a little help... cb360

cb(x)

New Member
Hey Guys, been lurking for a while and soaking up as much as I can from all the helpful wrenches in here. Hopefully someone can aim me in the right direction with this problem.

Last summer my son comes home from school looking to build a cafe racer. He found a CB360 runner that needed some love (and a lot of chopping) and it came with a CL360 basket case for parts or... Since I like to turn a wrench for fun I thought it would be cool to give this a go, so we went at it. Things went along ok for a first project. Not quite the quality of the bike I see here, but the boy has to learn, and we can always tear it down and clean it up some winter.

On to the problem: The with a set of shorty pipes and Pods (I know what you are thinking, but the kid wants that look) the bike would start and run at 3-6k rpms ok for a while, but wouldn't idle. I saw someone went to a bigger main jet and it helped, so i have a 115 main and the stock 68 secondary. Now it will only start and run with the choke on. But the bigger problem is we have noticed the right cylinder is dead cold. It is pumping air like a champ, but not hot exhaust.
I have checked compression (135 left, 140 right, cold). There is spark when I pull the plug out and kick it. I checked the points and re-gapped. I have cleaned the carbs about 4 times in the last few days. There is plenty of fuel flowing from the tank to the bowls. Since I dump a shot of gas from each every time I take them off the bike.
New plugs installed: Left plug is black, right plug is dry with a touch of black on it.
One thing I noticed is when I took the air filters off, there isn't any suction on the right carb mouth, certainly not as much as the left. So i am thinking either timing or valves. There is some sign of life in the Right side when i shoot a little starter fluid in. One more thing... i have tried the air screws at 1/2 turn out, 1 full turn out and increments of 1/2 to 3 turns out. No luck.

So, gentlemen... what am I missing? And be gentle, this has been driving me nuts for a few weeks. Thanks.
 

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Check float height and set to 21mm
Check valve adjustment, sounds like you may be loose one side (set at wrong TDC?)
I make sync adapters for 360's
 
Thanks guys.

So today I rechecked the points and the timing. I found the timing was way off. When I look into the cylinder with the plug out, i can see the valves move, so stuck valve is out. I have to check the float height again (doing that tonight) and I will have to buy a Carb Sync tool. Any suggestions? And I will have to get a pair of the adapters you guys are talking about. PJ, if you could shoot me a note about that, that would be cool.

As far as the bike's running condition today, it ran for a bit once the timing was dialed in better, and i could get it to idle and both cylinders firing. She ran for about a mile down the road then died again. Had to push her home. Later in the day, tried again (after yard work and a couple of hours out on my "big" bike) and my son nearly got the whole loop i did in the morning before she konked out.
The top end is kinda noisy so maybe some valve adjustments are in order.
When she dies, she only wants to start with the Choke on Full, then kick, blip to about 5k and sputters out. Tonight's cold start on second kick, no choke was perfect. Both sides firing. A mile later... done. I started thinking it was electrical, but it has to be carbs, right?
As always, input is much appreciated. I think we are soooo close. Today, even if for a little while, it felt pretty good.
 
best price I found on carb gauge...they have really gone up. I think I paid like $20 last year. Now their $45 - 50.
http://www.amazon.com/Carburetor-Synchronizer-carb-Gauge-cylinder/dp/B004MSJ7C8/ref=pd_sbs_auto_1 Also these gauges are really cheap and crappy...BUT they work great...and your not going to be using them everyday for 100 years. SO, follow instructions to calibrate ZERO by adjusting screw...if that dont get em to zero...unscrew lens cap and gently twist needle w finger to zero...then use screw to find center of zero adjustment. LOL its the proper technique use by professionals everywhere. LOL. it works.

Is your gas cap venting properly ????

Make sure fuel lines are not touching hot engine, hot engine mounts or frame.

Also I just solved a problem w mine. chunks of old rubber fuel tap gasket floating in tank. bike ran for a mile then would sputter like out of gas. stop. check things. run another mile...etc. It would almost die. check for clean tank.
did you adjust cam chain tensioner before setting timing. there is a method to it...also PJ says to trap crankshaft w 14mm wrench on bolt under stator cover. This IS the best method. then continue as prescribed in manual.
here is a link to get free official honda shop manual. if security code dont work keep trying like 10 times you will get it.
http://www.carlsalter.com/download.asp?p=840
 
Also, here is a generic run down list I send guys who ask for carb help. (dont get overwhelmed) the last guy I sent this to, sold his bike after receiving this from me. LOL. Apparently he didnt feel mentally prepared.

Carbs can not be clean enough, clean them. Clean tank and fuel tap.
1 are your carb diaphragms good?
2 do you have the original stock Keihin air/fuel adjustment needle springs installed (BEST) OR Did you file sharp edges off new carb rebuild kit air / fuel adjuster springs ? link to more info on my blog. http://1976hondacb360t.blogspot.com/2012/05/kehein-754-carbsso-close.html
3 Do you have in line fuel filters or screens on fuel tap? clean tank ?
4 Do you have good stock coils or new coils ? good condenser ?
5 Good plugs set proper gap (.7 - .8 mm), NGK B8ES, (NOT NGK BR8ES) and 5 or 10 ohm plug caps ? I have 10 ohm (pjs recommendation w stock coils) works great.
6 Timing set properly w timing light ? good points ? properly adjusted .3 - .4 mm gap
7 cam chain adjusted properly ? trap crank w wrench while setting adjustment bolt.
8 Valves adjusted properly?
9 Rubber carb manifold boots and gaskets in good shape (no cracks of leaks)
10 carbs properly synchronized w gauge?
11 gas cap vent?
Is there anything else forgot ?

It would take a big day to check all this...but it would only take a day. and its a great place to be sitting when getting started on carbs.
 
If carb diaphragms have any holes or splits, get some from here
http://jbmindustries.com/index.html
They work well and give a noticeably better pick up than old hard diaphragms. (although I wouldn't change old ones if they are not split)
I've done several now with these and only heard of someone having one split (it on here somewhere, sure someone has link to post bookmarked?)
 
Ok so I had a similar problem with my 360 turns out my mains were too big and it was fouling plugs went down to 105 main and it runs great now. Maybe a little lean at the top end but idles fine and runs down the highway like a champ.
 
Update...
Was in the garage, and online reading, until around 1am. Float heights were way off. I tweaked them to the 21mm PJ suggested. then I noticed the right side didn't have any bounce so I cleaned the float valve needle (again) and put it back together. Then I checked the flow out of both Fuel lines and the were not smooth or even. Gunked up Petcock was the issue there. Drained the tank, cleaned the petcock, blew air in through to get a clean passageway. In the meantime, it looks like the tank has a little surface rust inside. Guess I will be taking that off to clean again.
Checked the valves and I hope I got them a little closer. Thanks Trek for the checklist. Now I have a rainy day project. I have read here that there are some lousy carb rebuild kits out there, what do the Gods of Air and Fuel suggest as a good source?
Anyway, with just the bits I got done last night... My son and I got riding this morning! It isn't perfect but we rode about 75 miles around town and some rural areas around here. It was awesome, he was so happy and I can finally feel like we are making progress.
Pretty pumped to get the good news out. Tons more work to do, but the light at the end of the tunnel doesn't look like a train anymore! Thanks for the help, I will keep you guys posted.
 
Yeah, Sweet. So much better than the Clymer. Feels like 1974 in there. Thanks a bunch. My son got interested in this stuff, but i am having all the fun!
 
carb kits...(you better sit down for this one)
My latest purchase are these.
http://global.rakuten.com/en/store/keyster-shop/item/f142nh_e/
I havent found em in USA yet. Rakuten is a shop supplier in Japan. $40 each X 2. bout $95 total w shipping.
I believe any other kits are a complete waste of money.
As you will see they come w 4 sizes of needles an assortment of secondaries. stock # 68 primary, 3 pilots. float seat and needle. bowl screw. air fuel adjust needle, spring, crappy o ring gasket. A very complete STARTER set. You could literally spend years trying different combos. LOL
I get main secondaries from jetrus.com
PJ may start making some main primaries in different sizes.
I had a local machinist/buddy make some main primaries for me. ONLY because PJ wasnt making them yet. Apparently you can only get main primaries that come in the kits and only stock size #68s. right now. atleast I havent found em anywhere. And I have spent a fair amount of time looking.
 
cb(x) said:
Yeah, Sweet. So much better than the Clymer. Feels like 1974 in there. Thanks a bunch. My son got interested in this stuff, but i am having all the fun!

Im glad your having fun. I am too. I am having fun in a pulling my hair out kinda way. LOL. I enjoy working on this bike more than riding it. No coffee cup holder. I believe PJ enjoys working on em also.
Just dont have too much fun and get so frustrated you give up. I think it takes a very special kind of person to enjoy one of these old machines. persistence pays off.
AND woohoo...my next post will be 400 mark!!!
 
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