hst hesitating

zenchal26

Member
No one has an ideas why the hst is hesitating on my 2016 x1100c??? like i said push the pedal down (doesnt matter if its a 1/4" or all the way down) it takes a second for the trans to move the wheels? Is there a relief valve that controls this?? Charge pressure??? Any pics where this is located??? this is not normal operation my 04 did not have this issue and neither do the new ones at the dealer. Any help would be great
 

aurthuritis

Well-known member
Site Supporter
when you push the peddle and the hst speed lever moves it allows oil under pressure to activate the servo piston. the servo piston is what actually moves the swash plate not the speed lever. so yes you may have a charge or high pressure problem or an internal leak. do you have a shop manual?
 

hondajoe

Member
hydro problems

I should of posted a reply you should ck your pressure relief valve to make sure it is not stuck or adjusted wrong it should come all the way out.Now if you have a hand throttle crank it up about half way up then pull it in gear it should have power instantly that would mean you don't have the pressure at idle.JOE
 

Lee1935

Active member
Kubota changed X900 transmission pressure specs the spring of 2017, good chance they did the same for all of their side by sides
 

Lee1935

Active member
did they raise the pressure or lower it?:a1:

Raised, don't remember how much but it was quite a lot, have to stop at the dealer in the next week or so and ask. A kubota rep spent two days with them but then they are a rather large equipment dealer
 

zenchal26

Member
So in theory if I can climb steep hills and get 24-26 mph the high pressure valve should be ok and I should be looking at the charge valve correct?
 

aurthuritis

Well-known member
Site Supporter
So in theory if I can climb steep hills and get 24-26 mph the high pressure valve should be ok and I should be looking at the charge valve correct?

probably not. your problem is probably involved in the control valves that send oil to the servo piston befor it can move the swash plate. if your charge pressure was weak i don't think you would have power. it could be your charge pump though.
 

Maine

Member
There are two hydraulic pumps and circuts in the RTV-X HST. One is the swash plate pump which pumps the fluid which drives the swash plate motor which drives the wheels. The other is a gear pump which provides pressure to control the swash plate of the swash plate pump. Which one does "charge pressure" refer to?
 

aurthuritis

Well-known member
Site Supporter
there is a gear pump that puts up aprox 100 psi "i think". this charge pressure is what fills the high pressure pumps and operates some but not all of the controls servos etc. there is also a high pressure bleed of circuit that is used to buffer the servo solenoid and some other things. if you have the book it is all in there. if the charge pressure is low there can be cavitation occur in the high pressure positive displacement pump and motor. think about what i just said "positive displacement" once the oil is pumped it is exchanged directly to the corresponding "positive displacement" motor. there is no room for error or something gets bent. the high pressure relief valve is the safety to prevent failure. a misconception is if you turn up the pressure you will make it go faster.
 

Maine

Member
I'm away from my WSM for a few days. I'll have a look at the hydraulic flow diagrams when I get back. I remember that the gear pump supplies fluid for the swash pump control circuit.
 

Lee1935

Active member
Valves or values were changed? What are the new numbers?
at 83 my memory is not worth squat ☺, when I took my X900 in for it's 1st checkup, a factory rep had spent a days at the dealers working with their head mechanic. The manager told me they were adjusting up to the new standards, at that time this was all over my head (still is) my 900 today isn't no race horse but with the wind shield it will peg the meter at 26 mph. more importantly it will handle the hills on my place in BC. I would highly recommend that anyone who works their machine to install the hand throttle and learn how to use it☺
 

zenchal26

Member
Ok so I found out why it was hesitating. Apparently these newer rtvs use the hydraulic system in conjunction with the transmission fluid. I did a full service on this machine when I got it, drained and refilled hyd tank cycled the hydros and rechecked the fluid before changing the transmission fluid. Well I guess after changing the transmission fluid and starting to recheck the trans fluid after initial fill it pulled fluid from hydro tank. The tank was about a gallon low. I went to drive with the bed up and noticed that it took even longer to move than normal then it dawned on me. Filled tank all is well
 
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