660 grizzly

[keith660]

I have a 2006 660 with 1200km and recently the red reverse light flashes when I'm at top speed in high. Has anyone had the the same problem? I have asked 3 different yamaha dealers and they claim they never had that problem before.

[Garryese]

Flashng reverse light on Yamahas is usually only seen when reving the engine in neutral. Indicates over rev. Dealer should be able to find it in the service manual.

[keith660]

thanks, i'll see what they say. Myself, my brother, and a friend of mine all bought 660's. My brothers will do 103km, our friends will do 96km (backfires from time to time) and mine will do 107km. Do you think it's the way the carb is set up from the factory? Maybe it's faster because it's reving higher?

[Garryese]

Yes it is faster because it is reving slightly higher.

I know from when I worked at a yamaha dealer that float levels were problem in the 660 grizz. The genisis engines are touchy to fuel requirements. Float levels have to be exactly correct or they suffer from lost top end or they develope the dreaded studder on steep hills.

Quads come jetted for sea level and thus are way too fat for our elevation.

Big tires (read heavy), clutch kits, most exhaust systems, storage boxes, fairings and fender flares all reduce top speed.

Typically an out of the box 660 grizz will do 97 - 100 Kmh. Jetted properly with proper float level they will do 100 - 105.

[Garryese]

Oops, forgot to address the backfiring.

If it is backfiring when cutting the throttle at high speed or on a down hill then open the idle mixture screw 1/4 turn. Idle mixture screw is located on the bottom of the carb, just behind the intake manifold boot.

If it backfiring at high speed or under high load or while going up hill, check the float level.

If it is hard starting while cold and it backfires, then do a valve set.

If none of these helps the problem then check for air leaks in the exhaust system.

[keith660]

the bike only backfires when he slows down to stop or put along to talk to someone.

[keith660]

my bike is the fastest, it will go upwards of 107 km, should I adjust the carb to lower the revs, the red reverse light will usually flash when I'm going full speed. as soon as I let off on the throttle slightly it goes out. It runs great and will beat the other two bikes from take off to the finish line. It came this way from the dealer, I have not done anything to it.

[Garryese]

Keith, your friends machine likely needs the idle mixture screw turned out 1/4 of a turn. Run the warmed up machine a few times. If the backfiring continues then repeat the 1/4 turn until it quits. If the total adjustment is more than 1 turn complete turn then the pilot jet needs cleaning or the float level needs adjustment.

On yours, I would pull the spark plug and check the color of the insulator. If it is white or light grey then you are running lean, which makes more power, but too much heat. Ideal color is light brown or tan. If the insulator is black then your rich, but I would leave it alone as you are not suffering from lack of power and the rich condition will help the engine run cooler, thus avoiding the Griz 660 studdering problems.

Keep in mind that some engines just make a bit more power than others. My stock non HO Sportsman 500 beats every stock 500HO sportsman I have raced; my engine is tight where it needs to be and loose where it needs to be.

The flashing light does not put the machine in a limp mode so don't sweat it too bad if the spark plug color is good. The light indicates you are hitting the red line, but these engines can handle more than the red line if they are loaded and it is not for long period of time.

[rknight111]

Gary, your a weath of information, good to have you on this site.

[Tweaker 660]

Originally Posted by Garryese

Keith, your friends machine likely needs the idle mixture screw turned out 1/4 of a turn. Run the warmed up machine a few times. If the backfiring continues then repeat the 1/4 turn until it quits. If the total adjustment is more than 1 turn complete turn then the pilot jet needs cleaning or the float level needs adjustment.

On yours, I would pull the spark plug and check the color of the insulator. If it is white or light grey then you are running lean, which makes more power, but too much heat. Ideal color is light brown or tan. If the insulator is black then your rich, but I would leave it alone as you are not suffering from lack of power and the rich condition will help the engine run cooler, thus avoiding the Griz 660 studdering problems.

Keep in mind that some engines just make a bit more power than others. My stock non HO Sportsman 500 beats every stock 500HO sportsman I have raced; my engine is tight where it needs to be and loose where it needs to be.

The flashing light does not put the machine in a limp mode so don't sweat it too bad if the spark plug color is good. The light indicates you are hitting the red line, but these engines can handle more than the red line if they are loaded and it is not for long period of time.

Hey Garryese. You sound like the man i need to talk to. I have a 2004 Grizz with a bog I cannot get rid of. I had the 686 kit put in and the head ported and took it to have it Dyno jetted after to have it jetted right. After this it still has a bog. In high gear it bogs at 17kmph - 19 and if you go through this point slowly before you hit the throttle your fine but if you hit it it bogs. In mud it is almost immpossible to run in high because i need to keep it spinning above these speeds. In low the bog is at like 5 kmph but same if i am easy on the throttle and get past this there is lots of power. I talked to the dyno jet guy and we originally thought I could be alittle rich so I dropped the needle 1 and it got worse so I went 1 slot richer and it is better again but still there. I could go richer but when Look at my plug it is already black. I have done alot of the heat related fixs (wrapped my pipe, Engine ice, vented panels etc.) Just wondreing what you might think. Sorry this is so long but this is two years in the works. ?

[Garryese]

Tweaker, sounds like you have a nightmare that I cringe at when I have it in the shop. We will get through this, but it will take some time (but not two years) and I need alot more info.

The carb can handle the 686 kit with minor jetting changes. Depending on who ported the intake ports (or how well it was done) may or may not require further jetting changes.

Did you install the 686 kit and dyno-jet kit, and have the head ported all at the same time? Or, was the engine tuned with each step?

When (at what step above) did this problem start?

So I now we are taking about the same problem is your engine:

• Bogging: Loss of engine power without a miss. Engine runs smooth, just not making power.
• Stumbling: Engine cuts out like it is going to quit and then recovers either by itself or because you change throttle position.
• Studdering: Engine misses, recovers, then misses, and then recovers with the throttle in a fixed position.

What throttle position works (Idle, 1/4, 1/2, 3/4, WOT) to get through the problem?

What throttle position cause the worse problem?

Do you have the dynojet kit with all the spare and OEM parts?

Which main jet is installed now?

What is the idle mixture screw set to?

Is the air box lid installed or has the air box intake been modified in any way?

Was the diaphram spring changed to the dynojet spring?

Was the dynojet needle installed?

What slot is the clip in, on the needle? Slot 1 is the top one (fat end).

Has the needle jet ever been change?

**Can you pull the needle out, remove all parts from the needle (except the clip) and lay them out in the same order they came off in and then post a close up picture? Is this order of parts the same as it was orginally set up (refer to the dynojet instructions)?

Do you have a good place to do several cutoff tests if needed.

**Do you know for sure the float level is right (04's are really inconsistant)? Best way to check is to attach a small clear fuel line to the carb drain nipple, open the drain screw with fuel petcock on and with the clear line held up along side the carb. The fuel level should be exactly at the gasket surface between the float bowl and the carb body.

Do you need the choke on to start the engine cold?

When the engine is warm and no throttle (or choke) applied does the engine start immediately?

My gut feeling from what you described is you have a two problems: Rich on the needle and lean on the main jet. The two items marked with ** above are the usual problems that cause a rich/lean or lean/rich condition.

[Tweaker 660]

Hey Garry Thanks for taking the time to look at my problem greatly appreciated. Heres a little more info for you. This problem has been there since i bought just over two years ago but was very minor originally (stock). Seemed like the more performance I did the worse it got,Understandable but I thought the dyno and dynojet guy would get it. I originally thought it was a heat issue or the common grizzly steam issue but I am quite sure it is just jetting now. I will tell you what I know for sure now and will be pulling the carb again soon and will give you the rest then.
The guy who did the big bore and porting I picked from a refferal and experience. He seemed really knowlagable and charted proof of his work (airflow charts).He has been building race car and bike engines for years so I think it was done well. Also installed a Mudbuster cam from hot cams at the same time. As for the jetting it was done by a dynojet dealer after all this was done.
Now to get on the same page for the problem:With your description of bogging I would say that is not what I have because it makes power just not at the certain speeds I described. I would say it is a stumble as it will fix itself as long as I don't give it more throttle and if it does not I slowly back off throttle until it stumbles through the problem and as soon as the engine revs back up I can go to full throttle and it will take off. But if I go to full or lots of throttle before or during the problem point it will stumble loose all power and it sound like it does when you hit the reverse govenor. So for your next question about which throttle position get me through the problem I usually have to back off to 1/4 throttle or less and then slowly give it throttle till the engine picks up(very hard to do if already in mud). and like I said once the engine revs up past this spot I can hammer on it and it rips good as long as I can keep momentum up. The throttle position that causes the problem is from a stand still if you try to go wde open. Of course the more loaded down the wose it is. If I am just on gravel in high 2wd it will usually just stumble through it and go but if I try this in high in mud 4wd it will stumble and not recover without letting off.
I do not have the dynojet kit with all the spare and oem but will buy a kit if needed. Jet and idle screw settings and if the dynojet needle was installed,I will get to you ASAP. Airbox lid- Originally the dynojet dealer talked me into putting a extra inlet in the airbox throat but I should have known better as I don't avoid many water hole and filled my airbox with water. So I am back to stock. Just my theory but I do not believe this airbox is as restictive as some may think since the gains I saw on the Airflow charts was all through the airbox. I think the gains some people and finding by putting hole in there lid is just because they are originally fat and would be better of just jetting. Does this sound close to you?
Diaphram spring was modified when it was being dynoed. Cut some of the spring off to get rid of a lag that he saw right off the bat. The clip on the needle after being dynoed was on the fourth psiton with a shim under. Originally thought it was still rich so I dropped the needle half a notch ( went up to th third position but with no shim under. This made it worse basically unridable in high. Now at 5th psition with a shim under.
By cutoff checks do you mean plug checks. I do have somewhere I could do this. How do you rcommend doing it and do you need new plug for every test?
Choke on to start a cold engine YES
Engine does not star immediatly when engine is warm unless you touch the throttle.
Okay I will check the float height as you described Then check the carb for your other questions. Thanks again for your time!!