without fear. I'll try to send photos of my progress.

I put the engine together totally stock, including undersized gaskets. One by one I will fix things up and see the progress. The hill and a GPS should give me a measure of progress. Even completely stock, I am very pleased. Quiet and strong, even at low rpm. Vibrations are not bad, and it goes faster than I can pedal the mountain bike.

Steve

Chaz · Dec 15, 2015

Hey Steve, yeah we got the same temps here, even a little colder and, of course, the rain. I never worry about the heat except when breaking in over the summer.

The manufacturers suggest a heavy oil mix to protect the warranty so they don't have to deal with a lot of squeaked pistons etc.

I don't doubt that little changes can be noticeable so keep your head where you want it if you are getting good results. And it's great that you have motorcycle experience. Also good that you are breaking in with the stock set up. Best to do the performance mods afterwards if you want to go that route at some point.

Anyway, glad to hear you've got a good thing going there.

Venice Motor Bikes · Dec 15, 2015

Having the spark plug over the intake actually helps the engine run cooler (& thus perform a little better) by placing more of the heads cooling fins over the exhaust (which is the hottest part of the engine).

crassius · Dec 16, 2015

I've often heard a kind of popcorn popping sound on a motor at high revs during run in period. I've come to believe this is normal and just a bit of piston slap until the rings seat well, as it seems to clear up after a while. I just slow it down a bit & wait for run in to complete.

Ducati250Single · Dec 17, 2015

crassius said:
I've often heard a kind of popcorn popping sound on a motor at high revs during run in period. I've come to believe this is normal and just a bit of piston slap until the rings seat well, as it seems to clear up after a while. I just slow it down a bit & wait for run in to complete.

There is no ring seating to speak of on these motors, the cylinder bore is chrome plated, seating only occurs on bare metal honed cylinders.
Also the plug that came with my motor, ( stinger), was too short, but it ran perfectly. But, I still changed it to an NGK B5hs, which has the correct length threads.
I'd say that the angle plug head is just a gimmick to make people think this was a performance benefit, it makes no difference at all, you can't get any better than in the middle of the combustion chamber, which is what the stinger motors have, and all these China motors had in the beginning.

crassius · Dec 17, 2015

after about 100 miles or so, the black seating prep on the rings goes away leaving shiny steel

Angle head over intake

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