After looking at some prior posts regarding the shim inside the Begi regulator, I'd like to check the condition of mine and make sure it's the correct thickness. I have the all in one MR2035 Multi-Role but don't want to randomly start taking it apart. Can anyone let me know exactly where the shim is located, which screws to remove, what it looks like, etc. Thanks.
BEGI MR2035 FMU Shim
- Thread starter 65Cobra
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turbobusa2000
Registered
I've never used a 2035 FMU. Why are you going to check it? Is it not working properly? Its fairly straight forward. Four bolts on top I think. Then the diaphram, below that I believe theres a spring. Thats from memory and I don't currently use one. They're not very complicated and don't have many parts so you should be able to handle it.
I've got an earlier BEGI FMU. If the design is very similar, be careful removing the top. You will feel the spring pressure against the set screw. There is a flat washer on top of the spring which aligns the spring with the set screw. Just pay attention.........and go slow with it. Piece of cake, otherwise.
Thanks for the info guys but I couldn't get it apart. I loosened the four bolts around the top but the top wouldn't budge, even when I tapped it with a rubber mallet. So I tightened the bolts back down and let it go. I only wanted to check the thickness of the shim because of several prior posts where some units had shims that weren't the required .010" thickness, which could cause the unit to fail resulting in engine damage.
texas-buzzard
Registered
The top will come off with a little help from a thin blade and a small hammer. My Begi came with a .003 shim and gave me all kinds of problems. I would check it and save your engine. The best way to make sure is to sell it and buy a RCC FMU. This FMU is trouble free.
Curious where you got your Begi? Mine came straight from Bell Enginnering. His website claims issues with copies so I can't determine if the thinner shims were part of his doing, or only a problem with the immitation units. Mine hasn't been used yet, was only doing this as a precaution. Thanks.
texas-buzzard
Registered
Mine came with my first turbo kit. i would still check the shim anyway.
I talked with Corky at BEGI yesterday and even though I didn't follow everything he told me, I followed enough to give another try at opening up my unit. This time it went much better and the shims were just as he told me, although I get the feeling not everyone has the same setup.
The shims are located at the second gasket from the top. You have to remove the top four bolts, separate those sections, then remove the four bolts inside to get to the second gasket. He said there would be two shims, and there were, each shim being 0.003" thick with the gasket sandwiched between them, which makes me think there are two shims in every unit.
Apparently the shims flex under pressure so the thicker the shims the more resistance they create within the FMU, affecting the pressure in some way. I think he was trying to tell me it affected the minimum pressure at idle, with thinner shims allowing a lower idle pressure. If so then one would want to use the thickest shims possible that would still give the idle pressure needed for their setup. Apparently with the Hayabusa that would be a 0.010" shim based on what I read in other posts.
I have two shims and Corky mentioned only changing one of them but I'm not sure which one or why. Obviously I need to call him back to clarify a few items but wanted to run this by here to see what kind of comments I receive first.
The shims are located at the second gasket from the top. You have to remove the top four bolts, separate those sections, then remove the four bolts inside to get to the second gasket. He said there would be two shims, and there were, each shim being 0.003" thick with the gasket sandwiched between them, which makes me think there are two shims in every unit.
Apparently the shims flex under pressure so the thicker the shims the more resistance they create within the FMU, affecting the pressure in some way. I think he was trying to tell me it affected the minimum pressure at idle, with thinner shims allowing a lower idle pressure. If so then one would want to use the thickest shims possible that would still give the idle pressure needed for their setup. Apparently with the Hayabusa that would be a 0.010" shim based on what I read in other posts.
I have two shims and Corky mentioned only changing one of them but I'm not sure which one or why. Obviously I need to call him back to clarify a few items but wanted to run this by here to see what kind of comments I receive first.
texas-buzzard
Registered
My fmu had two .003 shims also. the one that is located against the main block does the regulating and was the one that cracked on mine. i think the top shim keeps the large rod from distorting the gasket from the spring pressure. i changed the regulating shim only.
I wanted to bring this topic up to date so others will have a better understanding of what can happen if you ever decide to change the shim inside the BEGI.
I checked the shims inside the BEGI I purchased directly from Corky at Bell Engineering. As I expected, both shims were .003" thick. After reading the posts on various forums, I decided to replace the lower shim with one that was .010" thick.
As I set up the LM-2 to log AF, RPM and TPS, everything appeared to be heading in the right direction, including the AF readings. Don't get me wrong, the AF readings weren't perfect by any means, but that's what I expected considering I'm trying to taylor someone elses map to work with my bike.
It wasn't until I began creating log files last weekend that I noticed something was seriously wrong. It wasn't noticeable while watching the LCD screen on the LM-2, but when I ran LogWorks, it showed the AF ratio constantly spiking between the lowest reading (7.35) and the highest reading (22.39) of my O2 sensor.
To make this short, I went back to the original .003" shim, and even before I began to record a log, I noticed the LM-2 display showed readings that were different, not by a lot, but different... as though the changes in the AF readings were slightly smoother. But after looking at a new log file? The difference was dramatic. Now I have something to work with.
One point I'm trying to stress here is this... the BEGI has a .003" shim for a reason. The thicker the shim, the less flex it has, and the less gradual changes in the AF mixture will be. It wasn't obvious when I initially set up the BEGI and it wasn't obvious as I watched the LM-2 display either. It wasn't until I recorded a log file that the problem became apparent. I'm guessing that's because the LM-2 display can't update as frequently as what the unit can capture during a recording, so the display can be deceiving.
I'm going to post screen captures of a portion of both log files. One is the log file using the thicker .010" shim, and the other is the log file using the original .003" shim. The difference is so dramatic you will instantly know which one is which.
Not that I plan to change anything soon, but I also have shim stock that's .005" so I may try that some day just to see what happens. But either way, I plan to check the shims inside the BEGI on a regular basis since I can easily get to them without even removing the BEGI from my bike... it's installed in an upright position under the tank. Just pinch the fuel lines and start removing the bolts.
So if any of you have replaced the shim in your BEGI with a thicker version, unless you've actually recorded log files, I'm not convinced the change is really what you want.
I checked the shims inside the BEGI I purchased directly from Corky at Bell Engineering. As I expected, both shims were .003" thick. After reading the posts on various forums, I decided to replace the lower shim with one that was .010" thick.
As I set up the LM-2 to log AF, RPM and TPS, everything appeared to be heading in the right direction, including the AF readings. Don't get me wrong, the AF readings weren't perfect by any means, but that's what I expected considering I'm trying to taylor someone elses map to work with my bike.
It wasn't until I began creating log files last weekend that I noticed something was seriously wrong. It wasn't noticeable while watching the LCD screen on the LM-2, but when I ran LogWorks, it showed the AF ratio constantly spiking between the lowest reading (7.35) and the highest reading (22.39) of my O2 sensor.
To make this short, I went back to the original .003" shim, and even before I began to record a log, I noticed the LM-2 display showed readings that were different, not by a lot, but different... as though the changes in the AF readings were slightly smoother. But after looking at a new log file? The difference was dramatic. Now I have something to work with.
One point I'm trying to stress here is this... the BEGI has a .003" shim for a reason. The thicker the shim, the less flex it has, and the less gradual changes in the AF mixture will be. It wasn't obvious when I initially set up the BEGI and it wasn't obvious as I watched the LM-2 display either. It wasn't until I recorded a log file that the problem became apparent. I'm guessing that's because the LM-2 display can't update as frequently as what the unit can capture during a recording, so the display can be deceiving.
I'm going to post screen captures of a portion of both log files. One is the log file using the thicker .010" shim, and the other is the log file using the original .003" shim. The difference is so dramatic you will instantly know which one is which.
Not that I plan to change anything soon, but I also have shim stock that's .005" so I may try that some day just to see what happens. But either way, I plan to check the shims inside the BEGI on a regular basis since I can easily get to them without even removing the BEGI from my bike... it's installed in an upright position under the tank. Just pinch the fuel lines and start removing the bolts.
So if any of you have replaced the shim in your BEGI with a thicker version, unless you've actually recorded log files, I'm not convinced the change is really what you want.
BTW, the difference is even more dramatic than what the above screen captures show because the top display is zoomed in further than the bottom display. You can tell by the timeline along the bottom of each screen capture.
Here are the same charts, zoomed in by equal amounts...
Here are the same charts, zoomed in by equal amounts...
Didn't test any other sizes Pinky. I have to admit, I'm anal which unfortunately means it takes me longer to do something than most people. But I don't mind for two reasons... I catch stuff most people don't and I really enjoy this in my own way. It can get frustrating at times but for the most part it's very relaxing.
Normally I would just jump in and create logs using shims of different thicknesses, but I want to concentrate on getting my map done first. I already have stainless sheets that are .005" and .007" thick which will make good test material, but I'm going to hold off until riding season is over. Since there have been multiple issues with the .003" shims 'wrinkling' or 'cracking' which causes failure, it would be nice to see if one of the other shims would work, yet not cause the AF spiking that the .010" shim causes.
But... I do have a theory as to why some users never have a problem while others say their shim failed in as little as 100 miles. I really think it has to do with the positioning of the shim and how tight the bolts are. I'm referring to the bolts that hold the second diaphram from the top in place... that's the one that is sandwiched between two shims. If the bolts are not tightened sufficiently, I believe the shims can shift as the plunger applies pressure causing the shim to slightly bow. Once that happens the shim can't return to it's original position due to resistance from edge of the shim pushing against the rubber diaphram. I looked at the original shims in my unit and the edges and corners were very sharp. Before replacing a shim, I round off the corners very slightly with scissors then smooth the edges and corners with fine sandpaper then a Scotch pad. Do not apply pressure... if the shim starts to bend while you're doing this, then your applying too much pressure.
As far as the BEGI is concerned, I think it's a misunderstood peice of equipment because it's difficult for many users to understand exactly how it functions and what part each component inside the unit plays, so when things go wrong, it immediately gets blamed. In this case, everyone seems to recommend a .010" shim which I no longer agree with. I think it would be a better idea to replace the shims with new .003" shims, smooth the edges and make sure they are centered properly... that means the corners should be positioned so they point in between the bolt holes. That will give the most holding power when the unit is bolted together. And of course make the bolts tight... and that doesn't mean getting carried away until the threads strip either.
Thanks for chiming in Pinky.
Normally I would just jump in and create logs using shims of different thicknesses, but I want to concentrate on getting my map done first. I already have stainless sheets that are .005" and .007" thick which will make good test material, but I'm going to hold off until riding season is over. Since there have been multiple issues with the .003" shims 'wrinkling' or 'cracking' which causes failure, it would be nice to see if one of the other shims would work, yet not cause the AF spiking that the .010" shim causes.
But... I do have a theory as to why some users never have a problem while others say their shim failed in as little as 100 miles. I really think it has to do with the positioning of the shim and how tight the bolts are. I'm referring to the bolts that hold the second diaphram from the top in place... that's the one that is sandwiched between two shims. If the bolts are not tightened sufficiently, I believe the shims can shift as the plunger applies pressure causing the shim to slightly bow. Once that happens the shim can't return to it's original position due to resistance from edge of the shim pushing against the rubber diaphram. I looked at the original shims in my unit and the edges and corners were very sharp. Before replacing a shim, I round off the corners very slightly with scissors then smooth the edges and corners with fine sandpaper then a Scotch pad. Do not apply pressure... if the shim starts to bend while you're doing this, then your applying too much pressure.
As far as the BEGI is concerned, I think it's a misunderstood peice of equipment because it's difficult for many users to understand exactly how it functions and what part each component inside the unit plays, so when things go wrong, it immediately gets blamed. In this case, everyone seems to recommend a .010" shim which I no longer agree with. I think it would be a better idea to replace the shims with new .003" shims, smooth the edges and make sure they are centered properly... that means the corners should be positioned so they point in between the bolt holes. That will give the most holding power when the unit is bolted together. And of course make the bolts tight... and that doesn't mean getting carried away until the threads strip either.
Thanks for chiming in Pinky.
cdhoroho
Registered
one thing i forgot to tell you when talking to you
they have done a redesign and that was they went to the 2 .003" shims from a single .002 or .003 shim this was a few yrs ago (but that is just what i was seeing in the past few yrs, of seeing some just had 1 and now they come with 2)
they have done a redesign and that was they went to the 2 .003" shims from a single .002 or .003 shim this was a few yrs ago (but that is just what i was seeing in the past few yrs, of seeing some just had 1 and now they come with 2)
That explains why some posts implied they only had one shim. I just thought they either missated or meant per side of the diaphram. I also recall a post that mentioned a .002" shim but just thought they really meant .003". Didn't really give either one of those comments much thought but now I know otherwise.
If Corky went from .002" to .003" he obviously had a reason for not going to .004" or larger. You would think he would have gone even thicker had there not been issues, but he is also understandably trying to keep his unit as universal as possible. Wonder if it's possible for a .005" shim to work fine on one setup, but not another depending on the variables, like fuel pressure, etc. If so, then assuming I ever get around to testing the .005" and .007" shims, the results could vary, but going all the way to a .010" shim is just too thick.
Thanks for the info. If you remember anything else let me know.
If Corky went from .002" to .003" he obviously had a reason for not going to .004" or larger. You would think he would have gone even thicker had there not been issues, but he is also understandably trying to keep his unit as universal as possible. Wonder if it's possible for a .005" shim to work fine on one setup, but not another depending on the variables, like fuel pressure, etc. If so, then assuming I ever get around to testing the .005" and .007" shims, the results could vary, but going all the way to a .010" shim is just too thick.
Thanks for the info. If you remember anything else let me know.
OZBooster
Registered
Yes the begi went from the single .003 to the twin spaced .003 , adding a .010 to a .003 is beyond what most have ,
Great info
, i found in bench testing that the single .003 creased at 125psi fuel pressure , and i figure some are getting to this point and causing there own probs without knowing, and long term use will most likely cause a crease at a lower pressure
Great info
, i found in bench testing that the single .003 creased at 125psi fuel pressure , and i figure some are getting to this point and causing there own probs without knowing, and long term use will most likely cause a crease at a lower pressure
Good idea on the bench testing OZ. So now I'm wondering at what boost level would require 125 psi fuel pressure? ??? I recall Corky mentioning early on that people were using his fmu for more boost than what it was meant for. I think he said the limit was 10 lbs boost. I'm not positive but I know it wasn't more than that.
In my experience, bench testing is close but not 100% accurate. You cannot use air pressure to simulate "boost". Intake pulses will create less pressure to the FMU causing pressure to be lower. I found this out when trying to get my custom turbo dialed in. Luckily I use a mechanical fuel gauge and wideband when tuning. Anyone else noticed this?? ???
OZBooster
Registered
The flow rate to the fmu on bench and on bike are very differentand the fmu is very flow sensitive, I once backed up the testing by having a known result on bike then put a restrictor in line from the regulator to fmu on the bench, and could dial it in with reasonable accuracy but never bothered more than that once, now for base setup i pressurise the system to 10 psi on bike and set the fuel pressure and rate of rise in place with reasonable accuracy ,
