How to adjust charge pressure on RTV 900

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razerface

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I have searched that horrible horrible workshop manual until I am blue in the face. I cannot find how to adjust the charge pressure. This is a 2011 RTV 900. Does anyone know how to do this?
 
Find the relief valve for the charge pressure remove the tamper proof cover and adjust the stem. You'll need gages and adapter. Probably though you just need plates. Always start with new filters and super udt
 
I already changed the filters and the fluid with Kubota stuff. I have the gauges and adapter in my excavator tools. I just pulled this out of a barn and bought it last week. It only has 138 hours on it. It just feels weaker and more mushy taking off than my 1100 so I wanted to turn up the charge pressure a little bit to see if that helped. The rtv900 workshop manual does not show the rear in the manual with that adjustment stem, but that adjustment stem is there on this one. This has a lock nut and is down beside the 17 mm Allen wrench cap on the rear of the transmission, behind the guard. Even though it doesn’t show in my 900 manual, it looks like the one in the 1100 manual. Use the same numbers/procedure as 1100?
 
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razerface said:
I already changed the filters and the fluid with Kubota stuff. I have the gauges and adapter in my excavator tools. I just pulled this out of a barn and bought it last week. It only has 138 hours on it. It just feels weaker and more mushy taking off than my 1100 so I wanted to turn up the charge pressure a little bit to see if that helped. The rtv900 workshop manual does not show the rear in the manual with that adjustment stem, but that adjustment stem is there on this one. This has a lock nut and is down beside the 17 mm Allen wrench cap on the rear of the transmission, behind the guard. Even though it doesn’t show in my 900 manual, it looks like the one in the 1100 manual. Use the same numbers/procedure as 1100?
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If i were you i would suspect the engine max rpm is set to low. And remember the 900 has a much smaller engine than the 1100 and it even has a small engine. The governor can be adjusted to 3800 rpm no load safely. I think the max on the hst is 4000 rpm. And you can also adjust the rack until you just begin to smoke and then back off just a skosh. Get all that done and the linkages synced and then mess with the pressure.
 
Well, I will try all that. Exactly what is “adjusting the rack”? Will the manual tell me how to adjust the governor?
 
There's a lever on the side of the injection pump. On that lever there is a low idle screw and a high idle screw that turn against a stop. Break the seal and turn the high idle screw and check with a tach until you get 3800 rpm max on a warm engine. The rack screw is under a tamper proof sleeve on the front of the injection pump. Break the sleeve and remove the acorn nut to expose the stem with a screw slot in it. Put a screwdriver in the slot and remember it's position then loosen the jamb nut and turn out the stem about a 1/4 turn then snug the jamb nut and test. Run the machine warm in all gears from idle to full throttle and keep adjusting and testing until you just begin to get a glimmer of smoke. Then turn the stem in 1/8 turn and jamb the nut. Your done. You don't need smoke but it's good to get right up to smoke and quit. You'll have more power and performance.
 
Thanks aurthuritis. That all seems pretty simple to do. I will have to find a way to read my RPMs as there’s no tack on my machine. I think I have one of those cheap portableones with a piece of reflectivetape laying around here
 
I watched that video, but mine is quite a bit different under the seats. None of that stuff comes out on mine to get to that rack screw. It looks like I’ll have to twist myself into a pretzel to get to it or completely disassemble all the plastic underneath the seat. The Kubota logo on the fender says rtv900 XT. The XT is just a regular 900 correct? I downloaded the RTV 900 manual because I had found nothing that said rtv900 XT on the list of manuals.
 
Yes that's an old video so your machine arrangement might be different but the adjustment is still relevant. A phot tach should do the trick. Also forgot to mention remove or clean the spark arrestor in the tailpipe
 
razerface said:
I have searched that horrible horrible workshop manual until I am blue in the face. I cannot find how to adjust the charge pressure. This is a 2011 RTV 900. Does anyone know how to do this?
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my shop manual on my IH-Case is same way as your manual. I would look in the user's-owners manual, thats where I find answers like that in my book.
 
I got a good look at the rack screw today. We decided it has already been adjusted correctly. The tamper proof cover is already removed. When we punch the go pedal or head up a hill, it puts out a faint black smoke. I haven’t found my tach yet to do the other adjustments but now reading on this forum, I believe the idle RPM is already adjusted up also as it seems to idle faster than my 1100. I will still be checking everything mentioned in this thread. I will be back out there tomorrow morning and start with cleaning the spark arrester. I hope to find something that will make a difference, as there is a distinct difference in the takeoff power between the 900 and my 1100 when you slam the pedal to the floor. I also think if I did not own the 1100 maybe I would’ve not questioned the 900 power band.
 
aurthuritis said:
Yes that's an old video so your machine arrangement might be different but the adjustment is still relevant. A phot tach should do the trick. Also forgot to mention remove or clean the spark arrestor in the tailpipe
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I will also apply all these adjustments to the 1100. I know the rack screw has not been touched on that machine because I bought it brand new.
 
I lost track of which 900 you're driving but I know in the older models, mashing the pedal to climb a hill is the wrong approach.
When climbing and the engine bogs down, let off the go-pedal to about 1/2 (you'll hear it power up) and an aux pump kicks in. Lots more power but at a loss for speed. It'll climb a cliff when done right. ;)
 
Don't be confused by the low idle. There is a max hi rpm set to 3600 or 3800 and a low side idle should be set at low until the machine doesn't shake like a paint mixer.
 
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