gsxr1385

I do understand engineering and physics, unlike you that only understands how to google a subject and then spews out the results in a jargon laced diatribe that is not even applicable to the issue being discussed. It is not my job to educate you, but I will make a few points. First comparing the situation under discussion to the operation of a two-stroke engine (the pressurized flow of fuel intake and exhaust through the cylinder ports in a closed combustion chamber) is baffling because it doesn’t apply at all. I’ll leave it at that. Even more baffling is you bringing up the subject of compressibility of gases and liquids and their resultant fluid flow characteristics. We aren’t comparing gas vs liquid flow; we are comparing the flow of an oil/air mixture via two different paths. Bizzare. The principle here is the path of least resistance - pushing a gas, gas/liquid mixture, or a liquid through an orifice will result in a pressure drop and impede flow. And the higher the velocity of that mixture, the greater the resistance to flow (velocities greatly increase through your notch pathway vs the reservoir path). You do not understand fluid dynamics, Bernoulli's principles, etc. so stop pretending you do. Let me see if I can put this in more easily visualized terms - you are arguing that it is easier to push a 335 cc oil/air mixture (of a downward moving big bore piston) through an orifice (or two series notches of about 6-10 cc) into a 335 cc cavity, than it is to dump it into a large reservoir (say about 5000-6000cc) which is at a lower pressure (vented to atmospheric pressure or even lower from which that volume can be displaced out of the engine). And you are similarly saying that the simultaneous upward piston movements will draw through those two notches before it will draw from that large reservoir that is at a lower pressure. That reservoir also undulates with 2 more +/- piston movements that all 4 equate to zero volume changes at any crankshaft position. If fact, I'd be surprised if there is any flow through those notches' vs the crankcase path. So, who is rewriting the laws of physics?? If you understood those laws, you would recognize it is you. But you don’t. When you get a master’s degree in mechanical engineering, a minor in physics, 40 years of experience in applying your efforts to effect solutions that actually work, then we can have an intelligent discussion. Until then, or if you can provide data and testing protocols from a controlled test that prove your point, we have nothing further to discuss.

I guess we are just going to have to disagree. While I will agree that high velocity moving parts in a crankcase that can move more easily in the high temperature oil/air mixture (say by smoothing edges) will reduce horsepower requirements, I do not agree that those little notches in the liners is reducing energy required to move displaced oil/air mixture to any measurable degree regardless of speed / RPM. Fluids and gases will take the path of least resistance. How can a claim be made that any volume is passing through those notches, especially considering the available volume in the crankcase to displace say 335 cc (in a big bore engine) is so much more and provides less resistance to flow than passing that volume through those notches. An analogy would be a suspension system damper - which is the path of least resistance, force liquids through an orifice or into a larger volume reservoir? That is engineering judgement and physics. And reinforced by not seeing that feature in all manner of racing engine internals, and industrial pumps, reciprocating compressors, etc. I suspect it is just one of those experiments someone tried on a racer to try and gain a small advantage, and then became one of those "old racers tales" that get circulated through the years. However, if someone can produce data and test protocols from controlled testing that conclusively proves a horsepower savings from that feature, I'm willing to look at it - (someone saying that Suzuki says so, just isn't convincing).

I appreciate that explanation. I am not trying to be contrary, but the volume of air in the crankcase is not changing at all by the travels of piston 1 and 2, regardless of those windows. No new displacement is being added or taken away with those windows, and the argument of shorter path (and time) for crankcase volume to be moved via those windows vs. drawn from lower (perhaps 1 inch?) in the crankcase just doesn't account for lower or higher crankcase pressure. That doesn't even take into account the crankcase is vented to either atmospheric pressure or into the airbox (less than atmospheric pressure). If the crankcase vent isn't large enough to reduce crankcase pressure, it would be more effective to reduce crankcase pressure in other ways. Engine temperatures are also a major contributor to increase in crankcase pressure. I wouldn't bother to cut those windows

Ok so I'll be the one to ask the question - how does cutting the liners in that way reduce pumping losses?

Actually Vortex is the brand name and these are made by Ward Performance in Zimmerman Mn US. I purchased a "Vortex" from APE and the banjo bolts were defective. APE sent me to Ward Performance to get replacements. Perhaps now Ward has ceased making them and sold to someone else who now is supplying to APE, but I assure you those were made by Ward...

APE Racing still lists them in their on-line store

Thanks for the clarification … I read in the carb/rubber sticky that rubbers from 1100 M&N are 45mm ID (for BST 40mm?)… checked afterwards from parts suppliers that the rubbers for the 1100 (USA) K/L,(BST 36), and 1100 M/N (BST 40?) are all the same so was confused. Guess I'll stick with 750 L/M rubbers. Wish I could have watched your engine build!

Bigger venturi is the way I was leaning, but reasoned a smaller venturi could increase torque/horsepower at low and mid RPM's vs. larger venturi's (higher velocities better cylinder filling) but would starve at higher RPM's with too much pressure drop through the restriction. Hmmm 1100 M rubbers - 46mm? May need to look into that... That's one hell of a motor 1460 … and turbo'd whoa talk about arm stretching !

Here's a question for those experienced engine heads on this forum. I am planning a 90 GSXR 1100L big engine build, either a 1342 (83mm x 62mm) or 1385 cc (Bore 83mm x Stroke 64mm). This will have a heavily worked head as well (ported, big valves, cams etc.); everything in this engine will be heavily worked. I have all the parts ready to start, except those awaiting final engine specs. I think I'm settling on Keihin FCR 41 carbs. Picked up a set that has an intake spigot with an ID of 37.5mm, seems small for carbs this size. Per Keihin's charts this spigot was for a GSXR 1100 water-cooled. I found out these spigots will fit the stock 90 GSXR 1100L carb rubber boots (for a BST 36). However a different intake spigot (33B) can be purchased with an ID of 40mm and will fit the GSXR 750 L&M carb rubbers. I know as I've done this before with a set of FCR 39 with intake spigots (21C) having the same dimensions as the 33b's. The head will be ported to match the rubbers I use. So the question is what are the pros and cons of using the different size intake spigot / rubber combination? Smaller 37.5mm vs. larger 40mm with a head ported to match?

Great thread glad I found it … wish I had it years ago when trying to fit carbs to my bikes! I thought I would add some information to this thread that I have uncovered in my trials and tribulations and may cause some wringing of hands as it conflicts with some of the info I read in this topic. The following is based on equipment that I have in my hands and measured for myself, and also cross referenced with the Suzuki part numbers on the inlet rubbers. - Carb spacing for the USA model GSXR 1100 K and L models is 78-90-78. Both measured on the stock rubbers mounted on the engine and the stock BST 36 carbs. - Carb spacing for a FCR 39 and 41 for the air-cooled GSXR 750 (and 1100) carbs measure 78-89-78. One of the biggest FCR suppliers in the USA (Bolt on Performance) confirms these dimensions. - Carb spacing of a set of Mikuni RS40 I took off a 90 GSXR 1100 is 78-93-78 - Carb spacing for a set of FCR 39 I was told came from a 93-98 water cooled GSXR 1100 was 86-92-86. Again I was told these came from that bike, I cannot confirm that. - FCR carb outlet spigots are NOT one size; various sizes can be purchased to fit different inlet rubbers (They screw in). - With that said, an FCR 41 spigot part number 869 will fit in the stock GSXR 1100 K&L rubbers (USA models) - FCR 39 spigot 21C fits into the GSXR 750 L&M rubbers (meant for the BST 38). - Per Keihin's spigot dimension and cross reference charts, the FCR 41 spigot 33B should also fit in these GSXR 750 L&M rubbers (I hope so as I am buying these for my setup).

Thanks for the write up and pics. I'd say you did about everything reasonable to get those out, just bad luck on one. Hope you can get that last one bored easily. I've installed plenty of inserts and helicoils. inserts require a larger bored hole than helicoils, so not sure there is enough metal in the case for threaded inserts. The charts from suppliers in the USA say helicolis require a 13/32" or 10.5mm bored hole, while threaded inserts require a 31/64", 14mm or a 16mm hole depending on insert thickness. The threaded inserts are stronger of course. Boring and threading a true hole in the case could be a challenge as well

I can only take a guess as to what you are seeing. Each size of thread have various grades of fit - tight ,medium, loose etc. (not official terminology). Even though they look the same, there are very slight differences in the size of the shaped thread to get the tightness of fit. Perhaps that is what you are seeing. If that is the case, be very careful in using taps and dies as they may loosen up the tight fit if manufactured that way. You would need a tap or die for that specific tightness of fit. I am about to do the same operation as you and have been fearing snapping a stud. I bought a special stud removal tool that mounts close to the case and also intend on heating the aluminum / steel joint to free the bond. Care to shed more light on how you attempted to remove the studs and why you think the stud snapped?

Measure the diameter of the a) chrome plated slider tube, b) the aluminum tube at the top triple clamp point and c) diameter at the lower triple clamp points. Compare to the data in the attached and perhaps this will nail it or narrow the list down. Good luck