K&B 6.5 What to do with
10-26-2010, 03:35 PM
#27
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RE: K&B 6.5 What to do with
So you K&B Experts are saying that the 6.5 & 7.5 aren't going to work well with a 10x6 and 10% CoolPower.
I have a couple of each and was planning on using a pumped 7.5 on a FK Magic 40 copy. I have a couple of
other questions for you guys. What is the purpose of that hole/intake just under the exhaust port as shown
in post 12? Also I have a couple of those K&B black carbs., are they any good for general use or are they
just go fast, go a little slower, and engine kill types?
Thanks
I have a couple of each and was planning on using a pumped 7.5 on a FK Magic 40 copy. I have a couple of
other questions for you guys. What is the purpose of that hole/intake just under the exhaust port as shown
in post 12? Also I have a couple of those K&B black carbs., are they any good for general use or are they
just go fast, go a little slower, and engine kill types?
Thanks
10-26-2010, 04:06 PM
#28
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RE: K&B 6.5 What to do with
10 x 6 on 10% will run just fine. Your engine may not be up in the RPM power band but it will run with authority. The little hole under the exhaust port, I have never seen before but the big hole with the end of the connecting rod sticking out? Well I have seen a few of those unfortunately! [:'(]
K/B black carb???? Post a picture. Sounds like you may have a K/B that someone installed a IRVINE carb on it.
K/B black carb???? Post a picture. Sounds like you may have a K/B that someone installed a IRVINE carb on it.
10-26-2010, 07:07 PM
#29
RE: K&B 6.5 What to do with
The holes (there is one on each side ) are a modification...to let a little extra air in at TDC...sub piston induction. Clarence Lee, and others used to modify these engines for F-1 racing...control line Rat racing...Free Flight...etc.
Ron...is your black carb alum. or plastic?
Ron...is your black carb alum. or plastic?
10-26-2010, 08:09 PM
#31
RE: K&B 6.5 What to do with
Not sure just how much of an increase? I think they worked best with the mini pipe (F-1 style )?
Sub piston induction, generally speaking, doesn't work well when you have exh. backpressure.
I don't actually have any with that mod. but I've seen it before, and I asked Mr. Lee what it was, and he told me...
I believe that the thing sticking out of the case (in Highplains pic ) is the alum. band (stuffer ring ) around the crank's counterweight? (or is it the rod Bob? )
I've seen that happen to an X-40 as well.
Sub piston induction, generally speaking, doesn't work well when you have exh. backpressure.
I don't actually have any with that mod. but I've seen it before, and I asked Mr. Lee what it was, and he told me...
I believe that the thing sticking out of the case (in Highplains pic ) is the alum. band (stuffer ring ) around the crank's counterweight? (or is it the rod Bob? )
I've seen that happen to an X-40 as well.
10-26-2010, 09:00 PM
#33
RE: K&B 6.5 What to do with
Could very well be a Perry (or Irvine ) if it's plastic...but there is also an anodized black Aluminum K/B carb w/ .312" throttle bore that was sometimes used as an air valve type for Q500 6.5's (there is also a red anodized version, with a larger .342" throttle bore )
The above mentioned alum. K/B carbs were (don't know if they still are ) also common on the marine engines.
The above mentioned alum. K/B carbs were (don't know if they still are ) also common on the marine engines.
10-26-2010, 09:21 PM
#34
RE: K&B 6.5 What to do with
ORIGINAL: DaveL322
I have a NIB 7.5cc DF series 9101 dated 10-96....came with the series 94 carb and K&B mini pipe. I also have a MACs #3452 Fuse Top header.
I'm curious as to the thoughts of this group as to the value, and if any interest? I intended this engine for a high speed wing which I'll never build at this point....and if I do, it will be electron powered.
Regards,
I have a NIB 7.5cc DF series 9101 dated 10-96....came with the series 94 carb and K&B mini pipe. I also have a MACs #3452 Fuse Top header.
I'm curious as to the thoughts of this group as to the value, and if any interest? I intended this engine for a high speed wing which I'll never build at this point....and if I do, it will be electron powered.
Regards,
Dave...I bought a couple 7.5 DF's a year or so ago...paid around 100. for ea.
Seen 'em sell for between 100. and 135.00 on epay.
10-26-2010, 11:54 PM
#35
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RE: K&B 6.5 What to do with
Here are photo of the carb. That spot of epoxy on the rear is covering the non adjustable
air bleed hole, could have been for boat use. I’ve included photos of piston/cylinder assy.
of the engine in post 12, just so all could see. I was thinking that maybe the holes/intakes
were used to bring in cooler air to help cool the top of the piston, rod and pin. I’ve also
included a photo of my next questions, the piston, connect-rod and pin. Why the use of
those restrictors? The crank/pin and rear cover should hold the rod in place. Or could they
be part of an upper end bush for the rod?
air bleed hole, could have been for boat use. I’ve included photos of piston/cylinder assy.
of the engine in post 12, just so all could see. I was thinking that maybe the holes/intakes
were used to bring in cooler air to help cool the top of the piston, rod and pin. I’ve also
included a photo of my next questions, the piston, connect-rod and pin. Why the use of
those restrictors? The crank/pin and rear cover should hold the rod in place. Or could they
be part of an upper end bush for the rod?
10-27-2010, 07:57 AM
#36
RE: K&B 6.5 What to do with
That's the alum. carb I was talking about...nice pics [8D]
That sleeve has SPI port openings under the Exhaust ports. The rear disc rotor engines are somewhat restricted as far as the I. (venturi ) bore dia. in the backplate, and the SPI was a way to help get more air into the crankcase.
Those spacers on the wrist pin end of the rod help limit rod walk back and forth on the pin. They cut down on wear on the faces of the rod, and keep the rod from wearing into the disc.
On an outboard boat version for example, the engine is mounted with the crank pointing straight up...the rod would want to fall back (or down ) into the disc. I've seen those spacers used on both 6.5's and 7.5's, boat and airplane use...they might also help with limiting angular loading on the pin and piston?
That sleeve has SPI port openings under the Exhaust ports. The rear disc rotor engines are somewhat restricted as far as the I. (venturi ) bore dia. in the backplate, and the SPI was a way to help get more air into the crankcase.
Those spacers on the wrist pin end of the rod help limit rod walk back and forth on the pin. They cut down on wear on the faces of the rod, and keep the rod from wearing into the disc.
On an outboard boat version for example, the engine is mounted with the crank pointing straight up...the rod would want to fall back (or down ) into the disc. I've seen those spacers used on both 6.5's and 7.5's, boat and airplane use...they might also help with limiting angular loading on the pin and piston?
10-27-2010, 03:50 PM
#37
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RE: K&B 6.5 What to do with
Yes...has K/B right in plain view. I'm getting old because the Perry carbs completely slipped my mind. Duhhhh! I am not a Perry carb lover since I had problems with getting the N/V to stay set since they did not have a ratchet and funny stuff happens at 20K+ RPM. I still have a very fine stash of K/B 3.5, 6.5, and 7.5cc, NIB and used engines and parts. Aside from a Nelson or a RE Jett 60LX, these are my favorite engines.
SPEEDY
SPEEDY
01-03-2014, 05:26 PM
#38
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Back in the day the K/B "metric series" engines were THE engines to have running in competition with the ST "X" series engines. I have many years experience with these engines and if ran right they will live a long life but that was somewhat the demise of K/B because in those days each engine was unique. You might have 4 good engines and then completely fry one on the first race. For racing each engine had to be handled as if to have it's own "personallity" and it was best to keep a "log" on each one. The wrong setting or prop/plug combo on the wrong engine resulted in another hunk of metal in the bottom of your flight box. Many of us aquired literally boxes of parts and they were a necessity to keep your fleet running. I still have many parts and also learned to keep good used parts. Used parts when properly sorted for a good fit are sometimes better than new parts. I still run these engines and when ran properly they are superb performers. Due to the metallurgy incorporated at the time these engine were being manufactured it was/is imperative to use fuels that incorporate some percentage of castor oil. Pure synthetic based fuels will work but extreme caution must be used to avoid lean runs.
Another thing to remember is that if the engine is of value to you it is wise to hold the nitro down to 20% and keep the lube up to a minimum of 20%. This was my 20/20 formula for diverting disaster. Now days they dont even run high nitro and FAI Formula 1 is restricted to 0% nitro. They are actually achieving more power with less nitro. Nitro is power but it is also heat which is the killer. It was ( and still is ) a common occourance to go the the field and burn up $20 worth of glowplugs and $5 worth of fuel! There is no need to "push" these engines since they are no longer legal for competition. My favorite fuel for these little fire breathing monsters is Powermaster 10/22 and I still have a couple dozen Rev Up 8 3/4x 6 1/2 wood props. The wood props are light and they seem to turn up the best. These engines must also be run-in properly. Getting in a hurry with this process will just result in another scored cylinder and piston. Aside from all my seemingly negative comments about this engine...I have a deep respect for them and a longtime love affair with my own personal stash.
I use my "metric" K/B's mostly for sport speed models now. See picture below.
My Shrike 40 with a K/B 7.5cc DF front intake/rear exhaust. The carb is an advantage over the rear intake rear exhaust. Without a throttle your engine can go lean in the air and all you can do is listen to it burn up. This plane is a blast to fly and has lasted me many a season but at the cost of several rebuilds and glowplugs. They seem to hold up ( and run ) best when ran between 17.5K and 19K RPM static. You can push them harder but be preparred to pay the piper! Don't load these engines with a big prop. They are timed to run hard and are designed solely for pylon/speed type applications
Another thing to remember is that if the engine is of value to you it is wise to hold the nitro down to 20% and keep the lube up to a minimum of 20%. This was my 20/20 formula for diverting disaster. Now days they dont even run high nitro and FAI Formula 1 is restricted to 0% nitro. They are actually achieving more power with less nitro. Nitro is power but it is also heat which is the killer. It was ( and still is ) a common occourance to go the the field and burn up $20 worth of glowplugs and $5 worth of fuel! There is no need to "push" these engines since they are no longer legal for competition. My favorite fuel for these little fire breathing monsters is Powermaster 10/22 and I still have a couple dozen Rev Up 8 3/4x 6 1/2 wood props. The wood props are light and they seem to turn up the best. These engines must also be run-in properly. Getting in a hurry with this process will just result in another scored cylinder and piston. Aside from all my seemingly negative comments about this engine...I have a deep respect for them and a longtime love affair with my own personal stash.
I use my "metric" K/B's mostly for sport speed models now. See picture below.
My Shrike 40 with a K/B 7.5cc DF front intake/rear exhaust. The carb is an advantage over the rear intake rear exhaust. Without a throttle your engine can go lean in the air and all you can do is listen to it burn up. This plane is a blast to fly and has lasted me many a season but at the cost of several rebuilds and glowplugs. They seem to hold up ( and run ) best when ran between 17.5K and 19K RPM static. You can push them harder but be preparred to pay the piper! Don't load these engines with a big prop. They are timed to run hard and are designed solely for pylon/speed type applications
Sounds like you have a handle on these old 6.5 fellas. I have a new old stock 6.5 FIRE Model 9130. Has a Perry carb on it. I have no experience with these engines so I have a question for you. Should I put a different carb on it or will this plastic one work well enough for a Q-500 sport flier? I need to run a quiet pipe because of db limits at my field. I will add castor to heli fuel as I read your comments above. Thanks
01-06-2014, 02:05 PM
#39
Senior Member
Very powerful little motor. I had a 6.5 on a DeBolt scratch built Solution in the late 70's. Hal recommended the 6.5/mini pipe combo for the solution and as Doxilia pointed out, the mini pipe was not a tuned pipe at all but a straight, open exhaust tube. Boy was this thing L O U D.....Almost megaphone like.....I'd gues around 105 dB, maybe a bit higher.
Back then I was flying next door to a par 3 golf course here in North Jersey. Whenever I'd fly the crate, you could nearly hear the golfers *****ing about the noise, their Saturday morning Nassaus interrupted. LOL!!
I thought it was comical but the club safety officer didn't. That clown wanted to cause me serious bodily harm. In retro spect, seems like a contradiction in terms, safety officer wanting to do harm. Oh well!!
The Solution flew a few dozen times over the next few Saturdays and was an extremely sweet flier. It should have been of course at 700 squares and only 5 1/2 pounds with the screeming 2 HP up front. I had enough of the noise and retired it way too early out of necessity.
Back then I was flying next door to a par 3 golf course here in North Jersey. Whenever I'd fly the crate, you could nearly hear the golfers *****ing about the noise, their Saturday morning Nassaus interrupted. LOL!!
I thought it was comical but the club safety officer didn't. That clown wanted to cause me serious bodily harm. In retro spect, seems like a contradiction in terms, safety officer wanting to do harm. Oh well!!
The Solution flew a few dozen times over the next few Saturdays and was an extremely sweet flier. It should have been of course at 700 squares and only 5 1/2 pounds with the screeming 2 HP up front. I had enough of the noise and retired it way too early out of necessity.
Last edited by MTK; 01-06-2014 at 02:12 PM.
01-06-2014, 03:06 PM
#40
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Matt, others,
any idea how these beasts perform on a Macs quiet tuned pipe and header? Will they turn a 10x6 without getting too bogged down? Will they throttle on the Perry's or is it more of an "on/off" proposition?
David
any idea how these beasts perform on a Macs quiet tuned pipe and header? Will they turn a 10x6 without getting too bogged down? Will they throttle on the Perry's or is it more of an "on/off" proposition?
David
01-06-2014, 07:10 PM
#41
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it will do just fine on the quiet pipe with a 10x6, a newer generation perry carb, or a adapted OS 40 carb....owned a few and they lasted forever on the 10x6 or a 9x7 , i flew that combo on the skooter and a kaos as well....one plug per season on pattern type airplane setups 15 percent fuels
Last edited by lfinney; 01-11-2014 at 03:57 PM.
01-06-2014, 08:44 PM
#43
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Thanks Lorin. Any preference between the 1040 (7.5 cc) & 1050 (8.5 cc) pipes on the 6.5 cc engine? Tank pressure still off the backplate bolt tap or off the pipe?
I have some OPS and ST carbs that might fit. Any reason not to try those?
David
I have some OPS and ST carbs that might fit. Any reason not to try those?
David
01-07-2014, 07:56 AM
#44
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I ran a 10x6 on mine, a standard for .40 cuin engines back then. It spooled up to around 14K I'd guess, un piped. Never ran it with a pipe and wish I had, It would've toned down the deafening noise. I'm certain a pipe would work great on that engine
01-07-2014, 05:15 PM
#45
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Has anyone ever tried or used the old Tatone muffler that would route the exhaust to the side, much like the Cox/K&B 15 on either of these engines? I have the old can muffler for these engines and I plan to test the engines I have on a Scat Cat 500 once I have the time.
David, a 7.5 would make that Mach 8 go real fast!
David, a 7.5 would make that Mach 8 go real fast!
01-07-2014, 08:17 PM
#46
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Dave, mine was Perry carb equipped. That carb worked exceedingly well with this engine and it actually had a nice idle and reasonable transition. I still have one disassembled in the parts drawer. I think. If I find the parts, I'll send them your way, NC
I ran a 10x6 on mine, a standard for .40 cu in engines back then. It spooled up to around 14K I'd guess, unpiped. Never ran it with a pipe and wish I had, It would've toned down the deafening noise. I'm certain a pipe would work great on that engine
I ran a 10x6 on mine, a standard for .40 cu in engines back then. It spooled up to around 14K I'd guess, unpiped. Never ran it with a pipe and wish I had, It would've toned down the deafening noise. I'm certain a pipe would work great on that engine
thanks for the info. I had sort of stored that one away thinking it wouldn't transition properly for pattern applications. but based on what both you and Lorin are saying, it sounds like its worth giving them a try. One thing I seem to recall being done often to the metrics was replacing the smaller slotted head bolts with stronger socket cap bolts like K&B did on the non metric engines (ironically the sport engines).
I appreciate the parts, thanks, if you locate them.
David
01-07-2014, 08:25 PM
#47
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Hey Ron.
It would indeed! In fact, I strongly suspect too fast for me.
I'll have to look into how much they weigh. I suspect they are a tad heavy. The other thing is that I'm keeping the design per the original in the engine compartment using a plywood mounting plate rather than a radial mount. It just integrates the model really well as the plate can be used for a nose retract as well.
I have the feeling that the M8 is going to be ballistic on just about any 35-40 size engine - I suspect it will be lightish at ~3.5 lbs dry.
I should have the first pair cut in the near future.
David
It would indeed! In fact, I strongly suspect too fast for me.
I'll have to look into how much they weigh. I suspect they are a tad heavy. The other thing is that I'm keeping the design per the original in the engine compartment using a plywood mounting plate rather than a radial mount. It just integrates the model really well as the plate can be used for a nose retract as well.
I have the feeling that the M8 is going to be ballistic on just about any 35-40 size engine - I suspect it will be lightish at ~3.5 lbs dry.
I should have the first pair cut in the near future.
David
01-11-2014, 03:54 PM
#48
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the 7.5 pipes are fine for aircraft..the 8.5 pipes were for boats and ducted fan useage..they will work but they have a much hard hit on the top end no reason not to use the st carbs or any os carb..IIRC the header length was 3 inches with ten inch props...i tap the header plate for pipe pressure...
01-11-2014, 04:31 PM
#49
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the 7.5 pipes are fine for aircraft..the 8.5 pipes were for boats and ducted fan useage..they will work but they have a much hard hit on the top end no reason not to use the st carbs or any os carb..IIRC the header length was 3 inches with ten inch props...i tap the header plate for pipe pressure...
thanks for the info. 3" from header plate front to rear of header? Or is it from glow plug to rear of header.
I'm going to pick a header up and try it on a 6.5 MP this Spring. I have two 6.5's but no 7.5's.
I was considering 10% Cool Power with 5 oz of castor added for a ~17/3% synthetic/castor oil content. Sufficient castor?
David
01-12-2014, 12:06 PM
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from front of plate to rear of header..tons of castor...sub 20k running is pretty tame on the engine..I usually switched to the polyamide bearing retainer types, if I run them over 20k