TOPIC:

So Ill start by saying Hello! New to the community although I have been lurking for countless years. Long story short I inherited a beautiful looking, but shitty riding 83 LTD550 Shaft and have been battling it for about a year. Recently got involved with her again and I wanted to pose some questions to the pros.

My problem: The bike is usually hard to start, if I haven't charged it overnight or at least a few hours it won't start at all, it takes lots of cranking for her to make up her mind and run. Once it starts, I can only give it the SLIGHTEST bit of gas slowly increasing until I get to about 3-4K RPM otherwise it will fall flat on its face. As the bike warms up, this issue usually subsides a little BUT, its still a big problem and keeps me from riding. On the road it will take the better part of 4 seconds from when I twist the throttle to when the bike actually starts to make power, similar to what it does on the stand, only it doesn't die because I'm rolling. (Usually downhill, lol)

What I have tried: Cleaning and syncing the carbs mutlitple times. I let the bike sit for about 4 months and recently pulled the carbs off for about the 5th time, cleaned all jets, including the pilots (to my surprise the pilot jets which are miserably small, were unclogged). I bought a vaccum sync tool from motionPRO and attempted a vaccum sync one afternoon, it kind of worked, but I am not a dark wizard so they remain as good as I could get them.

I replaced all plug wires and plugs, I found some resistor caps to be open, so this HELPED, but definitely did not alleviate my problem.

Measured resistance of the primary and secondary side of ignition coils, checked voltage at the coils, all seemed okay here.

Performed leakdown test on each cylinder. I ran the test with a warmed up bike and she held air quite nicely. 85 Held out of 90PSI across the board seems good for her 24K miles

Checked valve gap and appears okay. Some are at tolerance, but I told myself I would get the bike running well first.

Have checked for air leaks with starter fluid, minor change in RPM just from so much starter fluid near the airbox.

Tonight I have been looking at the alternator and reg/rec. Battery was dead so I couldn't do ACV on the alternator or DCV at the battery with RPM. Resistance between coils and resistance to ground measures okay for the coil. Did not do a resistance test on the rec yet. I figure a voltage test at the battery will show a failed reg pretty quickly.



At the very least, I'm gonna throw a new battery in it just for kicks. I know the wiring is old and probably bleeding somewhere but plugging a bike in every night just isn't something I want to have to do unless the thing is electric.

Has anyone ever experienced this something like this??? Or do you have anything you recommend me check out?

I have an FSM and have been running through all these tests according to it. I am still thinking it is electrical at this point but if the voltages check out then the carbs are going in the trash. Or ill just sell it, much to my chagrin. I really want to customize this bike a little and use it as a daily. Have had it for over two years and am getting nowhere.

edits: forgot to mention the bike will idle for hours. I have run a tank of gas through it like this, choke off. Jets are all stock.

When is the last time the valve clearance was checked? Tight valves will cause hard starting. Then after you checked the valves break out the carb sync tool again. Good luck Tim

usernamedoug wrote: edits: forgot to mention the bike will idle for hours. I have run a tank of gas through it like this, choke off. Jets are all stock.

Yikes! I hope you had a really heavy duty fan blowing air across the engine. Ed

Battery and valve adjustment first.
Steve

Compression seems okay.

With plugs removed, are there healthy fat blue sparks?

Sounds like imperfect carb primary circuits.
Carb cleaner sprayed through the pilot jet should visibly exit into the carb bore.

Assuming that the float bowls are all filling with gasoline as they are supposed to, and that the fuel levels are correct as evidenced by clear tube testing, the pilot jet must receive gasoline, and the gasoline must get through the pilot circuit, past the pilot adjustment screw (where the gasoline is mixed with air to form the fuel mixture), and through orifices into the main carb bore.

Here's a diagram that could be helpful even if not an identical CV carb.




Good Fortune!

Check and see if the spark advance is free, lubed and working correctly.
Steve

Alright Ill try to hit everyone here as well as post up some results from tonight. Unfortunately I am going to the beach this weekend and can't work on the thing as soon as I had hoped. Maybe Ill get a few things knocked out Sunday when we get back.

Timing advance is free moving, is it advancing correctly? Who knows. I will spend some time with this and report back.

Getting a healthy enough spark although it could be better. I changed the wires, caps and plugs. For a while was looking at a dynacoil set up. More on this with some multimeter work I did tonight...


Patton:

I am hoping it is not a fuel problem as I abhor taking these carbs off the bike. They were cleaned recently but it did sit for some time with E10. I will look into the clear tube testing, although if I have to take the carbs off again I would just as quickly swap in a suitable setup with mechanical slides. I don't like the idea of air pressure doing the work that my wrist can do!! After I exhaust my other options that is where I'm headed. Hopefully we don't have to go there. Could the air bleed for the pilot circuit be clogged?The plugs are pretty dark maybe its running rich at low speed?

What has me leaning towards fuel issues is that I have tried jump starting with a bigger 12V battery. While it is easier to start with a strong battery, the low RPM hang still exists. That being said I think is high time for a new battery. Possibly pursuing one of those fancy Lithium based cells.


Alternator or rectifier is definitely not performing as I could never get above 13V at the battery while running. I checked Vac between yellow alternator leads on the fuse side while running and measured 12-20Vac. Manual says I should have 75Vac here, but I did not disconnect like they suggested.

What about these mythical capacitors? Where are they located?

Moving forward I am probably going to replace alternator/stator and battery just to eliminate low voltages all around. I will look at timing advance which means I'll be getting a timing light. Once I eliminate all this, we have pretty much proved the issue is in the carburetor. I am going to look into some different carb options as well as I would rather be tuning a new set of flat slides then repeating the cleaning process and expecting different results.

Cheers guys thanks for the good feedback

usernamedoug wrote: . . . I changed the wires, caps and plugs. . . .

Solid core (non-resistance) wires?

Non-resistant cap or resistor style caps?

Non-R plugs?

Factory stock is believed to be solid core wires, resistor caps, and non-R plugs.

If any of these components have resistance, could swap out for non-resistant type and see if it results in stronger spark.

I enjoy the combination of zero resistance in the secondary loop for each coil, meaning solid core wires, plus non-resistor caps, plus non-R plugs.

The relatively inexpensive Dyna solid core plug wires come with built-in non-resistor caps.

When using resistor caps, adding resistance wires or R-plugs or both usually results in weaker spark and poor performance due to having too much resistance in the secondary loop.

Good Fortune!

Before digging into the big and expensive charging parts I would Try a new regulator. The newer electronic ones are not cheap but work much better than factory regular and the rectifier. The one I got was pretty much plug and play.

What is your head lite doing at night? On mine as RPM was increased the head light got brighter. I was over charging the battery when riding and under charging at idle. Tim

Patton wrote:

usernamedoug wrote: . . . I changed the wires, caps and plugs. . . .

Solid core (non-resistance) wires?

Non-resistant cap or resistor style caps?

Non-R plugs?

Factory stock is believed to be solid core wires, resistor caps, and non-R plugs.

If any of these components have resistance, could swap out for non-resistant type and see if it results in stronger spark.

I enjoy the combination of zero resistance in the secondary loop for each coil, meaning solid core wires, plus non-resistor caps, plus non-R plugs.

The relatively inexpensive Dyna solid core plug wires come with built-in non-resistor caps.

When using resistor caps, adding resistance wires or R-plugs or both usually results in weaker spark and poor performance due to having too much resistance in the secondary loop.

Good Fortune!

Wires are automotive type that I have in new NGK R-caps, Resistance measures close to the 5K of the stock system. May try the dynacore wires since as you mentioned are a cheap problem eliminator.

Update from this evening:

I have 73 or so VAC at alternator output, happy about that.


Z1 Driver:
Just installed a fresh GEL battery and reg/rec from electrosport. Ironically the new reg/rec doesn't create a voltage increase across the battery, only swapping back to the old unit gets me around 13V. I was originally thinking this was a problem, but other threads suggest that may be generally acceptable voltage? Thoughts?

Unit is here www.rmstator.com/en_ww/products/rm30004-...750-ninja-vulcan-zx#

They claim is direct fitment although it is missing red and white wire going to starter sol. From other threads this may not be necessary with the newer style rec but why doesn't it charge then???

New battery makes it MUCH easier to start, but I am still playing with the choke. When I get happy with the electronics, its time to clean the carbs and run pods. Quick HW suggested there are not too many easy mechanical options with the same intake pitch. As long as I can get away from these blasted intake boots!!!!

My mistake:

www.electrosport.com/street-bikes/kawasa...ulatorrectifier.html

this is the unit I purchased. Electrosport offers a warranty, Unless I'm doing something stupid and wrong, I think they sent me a dud. Let me know what you guys think.

Something is going on with reg/rectifiers I have. I just realized that on both units fwd measurements are infinity and rev measurements are 1.15 M Ohms. Resistance should be low in one direction according to the manual and high, but not infinity in the other direction.

Is something in my bike shorting these out?