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Post by theswede on Sept 7, 2006 10:52:30 GMT -5
Hi! I may have been a bit over-enthusiastic when starting the rebuild of my SR engine...  I have alredy fitted a wiseco 90mm 11:1 piston, and want to run it on 98oct. I guess it will be possible with a long-duration cam, but to be on the safe side I'm thinking of dual-plugging the head. So here's my question: Anybody have experience of adding an extra sparkplug to a SR/XT head? I think VD-Classic perform such a modification, and locates the extra plug right next to the intake duct. Does this mod require any welding, or can I just drill and tap? Also, what thread size, heat ratings, coils, etc? With this mod the engine will probably require less ignition advance. Is there a way to tamper with the CDI-unit, other than rotating the ignition plate? If it still does'nt work out, 85% ethanol fuel is becoming available here in sweden. A conversion would definately solve my problem! |
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Post by sjef on Sept 7, 2006 11:19:38 GMT -5
Hallo, to do it the right way, meaning ignition coming from boths sides to make an even fuel gas combustion,you have to make a second plug hole trough the camchaintunnel.I have it on my cilinderhead. plugs are 2 cr8eNGK, ignitioncoil is from MSD blastercoil, prim 1,2ohm sec 11.5kohm, just like the SR ignitioncoil. CDI is from Asuotani ,adjustable timing. there also is a french website with a d.i.y. programmable ignition kit for the SR.     btw are you jonasl from the www.srclub.nu forum? |
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Post by pablosrfivehundred on Sept 7, 2006 14:37:15 GMT -5
WOW that's all i can say.
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Post by StewRoss on Sept 7, 2006 17:35:07 GMT -5
Hi, Nice work Sjef... SR  |
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Post by wotavidone on Sept 7, 2006 18:59:02 GMT -5
You guys are legends.
I believed I knew a thing or two about the internal combustion engine, but it appears I am just a beginner.
Lemme get this straight. Am I to understand that the use of twin spark plugs is meant to give an even combustion on high compression? i.e. Eliminate the pinging that must surely otherwise result from running 11:1 pistons and 98 octane fuel?
Also interested in this here adjustable igniton. I would dearly love to be able to retard the top end of the curve adegree or three. Actually put a bit of a bend in the middle of the graph. I have pinging under load from about 4300 to 5300. Love to ease the ignition back a bit there.
Mick
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Post by theswede on Sept 8, 2006 9:00:13 GMT -5
Sjef, thank you for the pictures. Is that a special cast, or the result of some extensive welding and milling?! It sure looks nice! Just out of interest, do you want to share some more specs of your engine? Two sparks, located like yours, is of course ideal for combustion. Fitting a plug next to the intake seems like an easier job though, and I figure that it still performs better than just one plug. Mick, I'm not a rocket scientist myself  , but I believe that a faster combustion that starts later reduces the thermal load on the head, and therefore gains in knock resistance (if you just retard ignition you will loose power). Please correct me if I'm wrong! ...you guessed right, I'm jonasl... |
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Post by sjef on Sept 8, 2006 13:28:39 GMT -5
@ Stew, the head is performed by Daytona, not me, just organized the part. @jonasl the head is from Daytona the same ignition can be made on a srhead. it has been done by a german guy , you will need a lathe and milling gear.  except for the head: bigbore kit also daytona,crankshaft 91mm powroll,crank carillo, JE piston 91mm compratio 10.8/1 megacyclecam251-30 Over transmission, daishin dryclutch msd coil asuotani sp11 ignition. @mick here is the curve for the sr it is about the same  and if you like electronics www.transmic.net/index.htm |
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Post by StewRoss on Sept 8, 2006 17:30:53 GMT -5
Hi Sjef, Yes I see now...I missed the square finning..thought that you may have copied the idea of the plug placement. When I get some cash together I may start looking for one of these myself. SR  |
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Post by wotavidone on Sept 10, 2006 23:30:07 GMT -5
Hi Sjef,
I take it the curves on the graph are the ones available on your adjustable CDI?
If "Normal" is stock SR curve, then it looks like there is huge scope for me to address my pinging problems with this ignition. I'll wear potential loss of power for a ride that can coast along comfortably without pinging at 4500 rpm. Currently I cannot use the available power anyway, as I have to be very careful how much I roll the throttle on.
Mick
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Post by sjef on Sept 11, 2006 13:01:49 GMT -5
mick
have you tried to turn the statorplate?some of the plates have slotted holes.
high octane fuel?to lean around 4500rpm?
the sp11 might solve your problem but will cost you it is better to try to solve it the cheaper way.
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Post by wotavidone on Sept 11, 2006 20:03:30 GMT -5
Hi Sjef,
Yeah, I've done what I can. 330 main jet, needle as high as it will go and still run, cold plugs, stator is about as far around as it will go without little coil on out side hitting case, 98 octane fuel. Tried various alcohol blends as well. According to my timing light its a couple of degrees retarded.
I've pretty much made the low range (needle) as rich as I can, and the high range (main jet) rich as I can, in the hope of getting the overlap, around 4500, as rich as I can. This has been somewhat successful, but still pings under acceleration or when I hit a decent headwind or hill.
I am toying with a little fix that might or might not be feasible.
I am assuming the little coil on the outside of the fly wheel is the pulser coil that tells the CDI when to fire.
A close look at that reveals that there is a piece of metal with what I refer to as the flux gap in it. I reckon it is the magnet on the flywheel closing this gap that causes the little coil to send a pulse.
I reckon that even if the coil can't be moved any further around, an enterprising man with a hacksaw and a file should be able to make a new bit of metal with the gap displaced a couple of degrees in the desired direction.
I've been putting this off, as I would rather not risk wrecking a functioning stator.
Anyone out there tried such a thing?
The website you put up is in French and I'm not game to load translating software here at work. I'll give it a go at home on the weekend.
Regards,
Mick
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Post by wotavidone on Sept 11, 2006 20:13:43 GMT -5
Sjef,
Just found the English version of the site. Wondered why there was a pommy flag in the corner.
Looks v. interesting.
Might just knock up a programmable ignition form the Jaycar kit.
Mick
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Post by StewRoss on Sept 12, 2006 7:00:22 GMT -5
Hi Mick, Just out of interest, I have an 88.5mm piston in the black cafe racer, with a 38mm Mikuni and QA throttle and I run it on 100/130 AVGAS...this results in an immediate stop to the pinging (...which was a real problem) and instant flexibility to go with it. Open the throttle from anywhere now and it picks straight up with no effort... Plus it smells nice as it goes. But as an aircraft person I am biased I guess... SR |
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Post by sjef on Sept 12, 2006 16:53:42 GMT -5
Hallo Mick which carb are you running? btw www.kedo.de is selling a cdi manipulator part 40018 about 70 euro.timing till 24 degrees in 12 stages |
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Post by wotavidone on Sept 12, 2006 18:52:58 GMT -5
Hi Sjef/SR,
I have no idea what size piston I have, only the previous owners assertion that it's a 10:1 wiseco.
Carb is VM34SS, standard, but I'm up to #330 main jet.
When I bought the bike I tried to run it on 95 octane premium, but could not do anything with jets or plugs to make it run smooth.
Instant improvement came when I found a servo selling 98 octane BP.
AVGAS almost unprocurable up here, otherwise I would run it on that. Although, since airports are few and far between up here, I'd be limited to about 160 km jaunts.
I'd love to score at least 100 octane. I suspect, given the improvement the first 3 octane increase gave me, that another 2 octane would just about cure the beast.
Conditions must have been just right on monday night, cause I screwed it on coming home from the clubhouse, and the ol girl certainly answered the question when it was asked -120km with a heap of throttle to go and a nice surge forward when I twisted it on.. I feel there is a stock of untapped performance there if I can get to it before I stuff up my piston.
Currently considering three other steps to take.
1) Programmable CDI
2) Stepped key for shaft to make a fixed adjustment to the flywheel position. Presuming the flywheel is located with a key?
3) Copper head gasket, my calculation is that an extra 1.1 mm thickness would result in about one whole number lower in compression ratio.
I think that I shall contact the lad whose father built the engine for my GT Falcon, and see if he can do me a key.
Anyway it is rideable, if I don't flog it too hard, so its all part of the fun.
Mick
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I have alredy fitted a wiseco 90mm 11:1 piston, and want to run it on 98oct. I guess it will be possible with a long-duration cam, but to be on the safe side I'm thinking of dual-plugging the head.
, but I believe that a faster combustion that starts later reduces the thermal load on the head, and therefore gains in knock resistance (if you just retard ignition you will loose power). Please correct me if I'm wrong!