With the current market - get the ones you can get hold of...

 

With the current market - get the ones you can get hold of...

I've located a set of each, thus the question. Similarly priced, however one would require purchasing flanges.

 

My advice would be crank shops...either way make sure they're for your sled and RPM range you're looking for. Paperwork/receipts from when they were purchased is the best way. Otherwise you might be rolling the dice on used pipes.

 

or you can measure the pipes and see what rpm it's suppose to run.

 

As I understand it...

The Dynoport trails make power at ~8500-8600, just below the CK3 rev limiter.

The crankshops will make a lil more power, but want a lil more RPM to do so.

I can't speak for the 98 Mach Z and if that CDI box has a rev limiter or not.

 

My advice would be crank shops...either way make sure they're for your sled and RPM range you're looking for. Paperwork/receipts from when they were purchased is the best way. Otherwise you might be rolling the dice on used pipes.

Whats the reasoning for the crankshops over the dynoports? I spoke with crankshop and got measurements for pipe ID to determine what RPM variant they are, so this wont be a blind purchase.

As I understand it...

The Dynoport trails make power at ~8500-8600, just below the CK3 rev limiter.

The crankshops will make a lil more power, but want a lil more RPM to do so.

I can't speak for the 98 Mach Z and if that CDI box has a rev limiter or not.

Its my understanding that one of the only desirable things about the 98 (which is what i've got) is that the CDI has no rev limiter ha.

 

Are you milling the head and doing the matching .059" base gasket?

 

Are you milling the head and doing the matching .059" base gasket?

Likely to do so. I purchased this sled in february as I just wanted a triple, and now its clearly spiraling, ha. Its an unmolested 98 with e start / reverse.

I was planning to pull the engine this fall and clean out the engine bay, and generally clean it up. Measure the squish with the current base gasket, and figure out if I want to machine the head myself or send it out. For 75$ its probably not worth my time to fart with it, but I do like doing things myself. Sounds like crankshop mills around the domes so they recess into the cylinders slightly when removing enough material to run a 0.059-0.060" base gasket. I havent had one of thse triple heads in my hands before so I dont know if the domes are removable or not, and weather or not they're reshaping the squish chamber. I'm not a stranger to squish ect, i've done a few YZ motocross cylinder heads, and brought the volume back in the bowl after correcting squish clearance.

I've got a set of V force reeds I picked up that will be going on it too.

 

The domes in the stock head are not removable. The Crank Shop does mill out the triple heads and install removable and replaceable domes at a price.(not cheap) I know.

You have to supply the head for your engine. They do do nice work.

Check those carb boots closely for cracks or signs of deterioration.

Lynn

 

I'm assuming this '98 is a triple but is it a 700 or an 809?

Lynn

 

I'm assuming this '98 is a triple but is it a 700 or an 809?

Lynn

809 - 1998 mach z.

I had the carbs apart when I bought it and the boots looked to be in good shape but I know its prone to becoming an issue - purchased a set of used but in great condition boots to have as spares a month or so ago.

I dont need removable domes, and I dont care to make this some absolute fire breathing dragon. Frankly I HATE riding lakes. This will be for a quick local trail ride here and there. Not a chance in heck i'll be riding this thing over to the hill from Old Forge ha. I havent measured the squish on this engine yet or know what base gasket is it in, but assuming its say 20 thou currently, and I want to run the 59 Thou base gasket, is there enough material on the head to just skim 39 thou off without having to worry about cutting around the domes? I have access to a machien shop but for 75$ if its not cut and dry its probably not worth the setup time.

 

Likely to do so. I purchased this sled in february as I just wanted a triple, and now its clearly spiraling, ha. Its an unmolested 98 with e start / reverse.

I was planning to pull the engine this fall and clean out the engine bay, and generally clean it up. Measure the squish with the current base gasket, and figure out if I want to machine the head myself or send it out. For 75$ its probably not worth my time to fart with it, but I do like doing things myself. Sounds like crankshop mills around the domes so they recess into the cylinders slightly when removing enough material to run a 0.059-0.060" base gasket. I havent had one of thse triple heads in my hands before so I dont know if the domes are removable or not, and weather or not they're reshaping the squish chamber. I'm not a stranger to squish ect, i've done a few YZ motocross cylinder heads, and brought the volume back in the bowl after correcting squish clearance.

I've got a set of V force reeds I picked up that will be going on it too.

You are correct. Had many done over the years. Last one I had done several years ago at Crankshop Paula asked if I wanted "race" or "trail" cut. Go with the "race" cut. Not sure if they still give a choice, just a heads-up.

ALSO, very important, if you want YOUR head back be sure to let them know this by putting a large note in the box when you send your head to them! If not they will just do an exchange.

 

Mach D do you remember what the squish was for the "race cut"? just curious

 

Mach D do you remember what the squish was for the "race cut"? just curious

I don't remember off hand, but I ran 92 octane for many years w/o any detonation problems whatsoever.

 

Nice! on my old 440's we use to run mid .040

 

Nice! on my old 440's we use to run mid .040

I know some YZ125's running around close to 0.030!

My yz250 is running 0.055, with some extensive porting. Strictly race fuel, switched from C12 to T2 recently, no more having to dispense from a N2 pressurized 54 gallon drum and then mix, as its already mixed, and its oxygenated. Smells like heaven. Dont watn to get into race fuel with this mach z as it going to see mainly trail miles, albeit limited. If I put 300 on it in a year that would be impressive.

 

Too little squish isn't necessarily good. It will raise compression but you need area for "Swirl" when the fuel charge enters and sits in the combustion chamber. The squish area also allows room for the fuel charge to spread out when it is ignited and apply more even pressure on the top of the piston. Too little squish and you'll instantly burn a hole in the top of a piston. It's a fine line trade off.

One fault I have seen too often in triple heads is the squish is different across the cylinders from one end to the other. I have seen variences of 5 thousandths or more. These heads were mass produced and they met certain tolerances but the more discriminating engine builder will correct this if possible. It takes some set up time and some careful measurements on the resurfacer but in most cases it can be done.

Lynn.

 

Too little squish isn't necessarily good. It will raise compression but you need area for "Swirl" when the fuel charge enters and sits in the combustion chamber. The squish area also allows room for the fuel charge to spread out when it is ignited and apply more even pressure on the top of the piston. Too little squish and you'll instantly burn a hole in the top of a piston. It's a fine line trade off.

Lynn.

Understood entirely - on the large end most yz250's ping when ridden hard in stock trim due to a really lousy combustion event - They generally measure about 0.080" from the factory.

My background is mainly single cylinder 2 stroke stuff from motocross, built a turbo 600 ace in college on alternative fuel on a megasquirt, and now as a profession I work in an powertrain R&D in a dyno lab. Makes work fun, thats for sure!