My slightly nicer but also terrible Bobcat (742B)

[Scott Cee AKA 2drx4]

I got some expanded steel to put a guard in the louvers:

Much better.

I also tightened up the preload on the throttle lever, I thought it needed a new spring but I just tried cranking the nut in a bit more first, now the throttle stays put regardless of where it is. There's still a spring missing off the carb but eh. And I managed to adjust the parking brake so it holds it, the procedure seems super confusing but I decided that you can probably just turn it in and as long as there is free play with it off it must be okay.

[Scott Cee AKA 2drx4]

Got a cheapish new seat from Vevor. Seems pretty nice. Was almost bolt in, just had to drill 2 new holes a bit farther back for the rear bolts.

Edit, and I found some random GM seatbelts in the shed and put them in. I'm not a huge safety guy, and it doesn't matter a ton with these machines since it has the lap bar, but it annoyed me that it had seatbelts in it that didn't have the right ends on them to clip them together.

[Scott Cee AKA 2drx4]

I tracked down a Chicom water pump that is listed as crossing to the OEM Bobcat P/N, these are new to the market as obviously there is some demand for a waterpump that isn't $600 USD. The retailer is Jeenda Controls Co, seemed sketchy but I went for it in the name of science, and it is listed under the P/N 6632822. It was still a bit pricey at about $200 CAD, but since that was still way less than OEM, with no sign that they may even be making them still, I figured it was a fair deal.

Of course shortly after they shipped it I was informed that the correct Dodge Colt waterpump is from a 1978 with the 1.6L, so they did not in fact make one specific for the industrial engine. Rockauto had a Dayco DP1182 for just over 21 loonies. There was still a few other options in stock too.

They do look correct. Have not bothered to install them.

Jeenda left, Dayco right. I will probably never need both of them, but so be it.

[rdy2garden@gmail.com]

Hey Scott I have a 1986 642B with the same motor. My buddy and myself just recently put a rebuilt Mitsubishi 4g32 in the bobcat. Now we’ve got everything running but I noticed a hose unplugged above the air filter to some solenoid valve, that comes from the carb I believe. I’m having a hard time figuring out what that is? I’m new to all this mechanic work and trying to learn how to do things myself. Here’s a picture of the valve I'm talking about. Let me know what you think. Thanks man

[Scott Cee AKA 2drx4]

Hey Scott I have a 1986 642B with the same motor. My buddy and myself just recently put a rebuilt Mitsubishi 4g32 in the bobcat. Now we’ve got everything running but I noticed a hose unplugged above the air filter to some solenoid valve, that comes from the carb I believe. I’m having a hard time figuring out what that is? I’m new to all this mechanic work and trying to learn how to do things myself. Here’s a picture of the valve I'm talking about. Let me know what you think. Thanks man

It's an anti-dieseling solenoid. The hoses go to above and below the carb venturi. Basically it opens and kills the venturi effect, stopping it from pulling fuel into the air. I deleted mine, it shouldn't really do anything unless you're running the engine super hot as it should die just fine with the ignition off. Perhaps it had more relevance if you were still using points ignition (I'm assuming yours is converted), but I don't know. If you delete it, just make sure you cap the ports properly.

Hope that helps.

[rdy2garden@gmail.com]

Right on. I’m gonna study it a bit more to see what will work best but when we fired up the new engine, that hose was disconnected from the anti diesel solenoid and it sounded like it was running great. When I looked in there again I noticed the hose unhooked so I hooked it back up. Then it started to run real puddy. I noticed the hose half way was collapsed and when I used my hand to unkink it, it sounded like it was running fine. So I unhooked the hose from both shortened it and when I did this something happened to the carb. I think the hose was in the way of something moving and it was back to running weird. So I got a longer piece of hose attached it and when I tired to starting, it had a hard time so I pulled the choke and it started and ran ok, but only with the choke still up. I think when I was in there I bumped something on the carb. It needs some adjustment or something. Also this carb is leak from the spring in the front, I just don’t know what to do because I’ve bought 2 carbs online that say they are for that bobcat and the throttle linkage doesn’t comply. Anyhow I don’t even know what I said makes sense, I’m just trying to remember what I did.

[Scott Cee AKA 2drx4]

I bought a generic carb but haven't swapped it one. I say generic when it was sold under the Bobcat P/N for the original carb. It's totally different from the Mikuni Solex one, and yeah, the linkages are wrong and obviously for a throttle cable. Some Chinese company called "Sherryberg" is now making a clone of the (probably) correct Mikuni Solex unit, but it also has a linkage on it for some other generic application with a throttle cable. I got mine to run okay with the original carb in the end, you just have to be smooth on the controls because the accelerator pump does not work. I think you're going to be stuck having to fabricate the linkages if you go away from the original carb, although perhaps the Sherryberg one is closer and you could swap the parts over.

It's a bit of a pain and long term I'd like to sort it out, but I'd like to not do it by taking my machine apart, so I've been half hunting for a junk OEM Mikuni carb so I can clone the linkages onto a different one.

You did try rebuilding your OEM carb? I can't say how to help you without knowing for sure where it is leaking.

[rdy2garden@gmail.com]

No I haven’t. I’ve struck out on so much shit for this machine it’s hard to keep trying. I guess I’ve got so much in it at this point I’m gonna keep going. I just want to make sure I get the right kit to rebuild the one I have. It’s definitely original. I can post some pics tomorrow after work of where the leak is. I think you’re right, I can run it with this old carb but since I’ve replaced everything else it makes sense to make sure the carb is solid. Thanks for your help. This has been stressful. Trying to get the machine running so I can get some things done. Thanks again

[Scott Cee AKA 2drx4]

Post up the pictures and I'll do my best to help.

[rdy2garden@gmail.com]

Here’s some pics of the motor and the original carb that’s leaking a bit. It is leaking somewhere around that spring. When the spring moves side to side some gas leaks but I don’t know if there is a fix for this. I think over the the past few decades, it’s wore out a spot where gas can escape. I don’t believe it’s coming from a spot that needs a new gasket but I have no idea. Once I get a few things adjusted I think it will run pretty smooth. I just want to make sure everything is working properly. It seemed like when we fired up the new motor and it ran for a bit it started to get hot but I have no gauge or anything to tell. A friend told me to get a temp gun and shoot the block, the bottom of the radiator and the top of the radiator and that’ll tell you all you need to know…???

[Scott Cee AKA 2drx4]

I don't think the carb is leaking from that shaft, well, it might be but if it is that's not the actual issue. That throttle shaft just rides on a bushing there, the bushing may be worn, but there is nothing on the other side of it as it is just a plugged barrel. What does happen is the plugged barrel accumulates dirt/oil/some stray fuel and it will weep through, or more likely the entire top of the carb is leaking and it's just running down into that barrel. The split line between the top/bottom of the carb is just sealed with a gasket, and if it's original (35 years old sort of thing) it will definitely be dried out/cracked and leaking.

Carb needs a rebuild kit thrown at it, basically. Also, mine had been rebuilt/abused before and they managed to bent things enough that the sealing surfaces needed to be cleaned up extensively.

As to the engine temperature, the sender and gauge are available from the dealer for not too much. Make sure you get them to find the TB that shows the updated part numbers, the parts manual does not show this and the old numbers are NLA. I still need to change my sender (I want to plumb the heater back in at the same time), so I just use an IR gun to check the thermostat outlet and head temperatures. You can also feel the hoses to ensure that coolant is flowing/thermostat has opened. This is not ideal, my engine likely was roasted from the radiator being plugged and them overheating it, so I stop the machine every 10-15 minutes and check temperatures for the time being.

[Scott Cee AKA 2drx4]

Also, if the float height in your carb is wrong and too high, it will leak more.

[rdy2garden@gmail.com]

Right on. So I’ll start with a rebuild kit for the carb. It also seems like the throttle cable/arm is stiff and it gets stuck. I had it fired up earlier but when I tried throttling down it dies. I’m gonna have a friend come back over and adjust it. I actually just picked up the temp gauge and waiting on the sender from a different store. Looks like down on the block there are two spots for a thermostat or something to screw in?? Yea mine definitely ran hot as well. Not as hot as yours, my fan housing never melted but I do still have the original plate that covers the spot in between . I feel like I will do the same thing when running the machine. I want this machine to last a long time but I understand shit will keep happening.

[rdy2garden@gmail.com]

I’m not sure if this is the correct rebuild kit but it’s the one I found for the original carb. Let me know what you think..

https://partshawk.com/walker-products-1 ... xLEALw_wcB

[Scott Cee AKA 2drx4]

I’m not sure if this is the correct rebuild kit but it’s the one I found for the original carb. Let me know what you think..

https://partshawk.com/walker-products-1 ... xLEALw_wcB

That one works, it just has the wrong needle and seat for the float. Allegedly another kit has the right needle and seat, but it has none of the other correct parts, and I don't have the part number for it. I just lapped my needle/seat together and it is fine, although I did add the fuel shutoff valve just in case.