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Additionally, you might wanna think about increasing the mix ratio to like 32:1. You may want to also do a 50/50 mix of race gas with your 92 octane pump gas, mill your head to raise your compression, and advance your timing 4 degrees. With those mods, you should be somewhere between 50-55 HP, and have more usable torque that comes on sooner. Good luck with her....

Your tires are fine on the dyno. If they slip, you'll see big spikes in the curve. If someone has a plot of a clutch slipping, they can look similar. By looking at your curve to me, it looks like the transition from your needle to your main is way off. If the curves are progressive runs of leaning your main jet, then I'd say to order the next 2-4 jet sizes down on the main and keep tuning until you get it right. 30ft-lbs of torque at 6000 RPM makes 34.2HP 30ft-lbs of torque at 9000 RPM makes 51.4HP Get your motor to pull the higher RPM's right, and your HP will come right up.

The original question was which head is the best, not which one would you buy. I ran stock carbs on my 4mm motor, because I'm cheap as hell and they performed very nice as is. So, if I were to buy one for my motor brand-new, it would for certain be a NOSS because it is a far better value. Hoping you didn't take my RK Tek recommendation as a jab. Your head and customer service is top notch, Mr Noss.

You are correct, Sir! (in my best Ed McMahon). Cameron sells a ton of them, and recommends them highly too.

Wes gives the best head. Err, actually, I think RK-Tek heads are the best head on the market, but the NOSS is a better value.

Call cameron, he can do all of that machine work as well. Saw him trenching his cases for a 16mm, insane amounts of work to do it. Gotta add a lot of material for the larger cranks. Think his number 541.367.2453, but his website is in my sig, which has his phone number.

Wesw told me that Jim's Sand Toys or something like that charged 350 exchange, and you get a polished cover, which seemed reasonable. I paid substantially less than that for both of mine, but I had to polish the stupid thing, so 350 seemed worth it.

To be completely honest, I ran my 36's for a bit, then dyno tuned my bike, and with the addition of the carbs and some other stuff, I think I gained about 9HP. Yes, I could definitely tell the difference there. But a 3HP gain when you are talking about 100HP would probably only be noticeable if you had 300ft times to compare.

I picked up 3HP going from 36's to 39's on race gas. TQ numbers were pretty similar though between the 2.

If you get a 4mm 110mm rod crank, all you HAVE to buy is a 2mm spacer plate and some top end gaskets. The 4mm 115mm rod crank, all you HAVE to buy is the spacer plate and some 795 pistons. But you'd see better gains out of just porting your cylinders and sticking with your stock stroke crank probably. However, if you buy the 4mm 115mm rod crank, and get your cylinders ported for the longer stroke, you will not believe the difference in HP between a piped banshee and your new one. It is night and day with more power everywhere. My dune port 4mm motor put out over 76HP on pump gas and stock carbs with CPI's. I sold the cylinders to a kid on here, and he's just as happy with them as I was. Click the link in my sig, and give Cameron a call. He's the best guy I've ever dealt with.

HD, that chick wouldn't give you the time of day

Think the front rims have always been a 3/2 offset. Not 100%, but nobody else answered. The bolt pattern on the 87-90 may be different as well. I know the rears are.

Fresh out of prison or just free with your body? :ninja: Count me in (for the pipes giveaway).

How new is your clutch cable? You'd be very surprised how much better the clutch pull is with a new cable. Otherwise, you can alternate the HD springs rather than run all 6. That should be good for motors up around 75HP or so unless you do alot of trail riding where you are abusing your clutch. In that case, you will just need to tough it out. I've heard that some of the clutch levers/perches are easier on the pull as well. Maybe someone will chime in on here about them with a brand and price.

Yes, it's a conspiracy to keep people down on HP. Don't buy a big HP motor, because my tiny ego can't take someone out there faster than me. Engine setup is all about compromise. HP vs $ is one. HP vs setup is another. If you are looking at building a 10mm stock cylinder motor, you will spend more than you would've had you just bought a 4mm cub setup. The cub would most likely kill the 10mm stock cylinder in every aspect of performance dollar for dollar. Another compromise is HP vs chassis setup. Unless you like riding trails with a 8 - 12 inch over swingarm, I doubt you'll be happy with the rideability of your drag racer. Then there's reliability. The 4mm will have less rod angle than the 10mm which equates to less stress on the crank, rod, pistons, cylinders. A 4mm stock cylinder dune port is probably the best compromise of cost/performance/chassis setup that you could buy. There IS such a thing as too much HP. The people that won't admit it have a case of small penis disease.

The 4mm will be a much cheaper route to go. 10mm cranks are about 2x the cost, and you gotta pay to get your cases trenched. Additionally, if you plan on running your stock cylinders, a 4mm crank will be much more reliable and will develop more HP/$ spent. I've had 4 different 4mm motors now (2 cubs and 2 stock cylinders) and they are a very snorty motor for a stock frame bike.

I'd call the same number when you bought the clutch and talk to him over the phone. But it sounds like Champ might be dead on. Take your pressure plate off and rotate it 90 degrees and put it back on. Before you put any screws in it, you should be able to see if it's fitting flush against the outside fiber. If not, rotate it again. I think there are aligment arrows for the orientation, but I can't remember.

Alternating 3 stiffer springs with stockers is a pretty common practice which seems to be a good compromise between a stiff clutch pull and a tight clutch. It's not like you have half of your cluth with stiff and half with soft springs, it averages out to be somewhere between the stiff and soft springs.

congratz, man, stay with it.

33? Had no idea you were my age. Have a good one, man!

I'll echo the above sentiment. Stock carbs ain't the problem. If the port durations weren't altered much with your mild dune port, your CPI's won't be much of an upgrade, if at all. I ran stock carbs on a 4mm dune port, and that thing ran very hard.

I've seen stock carbs setup for alcohol for sale, so it must be doable. Whether you'd get good performance out of them......I dunno.

The caliper can actually slide in and out on the mount. Odds are it's hung up and just needs some encouragement to align on the rotor. I used a large flatblade and pry'd out on the caliper and got it freed up, then moved it back to where the pad wasn't rubbing on the rotor anymore.

The tusk clutch is pretty good. I ran one for a full season in my 4mm 80HP duner, and ran the same clutch for 3 months when I upgraded to my cub. For the mods listed in your sig, I think a $125 clutch is a waste of money. If RockyMountain has just the clutch in stock buy it, and buy 3 Toomey springs from Cascade Innovations ($3 each). You'll have a good solid clutch.

The Bible would be irrelevant here. What we really need are some anti-semetic lyrics from a death metal band to show us the truth.