Serval Cat

[RZBansheeMan]

I check a few of these sites out from time to time, and when I saw the questions asked in this post, (and where you were from), I recognized a question that I had worked quite a while on with one of my dealers very recently, (actually I think it was Friday).

The side view that I am attaching should show the use of a 4mill Serval cylinder with a 7mill crank, the port durations are shown at the top of the page when using a .012 gasket, and when using no gasket and sealing the cylinder down. Actually, the port timings are very close to where they will be when the 7mill Serval is finished.

Hope this helps,

Calvin Pollet

 

 

Hey Calvin, I have been curious to know if the Servals will ever have the power valve option or not.

 

Mike

[2Go-Fast]

I have been curious to know if the Servals will ever have the power valve option or not.

The Serval cylinder uses the banshee head layout, and that bolt pattern has a head bolt directly in front of each bore, so there is no way to use a power valve with that head bolt pattern....so, no, would be the answer to whether the Servals will ever have a power valve......sorry

[2strokespirit]

I check a few of these sites out from time to time, and when I saw the questions asked in this post, (and where you were from), I recognized a question that I had worked quite a while on with one of my dealers very recently, (actually I think it was Friday).

The side view that I am attaching should show the use of a 4mill Serval cylinder with a 7mill crank, the port durations are shown at the top of the page when using a .012 gasket, and when using no gasket and sealing the cylinder down. Actually, the port timings are very close to where they will be when the 7mill Serval is finished.

Hope this helps,

Calvin Pollet

Sideview of CPI-S6861P_Special_Serval_Cub .pdf

 

I guess this site does not allow opening of "pdf" files on the screen, so you will need to download the file....sorry

 

 

I Calvin, that was probably for me.... I was in the process of buying servals to go 7mm from a good dealer here.... :-)

[kingsley]

I check a few of these sites out from time to time, and when I saw the questions asked in this post, (and where you were from), I recognized a question that I had worked quite a while on with one of my dealers very recently, (actually I think it was Friday).

The side view that I am attaching should show the use of a 4mill Serval cylinder with a 7mill crank, the port durations are shown at the top of the page when using a .012 gasket, and when using no gasket and sealing the cylinder down. Actually, the port timings are very close to where they will be when the 7mill Serval is finished.

Hope this helps,

Calvin Pollet

Sideview of CPI-S6861P_Special_Serval_Cub .pdf

 

I guess this site does not allow opening of "pdf" files on the screen, so you will need to download the file....sorry

 

Hi Calvin. I believe the question i have asked here is directly related to the time that you spent on Friday for a 7mm crank in a 4mm serval. My reason for asking the question was to gain more of an understanding of the outcome of this combination. I am reasonably new to the performance workings of a 2 stroke. After looking at your PDF file. I notice the exhaust timing is practically exactly the same as the 4mm with 186.3 but the main transfer (inlet ports?) open fully at 3deg later. Again not knowing much on this subject. How different will the result be? My guess is that the torque will be slightly later in the RPM. Is the difference in torque delivery mostly noticed when the inlets are adjusted or when the exhaust is adjusted?

Obviously this combination will be different to a 4mm set up as the torque and HP will change again because of the 7mm stroke and i may not even notice a difference or see more. At the end of the day, i came from a poor designed 66.5mm bore with a 4mm crank and running 22cc banshee domes with blaster pistons. The combination was all wrong but i was very happy with performance i had.

[AKheathen]

3 reasons i'm against nicasil....- it's 3-4x as much to repair. yes, you loose bores. and, i was told how a coolant leak can blast the plating off. i know it definately has it's advantages, but running cylinders outside drag-type use, and normal level of attention put into such machines, sleved cylinders are the best option, imho. most of the time, any kind of failure can be repaired by anywhere from simple bore, to re-sleve. usually, that's like $100-$200 at worst, and free, at best...

about the 7mill, i was hoping to be able to see less durration with 4mill cyls.....oh, well. and, that +3 blow-down is going to narrow the powerband a bit, given the widths remain to keeping relative time/area. however, the extra stroke and trapped compression will make up for that on the lower side, but power should increase in the top-mid and up. correct me if i'm off, but that's what i see happening.

[dajogejr]

I'm gonna put my 2 cents in...even though I know this is not a plated vs. cast iron discussion.

 

AK... I've smoked two pistons in 5 years on my current 10 mil cub.

After 4 seasons of a TON of passes, it was finally time to replate my cylinder.

 

I just smoked another piston...and the plating is fine.

 

Your argument could go both ways. If you smoke a piston with plating, most of the time you run a hone through it and throw a new slug in, no down time.

 

If you blow a piston with cast iron, you remove it...bore it, hone it...get a larger piston for BOTH sides...etc.

 

I agree, IF the plating goes, it's expensive.

 

Plating is around 250 give or take. Bore job and new pistons are about the same...

[No Limit Powersports]

Nicasil has some major advantages that i feel you are overlooking that can imo out way its disadvantages. #1 you never loose bores so effectively you never wear out a cylinder. #2 it is way harder than any sleeve so time intervals between replating vs boring is much much greater. #3 Less friction nicasil has better friction reducing properties than steel does so it can effectively make more power. #4 and i think one of its best characteristics is that is tough. I cant tell you how many cubs i beat the pistons out of and the plating is fine. #5 Aluminum piston on a steel sleeve as we all know expands at different rates so with the plating there is less of a chance for a cold siezure or any siezure for that matter.

 

 

I think the numbers that we got figured on your cylinder will make it a broader tq curve than the 4mm would have made. When calvin casts the 7mm serval cylinder the blowdown will probably be a little less but these are really good numbers. The added stroke will broaden the tq curve threw out. Let me know if you need anything else.

[tecateman]

are the 10 mil servals gonna be close in price to the 4 mil? i mean just the cylinders. i know the crank and all will be more.

[kingsley]

Is there enough meat in the water gallorys to drill and tap a temp sender or even case a spot there for future barrels?

IS this a good place to put it apart from the top hose with a joiner fitting?

[2strokespirit]

Is there enough meat in the water gallorys to drill and tap a temp sender or even case a spot there for future barrels?

IS this a good place to put it apart from the top hose with a joiner fitting?

 

I would rather put it in the cylinder head..... I am also looking into tapping my head for this.... Would like to fit a VDO mechanical gauge, only issue is the vibration... There are other gauge as well that can take the vibration.... It has been discussed on here....

[AKheathen]

x2. there might be meat, but most likely it will be by the exhaust, which could read abnormally high, instead of mean temp......still concidering the nic.........it was you, dave, that mentioned coolant beaing able to instantly pit the plating, so that's what i'm going off of. i ride mostly trails to get to my favorite hill-climbs, and my rides can go for 4 days, since i do 3weeks on-3off and don't have to stick to normal week-ends. i bring a bunch of tools and supplies with me so i can fix shit that breaks, from flywheel coming off, to whatever. i'd like to know i can go back to camp and replace an o-ring and keep going, if i ever have to......can you tell me- what is the likelyhood that a blow o-ring would screw up the plating, in all honesty.....1:100, 1:10, 3:4? i'm just worried about having to pack it up for a long peroid for something so simple...... if i can really get the life you claim out of it, that would be great

[Snopczynski]

Mr. Gasket Thermo cap. If the radiator level drops and the bulb is not submersed in coolant due to a leak, you'll know it before you would with a leaking o-ring and a sender in the head.

[gizmoman]

Will these cylinders still make power with 28mm carbs or will they be starved i need to know because im either going ported stk or serval 4mils.

[Fastassbanshee96]

They will still make power just not as much as it would with bigger carbs. I think you'll just make more power down low.

[Forcefed]

42 pilot + CEL needle's in the middle - 1 main size = wholesome goodness in the midrange & 200 rpm increase up top