Jdx8 help!

[Jdx875]

First of all this is my first post, I'm new to the board. Hello everyone.

I have recently purchased a 1975 jdx8 and I'm having some issues.

First I'll state that I'm not sure if this is the original engine I will go look at the serial once I'm done writing this and update.( I do know that the carb isn't original as I don't think the owners manual listed a tillotson carb for any models.)

Anyhow. I rode it around after replacing fuel lines. Parked it for a half hour went to start it and no spark/ weak spark.
I changed the plugs and it ran. Parked it for the day. The next day I ride it for about 20 mins stopped for some food and to socialize. Hopped on and did a few loser laps. Ran amazing.
Again shut it off for an hour or so went to fire it up and it was really boggy. Wouldn't move under its own power any time I'd touch the trottle it wanted to die. So I loaded it up and brought it home.

Got home and pulled the plugs, they were wet still no spark
Went through the old ones in my pocket and found one that works, ( out of 6 ). ( 2 came with the sled when I bought it 4 of them I just bought two days prior) seems to me like it's just killing these plugs.

I've since cleaned the plugs, dried them with a blow drier and let them sit over night. Unplugged the kill switch and ignition switch, cleaned points (just with a business card as I don't have a flywheel puller). I'm just curious why it would be killing these plugs, are the just fouled? I've had success before cleaning and drying fouled plugs?

I haven't used a multimeter to check anything yet as I don't have one handy ATM. I just find it odd that out of 6 plugs one works, either boot I plug it into, consistently then try any of the other 5 plugs and they won't give a spark

Anyone have any advice? Sorry for the long post it's just hard to explain in full detail without being long.

[Matt]

The bad news is you have an ignition issue somewhere. After things get up to temperature, it fails. When it's cold, it's fine. If it is a '75 and has the update it should have a CDI. Chances are your CDI box is bad, maybe the stator. You can get a brand new updated stator and or CDI box from Hewtech Electronics, and they make great products.

[Jdx875]

So lesson learned today... even tho the plug looks clean the insulating tip near the bottom of the plug also has to be clean after it is fouled...
After i did all the above i decided i could clean the plugs real good and use a torch to bake them a bit, i now have spark again and she purrs like a kitten. now i have to look into why it is fouling plugs within 10 mins.

Im going to drain all the gas and try again with 40:1 as i have no idea what it was mixed at before but it smoked alot ( hasnt been started in 4 years)
Then ill play with the carb settings a bit


As for the cdi update i am not sure if it does have it or not. nor for sure if the engine is the same as original. i looked at the owners manual. it says for 75 the engine would be a kec440/22A

Now its that still a ccw engine or completely different>? because on the starter side it says ccw (still havent looked at the engine serial yet, it got dark.
Also it has points and i cant see a cdi box anywhere.

Another question i got if anyone knows, my tach isnt working nor is my low beam , all the lights in the gauge light but the needle kinda just bounces at 1000 while running, is it common to stop working? it all looks to be wired up the same as the wiring diagrams, i dont have an ignition on my sled at all ( someone unplugged it and never used it since i got it) if that needs to be in a certain position or something

[Steven Rempel]

I would personal run using 50:1 I tend to foul a lot of plug running todays fuels at any higher of a ratio ie 32:1 too much oil will cause spark plug to foul a lot.
a kec 440/22a sounds right and also a CCW made engine very close to the early one like a ccw kec 440 / 21 found in my 73
I have one 75 jdx8 that does not have the CDI upgrade and runs using points.

As for the tach I am not sure but would also like to know if they just go bad. I have 2 on the shelf that do the same thing in my other sleds.

[jep_800]

What Matt and Steve said are correct. I would also add that the sled IS supposed to be a KEC 440/22A. Your serial number stamped on the motor (front lower right) should state that... it may be a 440/22 also. It is supposed to be a Walbro WRA-31 carburetor. Not that you can't get other carbs to work fine, a lot of guys convert to Mikuni and it works great, but the Walbro would have been original. Do you have the tuned pipe? They only put them on in 75' so you'd know if it does. I've attached a picture when I was assembling mine for reference.

I believe you could have something weak in your coils, if you don't have the updated CDI. Those tend to get a crack somewhere, and when they get warm lose continuity. It should be able to re-start just fine after being warmed up. I know a friend of mine is upgrading his 75' to the CDI / prestolite stator, as his came with points but wanted the hotter ignition components, so that's an option too.

[Jdx875]

Thanks for the reply's guys.I believe it is a 75 ( tuned pipe, Plastic gas tank) the engine serial number was painted over when the previous owner rebuilt it so cant make out any numbers.but i do know its a reed valve engine. maybe someone just put the ccw recoil cover on if thats possible?

It does have points and no cdi box ive cleaned the points just with a business card but im 80% sure its not a spark issue as much as a fueling issue. as stated i clean the plugs and it fires up fine. unless maybe its just not good enough spark (nice and blue with new plugs) maybe would a non resitor plug work better since its old and doesn't have electronics to mess with?
Ive tried br9eya's as thats what came in the sled when i got it. br8's thinking maybe hotter,

Serial on the tunnel says JDX8D 031xx1M date of mfg 10 74 so im assuming as most things they would have been made in 74 and sold in 74 but as the 75 model? ill post some pictures.

I have good spark, fires up first pull once warm, 2 when cold, it runs great, then after a little bit of idling it fouls one or both plugs, changes which one sometimes.
When i pull the plugs they are wet and black ( brand new plugs) i can spray them with carb cleaner, give them a wipe/blow them out and they both work fine again starts first pull.
Or if it doesnt start running on one plug say after riding it a bit if i shut it off and attemt to restart it it will barely run/backfire, clean the plugs and fires right up.

Sooo, this being said im thinking its overfueling, maybe the metering arm wasn't adjusted correctly as ive saw in other posts and is flooding while shutting down the engine still pumping gas through?

[Steven Rempel]

Yes a 75 model from everything I can see.

have you changed the oil fuel mix yet? what results with that change?

Are you sure its not set too rich? I would go for a good run and then shut it down with little to no idle, and pull the plugs and let us know what you see, then should be dry and light tan color, not dark or black or wet.

by the way I want your guys sleds... every 75 jdx8 or early 400 seems to slip through my fingers my 75 jdx8 has a lot of issue to be dealt with yet.

[Steven Rempel]

is that a tillotson carb? any chance you read the model number off the top flange where it bolts up to the Y intake pipe

[Jdx875]

It appears to be a tillotson carb yes. I can try and find a number. I did let it warm up and took it to the end of my alley and back WOT killed it before commingled to a stop and pulled the plug. It was wet and black. Nothing is getting baked on if I wipe it it looks brand new.

Also I flushed the gas tank today mixed 40:1 or so and its got alot of throttle response now. Right now low speed screw is 1 1/4 turns out, seems to run best there ( if I screw it in 1/2 turn it idles high after that it bogs, should be lean there? High speed screw I'm at about the same 1 1/4 haven't tried to mess with it really cause it runs half decently.

Also is your return line from the carb supposed to be full all the time?

[Jdx875]

Carb model is HD 14A

[Steven Rempel]

Return lines on some of my sled are full most of the time, with a few air bubbles time to time, others are a 50 50 mix air fuel.
thanks for the info.

I am no expert, and have little experience with till carbs. I still think its running rich on the high speed screw, but I would get an opinion of some one other with more experience will till carbs. if it was my sled I would turn in a 1/4 turn and retest, and then see the results. With walbro carbs I think they only need to be out .75 of .875 turns out but I dont have a book in front of me to confirm. But hopefully someone with more experience will chime in.

but reading the plug I feel is the best way to tune the carbs. imo... I have been very surprised with power increased by reading the plugs and not the book settings with my sleds

[Jdx875]

I'm sure it's running rich, I've just never seen a spark plug so wet before. Hard to read the plug when it's wet and black lol
Just for a little piece of mind I'm going to put a clear pulse line on and see if maybe it's sucking fuel through there.

Where are the drain plugs on the crank in these? I saw two little bolts in the front I was thinking?

[Jdx875]

So new question ( old issues are still needing help if anyone knows)

Since my sled doesnt have the cdi update, what all would i need to purchase from Hewtech just a stator and cdi box? or would i need to replace the external ignition coils and plug wires as well?, also i read on another post that you need a cdi flywheel? where would i find one?

Also any links to which ones would be good as i see lots of different ones on there, are they the prestolite ones fire plug cdi?

[jep_800]

Ok, you've covered a lot of ground so I'll try and take a stab at most of them:
1. The CCW flywheel cover is correct for that engine. They all have that. It may have been a replacement at some point, but correct. (the letters stand for "Canadian Curtis Wright". These are in fact Kioritz engines).
2. It is running rich, and you are on the right track on how to adjust... But, it will be trial and error as it did not come with a Tilli carb to begin with, so adjustments per the manual is not going to be exact. It states specifically that the Reed Valve engines in the 75' JDX8 and 800 should NEVER be turned in more than 7/8 out. The initial setting is 1 1/8 out for both needles. But again, that's the WRA-31 Walbro, not your carb. So the only thing you can do is continue to test until the engine likes it.
3. Yes, check your impulse line to make sure you're not seeing a bunch of fuel going to or coming from your crank case.
4. You would need a different fly wheel, trigger, and stator assembly from a 440/22 Kioritz engine. Those can be found on another JDX8 or 800 that was updated, or 1976-1977 440 Cyclones & LIquifires.... Not sure but maybe the 340's used the same set up as well.
5. New stator from Hewtech for the setup just mentioned, and a new CDI box which is a direct Prestolite replacement. I have all Hewtech on my 75' and it works great.
6. You will need different coils for a CDI setup, and you would either need to modify your heat shield, or find one that is already set up for the CDI box and coils. These mount in a different location than points ignition. The external coils are the same ones used in a 340/s, 440 Cyclones, 440 Liquifires.
7. Your drain plugs are located in the front center of the motor. Kinda hard to get to as you have to deal with your mounting plate, but I've never drained mine, so don't know how hard that is.
8. If it continues to foul after you've leaned your needles, then you may still have a metering arm problem. I don't know how those are set in a Tilli, but the Walbro with a new diaphragm kit is nearly flush with the carb body. If it's .05 above it will flood.
9. I think your mixture is still a little oil heavy, so 50:1 should be what you're mixing. Also make sure it is premium (91 octane) no ethanol. Use a good quality oil. I use Klotz, but there are many, as long as it is TCW3. I also mix Seafoam in my gas and it work great keeping the carb clean.

Now, if you decide to update to the CDI system, your going to lay down a little money. Those items are about $155 - $165 each from Hewtech. And whatever the flywheel and trigger assembly runs after you locate one. But in my opinion it would be worth the effort.

Here's a shot of what the heat shield looks like (old and new) for a CDI update unit, and where the external coils mount. You can see the difference from the Prestolite original equipment and the new Hewtech. (By the way, I had the red and black wires crossed in this photo from the CDI to the coils. Red needs to go to the PTO side. Don't make that mistake or you'll get backfires when you try and start).

Let us know your results / progress is. Keep plugging away, you'll get it!

Jason

[jep_800]

Here's a few shots of the flywheel, trigger and stator assembly.