Ignition systems, small engines/clone, timing - discuss?

sho305

Anyone into ignitions? I see the newer vanguard does advance timing some with a transistorized magneto (magneto = flywheel powered ignition) as does the new honda.

The issue I was looking at is my G9 I will put a clone into has advance in the ignition; the manual shows iirc 0 degrees advance at idle I'd guess for easy generator starting action. Then at about 1K rpm it climbs to max of 30 degrees at 2500.

I did some reading a while back on it but found no real conclusions. It seems lawn engines are barely worth doing advance because it helps you primarily in upper rpm ranges they never see at 3600rpm. They also are not supposed to be loaded under what 1500 rpm, run low compression and not much advance, so pre ignition should not be an issue. Honda says they went to this new advancing mag ignition because it will save fuel, from what I read it does not advance that far like <10 degrees.

So anyway you get up to 5K rpm more like a car it seems some advance would help right? So I was thinking would it be a good idea to try to use the G9 ignition on the clone? All I would have to do is fab a mount near the flywheel for the pickup. I don't know the difference in the magnet used for the G9 compared to what the magneto in the clone has. I would make the mount adjustable for timing changes. Or you can buy the GY6 ignition parts pretty cheap even the adjustable boxes, but they have a different powerband/cam than the clone. The G9 and the stock 420 clone seem to be very similar aside from the clone making a lot more power. One could always try a vanguard/etc magneto coil on a clone as well.

I plan on cutting the head, minor porting, timing advance of some kind, different carb, better valve springs or shims. They say don't go over 6K or the flywheel is not safe anymore (for gokarts). I can't get much over 5K with the stock clone having only big airbox and exhaust. Also don't see me running it WOT down roads much at all, so close to 6K capable and more power everywhere would be a nice start. I'm curious if it will make much difference. The different carb is more for tuning I can't get the stock one to work well at low speeds and it might be limiting rpm as well, I'm thinking a 26-28mm or so? The stock carb spacer is about 28.5mm it measures 1.125".

BGW

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hookm

I've decided after 2 clone engines,a 390 & a 420 that the advice I would give anyone contemplating a clone or Honda 390 is to save your money till you can afford a V twin.I've spent enough money & time to buy a 23 from Tom & still don't have the power they do.I've done every thing but a cam in mine & it runs really good but the end result isn't worth it.
My latest version,the 420 with a NR Racing carb,340 head,rev kit & ARC billet flywheel runs good enough that I'm not going to take it out until after the CAW but it won't out run a V twin & to make it do that wouldn't make sense money wise.
Any body want to buy a couple of Clones?hookm

sho305

I had around 500 total into the clone I put in and this one will be cheaper, and it has around twice the power of the old tired yami motor far as how the cart runs. The owner (family) is very happy with it excepting the carb not being quite right (its 90%) at lower speeds. I see 1300+ just to buy the 23 v-twin ($1K+ for an 18?), sure its nicer, sure that is going to be ~3X or near the funds when its done.

I agree if you build up a clone you need flywheel, rod, cam, valvetrain just to start with and that will cost you near what a vanguard does. The package deal is 750 (NR also has). Not sure how good a deal that is then: 250+750=1K plus labor. You can get an easy 30hp with a cam, but you need that other stuff to use a cam lol. There is only one cam I found they say you can use with stock parts its a torque cam I think from Precision. And 30hp but the twin will have lots of torque, will need more clutch to get rpm on the clone.

None of these lawn engines will make much more power from mods unless you put a cam in them and usually at least a rod and valvetrain parts, with the clone you need a flywheel too.

I'm bummed it has not worked out for you Hookm, you made some great posts on clone stuff. I think I will be ordering a $250 420 clone here soon for my cart. But this cart I use for so much stuff it has to be reliable, I really don't want to go crazy on it and others use it too. The clone can run like stock just more power, I can find a different cart to go crazier with. So what the heck figure I might as well try those cheaper minor mods and then I can direct compare to the stock one and see what the difference is. Just wonder if more timing advance is going to make it rev better, this stock one will not rev no matter what lol.

Come on Hookm, get a rod and cam for that 420 and see.....

sho305

Darn, I was hoping some of you gurus would have some insight into timing curves and their use in small engines/etc....and if it is worth messing with.