Question about Blaster transfer ports

[99LRDblaster]

What's the secret behind these guys? :-/ They are never completely opened so is there some velocity gain from the smaller step up design or is it merely a matter of directing the flow towards the plug(not sure how). On top of that, how is this effected positively or negatively by running a stroker setup? This has been one thing that has somewhat puzzled me with the transfer windows.

 

[darederek]

I believe its just a flaw in the design. Look for a thread about a 1mm spacer. They talk about it lining up the transfers. Id imagine they are talking about the same thing as you

 

[99LRDblaster]

I believe its just a flaw in the design. Look for a thread about a 1mm spacer. They talk about it lining up the transfers. Id imagine they are talking about the same thing as you

Perhaps, but the engineers behind the engine.......even if they were subpar in performance, really strike me as odd if they decided to design the engine from the get go with subpar performance. :-/ If this was the case, why not just make the transfers shorter(less tall) and save some ring life? This is why I find it so odd and looking at them and they angle of travel, I'm just guessing there is some reasoning behind it either with velocity and/or the angle the air/fuel mixture enters the cylinder. I guess I'll have to do some research on it.

 

[darederek]

Maybe. But they really did design it as subpar performance. They could have put an exhaust without baffles in it. Or designed the head better or did yz-style ports. They designed it as an entry level quad with entry level performance

 

[sicivicdude]

The reason is, the blaster engine is a mix of three different other engines to save tooling costs. An older IT cylinder, a DT bottom end, and another IT clutch side. They mixed and matched the parts bin to get something to work.

Once they figured out that it did work (and was stupid cheap to make because it was just old parts) they kept making until 2006 when they stopped.

It was pure economics that drove those decisions and it was OK for that because for a beginner bike, the blaster is PERFECT.

 

[99LRDblaster]

The reason is, the blaster engine is a mix of three different other engines to save tooling costs. An older IT cylinder, a DT bottom end, and another IT clutch side. They mixed and matched the parts bin to get something to work.

Once they figured out that it did work (and was stupid cheap to make because it was just old parts) they kept making until 2006 when they stopped.

It was pure economics that drove those decisions and it was OK for that because for a beginner bike, the blaster is PERFECT.

Ok, I guess that could make sense then. I:I So I'm presuming a stroker setup with the Blaster would show a large % improvement than comparable stroker setups with other quads since the transfers are opened more?

 

[sicivicdude]

With a +3 stroker, the downward stroke passes .5mm BELOW the transfer floors instead of 1mm above the transfer floors.

Whether you do a head mod or a spacer plate, the stroker crank opens up a bunch more "possible power" with the right supporting mods and other porting.

 

[99LRDblaster]

With a +3 stroker, the downward stroke passes .5mm BELOW the transfer floors instead of 1mm above the transfer floors.

Whether you do a head mod or a spacer plate, the stroker crank opens up a bunch more "possible power" with the right supporting mods and other porting.

Alright so here is my next question.......why couldn't you just raise the transfer ports by like 3-4mm?....or hell even more? Granted I haven't measured the cylinder or know the degrees of duration off the top of my head where the overlap is with the open exhaust port and all that jazz, but IF POSSIBLE it makes sense to me to raise the port windows so when the flow comes up from the side of the cylinder, instead of taking an angle back through the port window, it flows at a lesser angle and directed at a steeper angle towards the head and spark plug. Like I said, I don't know the degrees of duration off the top of my head, so I'm presmuming there is some interference there otherwise it just seems like the better idea to raise the transfers quite a bit.......regardless of if it is a stock or stroker.

 

[sicivicdude]

Balancing act. Raising all of the ports lowers the compression ratio (which you cannot easily compensate for at a certain point)

Also, the transfer ports job is split into two parts. One, to transfer as much energy (in the form of fuel rich fresh air) into the upper cylinder as possible during a blow-down. Two, to void the cylinder of the previous burnt charge. The shape of the transfers is specific to those two functions. One transfer points nearly perfectly flat and the other is angled upwards towards the head. Together, they clean the cylinder of the last stroke.

Everything works as a system... nothing is ever cut and dry like "just raising the transfers". When you get increased scavenging, you lose somwhere else. Like in the case of a 125cc dirtbike. They worked those engines in a maddening frenzy to get more "power" out of them. They created engines which put HUGE HP numbers out of 125cc 2 strokes but are so peaky as to be nearly undriveable except in a flat out motorcross event. You always lose something...

 

[99LRDblaster]

Balancing act. Raising all of the ports lowers the compression ratio (which you cannot easily compensate for at a certain point)

Also, the transfer ports job is split into two parts. One, to transfer as much energy (in the form of fuel rich fresh air) into the upper cylinder as possible during a blow-down. Two, to void the cylinder of the previous burnt charge. The shape of the transfers is specific to those two functions. One transfer points nearly perfectly flat and the other is angled upwards towards the head. Together, they clean the cylinder of the last stroke.

Everything works as a system... nothing is ever cut and dry like "just raising the transfers". When you get increased scavenging, you lose somwhere else. Like in the case of a 125cc dirtbike. They worked those engines in a maddening frenzy to get more "power" out of them. They created engines which put HUGE HP numbers out of 125cc 2 strokes but are so peaky as to be nearly undriveable except in a flat out motorcross event. You always lose something...

Yea I kind of figured. I still think you could raise the transfers more...or in the case of a stroker, lower them 0.5mm to enhance the flow out of the window. What I'm seeing conceptually in my head seems a bit confused by other things. Thanks for clearing it up though. I:I

 

[sicivicdude]

You can raise the transfer ports. It's called a "port job" or "porting". It usually costs about $150 and takes a few days to turn around.

Call any of the builders on this site and ask about it! BWAHAHAHAHAH!

 

[99LRDblaster]

You can raise the transfer ports. It's called a "port job" or "porting". It usually costs about $150 and takes a few days to turn around.

Call any of the builders on this site and ask about it! BWAHAHAHAHAH!

......you sly bastard. I:I

This does make me want to find a cheap cylinder/head somewhere and "experiment".

 

[sicivicdude]

I undertook my own experiments with porting.

I determined that a proper right angle tool is needed for the job. The least expensive thing I can find with the ability to use an 1/8" carbide burr is a right angle pencil grinder or "micro die grinder"

They run about $130 but have the potential to do as quality a job as a foredom electric grinder with a right angle handpiece. If not as easily, (air tools don't have torque like the foremdom) at least as good a job....

The trick then is setting up a "test rig" and going for it.

 

[Blaner]

yes i run the 1mm spacer to get the transfers open, i did it togther with a head mod so its hard to say what did what in terms of performance but i made a impressive improvement. also remember that the blaster was made not only from old parts but also for the inexperienced/young rider who was at entry level. if you didnt want a ute at the time, you bought a blaster...no option...so people buying a blaster, wanted the nippy feel but didnt want a banshee, so obviosly the right amount of power was needed..not too much not too little, so i beleive they made the motor that way, sort of handicap its port timing and head design to make it less efficient (in terms of converting potential energy to kinetic) i think they purposfully made the barrel 1mm lower to do this.

so undo what the engineers did and you aye for away!

also, agreed with sicivic, raising it too much decreases your effective compression! a stroker has massive advantages in that regard.

 

[super noober]

i belive the stroker crank is a great mod and worth every penny, i noticed bug gains in torque mostly

 

[Larry's Shee]

Makes me wish I would have looked closer either before I pulled the cyl or at least before putting the head on , lol. Would think it's either an oversight or another intentional de-tuneing aid, much like the stuff in the pipe. Never realized it was such a combo of parts. I did realize early on that it was an air cooled jug on water cooled case , even before I was on here.
Guess the only way to fix this problem is a 3mil stroker I:I Might be sooner cause I know rod is getting close to service limit, and a stroker is only $20 more than stock

 

[sicivicdude]

The cylinder has to be ported for the stroker crank to take FULL advantage of the increased length.

 

[99LRDblaster]

Makes me wish I would have looked closer either before I pulled the cyl or at least before putting the head on , lol. Would think it's either an oversight or another intentional de-tuneing aid, much like the stuff in the pipe. Never realized it was such a combo of parts. I did realize early on that it was an air cooled jug on water cooled case , even before I was on here.
Guess the only way to fix this problem is a 3mil stroker I:I Might be sooner cause I know rod is getting close to service limit, and a stroker is only $20 more than stock

What sic said makes the most sense. It's just a combo of 3 engines to save on cost. Nobody in their right mind would INTENTIONALLY add wasted port window space if it was never needed in the 1st place......they would of just made the window smaller. That's where I was confused and what he said makes the most sense.