05 Eton Viper 90, no power or bogging out

[jrns281]

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Hi Guys,

First I must say I have been reading on here and gained some valuable advice when dealing with my kids quads and it is greatly appreciated. I have an lt80 and an Eton 90. My problem is that the eton 90 just has a hard time climbing sand dunes while the lt 80 does not. I can see the eton slowly start to lose power going up the hill, ala the "little train that could" and we have to tow it up. The bike is all stock and with the excep of a Unifilter. The bike just seems to bog or run as if it was running rich but when I check the plug it is fine (rust color) and not wet or black. Being an 05, it has the dial setting CDI. Any help would be greatly appreciate by both me and my son. I don't know if the fact that my son is nearly 100 lbs has a great deal to to with it because when he uses the LT 80 he is able to climb the hills.

1. Cleaned Carb
2. Added Unifilter in stock air box
3. Changed plug
4. remove spark arrestor
5. tested compression and it is holder at 105 PSI WOT
6. checked Ignition Coil with volmeter and it was below specs, so I replaced it.

As far as it looks, the clutch housing has never been removed.

[mmsoup]

Sounds to me like you need to replace the torque spring in the Clutch

While you are at it, inspect the belt for cracks inside the teeth

Check the rollers for flat spots

Check the condition of the clutch shoes

[EthansDad]

What soup said.

[jrns281]

Greatly appreciated,

I know it must have the stock torque spring, is there a specific spring rate I should purchase and also what weight do you guys recommend for the rollers? I know there are several different weights you can get for the variator.

[chunky0071]

What soup said and 105 psi is low on those. Should be higher some where between 140 - 180 psi. Most of the time on those when the torque spring goes out it will barley pull it's self on flat ground. You can not get a stock torque spring they changed them in 07 so if you put a new one on you will have to lighten the roller weights.

[jake55]

my e-ton 90 had same issue, found out that the packing in the muffler was clogged. seems as if the oil injection was giving more oil than it could burn off and all the excess was collecting in the packing eventually choking it off. bike would idle fine and run good up to about 3/4 throttle then bog and sometimes even stall the engine. removed packing and all was good.

[EthansDad]

for roller weight spring combo - I don't know the 90s that great, and know the eton 90 even less. I'd hope someone can give you a "as close to stock" setup suggestion on spring and roller so you don't get into a CVT redesign project.

[jrns281]

Thank you all for the quick responses. I am leaning to the packing in the muffler. Also, is it possible to remove 2 of the roller weights ala the LT 80 mods to increase the revs before takeoff? The drive belt looks fine and sure trying to avoid the a whole CVT project. I also heard of a Variator mod on these? anybody done this before?

Thank you

[jerkyboy]

Its a 05 you said, has the topend ever been done (piston & ring) cause 105 is low. Also dont recomend removing just 2 of the rollers this will give you more trouble.

[mmsoup]

Only takes about 5 minutes to change a torque spring and if you need a base line for a 90 use a 1500 torque spring and 4.5 gm rollers to start. Probably wouldn't hurt to replace the clutch shoe springs in the clutch as well (The little ones, go with stiff if you want to raise the launch RPM's)

The stock 52mm kits run anywhere from 140 to 170 lbs compression when healthy and fresh depending on where the squish is set (28 - 32 thousandths is a good baseline there)

Welcome to Mini Quad Purgatory, Somewhere between Heaven and Hell and with a defined time limit.

[jrns281]

I appreicate all you suggestions Soup, should I purchase the clutch springs (1500) to match the 1500 Torque Spring?

[mmsoup]

No need to match torque spring to clutch spring and if you do a little research on the site one of the dads did a phenomenal spring comparison for torque springs. 1500 TORQUE springs are not created equal. The force range is all over the place

On a stock clutch the 1500 clutch springs will launch a little earlier than the 2000 but that is all they do, when the clutch hits a specific rpm range the shoes jump out onto the bell and that job is done

The torque spring works in conjunction with the rollers, belt angle, width and length. I haven't run a stock motor since 09 so ask around for the best belt I want to say we ran 787 16 3O.
Get a Kombat 1500 or a Max RPM 1500 and some 4gm, 5gm and 5.5gm rollers. You can mix the rollers to fine tune weights (4 and 5 together =4.5) and avoid having to buy too many different sizes

Put it all together and test in WOT 100 ft runs change weights and do again. find what works best for your application and stick with it

Curious from the other sand dads on here if CVT needs special set up for sand?