ESR trx9 port match port timing

[Bowtie316]

My buddy had his motor apart so we checked the port timing on it.  It's a 310 trx9 port match power valve machined cylinder.  Short rod motor, no spacer.  The exhaust came out to 187.5 which is about what I would expect, but the transfer was only 120.  Actually for the transfers, the entire port(s) were low, as in the bottom of the port was 2mm below the top of the piston.  Is this normal? I would think it should be flush with the top of the piston at BDC.  Sleeve was perfectly flush with the top of the cylinder and the port matching sleeve to cylinder is fine so the sleeve didn't move.  

Does anybody have any ideas?

Would he gain anything with a few more degrees of transfer timing? It runs good now, just maybe a little soft on the bottom and tends to run a bit hot.

[udontknowme]

not sure if thats normal because i never seen a esr cylinder but i dont like the idea of trans floors below the piston top and certainly wouldnt intentionally set one up like that. 120 is pretty low. of all the engines ive ever messed with none of them have been that low. 124 i think is the lowest ive ever seen but i have almost no experience with 250r stuff either. if your intention was to raise it 2mm thats quit a bit.  you could put something about 2mm under your spacer and check timing then youll know for sure.  why the floors are lower than piston is hard to say as theres a number of reasons why it would be like that

[Jerry Hall]

My buddy had his motor apart so we checked the port timing on it.  It's a 310 trx9 port match power valve machined cylinder.  Short rod motor, no spacer.  The exhaust came out to 187.5 which is about what I would expect, but the transfer was only 120.  Actually for the transfers, the entire port(s) were low, as in the bottom of the port was 2mm below the top of the piston.  Is this normal? I would think it should be flush with the top of the piston at BDC.  Sleeve was perfectly flush with the top of the cylinder and the port matching sleeve to cylinder is fine so the sleeve didn't move.  

Does anybody have any ideas?

Would he gain anything with a few more degrees of transfer timing? It runs good now, just maybe a little soft on the bottom and tends to run a bit hot.

Does ESR make a sleeve for a about a 4 mm stroker crank?

[udontknowme]

maybe thats what they did. used a 4mm sleeve . sounds plausible anyways

[Bowtie316]

I would expect the port to be taller if it was for a +4 stroke. It's normal size, just lower than I think it should be.

[udontknowme]

im not sure dude. call esr and see what they say. floors 2mm lower is alot. something dont sound right about that.

[rsss396]

if the port is 2mm lower than the piston at BDC then more than likely this was setup as a +4 stroked cylinder. When you stroke the crank the crank will travel 2mm lower and and 2mm higher in the bore. Stroking the crank also adds a little more port timing to the exhaust duration and about twice the amount to the transfers duration

[Bowtie316]

I wish now that I would have measured the port heights and distances from the top of the cylinder.  I don't think ESR offers a 310 for the +4 stroke, I know they do for the 330.  I might try to get the ports measured and try to get ahold of Eddie.  I'll post some pictures up too if I get it back apart.

[udontknowme]

was 187 with the valve open ?

lets assume you degreed it correctly. 120 is very low for any type of high performance engine. not what i would expect from a trx9 port. plus the floors are 2mm lower than piston. somethings goofy

i havent degreed my ktm250 but i did trace the ports onto paper and the transfers are damn near the same height as a stock cr500. 72stroke on the ktm and 79 on the cr5. cr5 is 124 trans, if the 72stroke ktm are nearly as high that would put the ktm 128 ? 130 ? i dont know but theyre tall. its a bone stoke mx engine with power valve. your esr 310 should be similar i would think

[Bowtie316]

was 187 with the valve open ?

lets assume you degreed it correctly. 120 is very low for any type of high performance engine. not what i would expect from a trx9 port. plus the floors are 2mm lower than piston. somethings goofy

i havent degreed my ktm250 but i did trace the ports onto paper and the transfers are damn near the same height as a stock cr500. 72stroke on the ktm and 79 on the cr5. cr5 is 124 trans, if the 72stroke ktm are nearly as high that would put the ktm 128 ? 130 ? i dont know but theyre tall. its a bone stoke mx engine with power valve. your esr 310 should be similar i would think

It's a PV cylinder without the PV option added, it has a plug in it currently, so yeah, basically open.

I agree it seems low, the fact that the bottom of the port is below the top of the piston seems to confirm that it's low.  I would have expected around 126°.  Does anyone know how many degrees a change of 2mm would be?  I would check but the only one I have torn down right now is a +4 mil stroker and would be different.

[Jerry Hall]

I wish now that I would have measured the port heights and distances from the top of the cylinder.  I don't think ESR offers a 310 for the +4 stroke, I know they do for the 330.  I might try to get the ports measured and try to get ahold of Eddie.  I'll post some pictures up too if I get it back apart.

Does the sleeve match the aluminum along the top of the transfer ports?  or does it hang down approximately 2 mm below the aluminum port roof?

[Bowtie316]

Does the sleeve match the aluminum along the top of the transfer ports?  or does it hang down approximately 2 mm below the aluminum port roof?

The bottom of the port matched up perfectly. I can't remember if I looked at the top.

Sent from my SGH-T679 using Tapatalk 2

[udontknowme]

did you talk with esr. wondering what they have to say about it

[Bowtie316]

ESR said it happens sometimes on these cylinders but that it was nothing to worry about.  

It also blows out base gaskets, this is the third time.  Surfaces are flat, and the last time we put high-tack on it, it lasted longer but still blew out.  Could this be related?

[udontknowme]

you said the floor was 2mm below the piston top. did you measure that or just eye ball it and guess ?  if a cylinder is setup for a specific stroke, specific piston, specific rod etc etc, its hard to believe it can be 2mm off. not that youll lose 10hp or anything but it sounds like their castings arent very accurate at all. which is pretty sad considering they probly put quit a bit of time into it. then again i have to question how much time was invested after hearing of the coolant issues at the exh side. i think we already discussed this stuff. if your unsure the design will be sufficient, call in some experts to get a second opinion

doubt the base gasket issue has anything to do with your piston not level with the transfer floors. havent had any of mine blow out but bought used bikes with them blown out. generally on every engine i do ill put a few dimples along the thin section around the outside transfer area. 99% of the time i use a sealer also. this is only my way of doing it. you may have to find your own method, thats pretty much what i did. never had a base gasket blow on me. never had one leak either. only time i ever had a gasket problem is when i used some junk material from the hardware store on the reed block and it leeked. learned my lesson. after that day oem gaskets is the only thing ill use unless its a specially project and the cylinder needs to be at a certain height then ill either stack honda gaskets or use klingersil at what ever thickness i need