dlnoss

Like badassbanshee479 said, The builder doing the porting should be able to recommend the best dome for their porting. -David

The $58.50 with the BHQ discount is from Noss Machine and probably a couple of other site sponsors. I can't quote prices for them but they might sell them for the same price. -David

If you don't find some used ones or a better deal, new ones are $58.50 + shipping with the BHQ discount. -David

I'll ask Calvin if he cares if I make a head for the DM. I've had a few people ask about them. I know the DM dome sales have picked up lately. -David

I'm not slamming it. It's kind of cool looking except for the finned part. If it does use standard size domes, I don't see how it would work with a Cub or other 68mm bore because it doesn't 'contain' the entire base of the dome. I've seen the Phat heads before for small 2-stroke bikes. -David

I don't understand the question if it's a question for me. -David

Pro Design must use different language to describe their domes than I do. I don't really refer to any of my domes as 'big bore' domes. I just made some 85mm bore Sabre domes,,,,that's big bore. My 'standard' domes are for Banshee pistons up to 66mm bore. My 'Cub' domes, the ones engraved 'Cub 20', etc., are for 68mm bore, Blaster piston. My custom domes will usually be engraved something like 19 13 047 meaning 19cc, 13 degree squish area, and 0.047" squish step in the dome. If someone is buying a big bore dome, or any dome for that matter, they should be sure the squish angle (or sometimes the squish radius) matches the pistons they are using. .....Just a little info. -David

If you are close to sea level, 21cc would be my recommendation with 93 octane. If you order the Noss Head, be sure and mention your BHQ membership if you call or use BHQ for the coupon code on the web site. It will save you 10% -David

Your compression isn't bad for your elevation. The regular domes will work with up to an .080 bore so the motor work won't require any change in the head/domes unless you decide to do a Cub motor or something. The head would still work but you would probably need different domes. 19cc domes might be a safer choice for a stock crank. -David

I don't do any porting or tuning. There are several good builders in Oklahoma and Kansas. A couple of them are BHQ sponsors.

I don't use Pro Design domes. I make the domes that I sell including stock bore, big bore, Super Cub, Puma, Sabre, DM, DMX, late model Cheetah, and a few others. My domes will work in the Pro Design heads and visa versa. I don't think those are 'my' domes in the picture. I engrave the numbers. Those numbers are stamped. -David

19cc at 1000' with 93 octane sounds kinda risky to me. I'm in Oklahoma also running 19cc domes but I run race or at least avgas. You might get away with it,,,,but you might not. -David

20cc domes would be one size larger giving you a little lower compression than 19cc domes. Unless you are riding above around 900', I would recommend 21cc domes for premium pump gas. Advancing the timing very much has an effect on the dome size also. -David

It's a little hard to say for sure with someone else's dome design. If you have a specific volume you are shooting for, and a specific squish width (say 40%), you have some choice on the bowl shape, mainly how it transitions from the squish to the bowl. I prefer flatter bowls but they take a little longer to design because dome software doesn't usually calculate for multiple radii in the dome shape. I guess I'm not really answering the question, because the answer isn't really the same in all circumstances with the variables of porting, fuel, etc. -David

There are of course some limiting factors for the spark plug height; volume required, squish area width desired, etc.. If the piston doesn't hit the squish area, it won't hit the spark plug if the plug is flush with the inside of the bowl. I interpret the book to mean you don't want the bowl to be any deeper than it has to to get the proper volume. The wider the squish area, the deeper the bowl will be. I have made some domes with flatter, shallower bowls (keeping the spark plug closer to the piston) by stepping from the squish area 'up' into the bowl area instead of making the bowl area a constant radius. -David

The pipe rubbed a hole clear through the head? Wow!!! I don't do any welding but I would like to see a picture of that. -David

Your domes may be damaged. If you want to send them, and the head if you want, to me I will check them out. -David

You can get the stat-o-seals at Sealco or Seal Company since you are in Tulsa. They are over by Grainger. You can ask for the 5/16" ones. I don't know if they have them in metric sizes. -David

215 psi is pretty high. I wouldn't rule out detonation. The plugs backing out is a good indicator. 'Stock' domes are 66mm, or .080 over, so that could be an issue. Bigger bore domes with the oring groove moved to the outside edge would probably help. I'd consider going up a size or two also. If the acorn nuts are bottoming out, you can stack a couple of washers or use Parker Stat-O-Seals which are thicker and have an oring vulcanized into the middle. Just some ideas. -David

Noss Machine Web Site You can use BHQ as a coupon code at checkout to get the 10% BansheeHQ discount. It makes it $234 + shipping. I'd recommend 21cc domes for 93 octane if you stay at +4 or less on the timing. (Even if you get the PD head) -David

Have you checked the squish clearance to make sure you don't have way too much? 17's are small. I don't think I've ever had an order for 15cc domes, maybe one order for 16's in the past four years. -David

You could probably do ten or maybe nine degrees. You can calculate the volume of the cylindrical 'slice' that you add to get an idea of the actual flat plate volume.

There are so many variables in a 2 stroke, it's tough to make 'general' statements. Usually a narrow squish band is better for high rpm, wider is better for lower rpm although there are exceptions. Lunatic, I would cut the angle at 11 degrees for Blaster pistons running gas. A 7mm stroker dome with an additional 3.5mm step cut into it would cc at 11.97cc more for 66mm bore and 12.71cc more for 68mm bore so a 30cc flat plate would actually be 18cc at 66mm or 17.25cc at 68mm.

Flat plate volume is usually what is referred to when domes are ordered since that is how they are checked when not installed.

I put a plug in it and clamp a piece of lexan with a hole in it to the bottom of dome. I fill it (upside down) with a burett. A cattle syringe would work if you don't have a burett.