Tree Trimmer

can some tell me the center to center, deflection, and off set of the clutches, along with the correct belt number?

__________________
99 zrt 800

yamadad4

center to center on the sheaves is apprx 268.5mm or about 10 5/8".

the offset is apprx 15mm, or just over 1/2" but not quite 5/8".(9/16).

running a stock 8CH belt, your deflection would be set to where the belt rides just below the top of the secondary sheave, no more than 2mm below.

i found converting that sled over to the 8DN belts made a world of difference. you need to make a few clutch changes to accomodate.

if you unsure on how to set the belt deflection, let me know.

Tree Trimmer

how similar to the cat clutches are these yama's?

i got cats figured out.

this yama is my buddies sled, and he has finally decided he's done screwing with it, i have a lot of time tweaking mine, and he rode it last year, and is finally goin to let me help him set it up.

the sled in general, that is. he has the front and rear suspension so whack, it rides like chit and dont transfer weight for crap, the clutches are, for lack of a better term, just flat out "wrong", and carbs out of sync from him monkeying with them.

also, what is a good clutch combo, primary spring, secondary spring, weights, and helix, for this thing. where is the engagement rpm supposed to be, and it only has a can, no aftermarket pipe, so what is the max rpm supposed to be. i dont know what this thing is supposed to turn rpm wise.

also need a general gear combo for it as well. he rides with alot of us big bore cats. 8-900's trips and twins. if we want to say there is a balanced combo thats good out of the hole with good top end, he wants to sacrifice a tad of top for some bottom. we'll dial it in from there, just looking for a place to start.

and im very interested in learning about your 8DN conversion as well, as i already have to un-cluster*^* his clutches.

iirc he has it engaging around 38-3900, winding up to around 79-8200. how far off is he?

__________________
99 zrt 800

yamadad4

whole new ball game with the cat vs yam clutches but basics still apply. more on that when needed.

your not far off on the rpms, apprx 4000 engagement and full shift at 8300.

perhaps a safe place to start would be to figure out what you have to work with as far as whats in the clutches now as well as gearing in the chaincase. also, what elevation are you running?

things that will help me help you would be knowing the following:
primary spring color
cam arm number and rivet configuration(sometimes its hard to determine what rivets, pics would be good for this)
secondary spring color
helix angle(derived by the stamping number)
helix set angle(which hole is the spring in on the sheave and helix)
existing gear ratio(chaincase cover needs to come off)
current belt number

we can take it from there. there are a few other engine mods that can wake this sled up as well and they are basically free.

Tree Trimmer

fair enough.

when i get him to get it out of storage, i will definitely post up here.

im hoping to have my hands on it in the next few weeks.

just trying to learn about this thing in the mean time, so when the time comes to actually work on it, im not learning then, when i could have already learned.......stuff.

so far, your my new bestest friend.

thanks.

__________________
99 zrt 800

yamadad4

heres some basics to consider comcerning both clutches:

on the primary theres 3 cam arms, 3 rollers, and a spring with specific color, not unlike cats. rollers are available in different diameters and affect belt grab as well as shift out.
on the cam arms there are holes for rivets. there are several different rivets, about 6 off the top of my head. similar to your ac experience, the weight of the arms controls several functions. in addition, yamaha uses different profiles on the arms to make things even more confusing.

on the secondary, spring color, helix angle and degree setting on helix all affect the end result. you will see on the sheave 3 holes numbered 1,2 and 3. on the helix you will find 4 holes. 9, 6, 0, and 3. taking any combination between helix and sheave holes, add together, multiply by 10, and that will be the wrap angle. for instance if your in the 6 hole on the helix and the 1 hole on the sheave, 6+1=7x10=70. the higher the number on the angle, the slower the backshift and quicker the upshift.

theres some basic clutching yamaha style, if you want to bone up with knowledge beforehand, ask away, i will do the best i can.

Tree Trimmer

thats a awful lot of......messing around, to figure out some clutches.

suspension. are they fully rebuildable like my ac's? the front look like cheap throw aways, and the rear skid is supposed to be out of a srx, somewhere around 00-02, he thinks. we already know we need to freshen up the suspension, its pretty tired, so whats rebuildable and whats just replace? shocks wise. i got the rest.

also, is it worthwhile to add a grease zerk to the trailing arm "bushings" or is that a they will bend and need replaced before they wear out kind of thing.

how much travel is supposed to be in the front? and was the skid change a worthwhile thing? or was it just a change from one skid to the same skid just in a different model sled?

low compression still in the 100-110psi range?

in the arctic cats, on older stuff, we can do the aglt, to widen up the front end. is there a yamaha version of this? mine rides like it on rails, and he liked that. just wondering if we can do something to his as well. also looking for more travel up front to, though with the trailing arm, i dont know if its possible. imo, trailing arms are such a pita. dual a-arms ftw.

__________________
99 zrt 800

yamadad4

you just need to know what you have in there for a baseline. simplistic really once you see it. you can do most all with the clutch on the sled if you dont have a puller. secondary comes right off.

all shocks on that sled should be reubuildable unless someone has changed them out. easy confirmation: if they are aluminum bodied with threaded adjusters, they are rebuildable.

the arms have a zirk at the spindle head. no advantage gained adding one if your referring to where it bolts to the tunnel/footboard. that fitting is basically a rubber grommet with a steel sleeve and its pressed in.

the sx would have had about 7" travel on the front and maybe 8"-9" in the rear. it was designed to be low slung and it should rail the trails. ski stance should be around 41". if your still running the stock steel skis with the plastic skins, that part of the problem, along with an ill adjusted skid.

not much was gained by the skid swap except the 98 and up skids had stronger rails as well as some bump stops added.

ski stance, travel up front as well as the rear can be increased at a cost. basically it comes down to adding parts from different yamaha sleds. used parts are normally readily available.

compression wouldnt be a concern at this point in my opinion. depending on procedure, equipment, and mileage. 100 would be on the low side and may raise an eyebrow.

Tree Trimmer

any problem areas on this sled, that i should be aware of, when were disassembling to lube, maintenance, check things out.

and you had mentioned earlier about simple things relatively cheap that will wake this thing up.....

and do you have a manual for this sled? it would be worth the $12.50, if its still that cost.

i got a disk for my zrt elsewhere, and just printed it, and put it into a big 3 ring binder. lets me flip through it in the shop, and not have to get my laptop all greasy.

__________________
99 zrt 800

yamadad4

couple of things to keep an eye out for and in no particular order:

bolts securing the recoil pulley. had them back out before and it makes a mess out of the ignition.
heat cracks on the primary clutch along with condition of the wear components on both clutches.

from there one would assume any warranty issues would have been covered. there were some running issues but no way to tell this time of year. more on that if needed.

besides a gear swap in the primary(dropping one tooth on the upper), using a mtn max head gasket or pealing a layer or two off the stock head gasket bumps the compression considerably. proper clutch and carb tuning after this mod is a must, as is running quality fuel. pump gas is still good to go, you just need a minimum 91 or 92. a shot of octane booster is cheap insurance.

some airbox mods along with a silencer mod flows well and you more than likely will have to rejet. typically just the pilots.

i do have literature on this sled available in a cd format. (politically correct wording for legality purposes)

Tree Trimmer

hmmm, that reminds me. he had the primary explode on him about 85 mph last year, and he got a replacement.

how do find out just what he replaced it with. is there markings to distinguish the various models? the guy he got it from, said it would work, and he didnt ask farther. i ripped his butt when he got back with it, and ever since its just, like i said earlier, wrong.

is it possible to have a "non-matched set" of clutches on a yama? that was a concern he voiced today when i talked to him for a bit. that and he used the word, "adjustable weights?" something about you cut off the end to get a different weight or something?

__________________
99 zrt 800

yamadad4

as long as the replacement clutch was from 96 or newer yamaha sleds, your good to go. no issue with mixing and matching. yamaha ran the same primary and still does, differences are in the weights, rollers, and spring. not like other manufacturers that ran different clutches for different models.

you may be ahead of the game with the adjustable weights, depending on what they are. there are a few aftermarkets out there that make tuning much easier than drilling and peening rivets. the good ones used threaded bolts.

on the fixed sheave of the primary(if you happen to remove the clutch) theres a part number cast into it. same for the clutch cover on the underside. the 97 used a short style cover and most 98 and up used a tall cover. springs are different between the two.

you just need to dig in and see what you got. curious to know. mixing covers and springs will cause performance issues.