660 grizzly

[Murminator]

I'm going to tag on, Tweaker mine grizz does the exact same it stumbles in the mud in reverse there is no throttle it stutters like its bouncing off the limiter just by touching the throttle sometimes even after it is out of the mud you have to keep "burping" the flipper so it will "catch" then it's good lots of power it has always done that it sure is a PITA. I always thought of bypassing the limiter and put it on a toggle switch so i can have the reverse light but I just haven't yet, just to see if it would help. I choke it when it's cold but it seems to do nothing always got to be on the gas until it warms up then it will idle by it's self all day long.
Oh and mine is bone stock engine wise

[BIGFOOT]

Have not had much to do w/Yamaha....On that 2004, Do they have a electronic throttle positioner & I am guessing mikuni slide carb ? I had a similar problem on a different brand. I fixed, But don't want to go off in wrong direction until I find out answer to my question.

[Garryese]

Originally Posted by BIGFOOT

Have not had much to do w/Yamaha....On that 2004, Do they have a electronic throttle positioner & I am guessing mikuni slide carb ? I had a similar problem on a different brand. I fixed, But don't want to go off in wrong direction until I find out answer to my question.

No throttle position sensor on the grizz 660. No ETC like polaris.

Mikuni slide with an unsealed idle mixture and replacable enriching jet.

[Garryese]

Originally Posted by Murminator

I'm going to tag on, Tweaker mine grizz does the exact same it stumbles in the mud in reverse there is no throttle it stutters like its bouncing off the limiter just by touching the throttle sometimes even after it is out of the mud you have to keep "burping" the flipper so it will "catch" then it's good lots of power it has always done that it sure is a PITA. I always thought of bypassing the limiter and put it on a toggle switch so i can have the reverse light but I just haven't yet, just to see if it would help. I choke it when it's cold but it seems to do nothing always got to be on the gas until it warms up then it will idle by it's self all day long.
Oh and mine is bone stock engine wise

If it does this only in diff. lock then you are on the rev limiter.

[Garryese]

Tweaker, did you have a dynojet kit installed, or did you have it jetted while on a dyno, or both?

A work of advise for anyone planning on doing mods: Make sure the engine is running perfactly before doing any mods (even as simple as a slip-on pipe). Minor problems are usually magnified with mods and become much harder to find after.

The hot cams or the grizz 660 require that the centre intake valve spring be changed to an OEM rapter 660 spring as coil bind is a problem with the original spring. Was the spring changed??

It sounds like all is fine at or below 1/4 throttle, which eliminates the pilot jet and idle mixture as the source of the problem (though, some fine tuning may be required). 1/4 to 7/8 throttle are mainly controlled through the needle jet and jet needle, but float height does play a big factor. The pic of the neddle assembly and the float height check will help alot in determining the problem. A cutoff test (see below) will also help.

The air box is a big restriction of air flow. More losses there than your port job gained you. The bad part about this restriction is it is a necessary evil: These CV carbs require some air box vacuum in order to lift the diaphram properly. Some people who ride in areas with very large changes to altitude will jet their engine at the lowest elevation with duct tape across part of the intake snorkle, and then remove tape as they ride higher. So, yes large gains can be found with the air box lids but it is a slipplery slope in maintaining enough air box vacuum.

Cutting the diaphram spring (or using a lighter spring) is a common mod that helps throttle response. The dynojet kit comes with a lighter spring so cutting it more than one coil may cause a rich condition when on the needle. I believe you are lean on the needle if anything.

I still do believe you have a lean condition when on the needle, so I find your comment about the clip being on the fifth notch interesting. I work on so many different models these days my Yamaha days are slipping, but I am near positive that there should be a half-shim (if used) under the clip, a nylon bushing below the clip (or half-shim if used), followed by a thin washer at the bottom of that stack. On top of the clip there should be a wide nylon washer that holds the bottom on the diaphram spring, a small spring on to of that, and then the plastic holder on top of the small spring. The picture of the needle assembly will confirm this, but I suspect you are missing the nylon bushing and thin washer.

Cutoff Test: Warm engine up with existing spark plug. Let engine run until the cooling fan has cycled twice. Install new spark plug and go for a run at the throttle setting you are checking. This run should be atleast 1 mile with the throttle held in one position. At the end of you run and while still holding the throttle position hit the kill switch, then 1 second later hit the brakes and then release the throttle. Remove the spark plug and read the color of the insulator and note where on the electrode the heat line is.

Do a cutoff test at half throttle and at WOT. Use new plugs for each test. Post a (closeup piture) side and end view of each plug and I'll tell you what is happening with the carb/engine.

When you had this engine on the dyno, did the shop use an exhaust analyzer and/or an exhaust gas temeperture monitor?

Do you have a pipe on this machine?

[Tweaker 660]

Hey Garry first I had this machine jetted on a dyno but the machanic was a dyno-jet dealer.The center spring was changed with the cam. It sounds like you are right about the needle set up on the yammys but I will confirm this. Isn't the small washer a shim you use to get half steps if needed? I checked my float level as you expained I think it is good but I will do it again and send you pics so you can see what you think. i will see if I can find time for some cut-off tests. I also tried a colder plug as I heard this could help with a big bore. It seemed to help at the start but as soon as the bike was warm it acted the same. At the end of the last ride I did a wide open cut off and the plug looks nice I have pics I can send you. On the dyno he used a exhaust analyzer and it was running just under 13:1. And last I do have a pipe on this machine Pro-Cicuit with quiet (Quieter) Tip. Thanks again. Is there any way to post pics on this site or can I e-mail you.

[Garryese]

Tweaker, there is a shim that comes with the dynojet kit to get half steps for fine tuning. Dynojet kits expect all original spacers, washers, springs etc to be re-intalled with the new needle and half setting shims; The original setup on the needle had a very thin washer installed on the bottom. So there should be two shiney washers on there, but the half setting one may be on top of the clip (ie: not used and put there for storage).

Use the OEM plug. I know I have installed 686 kits, with the same cam, and same pipe wihout changing the plug heat range. When we get this thing running well, you can do a WOT cutoff test to get the fine tuning right and the plug heat range can be change at that time if warranted. I know the OEM plug will be a good indicator of combustion temperature.

I will assume the 13:1 is at WOT and helps confirm my lean/rich theory. Please check the main jet and let me know what size it is.

Pics can be posted with the addition options section just below where you type in your message. Click on Manage Attachements. Or email me at garryese@shaw.ca

[Murminator]

Originally Posted by Garryese

If it does this only in diff. lock then you are on the rev limiter.

Nope no diff lock on

[Garryese]

Originally Posted by Murminator

Nope no diff lock on

What year is this grizz?

You are suffering the grizzly studder problem, which comes down to one (or all) of three problems:

• The air box is sucking steam. The steam is coming from water being splashed on the hot engine and exhaust. Exhuast system can be wrapped with exhaust tape.
• High ambient temperture around the carb causing vapour lock. Remove side covers to help remove warm air around carb. If this works the vents on the side covers can be opened up more and then reinstalled.
• Lean condition which aggravates the above two items. Lean condition at mid and/or high throttle openings is most often caused from a low float level. Check the float level as mentioned in a post above.

The 660s usually idle well with the choke on until they are warmed up enough to run with out the choke; should not have to babysit it. Possibly a dirt/gummed up carb, which would aggravate the studdering in mud. Tight valve lash makes cold starts harder and causes poor idling while cold. Has the starter jet been changed?

Does the grizz have a similar studdering problem when driving up really steep hills?

[Murminator]

It's an '02 with the heat fighter kit installed it is not a steam issue forward works great it is always reverse as for heat it will do this in the winter also. Dunno if the starter jet(?) has been changed. So it must be the float and my choke does absolutly nothin you have to be on the throttle for the 1st 3-4 minutes until it's warm enough for the choke to take over then it will work
oh and no stutter on steep hills unless it's really really hot out +30 and up

[Garryese]

Originally Posted by Murminator

It's an '02 with the heat fighter kit installed it is not a steam issue forward works great it is always reverse as for heat it will do this in the winter also. Dunno if the starter jet(?) has been changed. So it must be the float and my choke does absolutly nothin you have to be on the throttle for the 1st 3-4 minutes until it's warm enough for the choke to take over then it will work
oh and no stutter on steep hills unless it's really really hot out +30 and up

02s do use a reverse rev limiter. You were on the right track; install the toggle switch.

The choke (enricher) must be plugged or the cable has a problem. Remove the carb, disassemble and soak everything that is not plastic or rubber in a parts and carb cleaner. Check the number on the starter jet; it should be between 50 and 70. Before you reinstall the choke plunger, operate the choke lever to see that the choke plunger retracts and that the cable has 1/8" of freeplay. After the carb is reassemble and before it is reinstalled, connect a fuel supply to the carb. Check the float level and adjust as required. Reinstall the carb. Ask if you need detailed directions to do any of this.

[navy]

i need some feed back on the after market c.d.i.box for an 05 grissly