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Post by tradrockrat on Nov 8, 2006 13:50:54 GMT -5
My head is spinning. I'm in the middle of two projects on two different bikes and I'm having a real issue keeping all the facts straight. Could I perhaps lean a little on the carb masters here to list the bennies and disadvantages to the following, as well as give some specific part numbers? I would love you all forever - in a manly, biker sort of way...  1.The minton mods to a stock carb - (might do this if I buy a used carb - my carb will stay stock on a shelf - I want to be able to restore to stock if I ever change my mind) 2.Round slide mikuni 3.flat slide mikuni 4.keyster carb kit (does this do anything other than return to stock?) I figure that one post with all of the info present would prevent another 30 of us asking this same question... again... thanks guys. |
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Post by hopwheels on Nov 8, 2006 14:14:02 GMT -5
Hey tradrockrat: My experience... (more experienced minds will step in I'm certain  ) 1) Minton mods on carb only may not work effectively (I believe the full mod spec to include aftermarket header and K&N air filter www.siue.edu/~rsutton/SR/carbmod.htm ). I am still sorting mine out (I did the slide cutaway, etc., but have stock header and exhaust). The mod (written when our bikes were new) I think assumes replacement of the stock exhaust system 'cause I believe it was universally hated. If you leave the exhaust alone (stock), it complicates the Minton Mod fiddling about. 2) I have a 38mm Mikuni VM roundslide on my '79 from Sudco.com, but have yet to get it running. When I questioned and read, questioned and read, a year ago on this subject, this is what I settled on. The engine is fully modded, with oversize header and supertrapp. I don't know yet what it'll do. 3) No experience with flat slides for me. 4) Keyster carb kit contains components for rebuilding to stock only. Mine came with a 300 main jet, which again I believe is stock. It does not include any diaphragms, and the float needle valve varies from stock. I did not use the one from the kit on my rebuild as it did not attach to the float arm in the same manner as stock and became suspect in my mind. Hope this helps and gets this kicked off in the right direction. Gary Hopwheels PS: How are you liking Texas? I may wind up there soon, in the Fort Worth area. |
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Post by tradrockrat on Nov 8, 2006 15:42:58 GMT -5
Thanks for the info - this is exactly what I'm looking for. Keyster = stock - check Minton requires aftermarket pipes and K&N filter - check Now we need some more on the round slide and flat. As for Austin - It rocks! I love it here, but I'm not a big fan of the gulf coast area - way too humid for me - I grew up in Maryland and I am all done with humidity. Dallas / Ft. Worth is crowded, but I have met some great people from the area (all Harley scum, but I can handle that;) ). Traffic is... interesting, but not near what LA was like. Just for everyones info - I'm looking at aftermarket pipes and K&N filter for my bike, as well as 17 tooth front sproket, but that's about it. The cosmetics have already been done (turn signals, tailight, etc.). I love the way the SR looks and don't want to change too much of it, but I'm 240 pounds and want it to be able to run strong and reliably. |
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Post by pablosrfivehundred on Nov 8, 2006 16:05:03 GMT -5
you moved?
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Post by tradrockrat on Nov 8, 2006 16:16:41 GMT -5
fraid so buddy. Got a deal on a house and moved all within 23 days
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Post by pablosrfivehundred on Nov 8, 2006 22:15:47 GMT -5
a deal is at the very least in the same state. but congrats.
you should see the bike you saw months ago. you wouldn't recognize it.
side covers, undented black tank, dual brakes, newer exhaust, and no oil leaks!! the whole front end looks different.
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Post by colinjay on Nov 8, 2006 22:16:26 GMT -5
I am currently running a 38mm EI Blue Magnum (flat slide) carbie on my hot SR engine. This carbie works well on my engine, with good responce etc.
Now that everyone is scratching their head going "what the F is a EI Blue Magnum?", it time for a history lesson. Way back in the distant past, thats the late 70's, Lectron made a flat slide carbie that become all the rage for racing engines. The guy who designed these carbies was one Sparky Edmonson (I think that how it is spelt) and he when out on his own and made the EI (Edmonson Industries) carbies, which were a further development of the Lectron flat side design. If you look at picture of the original Eddie Lawson Kawasaki Superbike of the period you may notice that it at time had bright blue carbies fitted.
Well I fitted a 38mm EI onto the 390 Husky I was racing in in 79 and fitted it to my SR when I hotted up the engine in 1980, mainly because they are very easy to adjust the mixture on and have been using one ever since.
More history, as in 78, CYCLE magazine did a series of hot up articles on the SR500, and one of the comparisons they did was between the std carbie. a 36mm round slide mikuni and a 36mm EI (Silver Bullet) then engine was std except for the removal of the airbox (which netted them a 2.5 HP gain) even running the std exhaust. the 36mm round slide mikuni gave a minor inprovment of about 1 HP , the 36mm EI (which actually has a 34mm throught size) gave a reduction of about 1/2 HP but gave better throttle responce over the 36mm mikuni, they quried Edmondson about fitting a 38mm EI (36mm throught size) but were told it would not give any inprovement.
The advantage that flat slide carbies have over round slides is basically one of less turbulences / flow resistance at part throttle since the the distance that the air has to travel across the bottom of the slide is much less. This allows the air velocity to remain higher (turbulent air is slower than a laminar air flow) which will give better fuel pickup from the jets and also better atomisation of the fuel. The better air flow and better fuel attomisation etc result in improved throttle responce and often more power if the engine is in a state of tune that it requires more air and has an intake port design that can supply more air without killing off the air velocity (big ports and valves are not allways the way to go, as too big will kill the air velocity, as CYCLE mag found out in the 2nd part of their hot up article in 78).
Anyway, hopefully some of the above might be usefull!
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Post by fenz on Nov 9, 2006 5:52:39 GMT -5
I too had one of those cool blue flatslides never did use it though swapped it for a 36mm mikuni.Carby came with an xt engine i bought,the guy had been using it on a bike that had been built for the Finke desert race.
Anyway back to the question at hand,i will be fitting a 34mm mikuni flat slide to my bike tomorrow and will keep you posted on how things go.
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Post by tradrockrat on Nov 9, 2006 12:26:07 GMT -5
great info so far. thanks all. Pablosfivehundred - e-mail me a pic! tradrockrat@ h o t m a i l . c o m (remove the spaces to make it work, of course ) of course I still have no idea what I'm going to get... |
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Post by hopwheels on Nov 10, 2006 11:43:10 GMT -5
Forgot I had this, might be helpful for some folks. It's Mikuni's tuning manual for the VM series carbs. Pretty useful manual. Most of you probably have it, but I've uploaded it to my server for download if you want a copy. Click on the link, then save it to your PC. Gary Hopwheels www.hopwheels.com/downloads/vmmanual.pdf |
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Post by fenz on Nov 10, 2006 16:56:30 GMT -5
Good document on the mikuni anybody got something similar on the flat slide???
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Post by tradrockrat on Nov 11, 2006 15:20:50 GMT -5
another point just for clarification on the minton mods - I understand that the mods are really rather pointless without shaving the slide -- correct?
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Post by hopwheels on Nov 11, 2006 16:09:40 GMT -5
That's what understand... I think the slide cut is the main aspect of the mod. I was pretty intimidated to start filing on mine, but with a fine file and a steady even pressure, it worked out. I used a fine tip sharpie to mark the area I wanted to cut away and that helped immensely.
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Post by fenz on Nov 11, 2006 17:14:00 GMT -5
If you dont feel confident filing the slide a much easier alternative is to get the slide machined off in a metal lathe.Only takes a minute a lot more accurate than taking to it with a file.
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