'74 JDX 4 low end bog

[jd ike]

I think I'm having the same issue as flacker36 & Danzig had...

-Rebuilt engine
-cleaned carb (Bendix)
-rebuilt fuel pump
-ran awesome for an hour or so after adjusting low and high speed jets
-both plugs (NGK BR9ES) were light brown during adjustment period
-ran again later in the day and noticed low end bog which turned into engine not wanting to idle, then hard to start
-rebuilt Tiltenson carb and swapped
-ran for a few minutes w/ low end bog, I had to choke the heck out of the engine and use a squirt bottle w/ mixed gas to get it to start
-inspected plugs and noticed #2 piston top was detonating (this is why I rebuilt it in the first place, the top of the #2 piston was pitted and the rings were stuck)
-I read through both flacker36's issue and Danzigs X8 issue so I checked the spark and noticed #1 was weaker and wasn't as blue in color
-I now would like to go through the points, condesor and whatever to make sure it is properly timed etc.

Anyone know where I can get a service manual for a CCW 340/5? People are selling homemade COPIES for $50 on ebay plus $12 shipping! Ridiculous.

I don't know a thing about timing this engine, when I put it back together I just lined up the mark on the stator plate to the mark on the housing. I would like to check timing but the aftermarket service manual I have only talks about engine and carb rebuilding, nothing about how to actually time it.

Any help would be greatly appreciated

[Danzig]

As of latley, the pro of timing the engines is HoosierDeere. He has had issues recently and could probably right up a post and get you back on line. My issues with my X8 were resolved simply by changing carbs and thoroughly cleaning the fuel system, I thought I had it rust free but it wasnt. My X8 probably could use some points and condensors too. But.......I have other projects to work on that I am much more enthused about.

[flacker36]

It sounds like you are having the same problems I had with my 72 400. I would recommend the following:

1. Replace the points with original CCW points (find them on ebay or someplace) I really think the aftermarket points are not up to par.
2. Replace the condensers (aftermarket seem to be ok).
3. If you have ignition gernerating coils under the flywheel, swap out different ones or get new ones. Even if you test them the ohms change as they warm up which could cause the problem.
4. Make sure you rebuilt the carb correctly & with the best rebuild kit available. Walbro carbs should be rebuilt with original kits because the gaskets of the aftermarket kits swell up effecting the operation of the carb.
5. Time the engine with a dial indicator & test light.
6. You can order service manuals from JD (new) or buy a used one on ebay someplace else. I got mine new & it already looks 35 years old!!!
7. Keep at it, take the time & spend the money because it really is worth it.

Joe

[jd ike]

It sounds like you are having the same problems I had with my 72 400.  I would recommend the following:

1. Replace the points with original CCW points (find them on ebay or someplace) I really think the aftermarket points are not up to par.
2. Replace the condensers (aftermarket seem to be ok).
3. If you have ignition gernerating coils under the flywheel, swap out different ones or get new ones.  Even if you test them the ohms change as they warm up which could cause the problem.
4. Make sure you rebuilt the carb correctly & with the best rebuild kit available.  Walbro carbs should be rebuilt with original kits because the gaskets of the aftermarket kits swell up effecting the operation of the carb.
5. Time the engine with a dial indicator & test light.
6. You can order service manuals from JD (new) or buy a used one on ebay someplace else.  I got mine new & it already looks 35 years old!!!
7. Keep at it, take the time & spend the money because it really is worth it.

Joe

Okay,

-Pulled the recoil and check the points gap. The gap is .012, the recommended gap is .014, is this acceptable? I also cleaned the #1 points with emery cloth. Now both plugs spark blue bright blue.
-Will the plug spark less when I put it back in the cylinder?

-Tried 2 different fuel pumps w/ the Bendix carb (primed them both). I could only get the thing started once by spraying fuel directly into the carb, but it wouldn't idle.

I'm going to try a Walbro carb off my brothers '72 500 when he gets back from the mountains. Will the WD8-5 from his work? the '72 and '73 400 which has the CCW 340 has a WD7-5.

If the WD8-5 works I will then have to look for the good and correct WD7-5, if not I will shelf the sled until next year and then I will go through the points and condensor.

I'm getting frustrated and this is starting to eat into my riding time....

Thanks for the help.

[JDT]

You said in the original post that you rebuilt the engine.
Did you replace the crankshaft seals?

Ran good for an hour than went down hill.
Sounds like it leaned out on the #2 side.

[jd ike]

You said in the original post that you rebuilt the engine.
Did you replace the crankshaft seals?

Ran good for an hour than went down hill.
Sounds like it leaned out on the #2 side.

Yep, replaced all seals and gaskets.

I thought it might be the PTO end seal also so I sprayed starting fluid behind the drive clutch when I had it running the time before last with no change in RPM.

[400brian]

'72 engines used a Walbro carb with a smaller mounting flange, so they are not a bolt on swap.

[jd ike]

Thanks, I probably would've taken it off and then realized it wouldn't fit. I guess I'll have to go through the points and condensor first.

Now I know where the saying "A snowmobile is like a woman, work on them all week for a 5 minute ride" came from................................