ESR trx9 port match port timing

[Bowtie316]

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

No we didn't measure the 2mm, it's just what it looked like.  And with the transfer timing low it seemed about right.  

Eddie suggested the use of an oem gasket, said they were better than what he sent.  I was just curious if low transfer timing could cause excess crankcase pressure pushing the gaskets out.  

Thanks for the idea of dimpling the surface, that should help.

As for the porting, I think he is going to send it off to another builder to have a look and raise the transfer ports up where they should be.

[udontknowme]

2mm is alot. .080" approx.  maybe it just looks like 2mm but really its much smaller ?  either way, if the cylinder was designed for your stroke,rod,piston then theres no reason the window floor shouldnt be even or very close to even with the piston top.  depending whats going on with the rest of the cylinder , stacking some gaskets in conjunction with porting might be a good option. who ever you send it to should be able to get it sorted out if they know what theyre doing

[Bowtie316]

It was a lot, going my memory it was around half the thickness of the sleeve.  And the transfer port timing was low by the same distance, like the entire transfer slid down.  He will have it apart again for new gaskets, I will try to post some pictures and get good measurements.

[Bowtie316]

We got it apart last night and measured, the lowest drop was 2.18mm and the largest drop was 2.54mm.  This is measuring from the top of the piston at BDC to the bottom of the transfer ports. It's hard to get a good picture but the exhaust port is the same way.





Eddie said this was normal and not a problem.  While it may be normal to him, it doesn't seem right to me, I think at the minimum we should get the port roof up where it's supposed to be.

[rsss396]

The most important thing when setting up the cylinder is to make sure the exhaust port and transfer open at the correct time.
when you add a + 4 stroked crank the cylinder will gain a bunch transfer port duration. You don't just slap a 2mm spacer under the cylinder like everyone thinks.

You need to put a degree wheel on it and come up with your port timing durations to determine if the porting is correct.

[Bowtie316]

The most important thing when setting up the cylinder is to make sure the exhaust port and transfer open at the correct time.
when you add a + 4 stroked crank the cylinder will gain a bunch transfer port duration. You don't just slap a 2mm spacer under the cylinder like everyone thinks.

You need to put a degree wheel on it and come up with your port timing durations to determine if the porting is correct.

I did, see the first post, exhaust was 187.5 and transfers were 120. The 120 kind of backs up our thoughts on the port being low.

And I certainly don't plan on cutting it 2mm blind, the plan was to degree it to maybe 125 or 126, scribe a line, and send it to somebody with the tooling to do a proper job.

[rsss396]

if you add a 1mm you will be around 124.5 and 190exh, i dont think you want to raise it anymore

Otherwise send it out to a shop to be ported to the specs you want for your application

[udontknowme]

somebody probly already mentioned it but i think what you have is for a +4 crankshaft. perhaps esr uses that cylinder for the standard stroke and the +4 to kill 2 birds with one stone. if using it on the standard stroke like your doing, if probly requires a different dome than the +4 that sits 2mm lower so the squish clearance is in the normal range.

if your using a +4 cylinder with a standard stroke crank then yes it would be normal to see the floors sitting low. but if the cylinder was originally intended for a standard stroke then no it wouldnt be normal to see low floors. so in a sense he is right about it being normal, but if you look at it in a different perspective, who would intentionally use a +4 cylinder on a standard crank. unless im missing something but this is what it appears to me

alot of people use +2 or +4 cranks with standard cylinders (and grind the windows to where they need to be) but rarely the other way around like what your doing

if you would of noticed your banshee with the +4 crank in the standard cylinders. the piston drops below the floors which is just oposite of what your friend has.

[Bowtie316]

if you add a 1mm you will be around 124.5 and 190exh, i dont think you want to raise it anymore

Otherwise send it out to a shop to be ported to the specs you want for your application

We wouldn't touch the exhaust, just bring the transfer up where it should be with that exhaust duration.

My trx7 port 330 was around 187 and 125 IIRC, I would have to check my notes to be sure.

[Bowtie316]

somebody probly already mentioned it but i think what you have is for a +4 crankshaft. perhaps esr uses that cylinder for the standard stroke and the +4 to kill 2 birds with one stone. if using it on the standard stroke like your doing, if probly requires a different dome than the +4 that sits 2mm lower so the squish clearance is in the normal range.

if your using a +4 cylinder with a standard stroke crank then yes it would be normal to see the floors sitting low. but if the cylinder was originally intended for a standard stroke then no it wouldnt be normal to see low floors. so in a sense he is right about it being normal, but if you look at it in a different perspective, who would intentionally use a +4 cylinder on a standard crank. unless im missing something but this is what it appears to me

alot of people use +2 or +4 cranks with standard cylinders (and grind the windows to where they need to be) but rarely the other way around like what your doing

if you would of noticed your banshee with the +4 crank in the standard cylinders. the piston drops below the floors which is just oposite of what your friend has.

I certainly understand what the extra stroke does, this cylinder was purchased brand new from ESR for a standard stroke.  If my buddy would have noticed this before running it, it would have been sent back.  Eddie said it happens sometimes and is normal, he didn't want to fix it.  Regardless of why it is like that, he wants to have it fixed (the transfer timing that is) and is the next step I suppose. He just doesn't want to spend the full 450 for a port job.

Don't take any of this the wrong way, this thing still runs strong and has held up well.  Mine also runs very good for a little ole 330.

[rsss396]

Believe it or not but 188/120 was pretty common porting setup from allot of builders back in the day because the stock cylinder is right about 120 on the transfers and everybody would just raise the exhaust because it was the easiest.

[Bowtie316]

Believe it or not but 188/120 was pretty common porting setup from allot of builders back in the day because the stock cylinder is right about 120 on the transfers and everybody would just raise the exhaust because it was the easiest.

I can believe that. I can even do the exhaust myself.

Is there much to be gained by fixing the transfers?

Sent from my SGH-T679 using Tapatalk 2

[udontknowme]

well if the cylinder was intended for a standard stroke then im stumped why the floors are so low. bad casting perhaps. would like to hear esr's explanation for it. im sure the engine will still run fine but making them floors so low just isnt something that you would do intentionally. im sure esr knows why but it sounds like theyre not talking

[rsss396]

Cometic does sell base gaskets in different thicknesses, factory is .018-.020  so if you tried a .040 or a .060 it will increase the port timing without any grinding and if you do not like it take it out and go back.
but by doing this the compression will drop. So eventually you would want to optimize your head setup also
bumping the transfers up will normally build more mid range power

[rsss396]

well if the cylinder was intended for a standard stroke then im stumped why the floors are so low. bad casting perhaps. would like to hear esr's explanation for it. im sure the engine will still run fine but making them floors so low just isnt something that you would do intentionally. im sure esr knows why but it sounds like theyre not talking

I believe the transfers are so low because Eddie is working with a single casting that he is trying to cover all the bases with.
remember he is tring to please the woods guys, MX guys, the duner guys and the drag guys. All which have slightly different port timing. Then you have 3 different strokes 72, 76 and 77 which throws a huge curve ball when you try to build a woods or MX style motor, the port timing very high with the long strokes.

i am building 2 cr500 based ligers motors for low and midrange power and both them have the transfers setting below the piston at BDC
They are like this because its the only way to do it without welding the exhaust port's roof to lower it. Neither customer wanted the added expense or risk involved in doing this.
Liger cylinders come from CP in a drag style port setup with 196exhaust 128 transfers by adjusting spacer thickness I was able to adjust the Trail bike build down to 188 exh and the SuperMoto  bike build down to 192 but on both cylinder I am grinding the transfer ports back up to where they need to be.

the split between the exhaust port and transfers is set by the casting and as a engine builder you have to do what it takes to make it work.