Fuel Injection ATVs

[timswi]

No, didn't really see the need...It's an option now. The 500 2-ups have that standard but at a big premium. Nice machines but I got what I needed/wanted for $6500 or so...I'm happy with it. Not into white, but I actually like this after digesting it for a while. Everyone else has some other color, none of them white.

Not mine, but it looks like the one on the left:

http://www.atv.com/gallery/gallery....g?g2_GALLERYSID=TMP_SESSION_ID_DI_NOISSES_PMT

 

[dfkrug]

I was thinking this as well. I adjust my valves once a year on my 4-wheeler and
3 times a year on my motorcycle. It definitely improves starts and idling while cold and you can burn a valve
if they get out too far.

Every year? Wow.

Note that some quads have very accessible cylinder heads and the adjustment is not a big job. Others, you
need to pull the tank and a lot of plastic, so it never gets done. Also, if a quad uses shims, instead of
screws to set the lash, then it is a LOT harder to do, but it rarely needs adjustment. Shims are on higher
performance units, however, and not generally on utility ATVs.

Since I have been working on so many ATVs lately, It is amazing that so many owners never change brake
fluid, let alone adjust valves.

(Even Hondas need oil changes.)

 

[jejeosborne]

Every year? Wow.

Note that some quads have very accessible cylinder heads and the adjustment is not a big job. Others, you
need to pull the tank and a lot of plastic, so it never gets done. Also, if a quad uses shims, instead of
screws to set the lash, then it is a LOT harder to do, but it rarely needs adjustment. Shims are on higher
performance units, however, and not generally on utility ATVs.

Since I have been working on so many ATVs lately, It is amazing that so many owners never change brake
fluid, let alone adjust valves.

(Even Hondas need oil changes.)

Yes, my wheeler requires removal of tank which is really not difficult. 2 screws. Most wheelers are set screws but my Honda motorcycle is shims which involves a little more time to adjust. I have the shim kit which eliminates a trip to the dealer. It has a 14,000 rpm redline and requires a new piston every 40 hours of use. Manual wants me to change the piston every 15 hours but I don't ride too hard all the time.

 

[WilliamBos]

All the new Polaris Prostar engines (325,570 and so on...) are dohc and have shims. Seems to be the way of the future on atv's too.

Every year? Wow.

Note that some quads have very accessible cylinder heads and the adjustment is not a big job. Others, you
need to pull the tank and a lot of plastic, so it never gets done. Also, if a quad uses shims, instead of
screws to set the lash, then it is a LOT harder to do, but it rarely needs adjustment. Shims are on higher
performance units, however, and not generally on utility ATVs.

Since I have been working on so many ATVs lately, It is amazing that so many owners never change brake
fluid, let alone adjust valves.

(Even Hondas need oil changes.)

 

[jejeosborne]

All the new Polaris Prostar engines (325,570 and so on...) are dohc and have shims. Seems to be the way of the future on atv's too.

The high performance motorcycles in the Hondas line like mine are 4 valve unicams with titanium valves. Not sure of the advantage of the unicam other than fewer moving parts and less high centered weight.

 

[PapaPerk]

Yes Sir! 455 cc Fuji with the Mikuni BST 34 carb. Love it. Next quad will be an AC XR 550, which is EFI.

I didn't know it was made by Fuji! Thanks for the info.

Mine has around 130 hours and so far so good. I've heard a lot of good things about the engine so hopefully it will last for many years.

 

[WilliamBos]

I didn't know it was made by Fuji! Thanks for the info.

Mine has around 130 hours and so far so good. I've heard a lot of good things about the engine so hopefully it will last for many years.

Yuppers, legendary cold starters. I have a service manual for my 400ho, if you want a copy, pm me your email address. the engine chapter should be the same as yours.

 

[dfkrug]

It has a 14,000 rpm redline and requires a new piston every 40 hours of use. Manual wants
me to change the piston every 15 hours but I don't ride too hard all the time.

Is that a motocross bike? FI on thumpers quite common now.

What do the piston & rings look like at changing time?

 

[jejeosborne]

Is that a motocross bike? FI on thumpers quite common now.

What do the piston & rings look like at changing time?

It is a crf250x and crf450x models. The they are very similar to the motocross bikes but geared, suspension valved and cammed for woods riding. They have a wide ratio transmission plus the magic button that this old man needs. Looking at them side by side you can only tell the difference by the x model having a kickstand basically.

Pistons show a little wear on the bottom of the skirt but the Rings are always still good. These pistons having very little skirt is why they have to be replaced so often preventing wearing the cylinder. Not much keeping them straight. Low mass is the name of this game.

 

[dfkrug]

It is a crf250x and crf450x models. The they are very similar to the motocross
bikes but geared, suspension valved and cammed for woods riding.

Wow, that IS a short skirt!

I had a CRF250r briefly, traded to me for a quad. It was before FI, however, and it was super-fast. The
'R' version puts out more power than the 'x' version, which has electric start and kickstand. The 'R'
version gets a red sticker in CA, instead of green cuz it has higher emissions. Mine was
almost unrideable since I weigh only 150 and the previous owner was 250+ and had changed the springs.

I would like to get my hands on an FI thumper.