Ever feel like you met your match??

[DGXSER]

OK, so it almost HAS to be some type of vacuum leak.

So far today, I put it all back together starting with the valve cover. That "Right Stuff" gasket in a can stuff is the wrong stuff for me. I found it hard to control the size of the bead, and also hard to control period. I much prefer the tube of RTV.

Anyway, after that I checked float heights, right on spec all across the board. Loaded the carbs back in, got the air box put back together, fired it up on full choke it sounds almost good, part choke still sounds better, no choke it sputters. Granted the engine is cold still, so I put it back at half choke, synch again just to be sure. No change.

Now, I am thinking it must be electrical, so I check no 1 again with the colortune, very intermittent combustion, but spark is there. So I check number four, fires well all the time, good combustion. So, I swap plug wires from 1 - 4. Problem stays on no 1. So, not electrical.

Carb was working great, been cleaned like it has never been cleaned before, yet, has to be a fuel related issue. Gets marginally better with half choke. Staring at no 1 and I see a sign. There is a crack in no 1 carb boot, right where the boot meets up with the head flange of the boot. And the crack looks a little wet. Sooo..it almost has to be a vacuum leak right there. Now the interesting part is that I intentionally sprayed this with carb cleaner and got no improvement. I pulled the boot off the head, look inside, no sign what-so-ever of this crack. Maybe , just maybe a sign of the area around the vacuum tube being a little overly mushroomed where it penetrates the boot. So I now have the crack gooped up and over with RTV. Will install the carbs again and see if this helps it at all. If so, new boots will be on order.

[natemoen]

Also it is like with any combustable material, you need the proper fuel/air ratio to burn. If you cram a buck of highly combustable carb cleaner into a cylinder and it doesn't have enough air, it won't burn.

[ddragon63]

TC,

A good carb cleaner ie Gum-out, Berrymans, and seafoam will bog the motor when fogged. they're are flammable, but when saturated in a concentrated area they are very heavy and burn slow. this is why people fog they're motors with them. cleans out all the unwanted carbon as the motor works to try and burn it all out of the combustion area.

[TopCatGr58]

I'm with Greg on this one. It's firing, but has nothing to fire. Carbs are clean, no obstruction to fuel flow as far as you can see/determine. Pilot circuit open, new pilot screw, pilot jet clear, so it's down to vacuum being able to pull fuel into carb. The valve clearances are okay, compression a little low, but same across all, and the other 3 work, so #1 should.

Intake boot has external cracks, but has been checked and is intact internally. You're able to synch the carbs but that's been done before WITH a vacuum leak. Other sources are mating surface of boot to engine, the synch port cap/tube, the carb's butterfly shaft seals, I think I remember something about the seals of the choke/enrichener plunger even!

I've been surprised at the comments about the combustability of carb cleaner? When I've used it years ago on a carbed car, it would cause the car to NOT run well, I would even have to rev the engine while spraying it into the carb throat and such and even then it could kill the engine if I sprayed too heavily. I was using GUMOUT brand back then. SO..I'm just curious about the comments about it "helping" to diagnose a lack of fuel flow by firing the non-firing cylinder when sprayed. Perhaps the carb cleaner formulas have been changed, don't know? Guess I'll get out my can of cleaner and test it on my bike to see if it actually causes it to REV vs. bog?

T.C.

[DGXSER]

I have a set of the Honda VF1000 coils, but the ones on the bike are stock. I needed new wires for the Honda coils. The colortune looked like it was sparking well, but only got combustion every so often and that looked bright yellow.

I am going to try swapping out pick-up coils tomorrow. I have the ones from the wrecked bike which were working fine. After that, I will get new wires for the Honda coils and try those.

[bikerphil]

Don... Didn't you do a coil mod of some kind, with Honda coils or something? Maybe one is weak and not firing properly, you did say the colortune wouldn't fire properly? JAT

[DCII]

Cracked Coil?

Don if that coil has a crack in it I think I would change that out with one of the units off the old bike if you still have them. If you need a coil let me know I am pretty sure I have a couple spare sets in the office. Have you ruled out any possible issue with intake boot or a vacuum line?

[BA80]

Try what I suggested with the carb cleaner Don. Just takes a minute.

I still think your chasing a carb problem in the elactrical system.

[bikerphil]

I do need to check the battery, but I had 14.5 volts at the coils red/white with key on bike not running.

That seems a little high, maybe battery is shorted.

[DGXSER]

Stole soem time this morning. I can confirm the valve clearances are all within spec. Most are on the loose side of spec. I do need to check the battery, but I had 14.5 volts at the coils red/white with key on bike not running.

[ddragon63]

food for thought... if there was build up (carbon or such) on the valves from PO and sitting and you adjusted valve. You could have easily cleared this build up now and the valves have tightened on the head causing the clearance between the cam and shim too get too tight in a hurry. Like I said food for thought.

[DGXSER]

NExt chance I get to work on it, probably Sunday, I may pop the valve cover and see what is going on. I know I re-shimmed the valves not overly long ago, like within the last 4-5k miles since that is all it has on it since I got the bike. And I know I put the gap to the wider end of spec if not a hair over spec.

When I started it and had to hold the choke open, that is what you get when you reassemble and put the ball in before you check for a spring in there, I could feel the popping backfiring through the carb body a couple times.

[ddragon63]

I had a similar problem started end of last year on Old Man. Decided to check the valves... all of my intakes were tight, all my exhaust valves were good, #4 was off alot from the rest. it popped a little @ idle and ran like a car with a flat cam till over 3500 and then ran fine... hotter it got, worse it got. JAT

Here the map of what I found when i popped mine open. as you can see the intakes were all a little tight. #3 was the worst... an #4 needed it on both ends. Before doing this my compression was pretty close except #4 and all seemed low #1-3 were 130's and #4 was 110ish (it was too many beers ago to remember, I need to write this stuff down ). I was expecting to do a ring job soon. After valves we are 167 to 173 on all 4... it may just be that simple my friend

[DGXSER]

OK, so, there are no carbs even fresh off the factory line cleaner than mine are now. Between pull them apart, using the USC, carb spray and compressed air, there is no place anything could be hiding. Unfortunately, the only thing accomplished is that I reminded myself what a total PITA that little flippin ball bearing can be to get into place. And it is a good thing they give you the extra one on the no 4 end.

I went through the coils, all caps are right at 5k ohms, coils are right about 12k ohms. And one has a crack in the outer casing. So now I know why the bike is such a PITA to get restarted after a trip to the car wash, but has no issues in the rain.

So, I seem to be down to electrical or a valve issue. Maybe, perhaps the cam chain is THAT worn and a cam skipped a tooth, but then it would seem like it would effect more than one cylinder.

Well, tomorrow is daughters HS graduation, so the bike will wait yet again.

[DGXSER]

Got the bike two years ago in very poor condition and had sat for years in a barn or field. Compression was worse then. Never really bothered to recheck till now. Improved about 20 and evened out. So the lower than spec compression is not as suspect as it may seem. Originally improved with oil which is indicative of rings, thought they might reseat with use. Not as much as hoped.