help ? Engine or carb options for an Attex 300 ( Jlo 297 )

[swfleur]

Does anyone have suggestions for a replacement carb for the Rockwell ? I have an TIllotosn and it is beyond hope

[Don]

Mikuni VM carburetors are a lot less trouble than the diaphragm type carbs. They're also relatively cheap and easy to find. What model JLO are you looking to recarb?

[swfleur]

Hi Don - The engine is a single cylinder 297 ( Attex 300 ST ) You mention the Mikuni VM - I will check this out ( Ebay ? ) any advice ?

[swfleur]

help ? Engine or carb options for an Attex 300 ( Jlo 297 )

Hello Amphibs - hope all the holidays and new year went well for all - Question to save my sanity from my Attex guru's - I'm working my old yellow Attex 300 ST - getting her back in action. I've read up on some carb issues I've had with the crappy Tilotson carbs - dang I dont like the Tilly carbs - anyways - I thought the engine was good - since it's been rebuilt - regasketed - new shaft seals - but didnt do the rings because compression was good - now I'm wondering
- what should my compression be? ( J_LO 297 engine )
- would I be better off just pulling the engine out and putting a 4 stroke in there?
- is there any benefit to keeping the old 2 stroke Jlo running ? or should I still a newer engine with a better carb system in the Attex?

Any and all thoughts are welcome from anyone that has swapped an engine or spit on the Jlo or tilly carb - my good gracious I have cussed that engine out and I actually enjoy tinkering and have lots of patience - ( just for proof - I've rebuilt my other Amphib - a Max II and never cussed at it once

I would like to just try a good carb first but I've been through a few already with minimal improvements.

Please - if you suggest a Mikuni - can you tell me what the size should be? in mm or etc?- that is confusing to me - are they measuring the output of the carb throat or the input of the carb throat - and for god sakes - why dont they advertise the bolt pattern size of the 2 bolts that mount the engine to the carb ?! - ok - feels like I need a beer and a hockey game - Maybe I should wear helmet during this game

[Mike]

What do you plan on doing with the Attex? If you are wanting to trail ride then the four stroke would be the way to go. However, since you already have a Max, I would be tempted to keep the jlo and just use the Attex when you have the need for speed.

[swfleur]

Thanks for reply Mike - trail ride is mostly my needs - but - I'm not familiar with the JLO or the Attex and it sounds like the JLO engine has more speed? Ok - this is helpful info - I'm guessing it revs higher and gets more speed than a 4 stroke ? keep the replies coming - anyone that wants to chime in please do so -

[Bazooo guy]

The attex 2 stroke will leave your max in the dust.
It will be much faster & louder as well.
What is the problem with your tillotson carb?
They are easy to rebuild and the kits are inexpensive.
Have you checked the website:

Tillotson

[swfleur]

Bazoo - I have rebuilt the carb and used the Tilly website as reference -even watched the youtube vids on them - I had issues getting too much fuel or not enough - finally got the float tang bent correctly for the fuel inlet seat to work right - I have replaced all the parts I can buy on this carb - it will start when I choke it but then it starves off and stalls - I soaked and poked and blasted air and got some improvement but still the ol girl stalls out. This carb and engine could make a Mormon swear

I have adjusted the hi and low needles and think I have them where they should be. I had already pulled the engine apart and replaced all seals and gaskets.

Now I'm wondering if it's timing How would I know and how do I fix that ?

[Bazooo guy]

Make sure there are no leaks in the fuel line or it could suck air.
Is the return fuel line going back to the tank and do you see any bubbles in the return line?
If you disconnect the fuel line at the carb is there good flow from the tank?
What type of pulse tube do you have to the pump?
External hose or thru the intake ?
It needs to be clear to pulse the pump in the carb.

[amphibious drew]

Personally, I would not be messing around with the tank or fuel pump until you know the carb is working correctly. I have an old gas tank I use as an IV line to whatever carb/engine I am tinkering with. Its just a tank I pulled off an old snowblower thats fram had fallen apart, but any small gas tank will work. Just make sure its mounted higher than the carb and let old gravity do the feeding.

[swfleur]

Okay here is my reply to Bazoo and Amphib Drew - thanks guys by the way -

The fuel line is new and flow is good - gravity does its thing
The pulse for the pump is coming from the engine and carb mount flange - there is no separate tube for the pulse pump - it gets its pulse via the carb mounting to the engine block
There is no fuel return line to the tank - just a fuel line feeding the carb bowl

I would like to keep the engine and slap on a known good carb that fits or could be adapted to fit - ( what is the throat ID ? )

Any takers on timing issues or should we stick to carb discussions first

[Bazooo guy]

"it will start when I choke it but then it starves off and stalls"
Sounds like a fuel problem not timing.
Make sure the pulse port is clear and the intake gasket is not leaking.
And no fuel leaks on the carb.
Iv fuel tank is a good idea.

"There is no return line to the tank"?
What is the model of the carb?

[dzg]

Probely tottally different but my Dad has an old IH Cub tractor that did this and the float was stuck in the up postion....starving the engine for fuel....

[swfleur]

HI Bazoo - sorry for the long delay in reply - I was out the country for work in Saudi Arabia - not a fun place but oh well -

The carb model is a Tilly HR 31 A ( the A stands for ARRRRGGGGHHHH!!! Do you have some advice or hints or a big hammer I can borrow ?

[Bazooo guy]

When it fires with the choke on stop cranking and hold the throttle wide open and crank it again.
(With the choke off)
It should start if its getting fuel.
If it doesnt start pull the plugs and see if they are wet.
2 strokes will flood very east and foul the plugs....when that happens there is no spark and no fire.
Dry the plugs and crank the engine with the plugs out a few times to clear fuel from the cylinders...reinstall the plugs and try again.
Try cranking it without the choke and use a spray bottle to spray fuel into the carb and see if it fires.
The high and low jets must be close to 1 1/4 turns....after the engine is running and warm fine tune them.
If the plugs are dry when you pull them its not getting fuel.
The 2 stroke will not idle when its cold so keep it around 2500 rpm till it gets warm and you can set the jets.
After its warm set the idle around 1800 to 2000.
The idle screw should hold the plate slightly open to get it started.