ESR trx9 port match port timing

[Bowtie316]

bumping the transfers up will normally build more mid range power

That is one thing this 310 is lacking. Thanks for the info.

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[udontknowme]

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.

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thats what i figured. cover all the bases with one casting. but if your going to use one casting for multiple strokes dont you think its better to cast it for standard stroke with low timings then you can take the ports in any direction you want depending what crank you use and what the engine will be used for ?  im sure esr was trying to make it easier for the end user and make it as much of a plug and play as possible by eliminating some of the cylinder grinding but im not sure you end up with ports in the best location by doing it this way. although i see his point of view by trying to make everyone happy

[Bowtie316]

I know Arlen told me that Esr cylinders are cast for stock stroke and its difficult to make one work on a stroker. Either the transfer ports end up too high with a spacer or you have to run the piston up out the top and cut the dome thin. That is if you want it to have any midrange at all.


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[udontknowme]

seems like we're just going round in circles here. i dont see why the floors would be hanging low if it was cast for stock stroke. makes no sense at all. unless the casting design was muffed. i can see no other explanation.

what rsss said sounds like a more plausible senario. use one casting for several combinations

[Bowtie316]

I don't think it needs to make any sense.  Eddie said it happens sometimes, I think that means that it's a casting flaw. Regardless of the cause, we're going to try to make the best of it.

[85drag250r]

The exhaust port floor below the piston crown is perfectly normal. Graham Bell stated that the exhaust port floor needs to be even with or below the piston crown at BDC or high speed gas flow will be disrupted.

Just something to think about before you start altering trans or exhaust duration, you need to keep in mind the amount of blow down degrees the engine will have.

With your current timing of 187.5 and 120, you have 33.75 degrees of blow down. Which in my opinion is to much for a mx style engine

[udontknowme]

some of what them old books said has proven to be inaccurate today 30yrs laters.  they were on the right track with a few things but keeping the exh floor level or below the piston isnt one of them.

hell jennings and bell couldnt even agree on what determines a specific engine speed.  ive got all them old books and frankly most of the info is useless imo

[udontknowme]

bowtie while your at it you may have a gander under the piston to make sure theres not a huge hole out the exh port. real small hole wont cause much harm but keep it to a minimum the best you can. completely sealed off would be even better

[Bowtie316]

We have another esr 310 TRX9 apart right now and the bottom of the ports are all flush, as were both of my esr 330 cylinders so I know it's not "normal".  I'm not worried about the bottom of the ports, just want to get the transfer timing corrected.

He has it scheduled in with Jeff at FAST for correction.  There isn't much talk of FAST on here, but be is big on bansheehq and we have seen one of his stock cylinder 250r's run and it ripped.

Good point [MENTION=146]udontknowme[/MENTION], I don't think it is enough to cause a gap with the stock stroke but we will make sure.