79 XS standard not starting

[BradW87]

Good evening everyone,

Soo I am in a bit of a pickle. Had 3 cars die on me in 6 months and got tired of buying new (to me) onesonly to have my luck continue. So I searched craigslist and bought the first gooddealfor a bikeI could find. A 79 xs standard with 20k on her that needed some tlc but overall in good shape. $400 later and i bought myself a newride.She was going to be my daily commuter so I could stopbummingrides off people as currently was(and still am) doing.Was runninggoodother than random day I played with the choke and pop pop pop it went and started to run rough. Sprayed some carb cleaner andshe was starting torunokay again for a couple days. Mind you the last couple weeks have been quite rainy and unpleasant to drive to work in, butthe mobile freedom and feeling of a motorcycle got me past the dampness. Took it to work ran fine, after work was raining so I thought that was a goodexscusetodrive to the local pub and have a drink or twotill it died down.( was more of a sprinkle) left about 10pm and she wouldn'tstart.Turnedover butno ignition. In fact when I gave it throttle italmostsounded less likely to start. No throttle, could hear a light put put put out the pipe. Gave it the night and called a cab and tried it the nextday...Same thing...roll started her a couple times but again throttle didnothing.Plenty of gas, battery was new and always had plenty of charge. Checked the plugs and they are not clean but not dirty. Read some posts about maybe being the coils?? Got wet maybe?? Strange thing isitrangreatinthe rain.Pretty much every day she ran was rainingcatsn dogs.Nice day Nadda.

I currently have an 81 Honda CM 400C half in Maine half in NH still from a rebuild before I moved. So that is out of the question.I am pretty handy and a quick learner... just need some helpanddirection.What should I do to figure this out... cabs are killing me??? I thank anyone in advance. Again not overly familiar with lingo of whatiswhatwharnit comes to the electrical system of this bikeso details would be appreciated like location and what it looks like.

[TopCatGr58]

Hey Brad,

Okay, first thing is to take the right control unit off, and check the emergency Kill switch. Rain and corrosion can cause it to have problems. There are a black-n-white wire, and a black wire=ground. IF the contacts are corroded together can cause unwanted connection which grounds the ignition module(TCI).

However, you are saying that it's sounding like it's trying to start, pops. You say battery is charged, but do you have a voltmeter to test it, both static power...~12.5 across the terminals, as well as while trying to start it. IF drops near 10.5 V less, ignition system won't behave. Being in the rain can contribute to both corrosion, as well as unwanted shorts in the harness.

Even the wires for the spark plugs can develop external leaks to frame or engine points where they may be touching?

Rain can cause problems at the harness connection near the PU coils...the triggers under the left engine case cover.

Plugs being dirty....perhaps not running at high enough rpm to help keep them burning cleanly? Many folks run these engines like Harley's barely getting over 3-4k rpm, these engines like to run....cruising at 3.5 rpm or higher is better....IMHO!

The fuseblock could also be problematic with the brass clips and glass fuses.
Also check the ground points..battery to frame, but also second ground strap behind engine below carbs/battery at starter to frame!

Sounds like you bought it, got it, gassed it up and started riding it?? IF it has sat for any length of time, it can get clogged, both in the carbs as well as the gas tank and fuel. Some application of Sea Foam will go just so far, but usually requires a proper disassembly to properly/thoroughly clean them(carbs).

So.....folks will say go back to the basics, compression, fuel, fire, but not necessarily in that order. After verifying compression, it's actually suggested to get ignition going before going to the fuel/carbs.

T.C.

[WMarshy]

I agree with TC about going back to basics... are the plugs wet, did you check spark by taking the plugs out one at a time and grounding them on the head (careful about vapors igniting from removed cylinder). What exactly did you fiddle with in regards to the choke? As many details as possible will help us help you... recent carb cleaning (or at al).

[BradW87]

Not much of a choice

Okay I will check on the elec system as soon as I can. Usually I would have cleaned the carbs first thing,but due to some cracked boots I didn't know if I wanted to hurt them further. Was planning on replacing them and rebuilding/cleaning them this week. Now my carb $ has turned into cab $... unfortunately my garage is my appartment driveway as well and was worried about the water getting in the engine if I took them off for a day or two as well.

As to the choke: little lever on the side of the carb. It was bogging out at the lights so I was running it choked out at the first position. Again was not a fix so much as a for now till I could rebuild the carbs. Was running beautiful for a good week quick throttle response, no backfiring. Then one night I was like oh maybe its fine so I put the choke aback in....and problems down the road. Sprayed a can of carb cleaner in her and was running smooth for the most part. Took it to work for two days and that's when it stoped starting .

He said he ran it all last summer, had the bike for a few years. As to if he was bsing me is another story.

Ill need to charge the battery due to the over attempts at starting it or just swap my fresh CM battery to eliminate that issue.

As of checking the plugs electricly... has not been a smart idea as I've said due to rain. Its still stuck 10 miles from my place till I can A fix it or B find someone with a trailor.
I've been pushing it to different parking spots to avoid tickets.

[donebysunday]

If it's left out in the weather, buy a good cover. I learned the hard way at a rally 180 miles from home.

[BradW87]

other question from tc

I really meant to say it was more of a very light put put put rather than a backfiring pop when it failed to start. But if I gave it throttle I no longer heard the puttering. I was running it high rpms as well as I do my 400. Thank you both for the quick responses. I will get back to you with my findings.

Much ablidged!
Brad

[BradW87]

p.s.s.

Also forgot to mention I did run a full fuel system cleaner in the first couple tanks.

[BradW87]

long way from home

If it's left out in the weather, buy a good cover. I learned the hard way at a rally 180 miles from home.

Ooohhh now that's a rough one. Yah its on the long list of to dos. I had a good cover that was eaten by mice and made into a nice nest this winter.

[donebysunday]

Ooohhh now that's a rough one. Yah its on the long list of to dos. I had a good cover that was eaten by mice and made into a nice nest this winter.

Covers really help your bike as well as giving the local wildlife a home. Ever found a mouse nest in your air cleaner ?

[BradW87]

Not yet

Haha no I have not had one as of yet and hope never to!

[TopCatGr58]

Okay,

More info was good. Well, the PO may have run/ridden this last summer, but storing it, especially with fuel in it without any fuel/carb cleaner in the fuel most likely allowed the fuel to varnish, especially in the small pilot jet circuit passages. These are required for the low throttle/idle response. When you ran it on the CHOKE you were bypassing the pilot circuit and so were able to get fuel into the engine to run it, and then once you were able to get it into the upper rpms, you were running mostly on the mains then.

But then pushing the choke(it's really a fuel enrichener plunger/circuit that feeds fuel directly into the intake) back in may have both dislodged a hunk of varnish or such as well as trying to use the pilot circuit which is already clogged! And the Starter jets....are in the bottom of the float bowls that feed the enrichener have also probably gotten clogged with varnish or such, and so that's now why it won't start or run even with the enrichener plunger/lever pulled back out to full "choke"!?

Spraying carb cleaner into the carb inlet bell just makes it pretty, but does nothing for the pilot circuit. You don't have to BUY a carb kit to clean the carbs. See the tech tip on Carbs 101 for what and how to take the carbs apart to be able to clean them, and then reassemble without necessarily replacing any parts. Being a 79, it has the solid float needle seals/seats instead of the viton/rubber kind, and so it can be cleaned and polished. You can even make the float bowl gaskets out of cereal box if they don't stay in 1 piece when you take the bowls off.

The pilot SCREWS have very fine delicate tips so care is needed when working on them. A good quality and proper fitting set of screwdrivers is paramount for being able to remove the pilot JETS as well as the main jets without damaging them. However, they are made of brass, and can be fragile if they are too tightly corroded/stuck in the pilot jet tower.

A small container of carb cleaner soak would be good for soaking the metal parts in...NOT the whole carb body. A few cans a spray carb cleaner will then be effective to spray/clean deep INSIDE the carb bodies, the orifices and passages. So...again, take a good look at the carbs 101 tip.

IF $$ is real tight, and you break a pilot jet tip, I'm sure folks here would have some old but still usable jets they could send to you for cheap if not free!

The other thing is to make sure fuel is actually getting to then carbs. Your bike is a special, it may still have the Octy vac. controlled valve, and it can get stuck, and not flow, so turn the petcocks to PRIME to bypass this valve and send fuel directly to the carbs. And be sure you have FUEL in the tank, and even pull the front fuel line from the petcock and then turn to Prime to verify that it will flow out the front spigot!

T.C.

[BradW87]

Thank You TC

I will take all this new info into consideration, thank you. I have rebuilt/cleaned carbs before so I will be gentle and break out the old toothbrush and coffee can on Tuesday. (Day off) Thought my 79 was a standard... is there something I don't know?? (Besides a lot obviously haha)

[TopCatGr58]

Hey Brad,

Sorry, CRS acting up again, lots of folks and bikes on my mind. Yep, you have a standard as far as you state, so you should not have an OCTY. You do have vac. controlled petcocks, and they can also get stuck...the inner diaphragm valve....or the vac. lines for them to the intake ports...the lines can crack and loose vacuum which will also prevent them from flowing while the engine is running.

Hope you find the problem soon so you can get back to riding.

T.C.

[BradW87]

Haha no worries, just didn't want to be blue holding a sign saying I'm red. Tomorrow is the day! I will be ripping the carbs apart, changing the plugs, and ill look into the petcocks as well. Leave no stone unturned. I also bought some wire dry just in case it was a water issue in the headlight bucket or kill switch. Thanks again for all the sound advice. Hope to be on the road wed.

[BradW87]

carbs clean.

Okay so cleaned all four carbs today,put them back on and still sounds like the same problem. Was dark by the time I got through with the project so didn't have any time to do compression check or check the new spark plugs. Managed to look at the kill switch and no corrosion seems to be an issue. Also checked fuses and all were good. Even cleaned the contacts and used dyelec grease...