1986 radian no start... ffffffffuuuuuuu

Alright, I know that I've covered at least most of my bases... I bought the bike a week and a half ago in running but ugly condition, good runner but with some noise from the valves and a slight knock from the clutch area, but neither too loud. I started it up on the center stand a couple days ago to show a friend the valve chatter and ran it for about 3 min. and shut it down. came out 3 hrs later and it wouldn't start. nothing but a quick stumble and a light backfire... now it just cranks and cranks.

I have done the following since buying it:

1. new paint (ran after reassembly)
2. header wrap (just to cover rusted head pipes)
3. round headlight conversion with a cb900 bucket (hated rectangle light)
4. new speedo(old one was dented up)
5. new break fluid
6. new chain
7. redid the fuse box b/c the old fuses were ziptied to the broken holders
8. new back tire
9. got a service manual for it

I've been investigating and havent found anything yet. I have good spark, good compression, and I'm pretty sure I'm getting fuel, but it doesnt matter if I spray gas into the airbox, it doesn't fire... I pulled the cam cover and with the "T" mark lined up to the upper coil mark, the I2 and E2 cam cap marks line up to the cam marks, so I would think that it didn't jump time... Any thoughts?

Matt.

 

How did you check for spark?

 

I used a spark tester in line between the plug and wire. I also took out the #4 plug at random and it arked to the block from about 3/8" away... just picked the plug at random, didn't try the other three for arc but they dont look too fouled and the po had just changed them. they have good gap too.

 

REPLACE THE SPARK PLUGS.

Replace. With BRAND NEW ones, properly gapped.

Fully charge the battery. Be sure you have fresh fuel; put the petcock on PRI for a few minutes before trying to start it. You might want to open the carb drains, drain out whatever's in there (LOTS of shop towels required) and be sure the bowls are filling with fresh fuel.

The "slight knock" from the clutch is primary chain slap and not a cause for concern, it will go away when you rev the engine because the chain is hydraulically tensioned via engine oil pressure.

How many miles on the bike? Did you replace the sprockets when you replaced the chain? (If not, your new chain's gonna wear out really quickly.)

Valve "clatter" = good. No valve noise = bad (tight valves.)

 

I may replace the plugs, but like I said, the po had JUST bought them on the 18th of march( have the reciept) and they in no way appear to be fouled...

The battery is at full state of charge (12.62dcv per dvom) and I have also been supporting it with a charger when I was doing all of the "diagnosis" this past couple of days. It is also new but I didn't get a reciept for it(it is a yuasa brand).

The carb bowls have been drained a total of three times now, once when I got her home just to see if there was any crud(none to speak of, just a couple of particals no bigger than 10-15 micron). the second time was just after the starting problem arose to see if I was getting fuel to each carb and how much, and the third just about 10 hrs ago to see if after all of the cranking and trying to start, how much was in each bowl.

I tend to use clear rubber hose shoved into the drain hole of the bowls before I open the drain screws. That way I can direct the fuel into a mixing cup with a graduated scale on the side so I can really see the amount of gas each carb bowl is holding(they tend to be fairly clear too, so I can hold it up to the light and search for junk floating around).

I suspected that the "knock" was probably either primary chain or throw out related, so I wasn't too worried about that. I was just trying to add any potential symptems.

Lastly, the valvetrain noise is fairly excessive, so a cam chain tensioner and fresh valve pads are in order at some point(the adjuster screw is broken off flush on the tensioner so I can't adjust it).

Oh, the miles are exempt, and the title says 46,000 and some change, but the odo says 4,600 and some. so your guess is as good as mine on actual miles... my new speedo says 22k

Thanks for the response,

Matt.

 

I forgot about your sprocket question... I did not replace sprockets because they look like they had been fairly recently done. the reason that I did a chain was just for the fact that I don't like standard chain and opted for an o-ring one instead(mainly because they had the proper one in stock when I went to the local bike parts shop. It is only at the third hash mark on the swingarm with proper tension so I'm not sure that much sprocket wear is an issue.

Matt

 

I bought new plugs, I'm going to give them a try here in a few... got to put the cam cover back on first.

Matt.

 

Did you spray gasoline or starter fluid (ether)? Typically if it does not run some on starter fluid you have an ignition problem; if it starts and runs some on ether you have a carb problem.

 

You need to see if you are sparking on all four. Otherwise, follow the bounching ball that Fitz has outlined for you.

 

It's running now...

I think I know what the problem was. I did go and get new plugs, but before I put them in, I let it sit over night because even though the compression seemed even on all four, it seemed a little low across the board. this morning it fired right up after I put everything back on, so I think that the plugs somehow became semi-fouled, causing the first firing problem(+1 to FITZ). I then tried to crank, add gas and crank, spray starting fluid and crank,etc., and I washed out the cylinder walls causing the compression to be too low. That would explain why the bike was cranking over so fast. I did mist a little wd40 in the plug holes last night before I called it quits, hoping that it would settle around the rings if that was the problem... any thoughts?

Matt.

 

If you are not real careful, just adding gas will often foul-out the plugs. You really need a very fine mist of gas in the airbox as a test (which is why most people just use the ether/starting spray which atomizes real well). Remember that the average stoichometric combo is something like 14:1, 14 parts air to 1 part gas.

 

Yeah, I like to use gas over ether on gas engines to prevent washing cylinder walls... although I still seemed to somehow do it on this motor. I usually put the gas in one of those refillable aerosol sprayers that have a glass jar that looks like a baby food jar on bottom with a propellant canister on top, those seem to atomize fairly well.

I see in your bike list that you have an '81 440 ltd... If you haven't, check out kz400.com, I go by 440cafeish over there. Lots of 400/440 tech and good guys that know their small kz's too.

Matt.

 

Another thing you should check is the charging system. I have a couple of 86 Radians and when I first got them they seemed to die for no apparent reason. Always started nice and ran well, but a few times when I was out riding they would start backfiring and sputter to a stop. Turns out what was happening was one of the alternator brushes was worn more than the other. When the engine got hot from running the short brush did not make good contact with the stator. I replaced the brushes with new ones from MotoLab for around $14 and polished the stator with my dremel. Now I have no problems and my bike's charge as they are supposed to. You can expect to need about 2000 rpm before you will be putting out 14v. Both of mine put out 12.5 at idle and I idle mine at 1400 to 1500 rpm to keep oil going to the cams.

Bruce