Topic: revisit to cb650 high rpm prob

[radman]

Sorry to bring this topic up again. I had posted awhile ago about my 1981 cb650c having some high rpm problems. I have had back from the shop for awhile now and just let it sit (again) for a month . I bought a new motorcycle. I got the new Kawasaki Ninja 650r with their new parallel twin engine and cool red frame. Love the bike but can't let go of my old CB. I rode it last night after I cleaned the petcock and petcock filter. Put new gas in, and took off the air filter cover as suggested by someone on this forum. It ran pretty good. Before it was hesitating and stuttering at 5000 rpm consistantly in every gear and could not get it over 60 to 65 mph. This led me to believe that it was an electrical glitch due to it being so consistant with it sputtering at 5000 rpm in every gear. Now its hit or miss. Sometimes at 5000 rpms then sometimes at 6000 to 6500 rpms. I was able to get it to 75 mph and it flattens out. Sometimes it flattens out before this speed but if I back off the throttle a little it will smooth out and accelerate. Does this sound like it is getting too much fuel?

Keep in mind that this bike ran like a raped ape for the three years that I rode it till I crashed it in 2002 or 2001 ( I forget now). 4 into 1 MAC exhaust with stock jets. Carbs have been cleaned and resynched and it idles and revs beautiful in neutral. I have had a mechanic check everything. No electrical issues that he can find. He replaced plugs, new fuel line and filter that I have checked again. I cleaned the tank and petcock filter. I believe he said the old plugs were somewhat blackened. Running rich right? I have not pulled the plugs again to check them. What do I need to look for when I pull the plugs? Do the carb floats need to be adjusted? What brand socket fits the two inner plugs or do I have to get a special 20 dollar tool? I can get the outer two out ok but will this tell me the whole story for checking if it running lean or rich?

Last issue. I had installed after market blinkers. I had them working before I took it to the shop. I had removed the headlight and front blinkers when I took it to the shop because I was tinkering. I tried hooking them back up and I get the front blinkers to light up but when I try to use the blinkers the front and rear blinker will light and just stay let. Is there a blinker relay or something that may have crapped out? I hear the clicking sound when I put the blinker directional on but it only clicks once and they stay lit either left or right. turn it off and the two front ones stay lit like their supposed too and the rears do not like their supposed too. These are after market and only have one filament in the bulbs. But like I said I had them working before. From what I remember I had them where they would not be lit at all and they only worked as blinkers and not as running lights up front like the originals.

Sorry so long, just trying to cover some of the questions some of you might have if you decide to respond and help me out. I had also stated that I would post pictures of my bike pre-crash and post-post crash but where are the instructions for posting pictures and where do we post them? When this site was a .net there used to be a big picture forum categorized by bike displacement. Used to have my bike pre-crash picture posted on that.

Thanks in advance for any help and guidance you all can provide.


Conrad

[HondaMan]

I'd check these things, especially since it sounds like it was sitting awhile, and because it's a CB650.

1. Pull the plugs (a CB750/500 plug wrench works great, if you don't have the stock one) and see if they are all the same color: should be light tan or light gray.
2. Check the intake valve clearance. It should be .002" or .003". I prefer .003".
3. Check the exhaust valve clearances. They should be .004, despite what the manual says.
4. Get some BG44K (NAPA usually carries this) and put 1 ounce in each full tank of gas until the can is gone. Keep the can sealed until you use it. This amazing stuff will clean off the valves and rings like new while lubricating them full time. It's pricey, $22 per can.

The CB650 suffered from "sticky valve syndrome" because of its design. It runs real well until they start sticking, then it will eventually burn the valve(s) because of the problem. Either disassembling the head and cleaning them or doing the above steps will clean them nicely. Disassembly is faster, BG44K is more fun. 

[Zeke]

I'd check these things, especially since it sounds like it was sitting awhile, and because it's a CB650.

1. Pull the plugs (a CB750/500 plug wrench works great, if you don't have the stock one) and see if they are all the same color: should be light tan or light gray.
2. Check the intake valve clearance. It should be .002" or .003". I prefer .003".
3. Check the exhaust valve clearances. They should be .004, despite what the manual says.
4. Get some BG44K (NAPA usually carries this) and put 1 ounce in each full tank of gas until the can is gone. Keep the can sealed until you use it. This amazing stuff will clean off the valves and rings like new while lubricating them full time. It's pricey, $22 per can.

The CB650 suffered from "sticky valve syndrome" because of its design. It runs real well until they start sticking, then it will eventually burn the valve(s) because of the problem. Either disassembling the head and cleaning them or doing the above steps will clean them nicely. Disassembly is faster, BG44K is more fun. 

Hondaman:

No kidding?  So on my 80650C you recommend .003 intake and .004 exhaust?

What's the explanation?

Thanks,

Zeke

[cb650]

What is your air filter like?  If stock try removing the cover.  I havent run into it but some people get a air intake issue.   I use the stock plug wrench on the plugs.   
Valve is always a little loser than to tight




           Terry

[78_SaltLick]

if it runs better without the air filter it is getting too much fuel. Try adjusting the needles up a notch and see if that helps. You can do that without taking the carbs off (on a 550).

[cb650]

if it runs better without the air filter it is getting too much fuel. Try adjusting the needles up a notch and see if that helps. You can do that without taking the carbs off (on a 550).

81 should have cvs and no needle adjustment.  Although I have seen a couple shimmed but it makes the needle solid and might rub/stick.  I'm not meaning no air filter but the cover.   Seems on some bikes it restricks.


                                      Terry

[HondaMan]

I'd check these things, especially since it sounds like it was sitting awhile, and because it's a CB650.

1. Pull the plugs (a CB750/500 plug wrench works great, if you don't have the stock one) and see if they are all the same color: should be light tan or light gray.
2. Check the intake valve clearance. It should be .002" or .003". I prefer .003".
3. Check the exhaust valve clearances. They should be .004, despite what the manual says.
4. Get some BG44K (NAPA usually carries this) and put 1 ounce in each full tank of gas until the can is gone. Keep the can sealed until you use it. This amazing stuff will clean off the valves and rings like new while lubricating them full time. It's pricey, $22 per can.

The CB650 suffered from "sticky valve syndrome" because of its design. It runs real well until they start sticking, then it will eventually burn the valve(s) because of the problem. Either disassembling the head and cleaning them or doing the above steps will clean them nicely. Disassembly is faster, BG44K is more fun. 

Hondaman:

No kidding?  So on my 80650C you recommend .003 intake and .004 exhaust?

What's the explanation?

Thanks,

Zeke

See my post about CB750 "F" valve issues. Same story.

[HondaMan]

Sorry to bring this topic up again. I had posted awhile ago about my 1981 cb650c having some high rpm problems. I have had back from the shop for awhile now and just let it sit (again) for a month . I bought a new motorcycle. I got the new Kawasaki Ninja 650r with their new parallel twin engine and cool red frame. Love the bike but can't let go of my old CB. I rode it last night after I cleaned the petcock and petcock filter. Put new gas in, and took off the air filter cover as suggested by someone on this forum. It ran pretty good. Before it was hesitating and stuttering at 5000 rpm consistantly in every gear and could not get it over 60 to 65 mph. This led me to believe that it was an electrical glitch due to it being so consistant with it sputtering at 5000 rpm in every gear. Now its hit or miss. Sometimes at 5000 rpms then sometimes at 6000 to 6500 rpms. I was able to get it to 75 mph and it flattens out. Sometimes it flattens out before this speed but if I back off the throttle a little it will smooth out and accelerate. Does this sound like it is getting too much fuel?

One thing: if it has CV carbs (not slide type), then the pistons in the carbs are getting stuck. This will provide the symptoms you describe. The clearances are VERY tight, on the order of .0008", so clean them exceedingly well, wipe at end with an oily (clean) rag and install. I worked on only one CB650 carb set (my brother's), and don't remember if they were slide or piston type.

Plus, someone asked me last week, "How many carbs have you rebuilt?" I added up the number of bikes (fours only), and it came to over 1,000... 

[radman]

Well I want thank everyone for he quick and helpful responses. I took her out for about two hours tonight with no air filter at all and she opened up and started to run great. It ran like she used to so fuel air mixture was dinked up. I guess Ill get some pod filters for it and run her like that. I have not used the stuff from napa but I have been running some Seafoam in this tank. A friend swears by it and it ran great tonight. I put three ounces in the fresh tank I loaded in the other night when it was running like crap.

But nobody has any idea about my blinker prob. Ill probably just run it without blinkers. I hate riding at night and hand signals alert drivers better sometimes in the daylight.

[Pinhead]

But nobody has any idea about my blinker prob.

It's probably a bad connection behind the headlight. When I bought my '79 CB650 it had a ferring on the front that looked like crap and the wiring was all ran through it (for turn signals and head light) Luckily they didn't butcher the wiring... I just had to figure out which wires plugged into eachother. If there was a single loose wire, it gave me the same symptoms you're having. It took me probably 5 hours of banging my head before I finally got them to work.

My bike's engine is having similar problems, though I think it's due to my faulty charging system. It runs great when I first re-install the battery, but after a while (when the battery runs down) it starts to miss at above 4k and has no torque to speak of. By then I'd better be close to home because it's not running for much longer. I'll try the BG44K to see if it'll help me any. I'm getting a rotor from someone on the forum, so hopefully my charging system should be sorted out.

So, Radman, did you rectify your problems completely?

[cb650]

Manuall also says it could be the air gap on the electronic ignition pickups.




                                   Terry

[radman]

Reply to Pinhead, sure you want me to call you that? As far as engine performance it is sorted out. Ill have to play around with the blinkers. But I have to be careful how much time I spend tinkering with this bike as my wife will get bent out of shape now that I have my new bike. But she says I can keep it instead of selling like I originally planned.

Sorry to hear you have electrical charging probs. Ill bet sooner or later Ill be plagued with that too as this bike ages.

Conrad

[Pinhead]

I was able to get it to 75 mph and it flattens out. Sometimes it flattens out before this speed but if I back off the throttle a little it will smooth out and accelerate. Does this sound like it is getting too much fuel?

That's exactly what my bike is doing right now. What did you do to fix it?

[radman]

took the air filiter out and ran her open with no air restriction. Seemed to work great for my bike. Im gonna put pod filters on. Seems to be a backasswards way of fixing my problem but I don't know carbs and don't have a lot of time and I have a new bike too.

[Pinhead]

took the air filiter out and ran her open with no air restriction. Seemed to work great for my bike. Im gonna put pod filters on. Seems to be a backasswards way of fixing my problem but I don't know carbs and don't have a lot of time and I have a new bike too.

Oh. You got lucky then, mine's the exact opposite. If I take the air filter out it'll just die...

[Zeke]

I'd check these things, especially since it sounds like it was sitting awhile, and because it's a CB650.

1. Pull the plugs (a CB750/500 plug wrench works great, if you don't have the stock one) and see if they are all the same color: should be light tan or light gray.
2. Check the intake valve clearance. It should be .002" or .003". I prefer .003".
3. Check the exhaust valve clearances. They should be .004, despite what the manual says.
4. Get some BG44K (NAPA usually carries this) and put 1 ounce in each full tank of gas until the can is gone. Keep the can sealed until you use it. This amazing stuff will clean off the valves and rings like new while lubricating them full time. It's pricey, $22 per can.

The CB650 suffered from "sticky valve syndrome" because of its design. It runs real well until they start sticking, then it will eventually burn the valve(s) because of the problem. Either disassembling the head and cleaning them or doing the above steps will clean them nicely. Disassembly is faster, BG44K is more fun. 

Hondaman:

No kidding?  So on my 80650C you recommend .003 intake and .004 exhaust?

What's the explanation?

Thanks,

Zeke

Bump

HondaMan:

Experience is king, I'd love to hear your thoughts on the extra valve lash.

Thanks,

Zeke