addition to: Advice for hooking up your Tecumseh Carb / Throttle Linkage on Small H

markus

Well-Known Member
#1
just an addition to already posted "sticky" thread on throttle hookup for the small frame sized 2.5-5hp sized mini bike engines: https://www.oldminibikes.com/forum/...ecumseh-carb-throttle-linkage-hs-engines.html Its not noted in the thread and I have seen it in the past where people have had problems hooking up the throttle (even me) becuase of it, thread is locked so you cant post to it so heres the info I wanted to add.

I am currently setting up a couple of late 73-up HS engines which used the late model throttles and thought I would just share this so maybe it will help someone down the line.

The current available spring return throttle controls # 73016a have a stop tab on them, This permits full travel for "recreational vehicle" style engines....It keeps the idle setting up high its more for a semi fixed setup where it relies on the govener more to kick it down. Right out of the box this setup wont work properly for a flathead mini bike or kart engine. All that has to be done is cut or bend the tab out of the way, so its nothing special or diffucult to do.

for example, loose in the center is a new throttle control unaltered, left is a recreational throttle control on a 1979 HS50 (from a go kart originally) right is and HS50 I am currently rebuilding where I used an altered new throttle control.



you can see here that the new replacement has that tab in it where the old ones did not



I usually just bend the tab out of the way (thats becuase I always forget to do something with it till everything's all bolted together :doah:) This time I was thinking about it, a simple snip with some dykes popped it right off there and then I just hit it with a file to clean it up before riveting it to the backing plate.


 

markus

Well-Known Member
#4
I was helping someone on facebook the other day that was missing the spring parts on his bike and thought it might be fitting to add this info to this thread for reference since it does pertain to this type of throttle assembly. I never did any thorough research on this till just recently and this may help for people that are wanting to do restoration/period correct look setups.


in this photo, engine on the right is an original setup for bike/kart use. In the earlier days it used spring part number 34653 and installed through the lower bolt hole and up to the lever. In later years (engine on the left side) they updated the setup and went to longer spring that is tension adjustable (relocation holes on the bolt on plate). that assembly is part number 33857.....but make sure you are getting the bolt on plate, bolt, and spring in the kit as they also came in that same part number with just the long spring, you need the plate to make it work. the governor extension spring is the one that goes from the assembly to the governor arm The 33857 assembly should come with the entire assembly, but I have bought one or 2 in the past where it was not there.

IMG_1985.JPG

With that said, best I can tell from engines and parts I have here the extended tab and spring look to start in the very early 1980's (the setup you see pictured is off a 1979 Kart engine, and a 1982 date coded off a Bird Thunderturd engine I have has the tab/extended spring. these type throttles began in 1974 and were in fact found on the smaller round top shrouds that were still being built up to 1975 (small frame H and HS40). So if you want to replicate the 1970's version with the new available units, using the spring number mentioned above (can still be found at the time of those writing) will make it look the part better, and it just make the whole assembly smaller and cleaner looking, and it is a strong little spring, don't let the size fool you.
 

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