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Porting at Home


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everything is looking preaty good so far im really curious to see how it turns out maybe that will inspire me to start grinding on mine

 

Thanks! You're post and questions are what got me on the ball again about grinding. For some reason that provided the spark and I just dug everything out and started in. I think I was over complicating it before when I was avoiding it. It's actually not all that hard. NOW, I had specs that were recommended to me, all I had to do was understand how to produce the specs, but knowing what and how the specs work are what you pay for with the builders, the knowledge. The theory makes sense to me and because of that I think I would have a pretty good guess on where to go from here as far as altering the timings more or differently; but, if I didn't have a baseline it would have been impossible to figure out where to start. I'm finding I need a couple more burrs, so that has slowed it from completion, but more or less one jug done in two evenings. I feel pretty compitent with hand/power tools so that definitely helps and there is DEFINITELY a learning curve in figuring out what speed to run the burr at for any given desired result.

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Thanks! You're post and questions are what got me on the ball again about grinding. For some reason that provided the spark and I just dug everything out and started in. I think I was over complicating it before when I was avoiding it. It's actually not all that hard. NOW, I had specs that were recommended to me, all I had to do was understand how to produce the specs, but knowing what and how the specs work are what you pay for with the builders, the knowledge. The theory makes sense to me and because of that I think I would have a pretty good guess on where to go from here as far as altering the timings more or differently; but, if I didn't have a baseline it would have been impossible to figure out where to start. I'm finding I need a couple more burrs, so that has slowed it from completion, but more or less one jug done in two evenings. I feel pretty compitent with hand/power tools so that definitely helps and there is DEFINITELY a learning curve in figuring out what speed to run the burr at for any given desired result.

 

ya I guess I just need to sit down and start trying to draw up some plans and do more research on the whole thing it would help alot to have one of those port tools too but we will see what happens. I just dont want to dig into it without some sort of idea what I am doing and be out a set of jugs hell who knows maybe you will have great results and start porting for extra cash. ohh and thanks for the spacers they worked out great

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the porting looks good. i would not be afraid to let you cut on a set of jugs for me.. doing your homework is what it is all about.. cutting metal is one thing, but knowing how much and where to cut is the key (knowledge as you stated) .. having some base lines and understanding what does what is going to make a big difference in making a set of cylinders scream, or making them paper weights. the port timings you are using should make the bike a fun all around bike.. i think you will be happy (and proud) of the outcome.. the first set of juggs i did where low on compression, so i ported them, bolted them back on to see the results BEFORE i sent them off for a fresh bore.. the porting alone made it feel better than a bike with a fresh topend (it was low on psi). then after i got them bored it was a runner for sure.. some of the guys that went to the badlands seen the bike run.. i am using t5's 19cc domes, single carb, and fmf reeds with +5 timing.. its a strong running bike all around.. good luck and let us know how it runs.

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ya I guess I just need to sit down and start trying to draw up some plans and do more research on the whole thing it would help alot to have one of those port tools too but we will see what happens. I just dont want to dig into it without some sort of idea what I am doing and be out a set of jugs hell who knows maybe you will have great results and start porting for extra cash. ohh and thanks for the spacers they worked out great

 

No problem on the spacers, I'm glad they worked out for you! Yeah, without the baseline specs to start from I would have been dead in the water. Definitely go and check out Gordon Jennings Two Stroke tuners handbook. It will take you some time to absorb a quarter of the knowledge and theory that is in there, but it is GREAT info. When I originally picked it up I took it with me on a couple long road trips, where I was not driving and just read and read. Haha, porting for cash... maybe. I need a lot more understanding on theory and just sets of cylinders to feel confident in it, but I suppose it's possible?

 

EDIT: Almost forgot, IMHO get some good tools if you are going to do it yourself. But, by doing that, you will be into it more than sending your cylinders out. For me, it came down to being able to say I'm doing/did them as opposed to the money spent. For instance, I know of some members back in the day saying all you needed was a dremel, but with my Foredom motor, it has a heavy cast foot pedal that controls the motor speed and makes the tool much more controlable!

 

the porting looks good. i would not be afraid to let you cut on a set of jugs for me.. doing your homework is what it is all about.. cutting metal is one thing, but knowing how much and where to cut is the key (knowledge as you stated) .. having some base lines and understanding what does what is going to make a big difference in making a set of cylinders scream, or making them paper weights. the port timings you are using should make the bike a fun all around bike.. i think you will be happy (and proud) of the outcome.. the first set of juggs i did where low on compression, so i ported them, bolted them back on to see the results BEFORE i sent them off for a fresh bore.. the porting alone made it feel better than a bike with a fresh topend (it was low on psi). then after i got them bored it was a runner for sure.. some of the guys that went to the badlands seen the bike run.. i am using t5's 19cc domes, single carb, and fmf reeds with +5 timing.. its a strong running bike all around.. good luck and let us know how it runs.

 

WOW, thanks sheerider! I don't think I am quite to the confidence level to start cutting someone else's cylinders, but hey if you'd like to let me practice! :biggrin: For now I'm going to run it with my T5's, probably bump my timing up a degree from +4 currently and go to at least 19's in the head, I bought a good used set a while ago, but I might go smaller yet at some point... I can already see that I'm going to be cutting on my cylinders once I pull them off to swap these on. Then like the addiction was at the start, it will go from there with pipes, carbs etc!

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I don't use compression gauge numbers to estimate fuel octane requirements so I can't comment on that specifically. However, assuming your cylinders have not been decked... And considering the port durations you mentioned... 19cc O-ring type domes would yeild a 100% safe CCR with decent 100 octane fuel IMHO. Truth is, you could go slightly smaller but you will be very near the deto edge around 18.25cc, especially on the right tube! One slip up and your done... I would not recommend it for what your doing. Again JMHO.

For polishing exhaust ports I start with the tight wound rosin impregnated 50 grit sprial rolls (sand paper rolls) from C.C. Specialty, then move to the 110 grit, then the 180 grit and finish with maroon colored scotchbrite strips (apx. 2"X 2") mounted in a slotted mandrel. If you have ever polished an exhaust port the "old fashioned" way (compound and buffs) you will never go back...

Try a little porting wax or bee's wax on your burrs. It cools things down and lubricates, less chatter and faster cutting plus longer burr life.

I am going to plug C.C. Specialty a little here... I have purchased supplies else where over the years because of initial pricing, but I always seem to go back. Their products are more $$$ up front, but they are second to none in quality and longevity and often available nowhere else that I am aware of. I have no affiliation with them other than giving them my hard earned $$$ and don't get any special pricing deals (damn it!). So take that for what it's worth... End of plug.

 

 

The 90 degree tool from CC is awesome; it's a spendy bugger, but I'll tell you, I worked the transfers over as far as timing, as fast as any other part of the porting. I got the specs recommended from my by Dan Wade (Patriot) back in the day a few years ago. As I recall he said he felt it helped with top end scavenging; As you said, you can't even "see" a difference, but it is there, even if a couple degrees of crank rotation. I know Snop knows Dan, I wonder if this sounds like familiar recommendations? Yes Snop, need to work the intake roof lip more for sure.

 

As far as domes are concerned I'm actually not sure, I wanted to ask around. I'm running 20cc currently and I kick 175psi at 1900' elevation, which I know is way higher than most feel it should be. I would actually like to maintain close to that, probably around 185 at sea level, currently right over 190, but I'm not sure what size to run. I have some 19's but guessing those probably won't be small enough to maintain that PSI. Okay running a healthy mix of Trick 116 at that PSI...

 

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Just curious though, how come you are opening the Bust before the main and 5th transfers? Not that it will matter much from a couple deg. in crank rotation, just don't normally see that.

 

i think he's doing that to help push the old exhaust gas out, before the new large charge of fuel/air comes in thru the main and secondary transfers.

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i think he's doing that to help push the old exhaust gas out, before the new large charge of fuel/air comes in thru the main and secondary transfers.

 

Exactly, Dan was telling me that it helps with scavenging in the uppermost portion of the cylinder. I'm no flow expert, but I can invision in my head, with the angle of the bust port that it would force fresh fuel/air into the top intake side of cylinder and the exhaust out of the cylinder through the exhaust. I believe he said this also helped to decrease short circuit between the transfers and the exhaust. Again, I probably would not have been smart enough to figure that out initially, but it makes sense in theory.

 

I think I'm already hooked on porting. The work is fun enough but the theory behind it all is the best part!

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for my exhaust ports when i polish them i do it in a way very similar to deckheight. Although i do not use premade sandpaper wheels, mainly cause i dont wanna buy them, :biggrin: . I just take one of my old 1/4" by 6" burrs that is dull and not used for cutting anymore and i wrap it with sandpaper. I start with usually 80 grit then on to 120, 200, 300, 400, and so on until i get the finish desired. Sometimes end at 800.

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here is a good pic of the stages. the one on the left is probably at the 400 grit stage the right one is 600-800 grit.

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the porting looks good. i would not be afraid to let you cut on a set of jugs for me.. doing your homework is what it is all about.. cutting metal is one thing, but knowing how much and where to cut is the key (knowledge as you stated) ..

 

If you'd like to contribute to my learning, I'd be happy to grind on some cylinders for you! :biggrin: :biggrin:

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If you'd like to contribute to my learning, I'd be happy to grind on some cylinders for you! :biggrin: :biggrin:

 

if you want I will let you grind on mine but you will have to take into consideration its for a 4mil and the deck height will be cut down a hair it might make you think a little more lol but it would probably save me the money of buying all the equiptment idk its up to you

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