350LC Issues

[sp885]

Hi Guys

Any advice appreiated and most welcome, I have an 82 350LC that I've had for nearly 8 years now, I had the engine rebuilt about 6 years ago and in that time it's never missed a beat, however all good things come to an end as they say

I'm in Sydney, Australia so it's ridden all year round and as often as I can, I've done 12,000km on it now, probably 10,000km since the engine was rebuilt, anyway

Totally standard with 4LO-01 carbs with 5K1 needles and standard jetting, it does have Boyesen Reeds that I fitted when the engine was rebuilt

The last few times I've been out on it, I always start it with the choke and it starts within 2-3 kicks, it doesn't run for long with the choke out, maybe 30 seconds and it will stall, but it's always been like that, normally just push the choke in and it will idle nicely while I'm getting my gear on and ready to go, but now it will not idle for long when cold until it stalls, it will start up again straight away, but when you try to rev it, it really splutters down low, when you get it going out on the road and it warms up it idles perfectly, but just at cruising speed it feels really shaky and stuttery, get it up to 4000 rpm and it will run fine

Tried a few simple things over the weekend, new B8 plugs and NGK caps, new air filter, checked carb sync and oil pump settings, all good, I'm thinking maybe it's time to take the carbs off for a strip and ultrasonic clean, they were last done about 4 years ago, I've never done the brass ball mod either, so will give that a go too

Could it be an electrical issue, I'm running the Banshee coils I got from Norbo when the engine was rebuilt, had the stator checked then and it was fine, but that's 10,000km ago, CDI issue?, I thought they either worked or they didn't

Anyway guys I've rambled on enough, any ideas appreciated

Cheers
Steve

[geoffers997]

Personally I’d start with a really thorough carb strip. Check, check again, clean and clean including brass balls out.

After that it’s the devils ekectrickery - CDI is the most likely culprit but being thorough and methodical is key.

Good luck.

[tony2stroke]

I would start with a carb strip and clean, also check your Boyesen reeds haven't started to fray on the edges.

[liffy16]

As said check carbs sounds like the pilot system, they can take some fettling if been parked up for a while

[muttsnuts]

give the engine a health check/service;


1. Compression test
2. Carb service/check pilot circuit and jets
3. Check coil resistance
4. Check stator resistances
5. Check reed block rubbers for splits/cracks
6. Check reed petals for "fraying/gapping"

That should keep you busy for a few hours

[JMW]

It’s an idle and low end issue so,
Whip the air screw out and check the O ring
Blast it through with a good carb cleaner and refit the screw
Bet you she bounces back tip top
If not, as suggested above, carbs off and give then a clean
It’s bound to be a bit of crap built up in there or something like that

😊

[mouse]

I'm no mechanic, but pilot jets blocked?

Easy and cheap to check/fix

Mouse

[sp885]

Many thanks guys for all your advice, will report back on this

[sp885]

Okay guys think I have this sorted I took the carbs off last week and took them to a mate who hasd an ultrasonic cleaner, he also has a 350LC and is pretty switched on with them, we stripped the carbs and found that it had 200 main jets in it, it had the correct 22.5 pilots, my bike is pretty much standard except Boyesen Reeds and I've taken the snorkel out of the air box, so we also drilled out the brass ball and it did look okay behind it on both of them, but anyway, we put them in the ultrasonic cleaner for about 20 minutes and then put them back together with new Mikuni 220 mains, 22.5 pilots new emulsion tubes (even though the old ones looked fine) new float valves, and instead of putting the brass ball back in we put the M5 grub screw in, set the float heights and I put them back in a couple of days later, made sure the needles were on the middle clip, they were, is it just me or is it a s#&t of a job getting the carbs back in position the right one was pretty easy but the left one kept pushing the airbox rubber back into the airbox and I had to walk away from it for a while, anyway I got the job done, synced the carbs in the windows and set the oil pump, I still had Arrows tips on how to bleed the pump and get it running with a litre of pre mix, all good and it started easily and ran well on the ramp

So I've just taken it for a run this afternoon and it seems good, not an ideal time to go as Saturday afternoon traffic is not ideal around here, but definatley better, what I dont understand is it ran well for almost 8 years that I've had it with those 200 main jets in it, and who knows how long they were in there before that

Any of your thoughts most welcome

Cheers
Steve

[midlifecrisisrd]

They were jetted safe as standard so in a warm country 200 may be perfectly fine

Did deffo sound rich when you were having the prob

Something like a slightly passing fuel valve will throw the mixture out

Fingers crossed it's solved

Steve