Questions about my 4 mill setup

[crustydemon]

I have a longrod 4 mill, 21cc domes at about 1600ft(pump gas),trinity pro mx port with 190 degrees exhaust and 130 degrees on the transfers.I have a set of pt mids and a set of pro circuit platinums. My questions are will either of these pipes be a good choice or should I get something else. Then I want to know if 34mm pj's will be ok or are they too big? Will stock ported reed cages with aftermarket reeds limit my performance or should I get some vforce? Will a stock clutch hold, and please clear this up for me one last time, if I run +4 on the plate where should I set the dyna? I'm getting closer,please help.

[AKheathen]

imho, the pro-circuits will take the 4mill and your porting better and make more power. you probably want to get your carbs closer to 30's. just play with the curves to see what one you like best. the clutch needs hd springs minimum and better fibres, or a lockup. you can go either way on the reeds. you're already ported for the upper midrange, so you can either go with the vf's or the carbon fibre boysen pedals, or corbon tech mids.

[crustydemon]

Do you think The pro circuits will hold back the motor? I wouldnt mind buying different pipes if I would get a substantial gain.Im also on a 2mm overbore.I thought that would be the case on the clutch and carbs. How do those port durations compare to a typical dune port?

[BigRed350x]

Do you think The pro circuits will hold back the motor? I wouldnt mind buying different pipes if I would get a substantial gain.Im also on a 2mm overbore.I thought that would be the case on the clutch and carbs. How do those port durations compare to a typical dune port?

 

If you have a dyna, don't adjust the timing plate. Set the plate at 0. The dyna will do the advance on its internal curves. I would do T5's over both of the pipes you listed. A stock clutch will not hold up for very long. I would do as the other guy said and at least get HD springs. But a lockup isn't really necessary with your setup. It would just make it hard to shift. HD springs with your setup, especially on pump gas, will be plenty. Stock reed cages will be fine, unless you really want to just go spend the $ on something. The Vforce reeds will give you better throttle response, but I believe someone on here has done some tests and the stock cages with aftermarket reeds flow about the same overall amount as the vforce reeds, the vforce just have better response. 34 PJ's will be ok for your setup. The smaller the carb you go, the more throttle response you will get, the larger you go, the more top end power you will get at the cost of throttle response. On a 4mil mx port I would do a set of 33pwk's. But your carbs will work just fine.

 

- Jared

[crustydemon]

I'm kind of just throwing parts that I have at it right now and really dont know where its going to make its power,lower-mid, upper-mid?. I just want to set it up correctly for wherever that may be and I'll adjust my riding style to suit.I should move this to Jetting and pipes but are the t5's better than pt highs?

[AKheathen]

well, you really need to decide what range you want. the pro circuits will really shine with the ported 4mill over the pt's with a nasty mid to upper mid punch. they don't rev out as far, but i don't really notice as the power curve is alot wider. do you have the reeds already? as for the timing- try the curves @ 0 on the plate, then try them advanced. sometimes the curves aren't good enough by themselves, and sometimes they are.

[crustydemon]

I would like to run as high a range as my porting will allow,upper-mid to high would be great for me but I just figured that the 4 mill wont crank as fast as a short stroke and move my torque curve down lower and limit my top? If the pc's will work good for that range I will use them,I just always figured them to be a lower range pipe. I have not bought any reed cages and wont if the opened up stockers will work ok. Thats a chunk of change between the two that I could use somewhere else.Thanks for the advice.

Where is a dune port suppose to make its power? Is it in a higher range yet?

[AKheathen]

well, as much as i hate to say it, maybey the procircuits aren't for you. they are a strait midrange pipe, but notorious for the lowend they give. i would still give them a shot, and then try out the t-5's. t-5's are all over and easy to move if you don't like 'em. so are the pc's. just remember to match your timing and reeds accordingly. try carbon tech mids and highs. just pedals, so you're not out 3bills. maybey snoop could step in as he has alot more info and dyno sheets, especially with the pc's on ported and strokers.

[misterww225]

I have a longrod 4 mill, 21cc domes at about 1600ft(pump gas),trinity pro mx port with 190 degrees exhaust and 130 degrees on the transfers.I have a set of pt mids and a set of pro circuit platinums. My questions are will either of these pipes be a good choice or should I get something else. Then I want to know if 34mm pj's will be ok or are they too big? Will stock ported reed cages with aftermarket reeds limit my performance or should I get some vforce? Will a stock clutch hold, and please clear this up for me one last time, if I run +4 on the plate where should I set the dyna? I'm getting closer,please help.

 

Your intention seems to be a trail machine with a WIDE power-band. The combination of 30 degrees blow-down and these pipe support that. The HP numbers will be moderate and clutch mods will not be required. The 34mm carbs will work great and provide you with all-around excellent drivability and power as well. The modified cages will be adequate for this low power level.

 

If you want more power and top-end, you can raise the exhaust to 196 degrees, install CPI pipes, add the v-force reeds, and make clutch mods at a later date.

[crustydemon]

Thank you for the advise. How low powered am I? If its going to be a dog I'll pull the jugs off right now before I go any further.

[misterww225]

Thank you for the advise. How low powered am I? If its going to be a dog I'll pull the jugs off right now before I go any further.

 

Well, not a dog, just more of a flat torque curve that never seems to "get on the pipe" but revs to the moon. To make more HP you need a dune port, not an mx port. Since the transfers have been raised to 130 degrees, you can't easily undo that to get the needed blow-down time. You can, however, change the exhaust ports. The exhaust ports should be raised to about 196 degrees but not more. The main transfers roofs should be around 3-5 degrees up and pointing about a half inch behind the piston center. The aux port roofs should be flat (0 degrees) and the front edges pointing towards the opposite aux transfer. Even with a 4mm crank the stroke is still relatively short and will make good mid/top end HP. Like I said, with the transfers now at 130 degrees, the option for HP is at a higher RPM and the pipe chosen should be one to coordinate with the port timing. As others above have mentioned, T5's or CPI's are a good choice. You are looking for a pipe length of about 24" to the start of the center section from the piston face and about 36" to the start of the stinger from the piston face. Running gas this would be about a 9600 to 10500 RPM setup- one screamin' machine you would have fun on.

[caseyt]

So I have been trying for 2 months to get this trinity single carb to work, can't get it to run rich enough. Have a 50 polit and a 220 main, even tried drilling a get out and still nothing. Cleaned entire carb twice all new gaskets and o-rings everything is sealed, no leaks. Just can't get it jetted right. Any ideas?

[crustydemon]

So I have been trying for 2 months to get this trinity single carb to work, can't get it to run rich enough. Have a 50 polit and a 220 main, even tried drilling a get out and still nothing. Cleaned entire carb twice all new gaskets and o-rings everything is sealed, no leaks. Just can't get it jetted right. Any ideas?

Don't hog my post.

[crustydemon]

Well, not a dog, just more of a flat torque curve that never seems to "get on the pipe" but revs to the moon. To make more HP you need a dune port, not an mx port. Since the transfers have been raised to 130 degrees, you can't easily undo that to get the needed blow-down time. You can, however, change the exhaust ports. The exhaust ports should be raised to about 196 degrees but not more. The main transfers roofs should be around 3-5 degrees up and pointing about a half inch behind the piston center. The aux port roofs should be flat (0 degrees) and the front edges pointing towards the opposite aux transfer. Even with a 4mm crank the stroke is still relatively short and will make good mid/top end HP. Like I said, with the transfers now at 130 degrees, the option for HP is at a higher RPM and the pipe chosen should be one to coordinate with the port timing. As others above have mentioned, T5's or CPI's are a good choice. You are looking for a pipe length of about 24" to the start of the center section from the piston face and about 36" to the start of the stinger from the piston face. Running gas this would be about a 9600 to 10500 RPM setup- one screamin' machine you would have fun on.

So if I got some t5's or the CPI's and didn't raise my exhaust for now would I be making decent hp in the upper range? I want it to "get on the pipe".

[misterww225]

So if I got some t5's or the CPI's and didn't raise my exhaust for now would I be making decent hp in the upper range? I want it to "get on the pipe".

 

I would get the CPI pipes (you will eventually get there anyway and the resale value is great). You will still have a wide power curve, but who know, you might like having a lot of "grunt" as opposed to having a machine that likes to either wheelie or looking for a gear that gets you back into the power band as will changing the timing will produce. Leaving the timing will also make it a lot easier to drive on a trail. You can always make the mods later- it really wouldn't be all that much more work for a winter project.

 

BTW, on YOUR engine, from 190 degrees to 196 degrees means raising the exhaust 0.061". An easy way to change (if you know the timing for sure) is to remove the cylinders, ink blue above the exhaust, and with small calipers set at the 0.061", scribe a line parallel along the exhaust upper edge- then you can grind to the line and re-polish the port and bevel the sharp edges.

 

Another method (which I prefer) is to use a timing wheel. With the engine cylinders still bolted on, place each cylinder at half way down and blue the top edge of the exhaust port. Move and lock the timing wheel to 82 degrees ATDC (to get 196 degrees) and using a small 90 dental tool, scribe a line along the piston top above the exhaust port. Do the same on the other cylinder (being careful not to rotate the wrong way and remove the bluing in the cylinder you just did). Then remove both cylinders and do the grinding/polishing. Be sure to maintain the exhaust port upper edge radius and bevel the sharp edges.

Edited October 15, 2009 by misterww225