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CB350 Has spark but wont start

4K views 6 replies 5 participants last post by  thedukeofsurl 
#1 ·
Happy to be here everyone,

I have read through several of these trying to diagnose an issue with a cb350 I just purchased. I have scoured this site trying multiple approaches but I am really not sure what my problem is and I am hoping someone here can help. Little background I basically got the bike for next to nothing and I know the previous owner had done a lot of work on the bike but I did not anticipate all the aftermarket parts he added which has provided me with a lot of headache because this rendered the manual pretty useless. I am no expert but I have some experience working with dirt bikes although I have never dove into an engine.

The bike sounds as though the engine is turning and making a whomp whomp sound and on occasion makes a whining noise after using the kickstart but I cant seem to get any type of spark or actual ignition. My original suspect was electrical but I believe I may have solved this issue and now have to look elsewhere.

Pretty sure the bike has enough compression to start, did the poor mans compression test and it blasts my thumb off the spark plug whole when I start it.
Bought a new battery and spark plugs.
The bike looks to have new ignition coils, condenser and points, I have power to points so I think that means the coils are working. Coils measure the same ohms.
I have set the points and they are near perfect. When setting the points however I noticed that the engine wanted to jump about quarter turn when I approached the LF and F marks. I thought this might be normal but Im not sure.
The bike did not have spark prior to setting the points, it now has spark. I thought I would be home free at this point but not so lucky.
When I use the electric start I only hear clicking from the solenoid. I do have power out of the solenoid when the ignition switch is clicked. I was told the bike had trouble with the electric starter before and just needed a new battery obviously not the case.
Changed the oil, it didn't look too bad.

I had taken the carbs out (looked recently replaced or cleaned) they looked clean but I may have to take a second glance.
My next concern, maybe the kick start gear is stripped?
The PO did removed the key ignition and replaced it with a switch. As far as I can tell my problem is not with the switch because I am getting power to the headlight and points when I flip it on. Luckily the new wiring seems to closely resemble the previous set up.

I would really appreciate ANY advice!

I have a few videos and pictures, couldn't get the videos to attach but would be happy to email them if anyone wanted to take a look to hear what it sounds like.
 
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#2 ·
Do the usual stuff first, are the spark plugs wet or dry? Gas in the float bowls? Did the po have the engine apart? If so, did you check to see if the points are opening on the compression stroke(both valves closed)?
 
#3 ·
Update:

Thanks for the advice.

I have pulled the spark plugs, they are dry and have spark. Points are sparking on compression stroke but when cranking the engine it wants to kick right past the mark. Could that mean I have another problem somewhere in the engine?

Made sure the float bowls had gas in them, they did. Checked to make sure the fuel lines were not clogged, all clear there. I had just decided to take the carb off anyways and clean it out before I did that I tired to spray starter fluid in the carb, same no start/sparking problem. Took the carb off and sprayed starter fluid into the cylinder, bingo I had ignition. Assuming this means fuel was not getting the cylinder.

I have yet to dive all the way into the carbs they don't look to be in bad condition but it seems like even a little piece of dirt could clog those jets up. Any recommendations on rebuild kits or just cleaning the original parts?

I also have another problem I'd like to tackle and I could use some recommendations on finding authentic headlights and turn signals. The PO had removed them.

Thanks for the help, much appreciated.
 
#4 ·
CB350 No Ignition

Day 25.....
I have an update on the bike but still not much luck.

Bike was getting gas.
Drained the carb floats, re-attached and checked to see if they refilled upon opening the petcock valve, they did. I had emptied the tank of old gas and refilled with 92 octane.

Assumed I had a carb problem. Took the carbs off and sprayed started fluid in the engine just to see if I had spark. BOOM I had spark and it ran for a few seconds. As a note I left the intake manifolds in place. Cleaned out the carburetors and it looks as if someone had done a rebuild before because all the valves and needles were brand new shinny brass. Either way cleaned it out and let it soak. Put everything back together and to exact specifications except air mixture screw near manifold I could not find any specifications on how far to turn that in. I had ordered some pod filters for the bike but heard those are not the best so I have not put them on yet.

Re-installed carbs and made sure I had no leaks. Checked the battery had like 12.8v running through it. My headlight was not running as bright as it was a few days ago after I installed the new battery, possible grounding issue or battery just losing charge since its been on a lot? I have also lost the clicking at my solonoid, I think I have an issue there.

Back to the carbs, installed the carbs with air filters on at first and sprayed some lighter fluid into the cylinder (I had opened the throttle body, maybe that was my mistake) attempted to kick start and had no ignition just the same boggy sound as before. Removed air filters and attempted the same process. Maybe I flooded the engine?

Removed spark plugs cleaned them off, they were a little wet/dirty, may have had oil on them. Let them sit for about thirty minutes performed a couple strokes after about a half hour later to try and dry off the cylinders with the carbs off. Re-installed plugs, sprayed starter fluid in engine again, attempted to kick and same result boggy sound. Pulled the plugs and they were dry.

Starting to think I might just need to cave and try to find a motorcycle mechanic. Not sure what I could off done differently that allowed the bike to start with the carbs off before and now it wont start again. I remember reading these bikes need to have a charge to start but the battery tested fine. Maybe a grounding issue? Maybe a timing issue, can the points get that out of whack with just a few kick start attempts and no riding? I am in North East Florida which is prone to humidity so that might be another factor to consider.


I appreciate the help in advance! This would be my first street motorcycle I fixed up my grandfathers old CL90 relatively easy and thought this couldnt be to much harder but turns out I was way wrong.
 
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