650 V TWIN valve adjustment

[wedooit]

Monday night, our 2006, arctic crap, atv, that the mrs drives, and uses around the property, wouldn't start yesterday. OK, time for surgery, find all the metric tools,remove lots of plastics, including airbox. Look for fuel filter. Found fuel filter, somewhat plugged. Pulled plugs (back cyl was difficult). Got on the net to see what spec plugs needed and oil filter, and oil, etc. Trip to oh oh oh some guy by the name of reilly. My daughter was singing the jingle, and laughing. While searching for a fuel filter, THEY HAVE A SECTION FOR SMALL ENGINE AND THE FUEL FILTER THAT DAN SUGGESTED for the china syndrome, they also have. Had to stop at building supply store for the mrs, lets build something together as they say. Back on task, installed fuel filter. Had a hard time starting. Got it running, awww, oh no, a little backfire. Probably why not cold starting. Time for another valve adjustment! Twin cylinder, 4 covers. Back to the net to get specs. MUCH MORE COMPLICATED than the china syndrome! Tuesday, am, valve adjustment time! Ill post my find.

[OneLeggedRider]

I don't wanna do any brand bashing because I personally haven't owned an Artic Cat.. But cousin Neil had a 4x4 and I think it was a 400 or 450, can't remember. Anyways after just 2 years of ownership he hated that thing. Said it needed constant maintenance and repair, and anytime he took it out of the yard or got it muddy it would need a new axle joint. He ended up trading it for a Suzuki 4x4 King Quad that he liked alot better.

[wedooit]

Had to take almost all the plastic off to get to the valve covers. Pulled covers off valves, tried to reset clearance. Of course, intake, too tight, specs are.....005. Exhaust .008. Cheater glasses on, light, fumbling fingers, cussing, 3 hours later, plus 2 hours to take the plastics off....set as best as I could. Starts right up, but a little backfire thru carbs. Am going to do the procedure again, and recheck. Going to have one of the young sons of my neighbor mechanic/fireman, assist, the dude with the fumbling fingers. My dexterity in my right hand has not come back completely, and may never will. But I wont give up.

This engine is Kawasaki, and found in the same mfg wheelers. Strong engine, sounds awesome. Three to five years, maybe, and then the chassis need tons of work. We have had several of these, as years ago, we were fans of arctic crap. Tons and tons of problems with them. (got tired of the problems with their sleds, converted to the Doo's) Maybe I shouldn't bash this brand, as maybe all brands have the same issues. Taking off all the plastics to do carb and valve work is silly. I can list what needs to be done to this machine, but would take a lot of room, and boring. HOWEVER we have drawn for an elk hunt, so I ll fix it and quit cussing!!!

[wedooit]

Slap slap me!!! Dan and Frank.....come on guys....don't wear any gloves!

Went thru the entire valve adjustment process AGAIN, double checking and triple checking. I have it right. I had a young fellow with better eyessight check me....BUT a little backfire thru carbs and out exhaust. Still wont wrap up. SLAP!!!!!

MISTEAK MISTAKE SLAP SLAP ME!!!!!

My mistake....I put the airbox and filter back on to set it outside to keep dirt out.

SLAP!!!! now it wraps up, no backfire. I should be SLAPPED, and known better. Runs and starts beautifully!!!!!

Valves needed adjusting tho!!!!

[wedooit]

The carb on this engine is complicated, and not sure of the "why" in its design. Maybe other twin motorcycles use the same carb concept, I don't know. There is a secondary, looks like a vac device above throttle shaft, and again, I don't know the "why" of that. A couple of years ago, I had it apart and cleaned it.

Since we quit using ethanol fuel in all engines, we have had less carb problems.

Years ago, on the double cyl and triple cyl sleds, there was a carb for each cyl. always mikuni…(still to this day, I guess)In fact I have my syncro carb tool. I don't remember in my old age how to use it. Ill explain carb synchronization to my daughter, and she will reply "is this going to be a bad dad joke?"

BUT WAIT!!!! We have a 700, fuel injected, arctic crap that wont start, (and a broken axle shaft)taking up shop space for at least 11 months. Hangar queen! Start with valve adjustment as I don't think I have adjusted it, prior. Then onto an injector, or maybe the fuel pump shot craps.

[Megadan]

My mistake....I put the airbox and filter back on to set it outside to keep dirt out.

SLAP!!!! now it wraps up, no backfire. I should be SLAPPED, and known better. Runs and starts beautifully!!!!!



I was reading through, and before I got to this point my first thought was, "sounds like CV Carbs misbehaving due to incorrect vacuum signal." Yep.

Some are more sensitive to it than others, but my GL1000 taught me this lesson very well. Without the resistance from the airbox and filter the carbs will not fuel correctly, often going very lean, then rich, then lean - resulting in both backfiring and after firing as well as crap idle and terrible throttle response. They are tuned around the entire intake system and the vacuum differential between the airbox and ports.

CV carbs are great for being much more tolerant to changes in atmospheric conditions, but very intolerant to the delicate balance of how they are tuned to the motor and the entire intake system. Standard slide carbs are used for performance applications for that very reason, they are easier to tune, but less forgiving to atmospheric changes.

As far as the EFI 700. Definitely do the valve adjustment. Before you get too involved start with the simple stuff. Clean power and ground connections, clean harness connectors. Verify spark, fuel pressure, etc. 9 times out of 10 an EFI bike failing to start is a very simple stupid issue. Make sure that the ECU start signals are all there - i.e. some systems require seeing oil pressure before they will trigger fuel and/or spark. That exact problem allowed me to flip a bike that I bought for $400 and sell it for $3000 - all for a $40 pressure switch and some fresh fluids and time cleaning/polishing.

[wedooit]

Thanks master Dan! We have had a lot of trouble with fuel pumps on efi atvs, as well. I will check valve adjustment, then onto your suggestions. Many thanks for carb info!

[Megadan]

Thanks master Dan! We have had a lot of trouble with fuel pumps on efi atvs, as well. I will check valve adjustment, then onto your suggestions. Many thanks for carb info!

very well could be a fuel pump. Those are easy enough to diagnose. My intent was basically to just remind you of the KISS approach to diagnosis. I have seen too many people tear into motors and sink hundreds of dollars into problems like this for me to come by, play with the wiring harness or trace the issue back to a switch or relay and fix it for essentially free, or with a cheap part.

[wedooit]

Finally got this back together! Runs sweet, valves NEEDED adjusting. Installed new tires and shock bushings. Needs upper ball joints. Sure love the sound of that engine! The mrs is ecstatic that her wheeler is running!!!

My thanks to Dan for the carb update. Next is a 700EFI taking up space in my shop, wont start. I am sure valves need adjusting as well, new battery, and has a rear broken axle shaft.

KISS approach from Dan.

[wedooit]

Now going to tackle the 700efi so I can have a wheeler to hunt with. Got it all apart, and will check the valves first. Quite sure that is a problem!!!!

Then fuel. The efi, arctic crap, 700 has an electrical fuel pump in the tank that is a big problem.

I quote Dan...

"As far as the EFI 700. Definitely do the valve adjustment. Before you get too involved start with the simple stuff. Clean power and ground connections, clean harness connectors. Verify spark, fuel pressure, etc. 9 times out of 10 an EFI bike failing to start is a very simple stupid issue. Make sure that the ECU start signals are all there - i.e. some systems require seeing oil pressure before they will trigger fuel and/or spark. That exact problem allowed me to flip a bike that I bought for $400 and sell it for $3000 - all for a $40 pressure switch and some fresh fluids and time cleaning/polishing."

[wedooit]

Update on the 650 vtwin...
Great hard working machine, ran beautiful....valves all adjusted, lot of suspension parts...WORKED GREAT ALL SUMMER....NOW A VALVE PROBLEM!!!

I am thinking to pull the engine out and take it apart, see what happened. I cant find a good used engine, or good used, well priced quad with a 650. All the used quads in our area are 2000 to 2500 overpriced.