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Ok, after a year off to pay some bills, I?m trying to get back into this game. The past month or so I have been going through my Rotax FR125 motor checking and cleaning everything. Prior to me touching it, it ran fine. Throttled up to 14,000 rpms no problem. But since I put it all back together I can?t get it to run faster than 3000 rpms. I also noticed it blowing white smoke.
This is the list of what I have done to it.
I pulled and cleaned the motor.
I drained its oil and removed the gear cover to check the plastic gears.
They were fine.
I put the cover back on and filled with new oil, to the level of the second bolthole.
There were no leaks.
Cleaned the carb and checked the floats (see diagram).
Cleaned the fuel filter
Main Jet 158
Air Mix Screw set to 1? turns out from completely in
The Idle Screw set to 3 turns out from completely in
(Note: I have never been able to get the thing to idled here in Denver)
Replaced all the fuel lines
Cleaned the gas tank
Used Fresh Fuel (MS98 with 1:35 Redline 2 Cycle)
Took apart the Fuel Pump and cleaned it.
(I did not replace the diaphragm because it looked good to me.)
Resealed the exhaust with high temp gasket maker
Installed a new sparkplug IW29
Cleaned the Air Filter and Air Box
Charged up the only battery left I have working
(I did notice that it drained really quickly. After running the motor for only a couple minute I put it back on the charger and the ?Below 80%? came on)I guessing it could be a weak battery not sparking correctly at the higher rpms or I did something to the Carb.
You guys have any ideas to try?
Thanks RandallNothing obviously wrong with what you did. The battery, though certainly sounds suspect. Also check your float level valve in the carb to make sure it moves freely, and the prongs on the valve should be parallel to the base of the carb when you hold it upside down. You might also want to check all your electrical connections to make sure they’re tight and make sure you’ve got a good ground connection.
I would be suspect of either a major vacum leak or a very rich mixture-run the engine and spray some carb cleaner or WD-40 around the gasket areas that you disturbed….if the engine changes tone or speeds up there is a starting point………..not sure if this procedure is as accurate as it is on a four stroke but I have let the engine idle then choked the intake with my hand-if the engine smooths out again suspect a vacum leak-weak battery could cause your issue also-white smoke would indicate a very rich mixture-is a gasket possibly torn or wrinkled allowing a full rich run condition-just my 2 cents but that is the direction I would hunt I have seen rotax service manuals on the web-check Scott Umbrights web site I think he has a link:cheers:
Randall,
check the fetzer valve, it’ll give you problems every time… 8)
Seriously, I’d swap out the battery. I can’t tell you how many times in two years I’ve had problems in that department…
By the way I wouldn’t believe anything Charles says. He cheats. He threw tacks on the track this weekend and I got a flat. The things some guys will do for a trophy is beyond me.
😀
@Mike Jansen wrote:
Randall,
check the fetzer valve, it’ll give you problems every time… 8)I?ll check that Mike, right after I finish refilling my blinker fluid. :bs: 😀
I went ahead and ordered another battery since one of the two I had already went bad. But I?ll give those things the once over and see what happens tonight and tell you how it goes.
Thanks guys
Snowman, we have rotax batteries in stock at Grand Junction Motor Speedway and are just over the hill. 970-640-8990
Hey Randall, make sure the fetzer fairies didn’t put your carb slide in backwards 😯 and maybe ck that the exhaust baffle material isn’t clogging the exhaust..
OK went down the list and rechecked the float level and it looked fine. I checked the gaskets and didn?t see any leaks. I fully charged the one battery I have left and was able to get into the higher RPMs last night. I choked the intake and almost killed it so I don?t believe I have any vacuum problems. (Oh and had a gun at the ready to blow away any mythical creatures if appeared from and mythical engine parts, always better to be safe)
The exhaust this time wasn?t as white, more of a blue and a lot less of it. But it was still a bit more smoke than I?m use to. I?m assuming from the oil residue on the end of the tail pipe that the blue smoke was oil. Is this normal when you guys run higher oil to gas ratio? (I use to run 1:50)
Also I can?t think that is healthy for the exhaust packing. Have you guys had much experience with the baffle going bad? What kind of effects should I be looking for?
If I can clear these items up I should be track ready soon.
Really appreciate the help?
SnowmanThat?s great Stacey; do you have a price list on your site somewhere?
Ok after getting home and starting it up again I begin to get the same condition as before, no revs above 3000. I removed the Air Box and found it filling up with fuel.
So I ran a test. I started the motor without the air box to see what was blowing fuel into the air box. It ran fine for just a minute but then fuel began to run, very quickly out the lower center hole in the intake to the carb. It then started to drop in RPMs and couldn?t run about 3000.
I also notice a fuel leak on the fuel filter side of the carb. It looks to be from the fuel line into the carb but I have that wire tied and it seems allot of fuel form that area.
I repeated the test but this time I was able to keep the motors rpms above 4000 and it didn?t bog down until I let it idle at 2000 for a moment. Fuel did begin to flow out of the opening at the bottom of the intake again so I revved it up and the flow slowed down.
I made sure the three bolts holding the bowl on where tight. The gasket between the bowl and carb appeared to be good. I did touch it up with some marvel mystery oil to try and make a good seal.
Now what have I done?
Pull your exhaust baffle out and make sure the tube is still intack and if the packing hasn’t been changed in 6-8 hrs you need to change it.
Also pull your fuel pump and make sure you got the gaskets and flapper values in the correct way.
Make sure you got the in and out lines to the pump correct.
Pull your fuel filter and check for a gasket and clean filter (that is where you noted a leak in your picture).
You could have an air lock in there. Pressure you gas tank pushing gas through your fuel pump into the carb and out the small fuel filter in your carb.
Yes sometimes you have to take your airbox off to get the thing started. I have run into that several times.
A new battery will help.
Have you checked that you may have some trash in your main needle-seat area-what makes me think this is I have had a harley with carb problem do the same thing-if it sat for a while what would happen is some gunk from it having sat so long would get sucked up into the needle seat area and run super rich and leak all over-an hour later you could fire it up and it would run fine-pulled the bowl off and checked the needle and sure enough there was a tiny bit of crud that would hold the needle off of the seat and then float away-if the needle is viton(rubber) tipped it may well have a shred missing or similar-maybe worth a look-seeing how the vacum checked out and your smoke is white then I would think it would definitely be a carb issue-might be a situation of spending the few bucks for fresh gaskets well worth it- good luck
:cheers:@Rich Vito wrote:
Pull your exhaust baffle out and make sure the tube is still intack and if the packing hasn’t been changed in 6-8 hrs you need to change it. .
My exhaust 3 rivets holding the baffle in. How do you get by them and once it is out do I use rivets to reassemble?
@Rich Vito wrote:
Also pull your fuel pump and make sure you got the gaskets and flapper values in the correct way.
Checked and they are correct.
@Rich Vito wrote:
Make sure you got the in and out lines to the pump correct.
Checked and they are correct.
@Rich Vito wrote:
Pull your fuel filter and check for a gasket and clean filter (that is where you noted a leak in your picture).
You could have an air lock in there. Pressure you gas tank pushing gas through your fuel pump into the carb and out the small fuel filter in your carb.
I tested this, not seeing any leakage from the fuel filter.
drill the rivet heads with a drill slightly larger than the body of the rivet 3/16 works well for a 1/8th rivet-just go through the head of the rivet and the body will detach-DO NOT DRILL TOO DEEP-if the rivet spins in its hole-its time to either a real sharp small chisel to shear the head off or use a dremel to grind the head off-yes re-rivet it back in
:cheers:It’s legal to use bolts and nylon lock nuts instead of rivets. Makes checking for a fried baffle and tube easier. Wish someone made a stainless tube.
That?s cool I was wondering if I didn?t have to rivet the exhaust back together. Has anyone tried to wire tie the cap back in?
The problem I?m seeing is that when I run the motor at a low rpm, 2000 or so, the carb for some reason loads up with fuel and it spills out the air intake through the inset hole at the bottom of the intake. From there it flows into the air box and down onto the air filter. This filter being not more than a sponge, soaks up the fuel and chokes off the airflow to the carb. This gives the carb a to rich condition lot letting enough air in to run higher than 3000 rpms and blows the unused fuel through the motor and out the exhaust.
Why would the fuel load up and low rpms and spill out this opening?
If this were a normal condition, wouldn?t there be an overflow line for this?Stacey, If this is something beyond me would you guys be game if I sent just my carb to them and have them go over it?
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