132 replies to this topic

[Stubeedoobee TT Newbie]

You can still buy some parts (complete carb, seat are available for sure)....
My investment was small. But these bikes are unique and very cool. It's up to you what you want to spend. Now that I am riding it again after many years, I can say I had forgotten how much fun they are. They are made for beach and off-road more than street.  Find new OEM parts here and check prices...
http://shop.thumpert...1973&model=2068

[AmeriRover TT Newbie]

they are hard to find....just thought i would post it

[AmeriRover TT Newbie]

On Aug 05, 2008......I bought this basket case. I finally got it to move this past weekend.....and boy did it!
My number one problem was the spark, and a dirty carb. I had to glue in a new coil wire to the coil, then cleaned the carb better. I had to steal a control cable from a push mower safety engine cut-off lever....to use as a clutch cable, I greased it and thread it through the RV90's clutch cable jacket, made some rough adjustments......wallaaa.....a working clutch! I ran it in the woods to break in the new rings for about a hour or so.....what fun. I tested it's top speed on a flat.....37 mph without tuning. Next is a new spark plug, fix the air filter, fixaflat in the rear tire, or new tube. Then beautification....

I'm running 3/4 quart 10w40 in the transmission
50:1 Premixed oil in gas tank,
Oil pump is still hooked up, with 10w40 in tank  (my oil pump is not working correctly, I want to unhook the oil line from pump to carb, and just run oil from the pump to engine case, I like the idea of mixing 50:1 for insurance)

Pictures to come.....

[lenstermania TT Newbie]

The oil tank is for holding 2 stroke motor oil not engine oil. If its still hooked up your pumping 2 kinds of oil into the cylinder. With the newer types of 2 stroke oil I would go 32 to 1. I just had mine adjusted to run this and it runs like a buzzsaw.

[AmeriRover TT Newbie]

..My oil pump is not working correctly.....so if it's getting any oil to the carb by the pump it can't be much. I have air in the lines, so it's not pumping....I will fix this soon....as for the 50:1, I will take it out and run 32:1.......better safe than sorry... thanks for your input.....

what adjustment did you just have done?

[lenstermania TT Newbie]

My carb was doing the overflow thing so I knew it needed rebuilt.I have a guy that I have been doing buisness with for years and I took it to him. I didnt want to mess with the whole rubber boot, in case thing. He said right away it was running rich but that 2 stroke oil in the 70's wasnt as good as todays stuff. He told me he would rebuild it and tune the pump for 32 to 1. He lives in a little town, Congress Az, so when I went to get it I had free reign of the desert. Boy did that thing scoot! I had it up to a smidge under 50, before I could only get about 42-43. Im thinking it had to be a combo of the carb work and the new tire's I put on it.

[Stubeedoobee TT Newbie]

"Super carb tuning" info in this manual....kinda interesting, check it out....

http://www.2strokewo...90/vmmanual.pdf

[presidio TT Newbie]

I just acquired a '72 RV90 in a trade and got new California plates on it so I'm totally street legal!  Funny thing, the guy who checked my bike at the DMV in San Diego actually has a '73 RV

I've read Mattydiah's postings on 2strokeworld and have seen AmeriRover's on RV90.org (I've been lurking and researching).  

This is a great thread, lots of RVs coming out of the wood work like mine.  


-AmeriRover, any news on your modified oil pump?

-Kdaug5 where are you in California?  I'm in SD

[zecatfish TT Bronze Member]

GYTR said:

Hi I am new to thumper talk but have an issue with my 1974 RV 90 and was hopping you may help. The issue is I have a lot of oil coming from the exhaust it runs and idles fine just have a lot of smoke at full throttle. I have the owner’s manual but it is not to clear on the oil pump settings. The bike has been sitting for 5 years before I got it started so it may just be bad oil or gas I have placed new gas in it but mixed with old. It has what I would say is oil splattering on the rear fender. I also have a RV 125 and it is not having this issue so any help would be great.

Typical of OLD two strokes it sounds like your crank seals are bad. So its sucking tranny oil into the crankcase.
I know its an old post you made, but no one answered so I thought I'd toss in my .02 worth.

Those are cool old bikes. wish I had one to play on.

[AmeriRover TT Newbie]

presidio........

Nice to see you have a RV90! Yes the modified oil pump is just that...MODIFIED! I'm afraid of the original setup doesn't pump much to the crank bearing if at all, my pump maybe bad on that side.....I dunno...I have yet to see any oil come out of that side.....so I capped it off, and switched it with the tube that went to the carb. I run 32:1. It's lubed thats all I can say.

Here is the link. http://i196.photobuc...ilpumpideas.png
I have a different problem now, that is carb running on the lean side, I have a rigged air filter setup. I got missing parts on the original airfilter.

Here is some pictures taken while I was recovering the seat with a old "Members Only" jacket...you can see that rigged airfilter.....it is just not cutting it, I start to overheat after about 30 1 hour into my rides.

http://i196.photobuc...orte/foamer.jpg
http://i196.photobuc...te/DSC02810.jpg

Other than that it runs great.....stuff keeps breaking like:

speedometer cable snapped
slipping clutch
no lights
no battery or working charging system
leaky tire tube
chain adjusters are toast- ordered new parts
engine case bolts are all miss-matched
no chain guards...eeeek!
exhaust manifold has a stripped thread on head, needs retapped.

It is a blast to run in the woods, but it handles loose, I layed it down once because it squirreled out on me coming out of a ditch.....but it was graceful....I'm glad it was not a bigger bike I might have be hurt if it was....

Good luck on your RV90! and post some pictures........

Amerirover

[presidio TT Newbie]

Hey AmeriRover,

I'm glad this thread is still going, there needs to be as much published info out there for these bikes as possible.  

So to confirm what you are saying about your oil pump,

1) You removed the tube going from the pump to the bottom end
2) You capped the oil pump on that side (you mentioned it might be busted)
3) You removed the tube going from the pump to the carb
4) You capped the carb oil injection
5) You ran a tube from the pump's carb side to direct to the bearing
6) You are using 32:1 premix in the gas tank which goes straight to the carb
7) You are running 2 stoke oil in the oil tank which is pumped into the bottom end

Basically the top right drawing on the image you attached?
  

As for your air intake, would attaching the aftermartket filter to the orginial boot help at all?

My case screws are pretty crappy too, I'm planning on going to a marine supplier in town and replacing the bolts with stainless steel ones!

[AmeriRover TT Newbie]

Basically i just switched oil to crank tube to oil to the carb port on pump, left the tube to carb tucked out of the way, put a aluminum spacer on the oil to crank side of pump and tightened it down, so it is capped off.

so........"Basically the top right drawing on the image I attached"...thats my mod i chose


10w40 is in the oil tank to lube the crank bearing.... but it needs to be lighter oil.....and the pump is adjusted so it has only half the pressure as normal. Then I run 32:1 premix in gas tank.....but I may just switch it back to normal......because it is a little smokey all the time now.......

What I really need to know is the flow to the crank bearing......it may just be real light????

My air filter is just to thin, I am going to make a filter with layers of foam to dial it in....and get it out of a lean mix state.

I like modding stuff, and because the parts are hard to find it almost is a must.....fun bikes,

Presidio how is yours running???

[presidio TT Newbie]

AmeriRover,
Your oil pump mod seems like a great idea for people who want to run premix and still keep the engine oiled.  Are you running Synthetic motorcycle oil?



Here is my '72 RV90J


UPDATE:
Got it running nice just now!  The throttle cable needs to be replaced but after tweaking with the carb I got it to run pretty well!  I'm stoked on how fun this thing is.  Neutral is sort of hard to find but I'll get used to that.  It shifts easily through the gears.  So fun!

The Bad:
- Broken speedometer
- Junky and loose new throttle cable
- Seems like steering wants to turn left
- Front fender is cracked
- No chain guard
- Gaskets, clips, springs and fuel & oil lines are 38 years old haha

The Good:
- New CA plates and Title in my Name!
- Got it for CHEAP!
- Its fun as hell

[talon67 TT Newbie]

I just picked up a 72 today as well.  It runs great!  the only issue I can see is it seems the oil injection is putting too much oil in.  It smokes quite a bit and doesn't want to rev out really smooth.  It's a little sluggish.  If you need pics of anything or info just drop me a line and I can look at mine or take pics for you.  Do you happen to know if the oil injection can be adjusted?  If not, Can you just let it run empty and then plug the hose and run premix?  I'm still confused about what needs to be done.  I'm a little slow!    Thanks!  dave

[talon67 TT Newbie]

presidio said:

AmeriRover,
Your oil pump mod seems like a great idea for people who want to run premix and still keep the engine oiled.  Are you running Synthetic motorcycle oil?



Here is my '72 RV90J


UPDATE:
Got it running nice just now!  The throttle cable needs to be replaced but after tweaking with the carb I got it to run pretty well!  I'm stoked on how fun this thing is.  Neutral is sort of hard to find but I'll get used to that.  It shifts easily through the gears.  So fun!

The Bad:
- Broken speedometer
- Junky and loose new throttle cable
- Seems like steering wants to turn left
- Front fender is cracked
- No chain guard
- Gaskets, clips, springs and fuel & oil lines are 38 years old haha

The Good:
- New CA plates and Title in my Name!
- Got it for CHEAP!
- Its fun as hell

Looks GREAT!  Mine looks just like it!  If you shift into second and then shift down into neutral it seems to be easier to find than shifting up from first.  Hope that helps

[zecatfish TT Bronze Member]

talon67 said:

I just picked up a 72 today as well.  It runs great!  the only issue I can see is it seems the oil injection is putting too much oil in.  It smokes quite a bit and doesn't want to rev out really smooth.  It's a little sluggish.  If you need pics of anything or info just drop me a line and I can look at mine or take pics for you.  Do you happen to know if the oil injection can be adjusted?  If not, Can you just let it run empty and then plug the hose and run premix?  I'm still confused about what needs to be done.  I'm a little slow!    Thanks!  dave

Mix up some premix, say 40:1 and pull the oil line off, and start it. Let it run for a few minutes at 1/2 throttle and measure the oil pumped out, then ride it a bit and see if its till smoking heavy. If so you will need crank seals.

Its common for vintage 2 strokes to need crank seals.

[lenstermania TT Newbie]

Well guys I bought this bike a year ago in real sad shape. After $600.00 (mostly on tires and tubes and oil pump) it is time to move on to a new toy. I aquired a 1973 ST90 in even worse shape than the RV. I am hoping to have this done by next spring. I am hoping my local used bike parts lot has parts, if not theres always bike boneyard in Montana. I will still keep and eye on this thread and hope to offer tips from time to time. I am still puzzeled as to why you would pump oil to the crank bearing? Before I replaced my pump I just deleted it and ran premix. The reason I removed the pump was it was putting to much oil in and it was pushing the crank seal out.

[talon67 TT Newbie]

zecatfish said:

Mix up some premix, say 40:1 and pull the oil line off, and start it. Let it run for a few minutes at 1/2 throttle and measure the oil pumped out, then ride it a bit and see if its till smoking heavy. If so you will need crank seals.

Its common for vintage 2 strokes to need crank seals.

I messed with it for awhile last night.  I took the carb cover off and sprayed some carb cleaner everywhere that I could.  There is one small jet screw that faces straight out at you at the venturi opening when you take the cover off.  I went to remove this to clean inside and noticed that it was completely screwed in.  I cleaned it and reinstalled.  Upon reinstallation I slowly backed it out 1/4 turn at a time and checked the effect.  At about 1.25 turns out, it revs much nicer and runs alot better.  More turns out than that and it idles too high and more turns in it starts loading up and smoking more again.  I don't know what this screw is, but it is still idling a little bit higher than I'd like.  Where is the idle adjustment?  Or is that what I am desribing?  Thanks for the help!  Dave

[talon67 TT Newbie]

lenstermania said:

Well guys I bought this bike a year ago in real sad shape. After $600.00 (mostly on tires and tubes and oil pump) it is time to move on to a new toy. I aquired a 1973 ST90 in even worse shape than the RV. I am hoping to have this done by next spring. I am hoping my local used bike parts lot has parts, if not theres always bike boneyard in Montana. I will still keep and eye on this thread and hope to offer tips from time to time. I am still puzzeled as to why you would pump oil to the crank bearing? Before I replaced my pump I just deleted it and ran premix. The reason I removed the pump was it was putting to much oil in and it was pushing the crank seal out.

I was wondering that myself about the premix / pump.  Also, the clutch seems to be slipping a little.  DO I your gearsaver gearbox oil in the crank case like my later model 2 strokes, or something like Suzuki 4 stroke crank case oil?  While I'm asking questions, what is the correct plug?  NGK 7HS?  Thanks for the help in advance!  Newbie here.  These are very cool old bikes!

[zecatfish TT Bronze Member]

talon67 said:

I messed with it for awhile last night.  I took the carb cover off and sprayed some carb cleaner everywhere that I could.  There is one small jet screw that faces straight out at you at the venturi opening when you take the cover off.  I went to remove this to clean inside and noticed that it was completely screwed in.  I cleaned it and reinstalled.  Upon reinstallation I slowly backed it out 1/4 turn at a time and checked the effect.  At about 1.25 turns out, it revs much nicer and runs alot better.  More turns out than that and it idles too high and more turns in it starts loading up and smoking more again.  I don't know what this screw is, but it is still idling a little bit higher than I'd like.  Where is the idle adjustment?  Or is that what I am desribing?  Thanks for the help!  Dave

That is the idle air screw, it adjusts air/fuel ratio off the pilot jet.
You just got it about right. It may not have a slide screw for idle adjustments, if there is one, it will be on the side of the carb body, about half way down from float bowl and the top of the carb.

Adjusting it and having idle change shows that the pilot jet is clean in and in working order.