Question on Secondary shifting/backshifting

sho305

So I put an all new secondary on my clone G9 with a Umax spring. It is the yamaha utility spring that is stiffer than stock. It ran the rpm a little higher than I liked at part throttle so I set it to almost no preload its in the first holes it can be. It works ok now, one might like it with more preload on the trail only riding but I ride around homes at times. So my issue is now when I spin in sand or (today found out) snow the rpm drop, like less pressure on the ramps makes it shift more. Maybe 500rpm lower then compared to when it has good traction.

I'm thinking I need to go to a stock spring with more preload that will still shift out at part throttle but not bog when spinning. Did not have this issue with stock spring on old secondary. My stock spring was really old however, I had stretched it even, so a new one may work better.

Am I right or wrong? Also plan to fit a new primary duster soon, it has the stock clutch yet but has been drilled some. But not sure why a new clutch would change it much.

BGW

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TheNewGuy

I tried many different combinations of springs and settings in the driven clutch on my B&S V-twin and on my clone carts. Both back to stock spring set at B-2. This seems to be best, for me anyway.

Ron


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DOOmsman

So my issue is now when I spin in sand or (today found out) snow the rpm drop, like less pressure on the ramps makes it shift more.
Yes, classic overshift. We would change helix's or go to a multi angle helix
to cure that on sleds
I had stretched it even,
When you stretch the spring you get back the preload at low RPM's but not
the shift rate.

sho305

These are the stock ramps, I don't think anything else is available for older yamaha. I did cut down the ramps on the old helix but only the first 1/3 or so. Then I could tow a lot better, it only worked up to 5mph or something and rpm would drop to stock. I made a jig and ground them with a fine flapper wheel to match, good enough for the cart must be but they were worn anyway. I could machine the ramps to a different angle if they are high enough, but lot of trouble and I'd be flying blind. I could even weld them up longer, again a lot of trouble.

I know less preload makes the rpm drop more at part throttle, but still run the same or very close at WOT. Don't recall having this issue on a sled did a lot of clutching on those back in the day, assume they were calibrated for better performance than a golf cart lol. When I got going maybe over 20mph in the snow it would shift back up to the higher rpm it runs on hard pack.

Yes NewGuy, thinking I should get a new stock spring which would be better than my 20yr old one (Dooms is right the rate will be worn out too), see what it does with some stock or slightly more preload and the new 94c on it. New primary will introduce more issues I am sure, but can't stand in the way of progress...lol...

It also has a cut sheave that really helps takeoff from a standstill, and the HD kevlar belt that is slightly wider that rides a little higher on the secondary.

And I want to investigate see if I can get it to shift out more get the belt out the top of the primary for less rpm at speed, not sure I can machine something or not but that is for later.

SkipBo00

you get it back home now???


Look out neighbors..... lol

pachanga90

I also use the B-2 setting with the Oppy,the rest of the secondary is bone-stock,worn sheaves too.It shifts great,can't wait to replace the sheaves someday.I have a Ez-Go primary on it,with the 200rpm higher engagement spring,stock Ez-Go Marathon 2pg belt,the combo works awesome.

bokeasmowl

I'm very new to gas carts and clutching. My driven sliding sheave has grooves wore into it. How does this hinder performance?

sho305

Yes I did, took some laps sideways in the snow around here....but as luck would have it I been sick all weekend so was only on it a few minutes. Snow all melted now but it will be back. Wanted to work on it some but laying around the house instead. I'm sure I will feel better Monday morning in time for work........after wasting a long weekend.

Its ok to have wear on the ramps but the shoes need to be good and the ramps smooth so the movement is smooth. If there are lumps in the ramps for example, that is not good at all.

Actually the 94c I have is for an ezgo lol.

pachanga90

I did find that when I'm cranking around the trails,If I throttle-jockey the motor,it keeps the clutch in high-range,and the power is more even.People ask me why I rev it like that,till they watch it run.Being sick on a long weekend sucks,get well soon!!

sho305

This will pull up rpm pretty quick and still makes good power at the lower rpm, it just should not be doing that. First found that in a sand pit I was climbing. Will try to order a spring here soon, maybe I can get working on it in the next week or two. Have to get the snows on the car first and couple other minor things before I plug up the garage with the cart.