Sleeve Transfer port matching

[3Razors]

Hi, heres the deal just pulled the cylinder from one of my K5's for the first time and to my dismay its has been sleeved.  It was ported by FMF from the previous owner and ran pretty hard.  Now here is where it gets interesting in the upper transfer port area the sleeve is not flush with the transfer port and it hangs down I'd say 2-3mm below the top of the port.  On the bottom of the transfers the sleeve is nice and flush/matched to the port.  I don't know whether somebody did this on purpose for better performance or was just a knucklehead not knowing what they are doing.

Next question for anyone that has installed a sleeve in a completely stock k5 cylinder did the sleeve match the transfer ports exactly? How much if any at all was the difference in overlap?  I have another virgin plated K5 cylinder and the stock transfers look larger than the openings on the sleeve.  I'm out of town for the week and havent got a chance to mic them out to compare them.

[jonny500]

has it been done on purpose? i have never heard of a mod like that (to ruduce tranfer duration). but 2 - 3 mm is massive interms of port duration.
or maybe the cylinder was ported by fmf and then some time latter was fitted with a standard linner.
 i presume you are suggesting that you grind the affending area flush. DONT. if you do this you will alter the transfer port duration, you will increase it by several degrees if you remove the 2 - 3mm. you need to get a port map of the standard cylinder and compare it to your cylinder. also the shape of the top of the transfer port is important to how the engine runs so any grinding needs to be done by someone that knows there stuff. my advice to you is if the motor was running ok before the strip down then leave it be. if you mess this up then you may have to buy a new cylinder.
 

[3Razors]

It appears it was done on purpose, or unless they forgot to match the top of the ports?  I mean all the lower parts of the sleeve were ground on to match up, same with the intake porting.  Maybe someone got in a rush at fmf and didn't do the job right?  It just doesn't make sense to me as ports in the sleeve don't even appear to be as large as the ones in this other stock cylinder.

The bike did run great and faster than a stocker for sure.  But I won't be grinding on anything, I have an expert engine builder here Jerry Hall that I'm going to take it to for his opinion.

[GREENKAW24]

The sleeves from L.A. Sleeve don't always match the ports in the cylinder and need extensive blending to get the ports back to stock size and height.Sometimes the locations of the ports in the sleeve are off too, making it difficult to match everything. It could be one of theirs installed in that cylinder, and nobody took the time to match the ports fully.

[kaw rider]

is it the left or right side rear transfer that has this.

[3Razors]

is it the left or right side rear transfer that has this.

Its on both the left/right side with the front/rear transfers, and also the auxillary exhaust ports seemed to have the same issue now that I remember.  Also FMF did porting in the tunnels in this area, how high or if they raised them I do not know until I get home and measure it.  One thing is for sure if the sleeve ports are not at least the dimensions of the stock cylinder something just isn't right imo.

[kaw rider]

razor
you are right it's not right. you will have to degree the cylinder or get the height of the ports to see if the sleeve are at stock height or it fmf ported the tunnel roofs too high. I would just put a plated cylinder on it and sell that sleeve cylinder. with this being a low rpm motor its not as important.

[3Razors]

Ok so here's some pics.  Turns out the transfer and exhaust ports are the same size as stock.  The intake ports have all been opened up quite a bit.  The roof height on the transfers is higher than the sleeve by 1.5mm.  From the top of the transfer to top of cylinder on both stock/fmf cylinder is roughly 69mm.  Now my understanding is that all this portwork on the intake is basically useless because the transfers/exhaust ports are same as stock? 

[jonny500]

sounds like this cylinder was tuned (or Fu#*@d up) and then bought back to standard. it depends on what you require from your engine, personally i think the standard tune is fine and would not need any more. if you open the transfer ports you will change the peak power. i have some mathematical formulas so you can calculate the port duration , but its pretty full on

[kaw rider]

razor
well the intake ports are a big problem on these cylinders. Whats done to that cylinder is a improvement from stock. don't raise the exhaust and raise the transfer.

[3Razors]

Good points guys.  This fmf cylinder is a mystery.  I'm still not a fan of the sleeve.  I think I'm going to throw on my virgin stock cylinder for comparisions sake and try it.  The exhaust looks small for a 500, seems it would be hard to modify with guillotine valve in the way. How many mm's do tuners usually raise transfers on these over stock?  I don't want anything that is too peaky in rpm though.

[kaw rider]

razor
yes the exhaust does look small but not for the rpm range the engine was design for. It sucks that to make these cylinders run great you have to drop some coin. But porting or cylinder layout is only small part of the puzzle to makes these run good.

[3Razors]

razor
yes the exhaust does look small but not for the rpm range the engine was design for. It sucks that to make these cylinders run great you have to drop some coin. But porting or cylinder layout is only small part of the puzzle to makes these run good.

I agree..I feel to truly make this cylinder run a hard a new custom pipe needs to be made.  My friend has a LT500 (same bore/stroke as KX) that is putting out 90+hp to the rear wheels on race gas.  It's nothng really exotic either..custom big volume pipe, right porting/head work, and 44mm carb.  Here is the dyno chart of it, it was on a dynojet inertia 248 model.  Notice how it has a nice umbrella power curve...not peaky like most the high hp 500 builds.  The other pic is of the pipe, it is monster..like 7-8 inches in diameter and larger stinger too.  I feel the kx can at least make the same modified hp as the lt if not more as the kx has a better port layout.

[kaw rider]

razor
the torque has a nice 2k range window, great for transmission rpm drop. I don't look at hp because you can be low or higher then that with almost same torque numbers. I like to shout for a 3k torque range. I know jerry and robert makes good power.

[GREENKAW24]

Ok so here's some pics.  Turns out the transfer and exhaust ports are the same size as stock.  The intake ports have all been opened up quite a bit.  The roof height on the transfers is higher than the sleeve by 1.5mm.  From the top of the transfer to top of cylinder on both stock/fmf cylinder is roughly 69mm.  Now my understanding is that all this portwork on the intake is basically useless because the transfers/exhaust ports are same as stock? 

The port work isn't useless, because even though the port heights are the same as stock, this cylinder will flow better than a stock one. The midrange will be better than stock on that FMF cylinder.