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1970 G6S oil injection pump problem


Foose
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Hi everyone!

 

I finally found the one that got away from me two years ago at Mid-Ohio...a 1970 G6S...rare little thing for the states, and fairly similar to the FS1 for those who are familiar. 

 

my oil injection pump was shot from the get go, so i took a chance on one from ebay and it seems solid as can be. so today i removed the oil injection pump, and tried to install the new one, but it seems to get hung up on something about .125" away from sealing to the case. if i kick the bike over, i can see the gear turning, so i know the crank is engaging with the pump, at least to a certain extent, but no matter what i try i cant get it on there! 

so then i thought, well, lets at least get the old one back on there. it doesnt go back on either....same thing: hangs up on something about .125 away from the case. well, dang it, i just took that one out, so i KNOW it can fit in there, and my new pump is identical to the old one, so what gives?  the G6S-B manual i have covers absolutely nothing about removing or installing the oil pump. so, my question is the obvious one: whats the trick for getting these things back on the crank?

 

any help anyone can give is greatly appreciated. im not a fan of premixing gas on bikes that have the injection pump; id much rather everything work as designed. i mean, ill likely not restore this to showroom, but im a stickler for the mechanical bits being right. anyhow, thanks again to anyone with the magic knowledge i lack.

 

Brian Foose

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Hi again,

 

ive been doing as much research on this as i can, it would seem the YG5T has the same oil pump configuration; indeed, many early yamahas had this same set up. 

 

everything ive read basically states "take it off, and then pout it back on, you dummy."

 

well im not refuting the dummy part, but that aint workin. 

 

so, if this is indeed a classic yamaha forum, and anyone out there has an oil injected small displacement bike, and youve removed the type of pump that goes around the crankshaft, did it just go back on or not? thats my only question now. clearly, ill have to figure out the rest. just someone please answer me that one little question.

 

thanks as always,

 

Brian

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Not sure what to say. That pump has in essence been fitted to everything 2Stroke made by yamaha.

The priming wheel disappeared over time and different bikes have different gear ratio's and pump stroke but the unit is the same. 

I have never come across any hang ups apart from gearing issues. Sorry. 

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well, i got it in today, and everything is fine. i have no idea what happened. i initially tried and it hung up, then i decided, for the first time, to put the banjo bolt, spring, and ball bearing for the output line in the pump while i installed it, and the damned pump fell right on. minor adjustments later and im properly smoking out the whole street like god and nature intended. it was my understanding the ball bearing was nothing more than a check valve to stop oil flow when the bike isnt running, so i figured it would have nothing to do with installing the pump. and i still doubt it does, but coincidence or not, thats what happened. so heck with it. im going to keep a wary eye on it, and then im going to make some smoke all over the county.

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