Front cylinders are dead

[Lil Venturous]

The front bank is not working. Cleaned the carbs twice and the bowls fill up. Has great fire. Hooked up the carb sync tool and it showed equalish vacuum on four. That leads my to believe they are pumping air at least.

 

Other little thing noticed is the tach is not reading anything. Tryed several different tci boxes. (thanks dad) Also installed other coil pack we had.

 

Going to find my compression tester tuesday or so.

 

But since dads bike is running again I should get some more help.

 

The bike is stripped of all plastic but believe only accs are unplugged right now.

 

Thanks Brian

[Pappa Bear]

pull the front bank spark plugs to see if they are wet! Floats may be stuck and flooding them! Good luck, these bikes can get finicky:fingers-crossed-emo

[bongobobny]

You may also be having an issue with your pickup coils or wiring associated with them. If one of the pickup coils. located along the stator cover, is dead that will knock out 2 out of the 4 cylinders. There should be around 110 ohms per coil as measured from the center tap wire...

[sgn]

OK Brian .... payup the $12.00 or I'm not coming over to the shop and "Help" you anymore.

 

I only say this because everbody knows RandyA is a lttle on the cheap side.

 

By the Randy, thanks for lunch!

[Lil Venturous]

Yea showing great fire. Plugs are a little wet. But not drowned like I thought they would be. Carb syncing made me think there is vacuum pulling in and cleaning carbs twice showed no blockage at all. The drain screws show gas running out. I will have to do a good compression test to feel more comfortable about the cam or chain not being an issue.

 

Was going to try some other carbs I knew were good but feel these are good right now.

[mbrood]

New plugs are in order after giving the two front cylinders time to air out. Do they fire up if you spray some carb cleaner down the throat of the carb? Has anybody messed with the idle mixture screws?

 

If you had synced them before and they are still pulling approximately the same, that tells you that the piston, valves and rings are doing a reasonable job of pulling air in.

 

If the TCI isn't responding, it's tied directly to the #2 output of the TCI and the bottom of the primary coil in the ignition coil. You can ohm this to the ignition fuse and should see about 3 Ohms. You can also Ohm the plug holder to the ignition fuse and see about 24K.

 

By the way, there are FOUR independent pickup coils and these need checked for proper resistance and also ohmed to the engine case to check for grounded coils.

http://www.bergall.org/temp/venture/alternator-a.jpg

[bongobobny]

He's right, each pickup actualy has 2 inside them, for a total of 4. I was thinking more on the linres of the cdnter tap being bad which would in effect kill both of the coils. The 110 ohms is from the center tap to each coil. Each block has a center tap and 2 windings. If the center tap line is out you will see around 220 ohms between the 2 other wires...

[Lil Venturous]

Will try and get back over tomorrow. But the front cylinders have some wicked spark when grounded to the case. Tryed three different tcis. Tach worked on none of them. Bike is stripped of all plastic but feel that only accs are unplugged. Also checked The pick ups before we knew anything about the bike because they halfway still had that cover off.

 

Will have it figured out by this weekend though I hope.

[mbrood]

you can see that the red line comes out of the TCI and feeds the #2 coil primary (low), the fuel pump (27) and the tach (21). This is a +12 volt line that is pulsed to ground when the pickup coil swings by (obviously) so it acts as a "keep alive" for the fuel pump and it has to be "counted" by the tach... I think you may have problems up in the tach at the dash... if the horn works, that line feeding fused +12v to the tach should be ok...

 

http://www.bergall.org/temp/venture/schematic-tach.jpg

Edited February 15, 2011 by mbrood

[Yammer Dan]

I had one that refused to go after I flooded it and I tried everything. New plugs and it fired right up.

[Lil Venturous]

New plugs always. Have boxes and the habit from the dirtbike days.

 

Going to check behind the cluster next trip over. Thinking of trying thursday night. Tomorrow is taxes I hope.

 

But did check again that there is good fire on the front bank. 2 and 4. Is there a way that that those two could be out of time? I do know one time I was not paying attention and plugged thre 3 and 4 coils backwards. Is there a way of plugging it up wrong at the pickup area? Like I say we bought a bike that was not running and had the left cover half off. Did check pickups with an ohm meter before installing that cover.

 

There appears to be good compression on those two cylinders.

 

Probably going to try other set of carbs off dads bike thursday night to to make for certain it is not a carb issue. Getting real good at pulling the carbs.

 

Main thing that I check with is a temp gun and the front two header pipes just do not show any heat rise at all to speak of.

 

 

Thanks again, Brian.

[Yammer Dan]

Not sure if they could be that far out of time. It sounds like it has to be fuel related.

[dingy]

But did check again that there is good fire on the front bank. 2 and 4. Is there a way that that those two could be out of time?

 

Thanks again, Brian.

 

There is no timing adjustment at the crankshaft.

 

The pickup coils are fixed in place in the stator cover. If they are tightened in the housing they are where they should be.

 

Did you do an official compression check with a gauge?

 

Are you sure you don't have the front coil connections reversed at the wiring harness? I don't remember if this is possible or not.

 

Gary

[Yammer Dan]

Remembering where they are to start with play with carb screws on those two while running. Just back them on out a few turns slowly and see what happens.

[bkuhr]

But did check again that there is good fire on the front bank. 2 and 4. Is there a way that that those two could be out of time? I do know one time I was not paying attention and plugged thre 3 and 4 coils backwards. Is there a way of plugging it up wrong at the pickup area? Like I say we bought a bike that was not running and had the left cover half off. Did check pickups with an ohm meter before installing that cover.

 

 

Who knows what a PO did, possible coil primarys are plugged up wrong(little yellow connectors at the coils), could verify wire color per schematic to verify correct primary to correct coil. Warning- very hard to get to- remove battery and get good light and inspection mirror. Also verify correct coil secondary spark lead to correct cylinder at this time. If ALL plastic is off, should see coils easy. Number connectors 1-2-3-4 to aviod future confusion.

 

I have also had problems with resistor caps- but you say you have good spark.

[bongobobny]

OK now I have to ask, are you using the right TCI? Not all TCI's are the same. An '83 will only work properly for an '83 due to the vacuum advance being 180 degrees out of phase from the rest of the years, the '84 - '89 are interchangeable but there is a slight difference in the advance curve for the '84 and '85 but all are interchangeable. The late MK2 '90 - up will only work on the late models as they went to a single pickup coil configuration. If you try one of those boxes on an earlirt model, the bike may fire up. or you will see spark on all cylinders, but the spark will be waaaay too fast, twice as many sparks per revolution. The reason I know this is I experienced the phenomonon when I accidently used one on my '84.

 

Yes it is possible to mix up the coil inputs because the connectors are the same. If I get a chance later today I will give you the wire colors for the different cylinders. Number one cylinder on the left side is the plug on the rear, 2 is the plug on the front...

[dingy]

Yes it is possible to mix up the coil inputs because the connectors are the same. If I get a chance later today I will give you the wire colors for the different cylinders. Number one cylinder on the left side is the plug on the rear, 2 is the plug on the front...

 

 

The bike should still start with any TCI from 83-89.

The 83 TCI will make it run like crap, but it should still fire OK, timing advance is just skewed.

If it is an 83 TCI it will have a 26H serial # prefix.

To help check, disconnect vacuum advance hose from #2 intake, this will eliminate any advance from the TCI due to vacuum.

 

Coil wire colors at coil/harness connector.

 

White wire is # 4 R.F.

Yellow wire is # 3 R.R.

Gray wire is #2 L.F.

Orange wire is #1 L.R.

 

Gary

[Flyinfool]

Can you not check the ignition timing buy using the timing marks on the flywheel. I thought that there was a timing mark for each cylinder at TDC used for valve clearance adjustment. This is shown on page 2-5 of the service manual.

By using a timing light you could verify that each cylinder is firing at the correct time and doing so would verify that everything is plugged in correctly.

 

I'm just thinking out loud here, not sure if this is a viable idea or not.

[bongobobny]

Gary (Dingy) is correct! Just came in from the garage where I was testing Vacuum advance modules ans double checked the colors, and 1 is Or, 2 is Gray, 3 is yellow, and 4 is white. Odd number cylinders are in the back, even numbers in the front. He is also correct about the modules and how different years work. The main difference between the 84-85 and '86-89 is the fact that one is designed for the 1200cc and the other is for the 1300. The difference in the curve is so slight that it does not make a noticable difference...

 

BTW the coil primary from #2 coil feeds the tach, but in thoery it really shouldn't make any difference as the tach is just looking for the time duration between the cylinder firing to determine RPM, divided by 2 as it is a 4 cycle engine, not a 2 cycle...

[bkuhr]

Can you not check the ignition timing buy using the timing marks on the flywheel. I thought that there was a timing mark for each cylinder at TDC used for valve clearance adjustment. This is shown on page 2-5 of the service manual.

By using a timing light you could verify that each cylinder is firing at the correct time and doing so would verify that everything is plugged in correctly.

 

I'm just thinking out loud here, not sure if this is a viable idea or not.

 

I think there is only a timing mark for #1, as I scribed marks for 2-3-4 when I did mine. As I recall your start valves at #1 then count deg of rotation ( wierd #s in book but correct) for subsequent valves- and don't forget, rotation is CCW on the left side

[bongobobny]

Hey!! I just noticed the service manual lies concerning the wire colors on the pickup coils!!! They list the orange wire as the center taps but in reality it is the black wire!!!

 

 

Hmmmmm, back to square 1 with my ignition problem. Glad I noticed BEFORE I pulled my stator cover again after putting in the High Output stator before the harness incident...

[dingy]

Hey!! I just noticed the service manual lies concerning the wire colors on the pickup coils!!! They list the orange wire as the center taps but in reality it is the black wire!!!

 

But grasshopper, one needs only to look at the redrawn schematics to see this has been corrected.

 

http://www.venturerider.org/forum/showthread.php?t=42358

 

 

Gary

[bongobobny]

Yeah, but, I ain't got no computer in the garage...

[dingy]

Yeah, but, I ain't got no computer in the garage...

 

What year bike you working on?

 

Is this Goldie?

 

I'll see what I can do for you.

 

Gary

[bongobobny]

Yah, Goldie. May have found a buyer from church that also works with me, and besides I need the garage space! The '85 won't be started til next year, but I have been sort of working on it already as everything I do for Goldie I do a spare for the '85. Doing a complete frame up on that one...

Edited February 17, 2011 by bongobobny