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Discussion Starter · #1 ·
Hey everyone!

my first post on hondatwin!

a 69 cb350 over-bored, mikuni vm32, mikesxs coils, pamco electronic ignition, Charlie's regulator and rectifier.


I tested both cylinders for compression. both with spark plugs out and carbs out. both read around 155-160 psi on both sides (cold).

tested the coils with a multimeter both read approximately 4.8 ohms for coils. then i checked the secondary which both read around 11 k ohms.

tested the spark plugs for spark and both have a spark. however the spark is not a fat spark, but it is a blue spark.



I tested the battery and it shows around 12 volts, but it is very weak so I am replacing the shorai battery with another shorai battery. should be coming in the mail shortly.


I suspect that my problem is a weak battery and the carb air/fuel ratio screw and idle screws. The bike was running fine last week until i decided to take the tank off.
I eneded up pinching the throttle cable not knowing. so i messed with the idle and air/fuel ratio screws. now the bike has a hard time starting without the choke up. and when it does run it runs rough with some light back fire. and seems like its spitting out oil though the exhaust.

also it does seem like the right exhaust is not as hot as the left exhaust.

any suggestions would help !

i posted in wrong section earlier, mod please delete in the 125's engine section.
 

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Discussion Starter · #3 · (Edited)
doode- I haven't had the bike for that long. the plugs looked like they are fouled so i ordered a bunch of them last night.

so an update of the bike, I took the mikuni carbs out and cleaned them up. installed them back into the bike.
the marking on the jets from what i found was 051 and 25. not sure what that means.

i had the air mixture screw for both 1 turn out.
idle screw 2.5 turns out.

i kicked the bike over and it started without choke this time. and was able to idle fine.


what i noticed was if i opened up the throttle fast to WOT it would bog down. however, if i slowly cranked the throttle it would be fine....


after i let the bike warm up i rode it around the block. and it had some slight backfiring. after i pulled the bike back into the driveway i let the bike idle. and 2 mins into idling, the bike started to rev out of control. and then just cut off.

i tired to kick the bike over again, it sounded like it wanted to start, but didnt start. another thing is the left exhaust seemed hotter then the right exhaust. They are still hot but left is slightly hotter.
 

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Are the carbs still synced? Also check the wires from the coils make sure they are all tight and clean in the connections.
 

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List the exact process you're using to sync your carbs. If none, do a search and give it a shot on your bike and report back the progress.

Is your tank vent working? May be the issue with revving out of control then not restarting.

Are you turning the gas petcock to off when you're not riding? If not, check your oil to make sure no gas has gotten in it.
 

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Discussion Starter · #6 ·
Are the carbs still synced? Also check the wires from the coils make sure they are all tight and clean in the connections.
I believe they are synced to the best of my ability. what i did was do the popsicle method that i saw on youtube. I check the coils many times now and they look clean and the connections are very tight.
 

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Discussion Starter · #7 ·
List the exact process you're using to sync your carbs. If none, do a search and give it a shot on your bike and report back the progress.

Is your tank vent working? May be the issue with revving out of control then not restarting.

Are you turning the gas petcock to off when you're not riding? If not, check your oil to make sure no gas has gotten in it.
the process i did was the popsicle stick on the carb slide with tape at the end. when I twist the throttle they should both open at the same time. i adjusted the top of the carb to make them close to sync to the best of my ability. the left side carb seems to always go up slightly before the right carb. Seems to me that the throttle cable doesn't go all the way into the nipple at the top of the carb as much as i try to get it in all the way it only goes in about 3/4 of the way. I can take a picture of this and check back in.

I believe my tank vents are working. I turn on the petcock and drain my gas though there when i take the tank off. and when i did run the bike yesterday it sucked up all the gas that i put it. it wasnt much maybe less than a liter of gas.

and i am turning the petcock off when i am not riding the bike anymore. I think i will be doing a oil change soon.
 

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Discussion Starter · #8 ·
okay another quick update

I removed the mikuni carbs, and replaced them with the stock keihin carbs. the carbs seem to get the bike to run. I just quickly put them on with boots that weren't in the best of shape so i know there are vacuum leaks that are causing high idle at times. I also didnt have filters on the bike. the right pipe had whitish smoke coming out while the left pipe just backfired once in awhile.

after switching back to keihin carbs i still noticed that the right pipe was colder than the other. I am thinking it is timing, or valves? I will be checking the valves and doing an oil change.

any other suggestions for me ?
 

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VM32s require head porting and a race cam to run properly (along with high compression overbore pistons)...sell them and focus on dialing in the stock carbs

your right cylinder is not firing...spray starter fluid into the carb mouth of the right carb...if it starts to run then your problem is fuel...if it still isn't running then your problem is spark.
 

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Discussion Starter · #10 ·
VM32s require head porting and a race cam to run properly (along with high compression overbore pistons)...sell them and focus on dialing in the stock carbs

your right cylinder is not firing...spray starter fluid into the carb mouth of the right carb...if it starts to run then your problem is fuel...if it still isn't running then your problem is spark.

Thats what i was thinking. selling the vm32's and either getting the vm28's or vm30's.

Would it still not be firing if it it idles and when i open up the throttle it revs ?
 

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Discussion Starter · #11 · (Edited)
I finally had time to take off the alternator cover. it looks like it has a aftermarket alternator? can someone confirm this? I don't see the marks where im suppose to line the LF and F marks.

since they dont have the marks where do i set it at TDC?

The oil looks horrible as well. Thanks previous owner.:cry:
Auto part Engine Rotor Wheel Disc brake

I dont know how to make the picture rotated.... sorry
 

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Discussion Starter · #14 ·
It's an early style stator. Probably original.
I don't see the mark, but to confirm tdc you can use a piston stop and an Internet search
Thanks doode, I did what you did and use a piston stop. then put a little park where TDC was.

This bike is giving me such a hard time. im starting to lose hope :(

1. I cleaned the petcock
2. changed the oil 2 times ( smells of gas but i left the petcock on overnight on accident)
3. adjusted the valves
4. got a new shorai LFX14L2-BS12 battery
5. got new spark plugs
6. switched out the mikunis vm32s for the factor carbs
7. checked compression with both spark plugs and carbs off i read 175 psi on both.
8. checked all the wiring.
9. checked for spark. ( for some reason it only wants to spark once in awhile.) and seems as though left side spark is brighter.
10. adjusted cam chain tensioner


I got the bike to run but rough... left side was running good, but right side was exhaust pressure wasnt great. when i applied throttle to the right side it would bog down. left side is great with great response.

im just so confused. i've tried everything... the only thing i didnt check yet was timing with a timing light. I didn't want to spend 50 dollars for one so im going to ask around if there is one i could barrow. Autozone doesnt rent them out as well.

could this all be a timing issue? i do have the pamco ignition system so i dont have points anymore.
 

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Discussion Starter · #16 ·
How do your plugs look?
Did you try starter fluid as post #9?
the plug for the left side is black and with soot, the right side is a little wet but doesn't have any coloring. my guess is its gas or oil. I have both carbs with the air mixture screws 1 and a half turns out. carbs are synced. I haven't tried starter fluid because it does start just dies.
 

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the plug for the left side is black and with soot, the right side is a little wet but doesn't have any coloring. my guess is its gas or oil. I have both carbs with the air mixture screws 1 and a half turns out. carbs are synced. I haven't tried starter fluid because it does start just dies.
Pamcos are notorious for failure, just Google "Pamco trouble". Mine lasted 80 miles, took months to get a refund.

Sent from my SM-G955U using Tapatalk
 
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