lawn boy duraforce questions?

[Rear engine 86]

We got talking exhaust and there is alot of motorcycle headpipes and exhaust parts that we can use to make what I described before. One thing at a time tho.
I still need to aquire a carb and some sort of air cleaner.

 

[rushking19]

I was at the metal fab shop a fiew hours ago and turns out he is abit behind on the machine work to the crank. He was tig welding my mount as I was walking in. Some more pics. I really hope the crank turns out (lol no pun ) as I expect.

It looks amazing,dont forget that you have to put a exhaust gasket between the aluminum plate and the engine

 

[Russ2251]

Lol if they ever invent teleporters...

It's being worked out as we speak. Heard of entanglement?

Have you ever been able to fully top out your dual engine kart?

Never could take it out beyond parking lot.
New York state laws have toughened up over the years. Kind of a zero tolerance thing.
There are no warnings given if caught by the cops. Immediate impound is the order.

That thing must pull hard!!

Indeed it does. The way God meant it to be.

Use a carb that has a .750" venturi. Does not have to be a diaphragm carb as long as it is properly oriented.

How are the vibrations on these Duraforces compaired to lets say a flathead briggs or clone?

Could not say as this was not a consideration.

 

[Rear engine 86]

Wow that was an interesting read lol. After the first paragraph I was pretty much lost but it's very interesting to know that people are constantly working to better understand the word we "think" we live in!

Thats to bad, maybe if the teleportation thing pans out you can come to my street and no one will bother us lol. Ontario has some tough "offroad vehicle" laws too and if caught in the right circumstances, you will be hung out to dry! Alot of police officers here in my town are gearheads, cars guys/gals and are pretty
understanding of small hobby type "Im testing it" encounters lol

Hahah right on and will it break the tires loose?

I was going to use the tillotson HL-334ab carb as I can get one from a vintage kart supplier about an hour away from my place. Are there any other carbs that could be easily adapted that have a. 750" venturi?
I was thinking a small Mikuni round slide but the again I like the idea of tuneable high and low metering circuts with a flathead instead of swapping jets.

Russ, would you mind sharing your carbon fibre reeds mod?
Thanks.

 

[Rear engine 86]

It looks amazing,dont forget that you have to put a exhaust gasket between the aluminum plate and the engine

This is another thing that I have been thinking about. I have a new short block with all new gaskets and the exhaust port gasket is rather thick. From my understanding, both the exhaust port flange on the block and the two mounting lugs or legs are at the same flat plane. If I use the supplied gasket the mounting legs will not sit flush with my mounting plate once everything is tightened up, so I assume. I was thinking of just using the Loctite 515 flange sealant instead. Any ideas or help would be great.

 

[rushking19]

This is another thing that I have been thinking about. I have a new short block with all new gaskets and the exhaust port gasket is rather thick. From my understanding, both the exhaust port flange on the block and the two mounting lugs or legs are at the same flat plane. If I use the supplied gasket the mounting legs will not sit flush with my mounting plate once everything is tightened up, so I assume. I was thinking of just using the Loctite 515 flange sealant instead. Any ideas or help would be great.

Just put washers between the engine and the mounting plate, were it bolts up to the engine

 

[Russ2251]

Are there any other carbs that could be easily adapted that have a. 750" venturi?

I can't advise on what other carbs to use.
I went through at least a half dozen before I found what I could use on Ebay.
A Tillotson HL239b. I purchased several for about $30 a piece. They were so old that every one of them had to be rebuilt even though they were NOS.

would you mind sharing your carbon fibre reeds mod?

I used them on the advice of a forum member called crazycart. He has not been around for about 5 years now.
Anyway, the ones he suggested (Boyesen Carbon Fiber Reeds) were for a CR250 and had to be cut to size to fit the L-B.
As you can see, they ain't cheap.
If you want to experiment, carbon fiber sheets can be purchased HERE.

 

[Russ2251]

This is another thing that I have been thinking about. I have a new short block with all new gaskets and the exhaust port gasket is rather thick. From my understanding, both the exhaust port flange on the block and the two mounting lugs or legs are at the same flat plane. If I use the supplied gasket the mounting legs will not sit flush with my mounting plate once everything is tightened up, so I assume. I was thinking of just using the Loctite 515 flange sealant instead. Any ideas or help would be great.

I'm not sure I understand the question. Could you supply a marked up pic so I can fully understand what you want to accomplish?

 

[Rear engine 86]

I can't advise on what other carbs to use.
I went through at least a half dozen before I found what I could use on Ebay.
A Tillotson HL239b. I purchased several for about $30 a piece. They were so old that every one of them had to be rebuilt even though they were NOS.
I used them on the advice of a forum member called crazycart. He has not been around for about 5 years now.
Anyway, the ones he suggested (Boyesen Carbon Fiber Reeds) were for a CR250 and had to be cut to size to fit the L-B.
As you can see, they ain't cheap.
If you want to experiment, carbon fiber sheets can be purchased HERE.

Thanks Russ.

I think I will go and use the tilly HL-334ab carb that I can get for about $90 with a throttle linkage kit.

Im all for maximum performance out of this engine but I think I will stick to stock steel reeds.

Now I am really on the fence about doing the head gasket elimination mod. Is this a big improvement over stock?
I'm thinking about doing this but still not quite sure.

Thanks again Russ.

 

[Rear engine 86]

Just put washers between the engine and the mounting plate, were it bolts up to the engine

Duhh lol...never really thought about that. KISS applies here!

 

[Rear engine 86]

I'm not sure I understand the question. Could you supply a marked up pic so I can fully understand what you want to accomplish?

I will take some pics and try to explain this better.
lol I think I have it figured out now.

 

[Russ2251]

I think I have it figured out now.

Excellent, I think I understand question....just want to be sure.

 

[Rear engine 86]

So I went to go pick up my crank yesterday, no bueno

Machinest said that his 3/16 mill bit to cut my keyway wasn't up to par so he had to wait till the next week to get a new fresh one.
I guess its good that he didn't rush to get it back to me using sub par milling bit.

Any tips or pointers for doing the head gasket elimination mod Russ and is Loctite 262 pretty much the same as 271?

 

[Russ2251]

Any tips or pointers for doing the head gasket elimination mod...

Just follow my guide lines HERE and you should be OK.

and is Loctite 262 pretty much the same as 271?

They are not the same and should not be used to replace head gasket.

 

[Rear engine 86]

I was going to use the loctite 515 flange sealant for the head gasket mod but in regards to the 262 v.s 271 I was more thinking about the reed screws and con rod bolts.

I just want to assemble this short block correctly and if possible, better than factory.

 

[Russ2251]

The Loctite 271 (RED) is the factory recommended product for rod and reed screws and does not need to be redone unless disassembled.

 

[Rear engine 86]

I have removed my crank to get machined from my new short block so I will have to reassemble the con rod cap bolts and reed screws. Do you think 262 would be acceptable? Because 271 is hard to find.

 

[Russ2251]

Do you think 262 would be acceptable?

I would have to say no.
These engines in their stock form are only meant to turn 2900±300 rpm.
For our application engine will run at ~7000 rpm and possibly much higher.
To use something less than the recommended is asking for real trouble.

 

[Russ2251]

Purchase LOCTITE 271 here and at a myriad of other places around the web.

 

[Rear engine 86]

I have made some more progress on the lawnboy build.
I got my machined crank back today and my engine mount and couldn't wait to to mock fitting stuff together.

Im super excited about this build as I love two strokes. I will be making the drive to Karts and Parts about a hour from my place to get a HL-334b carb.

What would be my options for a air filter for a tillotson carb?
Could I use a clone V stack and clamp on foam air filter that I see on alot of minis? I dont have much space.