Hot Rod HS40-Powered Full Suspension Cat 250

delray

Well-Known Member
#42
have dave, how close are you from firing up that little guy with the mikuni. reason ask is sometimes the float adjustment can be off from factory and if that carb has the spring loaded needle and seat. that too can through things off. you may know this already? when checking the float height with a spring loaded needle you do not want to check it with the carb up side down. it needs to be on it's side at about 15-20 degrees. just when the small tab on the float touch's the needle and does not push the spring in. if the float is not set right it can be a fighting battle with jetting and tuning the carb. i'm going to try one of my mikuni's on my hs-40 soon and see how the jetting go's and all. think going with a 125 jet and going to start with a 15 pilot. I will do a thread on it with my HS-40 build...…...:thumbsup:
 
#43
have dave, how close are you from firing up that little guy with the mikuni.
I'm pretty close. The carb is a used one. I had to repair the clip that retains the needle, and I just received my spare jets. Installed was a 12 pilot jet, and a 130 main, so I am not taking anything for granted. I'll start with 15/120 and the needle centered.

I had 17.5 and 130 going with a hot briggs flattie at this altitude, so theoretically I should be at something less than that with this one.

I didn't have a problem before with a fuel pump overpowering the float valve, but I did see others have.

Thanks for your input Brian.
 
#44
Finished up the major components of the engine, and torqued everything down. Installed in frame for testing once I get a black tank in there, and finish Pats bars when they arrive. Also awaiting a R.T.T. exhaust, standard 30 degree bends, not welded to the flange, which I will do once I get it where I want it. Also getting that nifty RTT muffling disc.





 
#49
KRC sells them. Downside is that they are very expensive, AND made for kart seat frames which are 1/2 inch. For some reason, after the three million Cat mini bikes I've restored, I always thought their frames were 7/8. "THIS" Cat frame is one inch. So I machined the clamp down, but it's thin, and a bit wobbly. I'll do something with a welder or with rubber later on to better secure it.

If I were a kid, I'd be plastering my growing collection of hot rod stickers all over the engine. :laugh: I think they'll go on my forehead to cover my third eye, once I stop making love with my new RTT exhaust and cool muffler flippy spring thingy.
 

delray

Well-Known Member
#51
hey dave I notes you only have a fitting at the top side of the catch can and a petcock valve at the bottom. your going to have make a return line back into the block or your going to fill that can up. when I start buzzing my motor over 5500-6000 it starts to pump oil out the valve cover into my catch can. I run my line right back into the rear drain plug. my rear fitting for the return line is pointing up so it's kind of hard for the oil run out into the line area and the motor sits at a angle too. you might have to make a slightly raised fitting/elbow and you might have to raise up the catch can just little more....:thumbsup:
 
#52
Got the RTT welded up and installed. Did a slash cut, and installed the old school muffler plate.



I hate to post this photo, because it is not a good one, but it shows the angle of the exhaust. I may support it, it's right there in the ball park. If I do, it will be a compact rear frame support with a slot for engine adjustment.

 

markus

Well-Known Member
#56
Check the link below. Robertson Torque Tubes. Max says he fabricates those based on an old trick with the Honda 305 Scramblers.

https://www.robertsonstorquetubes.com/product-page/snuffler-muffler
Yea those are based of the old "snuff-or-not" units. Nicely built and nice price too BTW :thumbsup:

Here's a thread with some info when another member Helped me ID one I bought off here a few years ago:

https://www.oldminibikes.com/forum/strictly-us-vintage/98401-exhaust-accessory-remember.html
 

delray

Well-Known Member
#57




dave, I wonder how sensitive the carb will be with that baffle plate installed? it will be interesting to see how well it will work..:thumbsup:
 
#58
Pat [MENTION=31471]mrpat[/MENTION] bent me up some bars, custom to my request, and created a 3/16 base plate per Cat dual shock specs. I can't say enough about his skills, or willingness to take this on- and then wanted only shipping for it- and it was his metal. I don't want to embarrass the man, but he's helped me out several times over the years. Thank you Pat.

I had some hickups, and my usual welding issues, but here are my version of some taller, angled forward Cat bars.







 
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