Help CDI intermittant spark

[TommyMoEmDown]

I'm restoring an old 78 SRX I picked up years ago and powering with an 83 vmax540. I'm using the wiring and cdi that came off the vmax. I believe it has T.O.R.S. I don't have anything hooked up except for the 8 wire CDI and the coil . He's the problem, the engine will fire once like a flywheel hit & miss engine. As it slows down it may hit again and once in a while it might actualy stay running and rev up for about 30 or 40seconds. I pulled the plugs an observed the spark while pulling the engine. As you pull the roap, first it has spark, then at the peak of the pull, the spark stops, then spark restarts as it slows. Does anyone know what the controller box does? Can the T O R S be eliminated? Do I just have a bad CDI Box? I ohmed the stator & it checks out ok. Anyone?

[tyler440]

hmmm spark problems are aways such a $%^*(... but one thing 83 and 84 did not have TORS... that started in 85... and yes it can be eliminated.... it could be a variety of things really... if i were you i would disconnected everything that i can... the key switch, tether, and push buttom kill switch and all be simply unplugged and eliminated... try that and let us know...

[tyler440]

oh once i went to vmax4 i realized you said you only have the cdi and stator plugged in... do you have a voltage regulator also plugged into the harness? check all of your connections from the stator to the the harness and from the harness to the cdi... sometimes you have to get a pair of pliers and carefully squeeze the female 1/2 of the connection to tighten them up a bit.... clean, tight and dry are what your looking for... let us know

[chrisrider63]

Aside from the ignition problem could we see how you got this baby mounted in the old SRX tub?? Im dying to see how you guys did it...

[TommyMoEmDown]

originally I did not have to Voltage reg plugged in, so I plugged the harness into the original Srx by the left foot rest. I assumed it's the same as the vmax..

[TommyMoEmDown]

I mounted the engine to a flat 1/4 inch aluminum plate and used the original SRX Front Mount. The V-max rear plate lined up with the original SRX but with only 1 mount dead center insted of 2. I used the SRX clutch alignment specs center to center 10.63 and .217 sheave offset. I will still need to add a stabilizer between the engine & secondary to handle the torque and compensate for the lack of the front VMax mount.

I am using stock 1980 SRX twin pipes/ don't know how well they will be in tune. Due to the 540 ex ports coming out nearly level I machined 2 17 deg wedges which matched the exhaust to the cylinder

see pic on previous post

[Vmax540]

Tommy, Welcome to V.V. ! Where in Pa. is Collegeville ?

Like Tyler said, check that all connections are clean, dry and tight.

Ignition Coil Resistance Primary/ Secondary 0.12 Ohm � 10%/ 4.0 Kohm +/-20%
Source Coil Color Code/ Resistance Brn~Red/ 245 Ohm +/-10%
White- Red~ Red/ 10 Ohm +/-10%

Pulsar Coil Color Code/ Resistance White- Green~ Black/ 100 Ohm +/-10%
Spark Plug Type/ Gap/ Torque NGK BR 9EV/ 0.7~0.8mm/ 2.75 m/Kg (19.9 ft/lbs)
Ignition Timing 1.6mm BTDC

[chrisrider63]

Those are nice flanges you made for the v-max project but i think like guys on the site here will tell you you gotta figure out a way to cram those v-max pipes in there because the 80 srx pipes i dont think will be sufficient backpressure for the engine. Correct me if im wrong...

[TommyMoEmDown]

Still having eractic spark esp on cold start-up. (vroom, vroom, vroom, then it may catch and run steady), We set the timing with dial indicator. Had running for for a while on a hot set of plugs, too hot, couldn't shut off motor even with the plug wires off. Had to choke her carbs. Yea coolant would have helped too. Put some liquid in her radiator, thew on the belt, put in the B9ES's & blasted her down the field. Good launch, good accel but moderate top end and no brakes, yikes, watch out for that tree.

Drove her back to the garage, that's always a good thing, then I put the timing light on. Timing mark (flywheel) was forward of mark by about 3/8 inch and fixed, no advance just fixed timing all the way to 8000+.

Can anyone tell me about the low speed & high speed charging coil and when it switches. I've read on some other CDI that one is base timing to start & the other runs an advance curve??? Has anyone check voltage ?

[tyler440]

ok so now your getting good spark? and it is starting correctly? the moderate topend could be cause by clutching... what does it engage at?

[TommyMoEmDown]

3500

[tyler440]

hmmm thats kinda low for an engagement..... i would like to see 4000-4400.... 3500 might be alright but if i were you i would get it higher.... the motor starts fine now right? carbs are all spotless? if that is the case then we can try to get the clutching right...

check your center to center and off set.... also your belt should be even with the top of the secondary... or at least DAMN close (within a 1/8").... what clutches are on it? what color is the spring, what are the weights, and whats the secondary set to?....

seems like alot of guys (previous owners) think they know what they are doing when it comes to clutching but really end up screwing stuff up.... (i dont know all there is to know, ill admit that for sure)

[chrisrider63]

Yes the primary calibration has to match the secondary set up...

[opsled]

If you look at the pic of his engine and study the clutch you will see that there is little (if any) wear on the top 1/2" to 3/4" of the inner primary sheeve. My guess is that he has a 108 (overdrive) Comet on it. I would also bet that he is running the stock 78 secondary (non overdrive) clutch.

Been there done that with a 78 SRX and 540 engine.

Even if you have the proper alignment and center to center there is not enough room for the secondary to open far enough to allow the belt to reach the top of the primary. It will pull great out of the hole but fall flat on it's face when reaching full shift out. Belt stretch is the issue and the solution is shaving some material off the back side of the secondary helix where the snap ring is located.

Draw lines with a black marker on both clutches from the center out and run it on a stand to make sure this is an issue before doing anything else. If you're good the belt should remove the lines completely. If not, you know where your problem is.

opsled

[TommyMoEmDown]

Thanks for the clutch info/ Your right about using the stock 78 secondary
Will the vmax secondary fit the 78 srx shaft?

I'm still playing with timing for now. The engine was siezed and I soaked the crankcase with marvel mystery oil. I know I may have to deal with bearings maybe in the future, but for now it seems fine. My concern is I may have twisted the crank. She's starting better. It runs pretty good. I may be expecting too much, I'm use to big 4 cylinder sleds. I also have a lot of oil in the gas and it leaves a plume behind.

Timing light is telling me it's advanced 36 deg but it jumps around alot and can't tell how accurate it is, sometimes it reading nearly 50 deg.
The chart in the back of the manual shows 14 at 2000 27 @3500 till 6500 then starts retarding back to 14 @ 9000. When I get a clean look at the mark, it stays fixed @ 36 at 1600 through 8000. Manuals aren't always correct and neither are timing lights or timing marks. I made my own mark @ tdc and using an mac advance timing light. The factory mark shows it being retarded 10 deg.