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Rt80 Corona 12R 5 Speed


glenpos

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What a little beast! Looks sweet mate, I just got an RT81 with the 12R motor, will start a cute little thread soon. Good work with the carbies, great idea.

hey, thanks, cool i'll check it out when its up, i put the 12r head back on today, i ported it and gave the valves a re-grind, and i gave it coat of silver, i'll get it shaved and the cam reground one day when i can afford it haha, and maybe a weber, the bike cars were just a pain, it didn't start on its own, and didn't run right, so its just easier haha
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The bike carbs are interesting- Do they have oil dashpots like an SU where the oil slows the movement of the slide going up?? or springs above a diaphram like a Stromberg?

 

Using different viscosity oils takes the bounce out of the slides at idle, and a hot cam would change the vacuum at idle and alter it all again.

 

Can you get needles for them? Do you use an oxy sensor to check rich/lean when under power?

 

If they were off a 400cc then each carb feeds 100cc at say 10,000rpm, and you're feeding 400cc, so getting 5000rpm was pretty good. If you had carbs off a 750cc bike it would fly.

 

Developing the SUs kept me busy for a while, but damm they work well now!

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The bike carbs are interesting- Do they have oil dashpots like an SU where the oil slows the movement of the slide going up?? or springs above a diaphram like a Stromberg?

 

Using different viscosity oils takes the bounce out of the slides at idle, and a hot cam would change the vacuum at idle and alter it all again.

 

Can you get needles for them? Do you use an oxy sensor to check rich/lean when under power?

 

If they were off a 400cc then each carb feeds 100cc at say 10,000rpm, and you're feeding 400cc, so getting 5000rpm was pretty good. If you had carbs off a 750cc bike it would fly.

 

Developing the SUs kept me busy for a while, but damm they work well now!

hey, they just have a spring above a diaphram, i think with a set of gsx 750 carbs it would be good, but i just don't have the time or money to play around with them for now, but on day i will probs try to do a better setup, but for now i just wanna be able to drive it haha, i think i'm gonna save up some cash, get the cam reground, the head shaved and get a headgasket, then i might look at doing carbs, but of course having a racecar drains the bank lol
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  • 1 month later...

Hey man, I just scored a set of mikuni carbs that look identical to the ones you had. Just wondering if these are worth using, and what you did for a choke?

g'day, well they didn't work that great for me, i didn't have choke, and they were too small, i think a good set of carbs would be some mikunis off a 81 ish gsx 750, but for now iv'e just got the stock carb on, and i'm keeping an eye out for a weber, just coz its a daily i don't wanna be stuffing around with it all the time, but on something you want a hotty motor in it, they would be good to play around with
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Hmmmm I've been told mine came off a 750, but I don't know much about them do dunno how to find out. The car is my daily so I just wanted to get a bit of info while I consider my options :) was throttle linkage an issue?

 

Wait.. Just checked, mine are off a FZR1000 (R1?). Lol

Edited by Mark90
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  • 4 weeks later...

hey guys, picking up another corona today, its a 1973 model, hopefully its got disc front brakes, its manual, black interior etc, should be a good spare car, or i might do something with it depending on how good the body is....

 

got it for $250 :y:

 

post-15067-0-55917200-1353706131_thumb.jpg

 

cheers

Edited by glenpos
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hey guys, picking up another corona today, its a 1973 model, hopefully its got disc front brakes, its manual, black interior etc, should be a good spare car, or i might do something with it depending on how good the body is....

 

got it for $250 :y:

 

post-15067-0-55917200-1353706131_thumb.jpg

 

cheers

 

Damn you!! Haha where'd you find it!?

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hey, haven't done much to it lately, i put a bit stiffer shocks in the front, i put a chrome air cleaner on it so it doesn't look quite as gay haha, iv'e been playing around with my old head that was on my old motor, iv'e ported it even more, and just cleaned it all up, the bike carbs i had on it were overflowing petrol out the air cleaners, but i realized that it was because the carbs are semi down draft, i had the set up as side draft, so when the petrol got up to the top of the bowl it was just coming out the overflow :/ lol, so iv'e fixed that and ill put the head on in a few weeks, i need a new master cylinder coz it leaks and makes the clutch go to the floor sometimes haha, i'm gonna get a 4age one day to put in it, ill run some sort of bike carbs on it, but when i do it i will do it without modifying the car, if possible, cheers

 

post-15067-0-52883400-1338720302_thumb.jpg

 

post-15067-0-86841900-1338720325_thumb.jpg

 

lol managed to get three cars in the shed!!

 

post-15067-0-66637000-1338720346_thumb.jpg

 

post-15067-0-27418500-1338720399_thumb.jpg

 

:y:

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