Topic: What could be the issue? cb350 four( very hot, white smoke, smells gassy)

[Dos]

Hello all I was wondering if someone could help me identify the issue.

I brought my bike to a guy to get the engine redone.
 
Long story short..

I got the bike back and it runs!

However it gets really hot. Yes I know this is the smallest four cylinder honda ever made but this gets way hotter then it ever did.

The engine breather tube also puffs out white smoke.

When starting the biking it jugs badly and will shut off  unless I rev the bike really hard right in the beginning. I never had to do this before.

It also seems to idle fast.. even at 1200rpm.. it's just cycling to fast I believe. how would i turn this down a bit? I do adjust the idle speed but the actuall cycling is just alittle to fast. for example it went like this cycle-----cycle----cycle.  now it goes. cycle--cycle--cycle.

so yeah those are the 4 hints I am getting from the bike. I think maybe they didn't sync the carbs or got the right air/fuel mixture with the carbs. O i forgot the bike really smells gassy.. very rich and there is no leakage out of the carbs.

If anyone could help me out I would appreciate it.

Thanks.

[harisuluv]

What exactly did this person do? 

They should have told you exactly what work they did, no?

[Dos]

Rather not say because it wasn't a great experience.  But this is the issue now

- smells rich
- gets very hot
- engine breather tube has white smoke coming out
- cycles fast

[flybox1]

1200 is NOT a fast idle for this bike.  1200-1500 is more reasonable.
If thebike were new, and in perfect tune, it might idle well at a lower rpm.

Can't help you much more if you won't provide details.  Like why you took it to him and what he did.
Give the bike your full attention and do the 3000mi maintenance items.   You might find something.

[harisuluv]

Rather not say because it wasn't a great experience.  But this is the issue now

- smells rich
- gets very hot
- engine breather tube has white smoke coming out
- cycles fast

Um... ok, well..  Sounds like it wasn't doing all those things before you gave it to him.  So I would deduce that what he did to your bike which only you know and won't tell us is what's wrong with it.

Aside from that, no idea.. oil starvation?  who knows.

[DaveBarbier]

I assume you paid money for this. Why would you not go back to this guy and have him fix it?

[harisuluv]

I assume you paid money for this. Why would you not go back to this guy and have him fix it?

Doesn't sound like he had a good experience with the guy.  On a related note it is HARD to find a good service guy for these old bikes.

[Dos]

I got it last summer and it ran great. I could even go 70/80 on the highway.

After winter I couldn't get her running correctly. It would just cut out and that's besides the fact that the cam chain tensioner bolt got snapped off.

I paid $1700 for an "engine rebuild"
 The guy didn't even put in new rings.

I brought it back since it was smoking before I even got it home. The young man said there was nothing wrong.. I had the bike in there close to three months so I just wanted to get it out.


They said my valves were really tight so they adjusted that, cleaned the carbs (synced), cracked the engine and put it back together. got a new tensioner bolt put in there.

I attached the "invoice"

[Dos]

It seems to struggle at higher rpms

Before I winterized it the very left carb would leak if I didn't touch it for alittle bit however when I would start the bike it would have no problems. It would start right up and sounded great.. even after leaving it for a day or two

When I start her up now I have to hold down the throttle and really rip it for several seconds and then it "warms" up but it does struggle in the beginning. it sounds like a jug jug jug jug

After riding for a little it will smell very rich, get very hot, and the breather exhaust from the engine smokes.
 Regarding the fast idle.. It idles fine in the 1200 rpm zone but what im saying is it cycles very fast.. so even at 1200 rpms it sounds like the cycles are fast.  this is what it was at 1200 rpm..   cycle--------cycle---------cycle. Now at 1200 rpm it is cycle---cycle---cycle---cycle


I learned my lesson but I want to fix this so I can have an enjoyable ride without thinking/worrying.

I am thinking this is something with my carbs? maybe a slight tune? I feel it is too rich and this is causing the bike to smell gassy (of course) and get hot?
am I on the right track here?
 

[harisuluv]

Thanks for elaborating that helps a lot. I'm on my phone so can't really make a proper response but will when I get home.

[Dos]

I am doing some research here, it could be the timing.

[harisuluv]

Next thing you should do is post some pictures.  Well framed, well lit, clear pictures.  Of the engine, carbs, etc.

You seem to be a little fixated on this "cycling" of the engine.  It seems to be running faster than you remember but rpms are around 1200 like normal.  What makes you think that before the engine wasn't "cycling" slow and is not normal?

You didn't mention using choke at all when you start your bike, do you use it?

Kind of sounds like maybe they just popped the bowls off and sprayed some carb clean in there and unclogged your pilot jets.

[DaveBarbier]

I assume you paid money for this. Why would you not go back to this guy and have him fix it?

Doesn't sound like he had a good experience with the guy.  On a related note it is HARD to find a good service guy for these old bikes.

Thought so. Normally I'd want someone to right their wrong, but after reading his above post I too would avoid the guy like the plague.

OP: Can you post a video of the idling? I, for one, have no idea how an idle could be faster or slower while still being 1200rpm. Was the tach or tach drive gear swapped with a different ratio one?

[Dos]

Just as I had thought . spark plugs are pitch black. These are from the very left and very right of the engine. I'm not going to bother with the ones in the middle they are probably just as dark too. I will have a video for you in several minutes.

[Dos]

Here are two videos. watch in 720p or 1080p so the audio is better.

1st: Getting it started

2nd: Started and trying to show that it runs fast... I could just be crazy lol

[harisuluv]

Hmm a little hard to tell, but that looks more like oil.  If you look at the center it's a nice tan color, which would be just about perfect for mixture.  I don't think it's fouled.  The second one is harder to see.

[saxamaphone]

If it were me I'd double check the cleanliness of the carbs, float heights, then re-check tappet clearances, timing, and sync carbs.  If you don't trust what they did to your bike you never know what might have happened.

[harisuluv]

At one point I did see what looked to be a new cylinder gasket, that's the only new gasket I could make out, though.

I want to say kudos for making a video, it helps a lot so good job!

The audio is really hard to hear though, I can't make out any kind of out of the ordinary idle.  It's also very hard to see anything for more than half a second with the camera shaking around.  It's like watching some deleted scene from "Fear and loathing in Las Vegas."

Also in your first video I think you show the choke and say while it warms up you have to pull it up (this is applying CHOKE) which means you are making the mixture rich.  Later on when the bike is warmed up, looks like choke is off (Not applied).  Maybe you have some kind of idle issue.  What are your mixture screws set at? 

[Dos]

I don't know what my mixture screws are set at. 

Could this be the timing points?

[Dos]

I completely unscrewed all of my mixture screws and turned them in to what I think is the right amount but I honestly feel I just made it worse...
 I know its 7/8th of a turn but how do you know in what position? Does anyone know how many turns in when the screws are completely unscrewed? And I mean just resting on the threads.

[harisuluv]

That's the opposite, you go all the way IN and then turn spec OUT (try 1.5 turns)

Wait, so you didn't check what they were set at first?  How would you know which way to adjust or be able to diagnose if you didn't check what they were set at?

[Dos]

Unfortunately not.. Rookie mistake.

What ever it was it was to rich the whole bike just smelled gassy.

[Dos]

Can someone explain why the breather tube spits out white smoke? Or gets really hot? The bike did it before but only after a while of riding.

[Dos]

I set all of the pilot screws about 2 turns and it seems to be back at square one. Still very hot and white smoke or of breather tube.. In neutral I will rev it and it will hang at like 2-3000 rpms and then drop back down to 1200.. What's the cause? how could I fix this?

[harisuluv]

Remember that is an air cooled engine.  You need a fan on it or something if you're not riding it, it's going to get hot just sitting. 

Did this hanging just occur?  What changed, just the mixture screw?  You can change it to where it doesn't do that then.

All evidence points to your bike running too lean, hanging idle, white smoke from vent, excessive heat.  These are all symptoms of a lean running bike.

[krusty]

What's the mileage? Do a compression test. If it needed new rings or rebore before this, I'm suspecting it may have been torn down then reassembled without regard as to original set up of pistons and rings. This could make any issue of oil burning worse hence oily plugs and incomplete combustion, gassy smell?

[Dos]

To prevent it from being lean do I just adjust the pilot screw on the carbs? But if it were lean would you smell the gas?

It's got around 12,000 miles


I really hope it's not the pistons/rings I really don't want to have to take it out

[harisuluv]

Turn out to make leaner, in to make richer.

I think it is a fantastic suggestion to do a compression test.  You really don't have any kind of hard data to work from, just pretty much guesses.

You could even be running rich on some carbs and lean on others.  Could it be timing?  Sure maybe, it could also be a laundry list of other things, or maybe just a vacuum sync.  Gonna take some trouble shooting to figure out what is wrong.

[Dos]

When it hangs after revving what does that mean and how can i fix it?

[carnivorous chicken]

First thing you want to do is a compression test, as others have suggested. You're going to be chasing your tail trying to diagnose anything else without knowing the state of your compression. If your compression is low, you need to find out why. Sounds like most likely rings, but could also be valves. Or both. If your compression is fine, then you've got to figure out other causes -- some of which have been stated already. Lean condition, rich condition, timing, points, valve adjust. If your plus are black and wet looking, it's oil. If they're black and sooty looking, they're rich. White smoke from the breather indicates lean (and hot). Plugs look like they're oil fouled.

You can get a decent compression gauge at an auto parts store for $30-$40 that will give you an idea of your compression. Make sure to follow instructions on how to take a reading.

Your invoice doesn't have a date on it, so don't know when the work was done. If it was relatively recently, despite the embarrassment of getting ripped off,  you should go back to this guy and complain. If you can prove your bike was running better and with fewer problems than when you went in, you should get your money back. I've heard quite a few horror stories from friends in NYC who have taken vintage bikes in to shops where the mechanics have no idea what they're working with. If, on the other hand, the mechanic gave you some options ("do you want me to change out your rings?") and you said no to save money, then... lesson learned.

I'll be in NYC to work on a few bikes in mid-August. If you haven't sorted this mess out, let me know. I will be bringing a full tool kit including compression gauge and carb sync tool.